| 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 five input variables in model. The risk of damage is modeled using the characteristics volume over bark, clear bole height, relative crown length, breast height taper, and ratio of height to diameter at breast height. Valid only for Scots pine in north Sweden. |
| Ispecfile | Similar to that for earlier Umea models |
| iexpspecfile | n/a |
| ivar1 | Volume over bark (v) |
| ifile1 | ? |
| idescr1 | m3 |
| isensitiv1 | Sensitive |
| isensdescr1 | Logistic procedure |
| ivar2 | Clear bole height (cbh) |
| ifile2 | ? |
| idescr2 | Height to living crown, m |
| isensitiv2 | Sensitive |
| isensdescr2 | Logistic procedure |
| ivar3 | Relative crown length (rcl) |
| ifile3 | ? |
| idescr3 | proportion (0 to 1) |
| isensitiv3 | Sensitive |
| isensdescr3 | Logistic procedure |
| ivar4 | Breast height taper (brt) |
| ifile4 | ? |
| idescr4 | Diameter at breast height/height-1.3, cm/m |
| isensitiv4 | Sensitive |
| isensdescr4 | Logistic procedure |
| ivar5 | Ratio height to diameter at breast height (rhd) |
| ifile5 | ? |
| idescr5 | m/cm |
| isensitiv5 | Sensitive |
| isensdescr5 | Logistic procedure |
| csumm | Volume over bark 1.2052 Clear bole height -0.3210 Relative crown length -3.2955 Breast height taper 1.0413 Ratio height to diameter at breast height 4.2336 |
| Model | ntprob=1-(1/(1+exp(-5.1597+(1.2052*v)-(0.3210*cbh)-(3.2955*rcl) +(1.0413*brt)+(4.2336*rhd)))) (then multiply by 100 to get the result in percent) |
| cspecfile | None |
| cexpspecfile | none |
| osumm | ntall |
| ospecfile | ? |
| oexpspecfile | See above |
| ovar1 | ntprob |
| 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 Scots pine Chi-square for covariates 107.005 with 5 DF (p=0.0001) Pr > Chi-square Intercept 0.0002 v 0.0001 cbh 0.0001 >rcl 0.0002 brt 0.0001 rthd 0.0001 |
| mech_mth | n/a |
| log_meth | Logistic model ntprob=1-(1/(1+exp(-5.1597+(1.2052*v)-(0.3210*cbh)-3.2995*rcl)+ (1.0413*brt) +(4.2336*rhd)))) (then the result multiplied by 100 to get in percent) |
| scope | Model developed from a sample of data from whole Sweden (1114 sample
plots). 2% 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 |