| user_name | Erik Valinger |
| user_organisation | Swedish University of Agricultural Sciences Faculty of Forestry Department of Silviculture S-901 83 Umea Sweden |
| date | 20th May 1997 |
| model_name | Tree characteristic model |
| description | Describes probability of snow and wind damage at sites using tree characteristics from the thickest sample tree at each sample plot. |
| software | Developed in SAS 6.10 but Excel 7.0 will do |
| operating_system | PC Windows 95 |
| isumm | There are six input variables in model. The risk of damage is modeled using the characteristics height, diameter, volume over bark, clear bole height, relative crown length, and ratio of height to diameter at breast height. Valid only for Norway spruce in mid Sweden. |
| Ispecfile | Similar to that for earlier Umea models |
| iexpspecfile | n/a |
| ivar1 | Height, h |
| ifile1 | ? |
| idescr1 | m |
| isensitiv1 | Sensitive |
| isensdescr1 | Logistic procedure |
| ivar2 | Diameter at breast height, dbh |
| ifile2 | ? |
| idescr2 | cm |
| isensitiv2 | Sensitive |
| isensdescr2 | Logistic procedure |
| ivar3 | Volume over bark, v |
| ifile3 | ? |
| idescr3 | m3 |
| isensitiv3 | Sensitive |
| isensdescr3 | Logistic procedure |
| ivar4 | Clear bole height, cbh |
| ifile4 | ? |
| idescr4 | m |
| isensitiv4 | Sensitive |
| isensdescr4 | Logistic procedure |
| ivar5 | Relative crown length, rcl |
| ifile5 | ? |
| idescr5 | proportion (0 to 1) |
| isensitiv5 | Sensitive |
| isensdescr5 | Logistic procedure |
| ivar6 | Ratio of height to diameter at breast height, rhd |
| ifile6 | ? |
| idescr6 | m/cm |
| isensitiv6 | Sensitive |
| isensdescr6 | Logistic procedure |
| csumm | height, h 0.1680 diameter, dbh -0.1192 volume over bark, v +1.2076 clear bole height, cbh -0.7248 relative crown length, rcl -10.2995 Ratio of height to diameter at breast height, rhd -5.2201 Model mtprob=1-(1/(1+exp(11.2908+(0.1680*h)-(0.1192*dbh) +(1.2076*v)-(0.7248*cbh)-(10.2995*rcl)-(5.2201*rhd)))) (then multiply by 100 to get the result in percent) |
| cspecfile | None |
| cexpspecfile | none |
| osumm | mgran |
| ospecfile | ? |
| oexpspecfile | See above |
| ovar1 | mtprob |
| ofile1 | ? |
| odescr1 | Site probability of snow and wind damage |
| stat_meth | Logistic procedure for probability of damage from snow and wind at a site using tree characteristics when dominating species is Norway spruce Chi-square for covariates 244.483 with 6 DF (p=0.0001) Pr > Chi-square Intercept 0.0001 h 0.0001 dbh 0.0001 v 0.0001 cbh 0.0001 rcl 0.0001 rhd 0.0001 |
| mech_meth | n/a |
| log_meth | Logistic model Model mtprob=1-(1/(1+exp(11.2908+(0.1680*h)-(0.1192*dbh)+(1.2076*v) -(0.7248*cbh)-(10.2995*rcl)-(5.2201*rhd)))) (then the result is multiplied by 100 to get it in percent) |
| scope | Model developed from a sample of data from mid Sweden (579 sample plots). 6.1% of the plots had one or more damaged sample trees, damage=1. Model have been proven to predict damage well by cross-validation |
| other | ? |
| copyright | Swedish University of Agricultural Sciences Faculty of Forestry Department of Silviculture |
| contact | Associate Professor Erik Valinger |