SILVICULTURAL STRATEGIES FOR PREDICTING DAMAGE TO FORESTS FROM WIND, FIRE AND SNOW: INTEGRATING TREE, SITE AND STAND PROPERTIES WITH GEOGRAPHICAL INFORMATION SYSTEMS AND REGIONAL ENVIRONMENTAL MODELS TO EVALUATE OPTIONS FOR FOREST MANAGEMENT

CONTRACT NUMBER - AAIR3-CT94/2392

Participants:

P01 Faculty of Forestry, University of Joensuu, Joensuu, Finland

P02 Department of Forestry, The University of Aberdeen, Aberdeen, UK

P03 Centro Nacional de Informacao Geografica, Lisbon, Portugal

P04 The Forestry Authority, Northern Research Station, UK

P05 Macaulay Land Use Research Institute, Aberdeen, UK

P06 Instituto Florestal, Ministerio da Agricultura, Lisbon, Portugal

P07 Faculty of Forestry, The Swedish University of Agricultural Sciences, Umeå, Sweden

P08 School of Engineering, University College, Galway, Ireland

Period of report: Period 3 January - June 1996

SUMMARY

WIND, FIRE AND SNOW: INTEGRATING TREE, SITE AND STAND PROPERTIES WITH GEOGRAPHICAL INFORMATION SYSTEMS AND REGIONAL ENVIRONMENTAL MODELS TO EVALUATE OPTIONS FOR FOREST MANAGEMENT

Participants

P01 Faculty of Forestry, University of Joensuu, Joensuu, Finland

P02 Department of Forestry, The University of Aberdeen, Aberdeen, UK

P03 Centro Nacional de Informacao Geografica, Lisbon, Portugal

P04 The Forestry Authority, Northern Research Station, UK

P05 Macaulay Land Use Research Institute, Aberdeen, UK

P06 Instituto Florestal, Ministerio da Agricultura, Lisbon, Portugal

P07 Faculty of Forestry, The Swedish University of Agricultural Sciences, Umeå, Sweden

P08 School of Engineering, University College, Galway, Ireland

Scientific objectives

This project aims at producing generic models which use the factors common to wind, snow and fire damage; to underpin, those models with an understanding of the forces and site factors acting on single trees or the fuel hazard risks associated with site factors to produce risk assessments to forestry to minor or catastrophic damage; to test these models as a way to derive long term strategies of silvicultural methods for managing forests against wind, snow and fire damage, that optimize wood production while appraised of the risk of forest damage. This project utilizes methodology where models for estimating the breakage and overturning due to wind and snow load and models to estimate fuel are integrated with the data bases for properties of climate and vegetation conntrolling the snow, wind and fire damages to forests in order to optimize wood production considering the risks to forests.

The progress within the period of report

Task 1. The planning report has been undergoing continual update throughout the current six month period. The complete report is now available on the web and Macaulay Land Use Research Institute ftp sites. Making the document "live" in this way has meant it is continuously available for update and perusal by all participants, without the need for temporally discrete stages of update and dissemination which leaves participants guessing as to the most recent updates. This is particularly crucial for such a large and geographically distributed group who are working in close collaboration. Metamodel and metadata forms, as detailed in Task 6 are also available on the web, and participants have been actively completing these forms in remote locations to provide instantly available documentation to the rest of the group. This has greatly enhanced the planning and management of the project, and facilitated a process of documentation for models and data which can be used as input to Task 6, and to increase inter-participant understanding of other participant's work which is vital when models developed by one participant are being tested on data supplied by another.

Task 2. The objective of this task is to determine the main factors which control snow, wind and fire damage for determination of values for the critical parameters required to support the development and the validation of the models to be done in subsequent Tasks. Within Sub-task 2.1, wood samples from 72 spruce trees have been collected by P02 for studies of wood property factors controlling wind damage. Some preliminary results are available for ring width, density, and compression wood characteristics of wind-damaged and undamaged trees. Root samples provided by P01 have also been tested to allow correlations between maximum turning moment and root strength and elasticity to be made.

Within Sub-task 2.2, critical tree parameters controlling snow and wind damage have been determined for a sub-sample of sample plots from the existing Swedish National Forest Inventory (NFI) by P07 and a data base from the same sub-samples made available to Participant 02. Logistic models have also been developed for Scots pine, which show that it is possible to predict future damage from snow and wind by using single tree characteristics as indicators of site risk (see Valinger and Fridman 1996a, 1996b).

Within Sub-task 2.3, the extensive tree pulling database of total number of 1800 trees has been constructed by P04, and linked to this work P01 has constructed Finnish tree pulling database of 94 trees (Scots pine, Norway spruce and birch sp), including trees pulled over both during unfrozen and frozen soil conditions. Regressions have also been calculated between tree and site characteristics and critical turning moments needed to cause uprooting of single trees or stem breakage based on these tree pulling databases by P01 and P04 for determination of values for the critical parameters required to support the development and the validation of the models to be done in Sub-tasks 3.1 and 3.3.

Within sub-task 2.3, P01 has also continued wind and tree swaying measurements at the edge of a Scots pine stand and within the stand approximately two tree heights from the edge after second thinning (see Peltola 1995, 1996a, Hassinen et al. 1996). Furthermore, P08 has developed a new video analysis technique to be used to estimate the overturning moments experienced by a tree during a storm event. P08 has also selected test sites with test trees (three site preparations on surface water gley) in Ireland and currently a field testing programme is ready for implementation. This field testing will consist of both monotonic and dynamic loading tests of trees on the various site preparations as well as a long term tensiometry study of the characteristics of the three site preparations (e.g. water table).

Within Sub-task 2.4, pure spectral data set has been prepared and biometric data collected by P03. Early results are promising and highlighting the value of using a spectral linear mixture for assessing some fuel loading. New field work for the collection of spectral data by P03 is currently being planned taking into account the previous experiments.

Task 3. Models predicting snow and wind damage have been developed and made available under Sub-task 3.1 (P04), 3.2 (P07) and 3.3 (P01). A database on snow and wind damage have also been made available by P07 in Sub-task 3.2. Within sub-task 3.3, the consistency of HWIND-model developed by P01 has been compared with the empirical wind damage model developed by P04 in Sub-task 3.1 to improve the methods for estimating critical windspeed (see Gardiner and Peltola 1996). Furthermore, HWIND-model has currently been tested by P01 to ensure that predictions are consistent with observations on the critical turning moments required to cause damage in Finnish tree pulling database constructed in Sub-task 2.3 by P01. In addition, a literature review has been finished on the factors affecting the snow damage of trees to support the mechanistic model development and its validation within Sub-task 3.3 (in a co-operation by P01, P04 and P05, see Nykänen et al. 1996). Dissimination of some research findings within this sub-task 3.3 is also currently under work (e.g. Peltola 1995, Peltola 1996c, Peltola et al. 1995, 1996a,b,c,d,e).

Within Sub-task 3.4, an allometric regional model to predict individual pine trees (Pinus pinaster) Leaf Area (LA) has been developed from data gathered by destructive sampling on 31 trees by P03. For further model developmental work to be carried out, an additional set of 11 trees has been studied and a new local allometric model developed for estimation of pine tree LA. This field work was also used to test the applicability of a sampling procedure, based on a stratified multistage probability sampling, proposed by Gregoire et al. (1995). A new instrument (DEMON) is also being tested for future use in the estimation of the Leaf Area Index from the transmittance of sunbeams. Presently, the next field work data gathering campaign is under preparation.

Task 4. This task involves an integrated approach to investigating the effects of variability by using existing data sets, making new measurements and developing mathematical models. Efforts have been made in identifying suitable data sets for analysis, testing methodologies for measuring stand variability, investigating the importance of variability in stand growth models, and calculating the effect of stand position on the wind loading on individual trees (the latter one; Peltola 1996b). Progress has been made on this Task in lately particularly with regard to the remote sensing aspects of the work (Sub-Tasks 4.2 and 4.3). On the other hand, there has been some delay in getting sub-task 4.1 up and running but alternative arrangements are now in place to provide the necessary information from this part of the programme. Sub-task 4.4 has not yet begin.

Task 5. A snow review paper has been prepared in collaboration with 3 participants (Joensuu (P01), NRS (P04) and MLURI (P05)) which summarises the current state of knowledge of snow damage to trees in Sub-task 5.1. This information then provides a means of identifying the key site and climatological elements which require to be modelled. A strategy has been identified for developing a snow model for the UK and is currently being implemented. Further work is also being developed to look at the joint occurrence of wind and snow, so that the correct interactions are included in the climatological modelling (Sub-task 5.1).

Within sub-task 5.2 the compilation of geographic database for the study areas has been continued and spatial data has been converted to agreed format. For finnish test areas, P01 has completed all the preprocessing of satellite images and field measurements of occurred wind damage The data has been stored to the geographic database. For the portuguese test area, P03, had made some layers ready for use, but satellite imagery processing and convertions of some thematic layers to a final formats are being done (Sub-task 5.2). The metadata forms, organised by the P05 are being used to collect and collate information about the datasets through the project World Wide Web (WWW) site. This is an efficient, simple and timely mode of gathering the information and storing it in a central location for viewing by all participants. The form ensures complete documentation of the information about the data in a standard format, and thus facilitates effective communication between participants, and provides documentation for present and future use (Sub-task 5.2).

Although Sub-task 5.3 comprises a live document which will be continuously updated, the groundwork for the majority of the information has been completed, and further updates will occur using input from the completed metadata forms on the web.

The data collected in Sub-tasks 2.4, 3.4 and 4.3, during this summer, will be integrated in the geographic database and used the for processing and analysis of the Landsat5-TM image acquired during this year. Using the field information and image processing techniques we will make a regional map of fuel types. The bulk of this task will be done during the next period report (Sub-task 5.4).

The work developed so far is conceptual and the Knowledge Based System conceived for this project (P03 and P05) is based on induction methods that seek to derive the rules underlying fuel distribution from the collected data set (point sample and maps) and then use the learned rules to map fuels for large areas, using the information of the geographic database. This task is slightly delayed because the data needed to proceed is to be collected during this summer and consequently the knowledge based system implementation has to be done slightly later than what was anticipated in the proposal (Sub-task 5.5).

Task 6. A demonstration to integrate some component models and data is being undertaken in order to test the integration framework, explore the possibilities and discover which aspects of integration are likely to cause the biggest problems both from a conceptual and from a practical point of view. The demonstration consists of three damage models, one from each damage type, which are being run on data from the country in which they were developed, and data from another participant country (Sub-task 6.1).

A further component of the integration work involves the study of scale issues with respect to the available data. Understanding the scale structure of the datasets available will permit sound judgements to be made concerning to what scales of data it is appropriate to apply models (Sub-task 6.2).

Task 7.

Task 8. The World Wide Web (WWW) pages are continuing as a valuable communication medium to communicate the aims, methods and findings of the project. The web site is also being used as a means of formally documenting the models and data for use in Task 6. The project publicity leaflets have been printed and were distributed to all participants at the last project meeting and also sent to DGVI. A poster for the project was presented at GIS Research UK Conference (STORMS, 1996) and was well received. A paper reviewing snow damage to trees (Sub-task 5.1) has been prepared over the last six month period as part of the investigations into the factors involved in snow damage, and this has just been submitted for publication to Silva Fennica. Dissemination of some research findings is also currently under work. In addition to this several short presentations about the project have been made to visitors to MLURI from the UK and overseas.

CHAPTER 1 INTRODUCTION

Scientific objectives of the project

Scientific objectives during the period under report

Task 1. Whilst most of the work associated with the Task 1 planning stage was completed in the first six months of the project, this task is ongoing. Further development of the planning report will be pursued using Task 6 as a focus. As individual tasks evolve and the development of the work becomes clearer, Task 1 will be updated to reflect the increasing detail of plans and the solution of issues. Scale issues cannot be addressed until other parts of the project are better developed. The links identified in Task 6 will determine the details of the scale issues.

Task 3. This task aims at developing wind and snow assessment models and Leaf Area Index estimations for Europe. In this initial phase of Project work is performed with different approaches, depending on the existing material in the involved countries. Thus a whole set of different models will be developed: logistic risk models using single tree data (in sub-task 3.1), empirical models of breakage and overturning of a single tree by wind (in sub-task 3.2), mechanistic wind and snow damage model (HWIND) using single tree data, and a model for prediction of Leaf Area Index for (Pinus pinaster) (in sub-task 3.4).

Task 4.4.The aim of Task 4 is to determine how the relationships and models developed in Task 3 can be applied at the stand level. There are two main approaches being adopted to help answer this question, i.e. the first effort involves developing measurement techniques to enable remote sensing of within stand variability (part of Sub-task 4.2) and variation in under storey fuel capacity (Sub-task 4.3). The second approach is to develop modelling techniques to calculate the impact of natural variability on within stand risk (part of Sub-task 4.2), to predict the variation in wind-loading within a stand (Sub-task 4.1) and to determine the best process for estimating fuel hazard. It is envisaged that a combination of data layers from satellite and aircraft images together with model predictions will be used to determine the within forest variability in the final risk model.

Task 5. Within Sub-task 5.1 has been worked on the development and applicability of a method for calculating the effect to topography and surface roughness on windspeed. The objective of Sub-task 5.2 is the compilation of a geographic database, aquisition and image pre-processing. The aim is the construction of a database for U.K, Finland, and Portugal for modelling and test the risks models. The work that is outcome in this Sub-task is the progress achived during the buiding up of geographic database from the site scale to regional level to more than 4 study areas (country scale). Furthermore, metadata forms to be used in the compilation of this data will be developed. Sub-task 5.3 aims at identifying and listing the data available which may be relevant to the modelling of abiotic forest damage, specifically by means of wind, snow and fire within the geographic range for which damage may be modelled. Constructing the models, deriving suitable data and assessing the validity of such modelling at different scales or resolutions is the key outcome of this project. Sub-task 5.4 started last year, and is going according to the plans. This Sub-task aims at regional mapping of fuel types using mixture models and functional/structural vegetation classification. The aim of Sub-task 5.5 is to produce a fuel hazard map and to develop a knowledge based system (NBS) for fuel hazard mapping using stand and regional level information. Sub-task 5.6 aims at constructing a model to estimate spatially distributed fire risk.

Task 6. To initiate the integration of component models and datasets from the project, it was agreed that a demonstration should be undertaken, to be completed as a first stage. The purpose of the demonstration is to test the participant links and the method of information elicitation proposed as part of the integration framework. It was decided that such a demonstration would serve several further purposes by addressing the conceptual and practical issues of applying models to different data in other countries at varying scales, and of developing understanding between participants as to the data and models available in the different countries. Furthermore the results would provide a means of discussing, as a group, the performance of the models and the quantification of risk assessment. The demonstration was conceived during the March Project Meeting in Inveraray. Following participant presentations, and from discussions throughout the year via email, it was obvious that there were potentially a large number of links between participants in terms of models and data. Several hitherto unforeseen additional links had developed where the expertise of one participant could be employed to explore issues involving another participant's work. It was decided that July would be a good deadline for an initial trial to integrate selected work, to test the framework devised by the Macaulay Land Use Research Institute and to discover some of the conceptual and practical issues which would be involved. Thus any problems or avenues of exploration could be identified at an early stage (Sub-task 6.1).

Initial scale studies will consider datasets which are already available at several scales (Pan-European - identified in Sub-task 5.2, regional and local) to look at the effect of generalisation and sampling strategies on the representation of different datasets. The results of these studies can then be used as a guide to the limits of resolution of different data at different scales for different areas, and the effect of changing scales. Using these results and information from the metamodel forms, it will be possible to explore the validity of model output compared to the scale structure of input data (Sub-task 6.2).

Task 7. The aim of this task was to test the models developed against independent data. Sub-task 7.1 has already been started by developing the change detection method based on Landsat TM images.

Task 8. Information continues to be widely documented and disseminated at regular intervals via electronic and paper media, and through inter institutional visits.

More detailed discussion of the work and achievements is given below Task by Task. Sub-tasks active during the period under report were marked with **.

Being done

in the year

Task 1: Project Planning

Sub-task 1.1: Planning Design ** 1

Sub-task 1.2: Scale ** 1

Task 2: Quantification of Component Factors Controlling Snow, Wind and Fire Damage

Sub-task 2.1: Wood Property Factors Controlling Wind Damage ** 1,2,3

Sub-task 2.2: Wood Property Factors Controlling Snow Damage ** 2,3

Sub-task 2.3: Tree and Soil Factors Controlling Wind Damage ** 1,2,3

Sub-task 2.4: Vegetation Characteristics Controlling Fire Damage ** 1,2

Task 3: Tree-level Models to Predict Circumstances for Damage

Sub-task 3.1: Empirical models of breakage and overturning of single tree by wind ** 1,2

Sub-task 3.2: Empirical models of breakage of single tree by snow ** 1,2

Sub-task 3.3: Mechanistic model for wind and snow damage of single tree ** 1,2

Sub-task 3.4: Leaf area index (LAI) estimation ** 1,2,3

Task 4: Defining stand-level Variability to Permit Application of Tree-level Models

Sub-task 4.1: Wind Flow across and within Stands Using Airflow Models ** 1,2

Sub-task 4.2: Variation in Measured Tree Characteristics within Stands

Using Various Methods Including Remote Sensing ** 1,2

Sub-task 4.3: Plot-level Mixture Modelling ** 1,2,3

Sub-task 4.4: Preparation of Knowledge Base for Fuel Hazard Mapping ** 1,2,3

Task 5: Regional-level Snow, Wind and Fire Risk Models

Sub-task 5.1: Climatology of Wind and Snow in Relation to Topographic Variability

and Temporal Incidence ** 1,2

Sub-task 5.2: Construction of Geographical Database and Use of Image Processing ** 1,2

Sub-task 5.3: Explore Relevance of Pan-European Datasets of Eurostat and CORINE ** 1

Sub-task 5.4: Regional Classification of Fuel Types Using Mixture Models and

Functional Vegetation Classification ** 1,2,3

Sub-task 5.5: Knowledge Base System Construction for Fuel Hazard Mapping ** 2,3

Sub-task 5.6: Fire Risk Model Construction 3

Task 6: Integrating Components from Tree/Stand Regional-level to Produce an Unified Risk Model

Sub-task 6.1: Integrating the Component Models ** 1,2,3

Sub-task 6.2: Scale Issues and Error Propagation 2,3

Task 7: Testing Models against Independent Data and Outlining Implications for Silvicultural Strategies

Sub-task: 7.1: Model Testing by Application of Change Detection System to Finnish Test Area.

Detecting Wind Damages on Stand Level by Landsat TM Images ** 2,3

Sub-task: 7.2: Model Testing Through Portuguese Forest Service 3

Sub-task: 7.3: Model Testing through Forestry Commission Windthrow Monitoring Areas

and Forest Districts 2,3

Task 8. Final Products, Documentation and Identification of New Opportunities

Sub-task 8.1: Dissemination of Project Information and Results ** 3

Sub-task 8.2: Documentation of Project Achievements ** 3

CHAPTER 2 MATERIALS AND METHODS

Task 1: Project planning

All participants have a copy of the Task 1 documentation, and this document is undergoing continual update as issues are identified and resolved with Task 6 acting as a focus. Previously the planning report has been disseminated as a paper document, also available on the ftp site, however in the last six month period, the document has been translated into hypertext macro language (html) and is accessible through the world wide web. Updates are made at the request of participants by MLURI and can be achieved within a matter of minutes using this system.

Task 2: Quantification of component factors controlling snow, wind and fire damage

Sub-task 2.1. Two badly wind-damaged (winter of 1994/95) stands of Sitka spruce growing in the North of England have been sampled in summer 1995 by P02. From each site, standing, snapped and uprooted trees were selected (12 from each damage status) for detailed study. Crown distribution data was collected from each tree, and wood samples taken at 2m intervals along the stem to be used for the assessment of stem shape, and wood characteristics. The main characteristics studied were ring width, density, latewood proportion and compression wood proportion. Furthermore, a subsample of 30 cm logs taken from the sampled trees (from just below breast height) was used in the investigation of modulus of rupture (MOR) and modulus of elasticity (MOE) of small clear specimens taken from snapped, overturned and undamaged trees (further details of the methodology are presented in P02 report). In addition, influence of height/diameter and slenderness ratio on damage type has been investigated in a different stand of Sitka spruce which had been badly wind damaged over recent years. In this study, every tree in the stand was measured for breast height diameter and height, and damage status (overturned, snapped or undamaged) was recorded. In total more than 100 trees were measured along with the average height, diameter and slenderness ratio of each type of damage status, to reveal whether these parameters had an influence with the type of damage. Furthermore, relationship between root strength and overturning moment have been studied within this Sub-task 2.1 (by P02) using root samples obtained from P01's tree pulling experiments (strength and elasticity characteristics tested). In this study, green roots (i.e. with greater than 35% moisture content) were subjected to axial tensile loading between the grips of the Instron 4483 testing machine. Correlations between MOE, maximum load per unit area and turning moment required to overturn the tree will be investigated.

Within this Sub-task 2.1 P02 is also performing some work additional to the technical annex following the occurrence of severe snow/wind damage during the winter of 1995/96 in a forest near Aberdeen, where about 20% of the trees on the site suffered stem breakage. These damaged trees will be used to determine whether snow damage is influenced by wood or stem properties. Field work at this site will be carried out mainly in June 1996. P02 has also used Criterion laser relascope for assessment and prediction of the occurrence of wind damage: a small study of the presence of pockets of wind damaged trees within a Sitka spruce plantation has been undertaken by P02, where the location of the pockets was recorded using a Criterion 400 laser relascope. Data were analysed in conjunction with P05 to create a data layer within a GIS for the prediction of wind damage.

Sub-task 2.2. A detailed analysis of the existing Swedish National Forest Inventory (NFI) database is being undertaken in this sub-task by P07 to be used to identify the tree stem forms which may be used as an indicator of site risk. The sub-sample of the NFI database (e.g. height, diameters at stump height, breast height, and at 5 m above ground) for the county of Västerbotten has also been used for development of models assessing future risk of snow and wind damage in this Sub-task. In addition, the database from the same sub-samples has already been made available.

Sub-task 2.3. Tree pulling experiments. Tree pulling experiment of 94 trees has been conducted by P01 in Eastern Finland (1995-1996) during unfrozen and frozen soil conditions, i.e., including alltogether 51 Scots pine, 12 Norway spruce and 11 birch sp having various tree characteristics of a range of sizes (in sites of Myrtillus and Vaccinium type). In this study, a winch system was used to pull trees over and turning moments needed to uproot a tree or break the stem were measured at the base of the stem. Also the modulus of elasticity of sample trees (about 10 trees of each tree species) has been measured by Young's modulus sensor on living trees (only during unfrozen soil condition). In addition, various kind of stem, crown and rooting characteristics of trees were measured along with stand and site information as described in details by Peltola and Kellomäki (1995). Sample of stem sections were also removed and returned to the laboratory for detailed studies by P01 (e.g. stem density). The tree pullings (of 20 Scots pines of first thinning age) during frozen soil conditions were conducted to find out if any differences exist between frozen and unfrozen soil conditions in respect to critical turning moments needed to cause stem breakage. For better comparison of the results, one of those sites studied during unfrozen soil condition were used in this experiment also ( the base of the stems were kept free of snow cover in order to have the soil deeply frozen). Finnish tree pulling database of Scots pine, birch and Norway spruce during frozen and unfrozen soil have also been added to the extensive tree pulling database produced by P04. In addition, additional data has been made available by scientists in Canada and New Zealand and it is hoped also to add data from Germany and Denmark in the near future to the existing database.

Wind and tree swaying measurements. Within sub-task 2.3, P01 has also carried out measurements of wind and tree swaying along the stand edge and approximately two tree heights downwind from the edge in a Scots pine stand. Windspeed measurements, by cup anemometers, and tree swaying, by accelerometers and video measurements, already been made in a study stand for stand densities of 2700 stems/ha and 1500 stems/ha (1991-1993), i.e. first without thinning and then two years later after first thinning, have been analyzed by Peltola (1996a). These measurements have now been continued in the same stand after second thinning (about 1100 stems/ha) and windspeed has been measured both by propeller anemometers and cup anemometers whereas, stem displacement measurements have been obtained using accelerometers (at stand edge and within the stand) site by site with a new prism based technology (currently at stand edge). New prism based technique (named earlier incorrectly as laser application) has been used instead of video based technique unlike planned in technical annex, because it has been proved to be much easier to do and very accurate (tested in laboratory conditions, see Hassinen et al. 1996). Any measurements based on displacement transducers have not been obtained yet (because of some problems in measurements), however these studies will be done during next autumn site by site with the prism based technique and accelerometers. Wind direction has been measured using directional vanes as done earlier. This experiment will continue for various stand densities, i.e. next thinning is aimed to be done in autumn 1996.

Monotonic and dynamic loading tests. Within Sub-task 2.3, P08 (a sub-contractor to P02) will be performing monotonic and dynamic loading tests to trees within in Ireland (County Sligo), and studying the effect of cultivation type on tree stability. For this study, P08 has already selected test sites and trees (three site preparation, and three trees from each). Initially the trees which have been selected for dynamic testing will be pulled with a small force to establish a relation between % strain and overturning moment. These data will subsequently be used to estimate overturning moments during the dynamic test phase. The video system developed will also be calibrated at this point by relating the deflected shape of the tree to the known moment. This will also be used to estimate overturning moments during dynamic loading. After the dynamic loading tests have been completed the trees will be pulled to failure. The ultimate overturning moments will be recorded. Estimates of the values for Young's modulus and the stiffness of the tree system will also be made during this phase. The dynamic loading tests will be conducted using a tree rocking device developed at University College Galway. It allows the test trees to be rocked in one vertical plane only ( Further details are presented in the P08 report).

Tensiometer etc. study. Within Sub-task 2.3, also the effectiveness of the site preparations selected for this study will be examined using fast response tensiometers in each plot by P08. This study will last for several months with results being downloaded to a laptop every two weeks and brought back to the laboratory for analysis. P08 will also record the water levels in the three test plots on a regular basis. To date access holes have been installed at the site to facilitate this. The levels will be recorded fortnightly at the same time as the results from the tensiometer study are being downloaded. A brief study of the soil profiles in the three site preparations will also be conducted using gouge augers. The soil profiles will be determined at several points within each plot for comparison purposes. In addition, it is proposed to conduct a brief study of how the root architecture varies among trees planted on the different site preparations. It is hoped that the image analysis techniques could be employed in this aim. It is also hoped to obtain data on rooting depth, spread and density. Furthermore, a comprehensive survey of the density and moisture contents of the top 300 mm of the soil in each test plot will be conducted using a nuclear probe.

Sub-task 2.4. Within Sub-task 2.4, pure spectral data set have been prepared and biometric data has already been collected by P03. The methodology which will be used during the forthcoming months is as follows : an optically dense amount of elements is stacked in an open and well illuminated area close to the collection site, and the structure and architecture of elements are preserved. Thirty measurements of each stack will be made with a Barringer MKII radiometer, pointing at different zones, to cover the natural variability. At the same time, the spectral signatures will be collected by another operator using a spectroradiometer (Fieldspec 512 UV/VNIR ASD^®). The collection of spectral data will take place, within the study region, during the Summer season, between 11.30 and the 15.30, only in cloud free days with no diffuse radiation.

Task 3: Tree - level models to predict circumstances for damage

Sub-task 3.1. Computer based mathematical models are being developed by P04, these models being capable of calculating the wind speeds required to break or overturn trees based on a knowledge of the tree species, tree height, tree stem diameter, inter-tree spacing and soil type (currently test versions available). The models use the fundamental information on wood properties and resistance to overturning being obtained in sub tasks 2.1, 2.2 and 2.3. Initially model development is carried out using Mathcad 6.0 for ease of construction and is then converted into a Turbo Pascal programme for integration with the GIS and for use by other participants. The model takes the tree characteristics and calculates the aerodynamic roughness and zero plane displacement of the forest. From this information the drag of the forest can be calculated which represents a force due to the wind on each tree. This force can then be converted into a bending moment which the tree must be able to resist to avoid breaking or overturning. The wind speed at which the applied bending moment is greater than the resistive moment offered by the soil and roots is the critical wind speed for overturning. The wind speed at which this bending moment induces stresses in the stem greater than the Modulus of Rupture of the wood is the critical wind speed for breakage.

Sub-task 3.2. To apply logistic statistical analysis technique permanent sample plots (25 000) within the existing Swedish National Forest Inventory (NFI) data base have been used. Permanent sample plots are used so that the progression of damage can be monitored. Data will be separated according to species (Pinus sylvestris, Picea Abies, and Betula spp.), site type, and management treatment. Data inputs used from the Swedish National Forest Inventory (NFI) are tree species, various tree and stand characteristics (i.e. height, diameters at stump height, breast height, and at 5m, stand density, standing volume). The NFI data base used for the development of logistic models developed under sub-task 2.2 have been continuously utilized by the inclusion of site and stand characteristics for different counties of Sweden. The database on snow and wind damage including tree, site and stand characteristics from the county of Västerbotten is available at our ftp-site (see sub-task 2.2).

Sub-task 3.3. The testing version of mechanistic model of wind and snow damage of single trees (HWIND) capable of calculating the windspeed to uproot or break a tree has been constructed (Peltola et al. 1996a). The HWIND-model attempts to fully describe the mechanistic behaviour of trees under wind and snow loading, i.e. trees of Scots pine, Norway spruce and birch sp. under normal Finnish conditions dealing with stand edge adjacent to clear cuts as well as within the stand conditions. HWIND-model calculates the drag at each height in the canopy using a predicted wind profile within the canopy. To calculate the resistance to overturning HWIND-model uses a prediction of root plate mass to derive a resistive moment. Whereas approach used to predicting when a tree will break relies on the assumption that the stress in the outer fibres of the tree stem are constant at all heights and values of Modulus of Rupture determined for different timbers. The snow damage risk of trees is modelled in terms of maximum snowload as the product of the projected area of the crown and a snow load, corresponding to snowfall accumulated in the crown.

The empirical and mechanistic approaches developed (Sub-task 3.1 and 3.3) are currently being compared in order to improve the methods for estimating critical windspeed and snow loading.These two models have been developed completely independently and, however, both are designed to take site and stand information and predict the canopy top windspeeds at which the trees in the stand will break and overturn. As can be seen from description of model approaches used in Sub-task 3.1 and 3.3, these models compared have adopted different approaches to both the method for calculating the wind loading on the trees and the resistance to overturning provided by the trees (see Gardiner and Peltola 1996). However, both models use a very similar approach to predicting when a tree will break.

The HWIND-model is also currently being tested by P01 using Finnish tree pulling data from Sub-task 2.3, i.e. currently especially tests on the critical turning moments required to cause uprooting or stem breakage of single trees are carried out, and the relationships found between various tree characteristics based on Finnish tree pulling experiments are used to test the tentative equations of HWIND-model by P01 (both Scots pine, Norway spruce and birch sp. with various tree and site characteristics). Whereas testing of the HWIND-model against windspeed and tree swaying measurements carried out in Sub-task 2.3 will be made in forthcoming months.

Sub-task 3.4. The aim of this Sub-task is the development of practical, easy to implement mathematical models to predict pine stands LAI by field measurements. Stand LAI is estimated by ceptometer measurements of the canopy transmittance applying the Beer-Lambert´s equation. In order to generalize LAI estimations to the study and regional areas, these data will work as ground-true data for satellite imagery calibration in Sub-task 5.4. The methodology followed entails three main steps: Development/Selection of allometric models to estimate pine trees Leaf Area (LA) using easily measurable tree variables; Estimation of LAI per plot; LAI estimation by canopy transmitance measurements. An allometric regional model to estimate the pine trees LA was developed within first year of this project with data from 31 trees. Within this year (1996) in step 1, progress have been made further since 11 more trees have been studied by destructive methods and a new local allometric model was developed for estimation of pine trees LA of Viseu study area (new model has better statistical results than the regional model developed). Presently, we have a total of 42 trees studied by destructive methods. Furthermore, because the application of destructive methods to evaluate the LA is very time consuming, a sampling procedure proposed by Gregoire et al (1995) named Randomised Branch Sampling (RBS) has been tested. This method is based on a stratified multistage probability sampling procedure where a minimum of two first order branches are selected (randomly with a probability proportional to the squared diameter) in each third of the crown. To direct the entire sampling procedure a field computer was used to run a FORTRAN program developed by Valentine (1994).

In step 2, during this year (1996) field data gathering campaign a new instrument, named DEMON, will be used to measure the canopy light transmittance. The measures obtained with this instrument will be correlated with the LAI of the plot estimated by means of allometric models developed in step 1. As soon as the DEMON is calibrated for the pine stand characteristics, it will be used to estimate the LAI over large areas in step 3. The Sunfleck ceptometer (Decagon Devices), will also be used to collect data along with the DEMON, which will enable to make some comparison between the two devices. At the moment testing of the DEMON instrument is being carried out.

Task 4: Defining stand-level variability to permit application of tree-level models

Sub-task 4.1. Stand growth models using both tree and stand characteristics developed by Soederberg and Ekoe are available from the P07 and can be used to determine how much variation in tree characteristics exists within stands and how this changes with species and climatic conditions. The effect of position within the stand on the wind loading experienced by a tree is also being explored within this Sub-task by models of tree loading developed by the P01 and models of airflow across forest edges being developed by the P04. The results of these models will be compared against measurements of wind speeds and wind loading back from forest edges from field and wind tunnel experiments. Currently the prediction of within stand wind-loading will make use of existing airflow models developed by Miller at the University of Connecticut and by Green at DSIR in New Zealand. A further model is being developed at the Forestry Commission as part of a PhD thesis and in collaboration with Leeds University as another PhD project. Initially mathematical relationships are being derived from existing field and wind-tunnel measurements to allow progress until results from the modelling effort are available.

Sub-task 4.2. This Sub-task involves the use of existing data, measurement of stand variability and modelling of the effect of variability. A great deal of existing data exist from the wind damage monitoring areas within the United Kingdom and the extensive sample plots maintained in Sweden. Statistical analysis is being used to define the variation in stand vulnerability from the detailed set of sample plots in Sweden. It is hoped to be able to identify the risk for a particular stand from the physical characteristics of a specified tree, for example the oldest tree within the stand. Suitable aerial photographs of monitoring sites within the United Kingdom along with ground control points obtained with a GPS system have been selected and sent to P01 for analysis of the stand variability. New measurement techniques are becoming available which allow rapid assessment of tree characteristics within a stand. The combination of GPS system and Criterion laser relascope for rapidly measuring tree diameter at breast height and position within a stand are being explored by P02 and the P04.

Sub-task 4.3. P03 have carried out some initial analysis of the spectral data obtained in Sub-task 2.4 which is designed to allow remote sensing of regional fuel loading. The analysis has shown some variability in the measurements and highlighted the noisy nature of data from the spectroradiometer. This has lead to a redesign of the measurement protocol and recognition of the need to apply smoothing techniques to the data. Further data collection will take place in spring/summer 1996. Within this Sub-task remote sensing techniques are also being tested by P04 to determine their potential for rapidly mapping within forest variability. An area in Cwm Berwyn forest in Wales, which is to be used in the validation tests in Task 7, has been identified as a test area. Computer comparison of derived elevations from photographs taken prior to tree planting and a few years ago have been compared in order to extract tree heights. The derived measurements are being compared to existing ground survey measurements and specific transects made using a Criterion laser relascope. The next stage will be to identify whether the derived tree characteristics are related to more easily measurable parameters such as soils, distance from stand edge, slope angle, exposure and aspect.

Sub-task 4.4. P03 and P05 are developing a knowledge based method for determining the fuel conditions within a stand based on site conditions. For obtaining information on fuel loading over a wide area it is clear that satellite remote sensing provides the best opportunity, particularly because there is a large temporal variability during the year. The method is to test the applicability of NDVI sensing from the Landsat and AVRIS satellites for determining the canopy structure of forests. Initial trials have simulated the NDVI spectral signal of canopies with different Leaf Area Indices and sub-canopies in order to determine the feasibility of the technique. The next stage will be to measure the reflectance of actual canopies and understories with a ground based spectrometer and to determine how well the measurements are related to measured canopy and sub-canopy leaf areas.

Task 5: Regional-level snow, wind and fire risk models

Sub-task 5.1. Long-term wind speed data has been provided in co-operation with the Finnish Meteorological Institute (FMI) for generating the surface of wind speed for Finnish test area by P01. P04 is comparing several methods that treat topographic effects on wind speed. Results from the various modelling approaches are compared to existing field measurements to assess which method is suitable for recommendation for wider use in the project. Jackson's statistical models for the occurrence of falling snow in the UK are being encoded using AML in the ARC/INFO GIS, by P05. The data required are a digital elevation model for the UK, statistical relationships, and a contour map of snow days for the UK at 100m elevation (produced by Jackson). Meteorological Office snow reports are being used to validate this model where possible, and further refinements will be made using other site data, for example TOPEX. It is proposed that some contact be made with meteorologists to explore the possibilities of studying the combined probabilities of wind and snow in the UK.

Sub-task 5.2. P01 has continued the compilation of information for the geographic database, and stored in it. The test area database has been completed with digital elevation model covering the whole test area. The field measurements of occurred wind damage in the test areas has been completed with new measurements during February 1996. Wind damage occurred during 1990-1995 has been measured at totally 37 stands in the test area. P03 has continued the compilation of all the relevant analogic and digital available dataset, for the portuguese study area. The software used is mainly INTERGRAPH and IDRISI. The coordinate system adopted is the military one, based on the Hayford ellipsoid (International) with a Gauss-Kruger projection. P04 will be assembled the data within a GIS representing the necessary locational, site, and tree data required to run the damage probability models. These datasets will then be used for validation of generic models. P05 have been converted the metadata forms to html (hypertext macro language) and the pages connected to the project web pages. Forms can be filled in by accessing the pages using a web browser and the contents are automatically captured using a PERL program and written to a file, which can then be viewed on the web. These forms are, however, protected and secure, such that only participants can access this information. Due to the success of the metadata forms, the documentation technique has been extended to the models by the production of metamodel forms (see Task 6 for details). P07 will digitise snow and wind atlases for Sweden making them available during autumn of 1996 to be used as GIS-layers for the continuous work within task 6. (The reason for this delay has been presented in the above introdution.)

Sub-task 5.3. Pan-European datasets report has been completed using input from FIRS project, other EC documentation (CORINE, EUROSTAT) and information from project participants. It will be updated using information collected and collated via the web site. The report is set out in the same style as the metadata forms and shows clearly how little crucial metadata (particularly error and accuracy estimates) are associated with any of the datasets detailed.

Sub-task 5.4. The data collected in the Sub-task 2.4, by P03 and P06 during summer 1996, will be used as reference end-members for the unmixing of the Landsat5-TM image acquired during this year. During summer 1996, P03 planns on gathering training areas, using a GPS, that will be used as potential image end-members during the unmixing process.The data collected in Sub-task 3.4 and 4.3, the Leaf Area Index (LAI) of pine forest, will work as ground-true data for satellite imagery calibration, and later, for generalise LAI estimations to a regional level.

Sub-task 5.5. The Kowledge Based System conceived for this project (P03 and P05) is based on induction methods that seek to derive the rules underlying fuel distribution from the collected data set (point sample and maps) and then use the learned rules to map fuels for large areas. The approaches to be used are based on methods of pattern reccognition and induction of rules based on examples. The methods are applied in a geographic information system.

Task 6: Integrating components from tree/stand regional-level to produce an unified risk model

Sub-task 6.1. A formal documentation process is being implemented in order to achieve the integration of components and models which ensures the validity of model application and data use. Information is being elicited from participants via two forms which can be accessed and completed interactively through the World Wide Web Site. One form documents the models and the other the data. Both forms have been carefully prepared so that all the criteria required for full description of the model or dataset exist, but the form has been organised so that its completion is as straighforward as possible. The most important items on the forms, in terms of the integration, are scale and resolution information, information relating to model scope and limitations, and copyright details. Thus using information from these forms it will be possible to assess the compatibility of scales between models and data, and between data for different countries, the tolerance of models to different types of data inputs, the suitability of data from different countries as input to models, the scope of the models, and the validity of model output results. In the short-term, the forms are providing an effective means of exchanging information between participants for the purpose of the demonstration preparation. Developing the demonstrator is being carried out in stages with each stage being completed before the next stage can begin.

Whilst many links and possible exchanges were identified in Argyll, only a subset has been selected for the short time period under consideration, although it is envisaged that most of the links will come to fruition during the project period. The matrix of model runners and data providers has thus been reduced to spread the work as evenly as possible so that no one group is over-burdened but the links proposed address the three damage types equally, involve most of the participants, and capitalise on existing data and models which are already developed and immediately available. Whilst P03 was not planning to run a fire spread model as part of their specific remit, their methodology was not due to be completed for some time, and so it was agreed that a fire spread model would serve the purpose of providing a demonstration for data exchange. As with the other damage types, discussions of the results of the model run would be extremely profitable for the whole group by increasing understanding, and allowing exploration of the issues relating to fire.

Sub-task 6.2. After stage 1 (Sub-task 6.1 above), MLURI will begin a study to assess the scale and structure of some of the data sets being used at Pan-European data scales (Sub-task 5.3), and develop guides for the appropriate scale of data which can be used in the models (Sub-task 6.2). This work will use information from the completed metamodel forms (model sensitivities) and metadata forms (scale and error).

Task 7: Testing models against independent data and outlining implications for silvicultural strategies

Sub-task 7.1. The change detection method was developed and tested using multitemporal Landsat TM images, forest stand data and field inventoried wind damage data by P01.

Task 8. Final products, documentation and identification of new opportunities

The WWW site is serving as a valuable means of information collation and dissemination both between project participants and to the wider scientific community. The WWW site currently facilitates participant input via web forms, which have been carefully devised to elicit clear and concise information about the data and models being used within the project. These are proving successful, both in terms of collaborative communication, and as input to the integration of component data and models in Task 6. Dissemination of scientific results is being effectively achieved via journal and conference papers, presentations made to institute visitors (e.g. from the UK overseas), and by distribution of the project leaflet.

CHAPTER 3 RESULTS

Task 1: Project planning

Now that Task 6 is underway, the planning documents have been invaluable reference sources for data exchange, and the numerous visits by participants to the web site is evidence of this. Participants are referring to the web documents to ascertain the appropriate formats for exchanging information with other groups which has saved much long-winded communication, and therefore time.

Task 2: Quantification of component factors controlling snow, wind and fire damage

Sub-task 2.1. The effect of individual tree height, diameter and slenderness ratio on damage type. Snapped trees have been found to be thinner and shorter than trees which did not snap, and they were found to have a greater height to breast height diameter-ratio. The difference between diameters of snapped and undamaged tree has also been found almost significant (p=0.051), and the difference between slenderness ratio of snapped and undamaged trees significant (p<0.05). No other differences were significant.

The stem shape of trees which are overturned, snapped or undamaged. Graphs of "normalised" stem shape have been created for each damage type at both sites. Although differences between trees are present, no clear trend of different stem shapes is discernible at the current time.

Wood density studies of trees which are overturned, snapped or undamaged. In these studies, average basic density of wood produced during specific 5 year periods has been recorded (presented in P02 report). Although some differences in average density were found, these were generally not significant. A clear relationship between damage type and density was not found either.

Latewood proportion was studied of trees which are overturned, snapped or undamaged. Latewood percentage was found to increase from about 20% in the wood produced between 1970 and 1974 to around 35% in the wood produced between 1990 and 1994. Snapped trees generally had a slightly greater latewood percentage than either uprooted or undamaged trees, but the magnitude of the difference is generally not significant and is unlikely to be of importance.

The strength properties of small clear specimens of wood taken from undamaged, overturned and snapped Sitka spruce trees. The average MOR, MOE and density of wood from snapped trees was found to be greater than that from either wind thrown or undamaged trees, which was unexpected result. The difference in MOR between damage types is almost significant (p=0.064). No other differences are significant. In the wood near the bark, on the other hand, which within the living tree is subjected to the greatest stress due to wind loads, MOR and MOE was found to be lowest for the snapped, and highest for the undamaged trees, despite the wood density being greatest in the snapped trees. However, while the differences in MOE were almost significant (p=0.06), the differences in MOR and density were not.

Compression wood proportion of trees which are overturned, snapped or undamaged. The proportion of the breast height section occupied by compression wood was recorded. For the trees from both Hamsterley and Grizedale, the snapped trees contained a higher proportion of compression wood than either the uprooted or undamaged trees, although in neither case is this quite significant. The trees at Grizedale consistently had greater proportions of compression wood than the trees from Hamsterley forest, although the reason for this is unclear. Measurements of compression wood proportion at other heights of the tree are yet to be analysed, but appear to be following the same general pattern of being higher for snapped than for overturned or undamaged trees.

Sub-task 2.2. During this period of work critical parameters controlling snow and wind damage for a sub-sample of sample plots have been determined and a data base from the same sub-samples made available to P02. The preliminary logistic model developed show that it is possible to predict future damage from snow and wind by using single tree characteristics as indicators of site risk. In this work we identified the following characteristics; for spruce diameter at breast height (1.3 m) and height, for Scots pine upper diameter and height/diameter quota (i.e. diameter at 3 or 5 m, height/diameter at breast height, 1.3 m), and for birch height and whole quota (i.e. diameter at 5 m/diameter at stump height [1% of tree height]). Dissemination of some research findings have also started within this Sub-task (e.g. Valinger and Fridman 1996a, 1996b). Further information from this Sub-task will be delivered for Task 4, 5, and 6 during forthcoming months of project work.

Sub-task 2.3. Tree pulling experiments. The Finnish tree pulling database is now available for the tree pulling experiment of 94 trees, and it has been delivered to P04 to be added to the extensive database already constructed from tree pulling experiments (to date thus from over 1800 trees) held by P04. The integrity of the recently added data to the extensive database held by P04 is being checked and quality assurance is being carried out on all the data. Following this the new data set will be made available to the other participants and analysis will begin to determine the effects of cultivation and spacing on tree resistive moments. Within this Sub-task regressions (and correlations) have also been calculated for combinations of various tree (and site) characteristics and critical turning moments needed to cause uprooting and stem breakage of single trees in tree pullings (unfrozen and frozen soil conditions) by P01 and P04 for determination of values for the critical parameters required to support the development and the validation of the models in Sub-tasks 3.1 and 3.3. Furthermore, the relationships found between various tree characteristics measured (e.g. breast height diameter versus rooting characteristics and crown characteristics) have currently being used by P01 to test the tentative relationships for various tree characteristics used in HWIND-model in Sub-task 3.3 (the detailed results of Finnish tree pullings are presented more in details in the P01 report).

Wind and tree swaying measurements. P01 has also continued wind and tree swaying measurements at a Scots pine stand edge and within the stand two tree heights from the edge after second thinning (stand density of 1100 stems/ha). Mean wind profiles and stem bending of trees at the stand edge and within the stand have already been presented for stand densities of 2700 and 1500 stems/ha by Peltola et al. (1996a). Furthermore, some preliminary results of the swaying of a Scots pine located at the edge are also available for current stand density after second thinning (see Hassinen et al. 1996, P01 report). In addition, the accuracy and repetability of new prism based technique have been tested in laboratory circumstances (see Hassinen et al. 1996). The wind and tree swaying experiment by P01 providing further information on tree stem bending and windspeed profiles at the stand edge and within the stand for varying stand densities, give essential information for subsequent modelling work and model testing to be carried out in Sub-task 3.3 by P01.

Monotonic and dynamic loading tests and tensiometry study. P08 has developed a new video analysis technique to be used to estimate the overturning moments experienced by a tree during a storm event. P08 has also selected test sites with test trees (three site preparations on surface water gley) in Ireland and currently a field testing programme is ready for implementation for both monotonic and dynamic loading tests of trees on the various site preparations as well as a long term tensiometry study of the characteristics of the three site preparations (e.g. water table).

The correlation between root properties and turning moments required to overturn or break trees by static loading. No significant correlation has been found by P02 between root modulus of elasticity and turning moment for Norway spruce, Scots pine or birch. Typical values of r² were around 5%. Similarly the regressions calculated between root strength and turning moment were not significant for any of the species, but while the r² value for Norway spruce and Scots pine was less than 6%, for birch it was 37%. In the present study, data is only available for 7 birch trees, and it is plausible, that had even twice this number of samples been tested, then the regression would have been significant.

Sub task 2.4. Preliminary results are promising highlighting the value of using a spectral linear mixture for assessing some fuel loading. Preparation of the pure spectral data set has also gone well. However, no new data are yet available from P03 for this sub task.

Task 3: Tree-level models to predict circumstances for damage

Sub-task 3.1. A series of models for calculating critical wind speed for tree damage have now been constructed based on the theoretical arguments set out in the Materials and Methods section (by P04):

Break.exe: A Pascal programme designed to take information from the IDRISI GIS programme and produce a file of critical wind speeds which can be read back into GIS for subsequent display or conversion into a probability map. Information provided from the GIS includes tree height, tree dbh, tree species, tree spacing and soil type. Integration of this model with the GIS has already been successfully tested for the Cwm Berwyn forest in Wales which is one of the sites being used in Task 7 for model validation.

Treesnap.exe: Pascal programme designed to directly accept information from the user. Species and soil are selected from menus and tree height, tree dbh and tree spacing are manually input. The model outputs the critical wind speeds for breakage and overturning at both canopy top and at 10 metres above the canopy and the base bending moment at failure. Information for this model has been entered onto a Metadata form constructed by Participant 05.

Treebreak1.exe: A Windows based programme written in Delphi software which has the same function as Treesnap.exe. Programming in Delphi will allow much easier integration with other Windows computer packages.

Sub-task 3.2. The logistic models developed under Sub-task 2.2. have been further developed, not only for separate species, but also for different soil types and management treatments. A database on snow and wind damage has also been prepared during previous report periods and is available at our project ftp adress at MLURI in Aberdeen. During this period of work the developed logistic model for prediction of damage, and a separate dataset in Excel-format have been made available to all other Participants through our www-pages.

Sub-task 3.3. The testing version of mechanistic model of wind and snow damage of single trees (HWIND) capable of calculating the windspeed to uproot or break a tree along the stand edge and within the stand (see Peltola et al. 1996a) can be run in PC-computer both within Windows (figures and tables drawn by specific graphical application made by Visual Basic) or without Windows (tables available).

The HWIND-model developed by P01 within this Sub-task has been compared with the empirical wind damage model developed by P04 (Sub-task 3.1) to improve the methods for estimating critical windspeed (see Gardiner and Peltola 1996). These models adopt different approaches to both the method for calculating the wind loading on the trees and the resistance to overturning provided by the trees. However, both models use a very similar approach to predicting when a tree will break. To date the models have been compared for Scots pine and Norway spruce growing on podzolic soils which are two of the few situations common to Great Britain and Finland. Tests have been carried out for a variety of tree heights, stem diameters and inter-tree spacing. Good agreement has been obtained between the models in tests carried out for a variety of tree heights, stem diameters and inter-tree spacing, although some discrepancies have arisen which have necessitated further investigations into the assumptions on which the models are based. Also sensitivity tests have been conducted on both models to determine the critical parameters involved and the reliability that can be placed on the critical windspeed predictions.

Until now some preliminary results are available also for the consistency of HWIND-model with observations on the critical turning moments required to cause damage of single trees in Finnish tree pullings by P01 (Sub-task 2.3), and of the relationships of various tree characteristics observed in tree pullings with those ones used in tentative equations of HWIND-model. To date tests have been carried out for Scots pine, Norway spruce and birch sp. with a variety of tree heights and stem tapers. Quite good agreement has been obtained between the HWIND-model predictions and relationships found in tree pullings especially in respect to critical turning moment needed to cause stem breakage (as well as in tentative equations of HWIND-model versus observed relationships of tree characteristics). However, some discrepancies have arisen especially in respect to critical turning moment needed to cause uprooting of a tree, which have necessitated further investigations.

In addition, a literature review has been finished on the factors affecting the snow damage of trees to support the mechanistic model development and its validation within Sub-task 3.3 (in a co-operation by P01, P04 and P05, see Nykänen et al. 1996). Dissimination of some research findings within this sub-task 3.3 is also currently under work (e.g. Peltola 1995, Peltola 1996c, Peltola et al. 1995, 1996a,b,c,d,e).

Sub-task 3.4. The regional model developed within first year of the project and used to estimate individual pine trees Leaf Area (LA) by field measurements is a generalization of the simple allometric model using as independent variables the tree total height and the diameter at the base of the live crown, as well as the stand basal area as a linear combination on the parameters and on the allometric constant. To date new data have been gathered in the 11 trees recently studied in Viseu study area, which resulted in a new local allometric model to predict individual trees Leaf Area (LA). This model [1] is a generalisation of the simple allometric model using as independent variables the tree total height and the diameter at the base of the live crown, as well as the stand mean diameter as a linear combination on the parameter of the height variable and on the allometric constant. Some research findings of this Sub-task have been presented by Caetano and Pereira (1996).

Task 4: Defining stand-level variability to permit application of tree-level models

This task is still at an early stage and all progress to date has been devoted to determining the best approaches to tackling Sub-tasks 4.1-4.4, the identification of existing data sets and models, and the development of existing methodologies. However, previous wind tunnel measurements of the mean and extreme wind loading on trees are reproduced as a function of the distance from the forest edge and the stand density. Information is now available (ACSCOTP.XLS) on the calculated risk values for the sample plots within the County of Vasterbotten in Sweden based on single tree characteristics (Sub-task 4.1).

A three dimensional model of the forest stand in the Cwm Berwyn forest, Wales has been obtained from aerial photographs in 1957 and 1995. Estimates have been made of the accuracy of the derived X, Y and Z values based on comparison with data from a number of 'ground truth' points. It appears to be possible to obtain a good enough resolution to provide tree heights to within 0.1m, to identify pockets of wind damage and to possibly identify intensity of thinning (Sub-task 4.2).

The simulations of the spectral signals from different simulated forests has identified the problems of using analysis techniques derived for multispectral analysis in the analysis of hyperspectral data (Sub-task 4.3). For low canopy LAI the ground cover dominates the spectral signal so that the same signal can be obtained from forests with different LAI values which also happen to have different ground cover. For LAI values between 2-3.5 the type of background is less important and the NDVI technique may be of value in determining canopy LAI. At higher values of LAI the spectral signal is little affected by changes in LAI and the technique is no longer of use. Future work will concentrate on developing new analysis tools for hyperspectral data and obtaining good quality field data for testing the applicability of these tools.

Task 5: Regional-level snow, wind and fire risk models

Sub-task 5.1. Long-term annual hourly maximum windspeed data measured at 10 m above ground covering time period 1971-1990 has been provided, by P01. Wind aspeed at 40 m above ground has been calculated for wind atlas classes 2 (above open field) and 4 (above forest). The main effort made by P04 during the last reporting period, has been to test various airflow models against a set of wind data obtained from the Cowal peninsula between 1/9/90 - 1/2/92. The Cowal peninsula is much more highly incised (slopes are typically 1 in 4) than the Kintyre peninsula which is the area for which the previously reported model comparisons were tested. Six anemometer masts operated during this period and although the spatial coverage was poorer than for Kintyre the masts operated for much longer and allow us to test the ability of the models to recreate the wind climate for an area. The most Westerly mast on Sron Cruaich is used to initialise the models. An attempt has been made to obtain regressions between this site and the other sites so that periods of missing data can be filled in but the regressions are poor except for the hill top site at Cruach Buidhe, illustrating the difficulty of modelling wind speed in this kind of terrain. A further airflow model, MSFD, has been included in the comparisons. This model has shown some promise in simulating the patterns of wind damage in New Zealand and some improvement over previous models in predicting the wind speed fluctuations across the Kintyre peninsula. This model does not linearise the fluid flow equations, which have to be solved numerically, and consequently it takes substantially longer to run than the previous models discussed. The models require surfaces of topography and roughness to initialise them. Links have been established with P05 to derive the roughness surface from land cover datasets held by them; the data has been transferred by FTP but there have been a number of format problems to overcome before the roughness layer is ready.

A Contact has also been established with Dr X. Cai at the Dept of Geography at Birmingham University who has access to the RAMS airflow model from Colorado State University which is regarded as one of the most accurate airflow models available. Dr Cai will test the RAMS model against data from the Kintyre peninsula to determine whether this highly sophisticated model is able to perform better predictions of wind speed variation in complex terrain than the linear models we have tested up to this point. Efforts continue to refine the DAMS windiness scoring system (Bell, Quine and Wright, 1995; Quine and White, 1994) by considering the effects of local shelter through distance limited topographic indices. The relationship would be explored by P04 between mode/range variables of the extreme value distributions and windiness score using data from a number of Meteorological Office sites in Britain. P04 compares also the method on an independent dataset produced by a Wind Energy company as part of a renewable energy project. Climatological, site, silvicultural and tree factors which affect the risk of snow damage have also been identified in a snow review paper produced by P01, P04, and P05 and are considered as important inputs for the tree and climatological modelling. It is envisaged that the model will be encoded on a GIS and will be able to calculate several outputs relating to snow incidence in the UK (number of days with falling snow, probabilities of return periods of snow days which exceed the average winter, the duration of falling snow and snow accumulation) with the risk of damage enhanced by site factors such as exposure and aspect. Results from the snow modelling will be reported in December when this sub-task is due for completion.

Sub-task 5.2. For the finnish test areas, P01 have stored in the geographic database the forest stand boundary layers together with the forest stand attribute data. A metadata form of the Finnish test area has been filled for integration (task 6). A digital elevation model covering the whole test area has been added to the geographical database. The wind damage measurements have been completed during February 1996 and the wind damage data of totally 37 stands have been stored in the geographic database and added to the existing data. The satellite images have been preprocessed for further use (task 7.1).

For the P03's study, P03 have made the digital terrain model ready to use, i.e. 45 (each with 16x10 Km wide) military contour maps (1:25000) were assembled in a vectorial format and converted to a single raster file. Slope and aspect maps are also ready. To date P03 is waiting for the availability of the aerial photos of 1995 and for the digital files with the landuse extracted from the aerial survey of 1990. Burned areas digital maps for 1990, 1991, 1992, 1993 and 1994 were provided by P06, and this information was merged and co-registered in the digital database (GIS). Field plots boundaries are stored in the database using a GPS.

For the UK test sites, P04 has continued the construction of datasets for windthrow monitoring areas. Aerial photography obtained during summer 1995 has now been interpreted and added to the GIS datalayers. Further photography has been commissioned for 1996.

GPS survey is being extended to add to the number of precise locations of basal area plots, windthrown gaps and boundaries. The method of collating metadata information via the web form has already proved highly successful with participants completing forms as data sets become available. P05 have made available on the web several datasets (that were provided by the others participants) and the method has been particularly useful for the initial demonstration work, due to be completed by July and discussed more fully in Task 6.

Sub-task 5.3. The results of the data investigations was a report documenting what data was available for where and from what organisation the data could be obtained. It also includes other information such as data format, coverage, scale and error. This information will feed into a task 6 component to assess data availability for areas where model output might be required. The Pan-European datasets report has been completed, distributed and is now available on the ftp site and will eventually be available on the web site.

Sub-task 5.4. No result to present yet. However, some work have already been carried out by Caetano et al. (1996) and Vasconcelos (1995) within this Sub-task.

Sub-task 5.5. No result to present yet.

Task 6: Integrating components from tree/stand regional-level to produce an unified risk model

Sub-task 6.1. To date all stages are running approximately to schedule. The metadata and metamodel forms are on the WWW site and have been accessed by all of the groups involved via a matrix interface. Several forms have been completed and the metainformation is available for use by participants on the project WWW pages. Forms have also been completed for datasets and models which are not involved in the demonstration. It is a huge advantage that this is happening at this stage since all parts of the project will require documenting in this way, and early completion is beneficial to all groups. As models are further developed to include more parameters, the forms can be updated easily, and instantly. The final results will be presented at the Mid-term meeting in Brussels at the beginning of July.

Sub-task 6.2. There are no results from the data-specific scale investigations yet.

Task 7: Testing models against independent data and outlining implications for silvicultural strategies

Sub-task 7.1.

Task 8. Final products, documentation and identification of new opportunities

To date, major datasets and models from all partners have been collated and the information is available for participant perusal on the web. This not only allows the information to be standardized and communicated clearly, but limits the capacity for misunderstandings between participants and therefore the number of unnecessary queries which would otherwise be required for the interaction and integration of data and models. It also provides a detailed documented record of data and models. The public pages on the web site are being further developed to explain, in more detail, the objectives of the project and eventually to present some of the project findings and provide visitors with references to papers and documents which have been produced by the project.

Presentations have been made to various groups over the last six months to communicate the objectives and progress of the project. For example, in MLURI visitors (during the last six months) to whom the work was presented i.e. senior representatives of the Forestry Commission in the UK and visitors from the Newfoundland Environmental Industry Association. Both groups were impressed by the work being carried out and wrote complimentary letters expressing their interest and desire to sustain contact, and obtain progress updates.

Some dissemination of scientific results is being currently effectively achieved via journal and conference papers, presentations made to institute visitors and by distribution of the project leaflet.

CHAPTER 4 DISCUSSION

Task 1: Project planning

The increasing use of the metadata and metamodel forms to document the models and datasets used in the course of the project have proved an invaluable means of communication and provision of information for input to the Task 6 framework development. The rapid change in software packages and the availability of data (particularly digital versions of datasets) is now reflected in the rapidity with which the information can be updated and accessed throughout the project.

Task 2: Quantification of component factors controlling snow, wind and fire damage

Sub-task 2.1. The results from the work to date are provisional and further analysis is required before conclusions can be drawn. The work to date suggests however, that although differences in stem properties may exist, they are generally small in magnitude, although it is possible that several factors are working collectively to determine the type of damage which occurs.The work on wood strength properties suggests that these may be involved in the determination of whether damage occurs, and if so the type of damage. The work suggests that snapped trees contain wood which is denser, and less stiff than the wood from overturned or standing trees, although the results are currently inconclusive and require repetition. Furthermore, data sets and correlations on crown architecture and taper indices linked to wind damage are almost complete for Sitka spruce, but no data is currently available for Scots pine due to the lack of suitable damage having occurred in pine stands in the Winter of 1994/95 (production of deliverables). Also the data sets of basic wood properties of broken, uprooted and undamaged trees is proceeding well. No predictive correlations have yet been produced due to the generally non-significant differences between the data for the different damage types.

Sub-task 2.2. All data needed is already available within this task and are possible to use by other participants. The parameters controlling snow and wind will be further developed for the whole country during the following months of project work, and included into model development.

Sub-task 2.3. Within this Sub-task, the extensive tree pulling database of total number of 1800 trees has been constructed by P04, and linked to this work P01 has constructed Finnish tree pulling database of 94 trees (Scots pine, Norway spruce and birch sp), including trees pulled over both during unfrozen and frozen soil conditions. Regressions have also been calculated between tree and site characteristics and critical turning moments needed to cause uprooting of single trees or stem breakage based on these tree pulling databases by P01 and P04 for determination of values for the critical parameters required to support the development and the validation of the models to be done in Sub-tasks 3.1 and 3.3. P01 has also continued wind and tree swaying measurements at the edge of a Scots pine stand and within the stand approximately two tree heights from the edge after second thinning (see Hassinen et al. 1996, Peltola 1996a). Furthermore, P08 has developed a new video analysis technique to be used to estimate the overturning moments experienced by a tree during a storm event. P08 has also selected test sites with test trees (three site preparations on surface water gley) in Ireland and currently a field testing programme is ready for implementation for both monotonic and dynamic loading tests of trees on the various site preparations as well as a long term tensiometry study of the characteristics of the three site preparations (e.g. water table) to be carried out in forthcoming months. In dynamic loading tests, it remains to see how appropriate for a large-scale tree a rocker system in the field will be (tests made using a small scale prototype rocker and a young tree). It is hoped that if the system proves successful it will enable to make one of the rather cumbersome deflection measuring systems redundant and will make the study of trees under natural storm conditions much simpler. The aim of finding a factor relating monotonic overturning moments to that obtained at presumed failure in the dynamic tests may prove to be soil and/or site specific but this remains to be determined.

Sub task 2.4 Vegetation characteristics controlling fire damage

The results collected in the last summer are encouraging, although some redefinition of the experiments are necessary. This will be done in the next Summer field work campaign. Furthermore, there were no deliverables or milestones to be achieved by P03, at the present reporting period. The objectives for this period of report have been fully achieved and the work developed is within the pre-defined time frames. This sub-task is well under way, and the 2^nd data collection campaign (August 96) is being carefully planned.

Task 3: Tree-level models to predict circumstances for damage

Sub-task 3.1. The models constructed are only as good as the parameter values used in the calculations. For this reason a good deal of effort has been spent in checking and improving the Forestry Commission tree pulling database. This database provides the relationships used in the models to calculate the turning moment required to overturn a particular tree and these will be modified and improved as further analysis is carried out. In particular it is hoped to soon add method of cultivation as an option. The relationships to determine the wind speed for tree breakage rely on knowledge of the Modulus of Rupture of green timber. Values for all species in the model have now been entered based on data from the huge number of tests on timber strength carried out at the Building Research Establishment, in England (Lavers, 1983). However, these tests were only carried out on clear specimens and it is hoped that information on tests carried out on whole poles will allow us to account for the presence of branching and knotiness in trees, particularly those at wider spacings. Further analysis of the tree pulling database, including the Finnish pulling tests (P01), and the work being carried out by P02 and 07 in Task 2.1 should help to determine the effect Modulus of Rupture for trees.

It has also just been started to enter mensurational relationships for Sitka spruce growth in the United Kingdom into the model by P04. This allows trees to be grown forward with time and to observe how the critical wind speed changes with age. It is planned to incorporate mathematical mensurational relationships for other species and other parts of Europe as these become available from the scientific literature and from other participants.

Currently the method for determining the wind loading on a tree relies on calculating the aerodynamic roughness and zero plane displacement of the forest and relating this to the drag exerted on the canopy. As an independent test a 1D numerical model using the method of Lee at al. (1994) has been written which allows calculation of the wind profile within the forest canopy. From this profile it is possible to calculate the bending moment at the base of the tree by adding up the wind loading at each point in the canopy. Tests will be carried out to compare results obtained with both methods and the 1D system will be built into the tree damage models discussed above as an selectable option.

Sub-task 3.2. The data needed for the work is already available at this state of the work. The preliminary results obtained, show that characteristics of single trees are possible to use as measure of future risk of damage from snow and wind. During the period until month 21 risk assessment models for the whole country will be developed and the developed logistic model (Scots pine) will be evaluated using Finnish data.

Sub-task 3.3. The testing version of mechanistic model of wind and snow damage of single trees (HWIND) capable of calculating the windspeed to uproot or break a tree has currently being tested by P01 to ensure that predictions are consistent with empirical wind damage model developed in Sub-task 3.1 (see Gardiner and Peltola 1996), and with observations on the critical turning moments required to cause damage in tree pullings in Sub-task 2.3 by P01. In addition, a literature review has been finished on the factors affecting the snow damage of trees to support the mechanistic model development and its validation (Nykänen et al. 1996), and dissemination of some results findings have been started within this Sub-task 3.3. (Peltola 1995, Peltola et al. 1995, 1996a, 1996b, 1996c, 1996d, 1996e). The next period will see progress across this Sub-task, i.e. the HWIND-model will be further tested against data from Sub-task 2.3. More detailed comparisons of the HWIND-model by P01 with the empirical wind damage model by P04 will also be made to improve the methods for estimating critical windspeed.

Sub-task 3.4. The developed allometric model to estimate the LA for the maritime pines of Viseu has a high goodness-of-fit score (R²_adj= 0.94). Several models with different independent variables were tested but, from their analysis it was clear that the diameter at the base of the life crown (DBC) had a strong correlation with the LA, and keeping it out from the model would decrease drastically its performance. Therefore, the DBC was included in the model and, at the moment, P03 is testing the use of surrogate measurements. The measurement of the DBC in the field is a very time consuming task which would certainly reduce the number of feasible plots. Besides that, the measurement of the DBC by means of a telerelascope is itself an indirect method which entails an unknown amount of measurement errors. This model uses, in the allometric constant, a linear combination of the stand mean diameter. This variable proved to have a better fit to the data than the basal area. This might be explained by the fact that the mean diameter increases with the stand age, meanwhile the basal area tends to be a more stable variable along the whole live of the stand, with some oscillations due to thinning.

The Randomised Branch Sampling (RBS) procedure, tested on a subset of 6 trees of the 11 studied in the Viseu study area, did not provide reasonable estimates of the foliage weight of the trees. The testing of the RBS was conducted comparing the foliage weight of all needles per third of crown and the estimated weight obtained for each third applying the RBS method. The differences of weights obtained in the two methods were particularly high, in some cases reaching 70 %. Although difficult to explain, these differences might be due to the high number and different sizes of the first order branches that can be found in the maritime pine. However, P03 will test the RBS again in some more trees to reassure that it was properly applied.

Task 4: Defining stand-level variability to permit application of tree-level models

Identification of the existing data and available models in order to determine the best way to calculate relationships for wind-loading within stands continues (Sub-task 4.1) as well as the provision of test data (Sub-task 4.2). Pogress has been made on this Task in last period of report particularly with regard to the remote sensing aspects of the work (Sub-Tasks 4.2 and 4.3). There has been some delay in getting sub-task 4.1 up and running but alternative arrangements are now in place to provide the necessary information from this part of the programme. Sub-task 4.4 has yet to begin.

Task 5: Regional-level snow, wind and fire risk models

Sub-task 5.1. The sub-task is being developed according to the plans and there were no deliverables or milestones to be achieved during this period, although a short delay happened with the data of P07. P04 will shortly be able to compare wind climate estimates using weighted model outputs, with DAMS predictions and with actual field measurement. This will give a clearer idea of which method can be recommended, or whether a further hybrid method must be derived to cope with extreme topography. Encoding Jackson's statistical model on a GIS, will allow a small scale risk assessment to be calculated for a particular location in the UK. Regional site information for that particular area can then be used to modify and refine this crude risk estimate to a value which accounts for the individual site factors in a particular location. Thus small (national) scale climatological information can be used together with site factors to define the climatological site risk for any area in the UK. Using a GIS will make the model interactive and user-friendly and allow spatial manipulation and integration with other spatial information.

Sub-task 5.2. The Sub-task is being developed according to the plans and there were no deliverables or milestones to be achieved during this period.All the geographic databases for tests sites of each participant are still under development. Further deployment of the GPS and acquisition of aerial photography is being undertaken during summer 1996 will be made by P04. They have acquired a simple vector-based GIS ARCVIEW2 to complement the existing raster-based system, and enable us to view the datasets of other participants produced by ARCINFO. A new road is being put through one of the test sites and this will prove an interesting feature to monitor inthe coming winter.

The potential to acquire a vector-based GIS to complement the existing raster-based system is being investigated. For the Finnish and Portuguese test sites, the aims identified, receptively for the period of report has been achieved and the compilation of geographic database of test areas for wind damage model testing has continued as planned.

The metadata forms are proving an extremely useful method of eliciting detailed information about the project data sets. Having the forms on the web has allowed efficient collection, collation and dissemination of this material, which is fundamental to the success of the project. Furthermore, the metadata forms were kept simple for ease of use but are comprehensive enough to ensure that all relevant criteria are covered. Completion of these forms will save time in the future by minimising the possibility of important information being omitted during the collection process which might be difficult to recover later in the project. The forms constitute a summary of important metadata necessary for data use. Minor changes were made to the forms in response to comments from MLURI data capture personnel and project participants who have some experience in the area. A system of metadata documentation exists whereby participants can complete forms remotely, in their own time, which will be automatically stored, in a central location, for viewing by all participants. This maintains clarity of communication with minimal effort. All this information will be used in the Task 6 integration of components, as reference material for participants who are exchanging data and models, and as a general form of documentation to collate what data is available in a European context.

Sub-task 5.3. The report is complete but "live" and so additions will continue throughout the project. Will serve as a useful reference document for this project and future European work. The information contained in the report will be important for use in Task 6 to create a system framework which has valid links between models and data. There also exists the possibility of graphically incorporating this information into the system to allow easy identification of relevant data sets for particular model runs and to enhance its user-friendliness. The report revealed some major gaps in European coverage and the inadequacy of data sets currently available when compared to the metadata form resulting from Sub-task 5.1. A significant contribution of this project to the whole subject of European data collection, dissemination and use is that these issues are being addressed in the context of metadata provision. The report has been a useful basis for organising Pan-European and participants data and identifying gaps in data sets available and gaps in the metadata associated with the data which is available.

Sub-task 5.4. The Sub-task is being developed according to the plans and there were no deliverables or milestones to be achieved during this period.

Sub-task 5.5. The Sub-task is being developed according to the plans and there were no deliverables or milestones to be achieved during this period.

Task 6: Integrating components from tree/stand regional-level to produce an unified risk model

Sub-task 6.1. It was seemed important to avoid compressing all the integration and related issues into the last few months of the project. Many of the issues can be identified at an early stage, which will allow testing and developmentof the framework as the project progresses, so that problems can be solved in stages through consultation with all participants. Documentation of the models and data is particularly important to provide structured information to participants which will ensure effective integration, mutual understanding between participants of different national and regional datasets, models and damage issues. Mutual understanding is vital to effective collaboration. This was demonstrated at the Inveraray Meeting in January where it became apparent that, for example, the skills of the engineers and foresters working at the tree and wood properties level, could be used more effectively than had previously been envisaged, to addresses issues of scale and modelling. Many other links were identified which may later be exploited during the project, or could be taken further in the future beyond the scope of the current project.

Sub-task 6.2. Preliminary findings from these scale investigations (currently in progress) for a single dataset will be used to determine the method of investigation for subsequent data sets, since the scale structure of data will differ depending on the type of information and method of recording.

Task 7: Testing models against independent data and outlining implications for silvicultural strategies

Sub-task 7.1.

Task 8. Final products, documentation and identification of new opportunities

A number of papers has been published or submitted to scientific journals. The public pages are being further developed to provide more detailed information about the project and include images of damage being studied. In addition, a significant expansion of the private pages is permitting exchange and development of research ideas, and the display of preliminary results to facilitate communication and mutual understanding which enhances project progress. Full participant details have also been added to the web, and participant web sites, personal pages and email addresses are available for direct access through the pages.

CHAPTER 5 DISSEMINATION

List of publications:

There has been the following publications and scientific manuscripts have been published, are in press, or in preparation within the first 18 months of Project:

Caetano, M.S.; Mertes, L.A.K.; Cadete; L.and Pereira J.M.S. 1996. Assessment of AVHRR data for characterizing burned areas and post-fire vegetation recovery. EARSEL International Workshop: Remote Sensing and GIS Applications to Forest Fire Management. Alcalá de Henares, Spain Sept 7-9 . 49-52pp.

Chalmers, S. 1996. The use of the Criterion Survey Laser and ARC/INFO Geographic Information System (GIS) to Survey, Analyse and Predict Windthrow. BSc thesis. University of Aberdeen (unpubl.).

Gardiner, B.A. and Stacey, G.R. 1995. Designing Forest Edges to Improve Wind Stability. Forestry Commission Technical Paper 16, Forestry Commission, Edinburgh.

Gardiner, B.A., Stacey, G.R., Belcher, R.E. and Wood, C.J. 1996. Field and wind tunnel assessments of the implications of respacing and thinning for tree stability. Forestry (in press).

Hassinen, A., Lemettinen, M., Peltola, H., Kellomäki, S., and Gardiner, B.A. 1996. Application of prism based techniques to measurements of tree swaying under dynamic wind loading. Manuscript in preparation. 9 p.

Lundqvist, L. and Valinger, E. 1996. Stem diameter growth of Scots pine trees after increased mechanical load in the crown during dormancy and (or) growth. Annals of Botany 77, 59-62.

Nykanen, M-L, Peltola,H. Kellomaki, S., Broadgate, M.L, Quine, C. 1996. Factors affecting snow damage of trees: A literature review. Silva Fennica (submitted).

Peltola, H. 1995. Studies on the mechanism of wind-induced damage of Scots pine. Research Notes, University of Joensuu, Faculty of Forestry. D.Sc. (Agr. and For.) thesis. 28 p.

Peltola, H. 1996a. Swaying of trees in response to wind and thinning in a stand of Scots pine. Boundary-Layer Meteorology 77:285-304.

Peltola, H. 1996b. Model computations on the wind flow and turning moment by wind for Scots pine along the margins of clear-cut areas. Forest Ecology and Management (in press).

Peltola, H. 1996c. Modelling the mechanism of wind-induced damage of Scots pine. In: The Finnish Research Programme on Climatic Change. Final Report. (Ed. Jaana Roos). Publications of the Academy of Finland 4/96. pp. 260-263.

Peltola, H., Kellomäki, S. and Väisänen, H. 1996a. HWIND: A mechanistic model for wind and snow damage of Scots pine, Norway spruce and birch sp. Manuscript in preparation.

Peltola, H., Kellomäki, S. and Väisänen, H. 1996b. Model computations on the impacts of climatic change on soil frost with implications for windthrow risk of trees. Climatic Change (submitted).

Peltola, H., Nykänen, M-L. and Kellomäki, S. 1996c. Model computations on the critical combination of snow loading and windspeed for snow damage of Scots pine, Norway spruce and birch sp at stand edge. Forest Ecology and Management (submitted).

Peltola, H., Nykänen, M-L. and Kellomäki, S. 1996d. Model computations on the critical windspeed for wind damage of Scots pine, Norway spruce and birch sp at stand edge. Manuscript in preparation.

Valinger, E. and Fridman, J. 1996a. Modelling probability of snow and wind damage in Scots pine stands using tree characteristics. Submitted manuscript.

Valinger, E. and Fridman, J. 1996b. Modelling probability of snow and wind damage in Scots pine stands using tree, stand and site characteristics. In prep.

Valinger, E. and Pettersson, N. 1996. Wind and snow damage in a thinning and fertilization experiment in Picea abies in southern Sweden. Forestry 69, 25-33.

Valinger, E., Lundqvist, L. and Sundberg, B. 1995. Mechanical bending stress applied during dormancy and (or) growth stimulates stem diameter growth of Scots pine seedlings. Canadian Journal of Forest Research 25, 886-890.

Varjo, J. 1996. Controlling continuously updated forest data by satellite remote sensing. International Journal of Remote Sensing 17(1):43-67.

Vasconcelos, Maria J. Perestrelo. 1995. Integration of remote sensing and geographic information systems for fire risk management. EARSEL International Workshop: Remote Sensing and GIS Applications to Forest Fire Management. Alcalá de Henares, Spain Sept 7-9 129-149 pp.

Wade, N. 1996. A comparison of the strength properties of windthrown, windsnapped and standing timber, derived from testing of small clear specimens of Picea sitchensis. BSc thesis. University of Aberdeen (unpubl.).

Poster and oral presentations

Broadgate, M. 1996. STORMS Project Group 1996 Integrating tree and environmental models using GIS to develop silvicultural strategies for minimising forest damage. GIS Research UK Conference Proceedings, April 1996 (Poster presentation).

Caetano, M.S.; and Pereira, J.M.S. 1996. The effect of the understory on the estimation of coniferous forest leaf area index (LAI) based on remotely sensed data. Submitted for presentation on the conference on Signal and Image Processing for Remote Sensing, Taormina, Italy, 2327 September, 1996.

Gardiner, B.A. and Peltola, H. 1996. The development and testing of models for predicting the critical windspeed to damage trees. Oral presentation to be held in: Second International workshop on disturbance dynamics in boreal forests, in Quebec, Canada, in August 26-30, 1996.

Peltola, H. 1996d. Model computations by the mechanistic model for wind and snow damage of single tree. Oral presentation to be held in: Second International workshop on disturbance dynamics in boreal forests, in Quebec, Canada, in August 26-30, 1996.

Peltola, H., Kellomäki, S., and Väisänen, H. 1995. Model computations on the impacts of the climatic change on the soil frost and the risk of trees for windthrows. In: Climate Change, Biodiversity and Boreal Forest Ecosystems -Conference Abstracts, in Joensuu, in Finland, 30th July to 5th August, 1995. (IBFRA). Poster presentation. 1 p.

Peltola, H., Kellomäki, S., Väisänen, H. and Nykänen, M-L. 1996e. Impacts of climatic change on soil frost and the risk of trees to windthrows. Poster presentation held in Finnish Climate Change- Conference in Tampere 4-5, June 1996.

Meetings:

Project planning meeting was arranged on 24-25th February 1995 in Lisbon, Portugal.

Second project meeting was arranged on 10-13th, August 1995 in Tampere and Joensuu, in Finland.

Third project meeting was arranged on 13-17th, March 1996 in Inverary, in Scotland.

Project mid-term meeting was arranged on 4-5th, July 1996 in Brussels, in Belgium.

Model s developed:

A self extracting copy HWIND-model for Windows 3.1 is available on Joensuu University ftp-site (gis.joensuu.fi /hwind/windows/hwind05.exe).

The first version of the stand alone empirical model (treesnap.exe) to calculate critical wind speeds for damage and base bending moments has been made available to participants on the Edinburgh University ftp site (ftp.ed.ac.uk/pub/risk)

Growth models developed by Soederberg and Ekoe at Umea University, Sweden using single tree and stand characteristics made available to other participants.

Other documentation:

The results of each task are being made available on the World Wide Web site for dissemination.

The updated Task 1 document pages and summary diagrams can be found on the ftp site in the directory air/task1/. They are stored in Word Perfect 5.2 and Word for Windows 2.0 format.

A report has been produced as a result of the snow modelling workshop and has been distributed to both workshop and project participants. A subsequent workshop is planned to discuss the success of the adopted strategies to the modelling approach (Sub-task 5.1).

The metadata form is currently available on the MLURI ftp site and it is planned that web pages will also be available shortly, which will allow participants to fill in the metadata form on-screen direct to the Macaulay Land Use Research Institute over the internet. The information added using the form will be stored automatically on the ftp site, and will thus be available for perusal by all participants (Sub-task 5.2).

The report detailing information about Pan-European data sets will be available on the ftp site and accessible via the WWW pages (Sub-task 5.3).

The summary diagrams are currently available on the ftp site and can be accessed by all participants there. They are also to be added to the Task 1 planning document (Task 6).

EDGE.XLS (Data on bending moment as function of distance from forest edge and stand density in Excel 5.0 format) has been placed on Edinburgh University ftp site (ftp.ed.ac.uk/pub/risk).

CHAPTER 6 CONCLUSIONS

Coordination and management of the project is crucial to the successful integration of components in Task 6. The web site has proved an effective medium for display and update of the planning document, through which project planning and management, and data and model integration can be achieved. The interrelations of Tasks, Sub-tasks and deliverables, and the participants involved in each stage of the project is fairly complex, and this fast and visual means of communication is now considered an essential ingredient to the success of the project integration. The Web pages, the ftp site and the mailing list have afforded efficient and timely communication and made coordination and management much easier, providing not only mass communication of inter-participant messages, but the exchange of images, documents, diagrams and forms which can be instantly updated with no time delay.

The integration of such a wide variety of models (statistical, mechanistic, logistic, regional, tree scale) and data (Pan-European to wood property scale from many different countries) on such a large collaborative is a major task which requires a simple yet robust framework. The methods described above appear to be working effectively towards facilitating this integration, but many of the details still need to be resolved. Many of the issues should be identified when the demonstration is complete, and discussions at the next project meeting should resolve many of the problems and identify the next stages towards integration.

The web site, the leaflet and the verbal and written presentations have been used at frequent intervals, ensuring that the project is receiving good exposure at major fora and instigating keen interest, useful links and contacts. Communication between participants is extremely good, shown particularly by the development of a demonstrator and the submission of a paper which was the result of input by three different participating institutes, and a poster which was the work of the entire project group.

CHAPTER 7 ACTION

No specific action are proposed, since the activities planned to be executed during the the next period July 1996 - December 1996 are well in line the experiences during the current period.