%0 Research article
%T Modelling cowberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus) yields from mineral soils and peatlands on the basis of visual field estimates
%A Ihalainen, Marjut
%A Pukkala, Timo
%D 2001
%J Silva Fennica
%V 35
%N 3
%R doi:10.14214/sf.588
%U https://silvafennica.fi/article/588
%X This study presents new models for predicting bilberry and cowberry  yields from site and stand characteristics. These models enable one to  evaluate the future states of forests in terms of berry yields. The  modelling data consisted of visual field estimates of site and tree  stand characteristics, as well as berry yields from 627 forest stands.  Berry yields were estimated using a scale from 0 to 10. Using these  data, models were prepared which predict the berry yield scores from  those site and stand characteristics which are usually known in forest  planning calculations. The model predictions correlated positively and  often quite strongly with earlier models. The results were in line with  previous studies on the effects of site and tree cover on berry  production. According to the models, sites of medium and rather poor  fertility produce the highest bilberry yields. Increasing tree height  increases, and the basal area of spruce and proportion of deciduous  trees decrease, bilberry yield. With mineral soils, cowberry yields are  best on poor sites. A high proportion of pine improves cowberry yields.  The yields are the highest in open areas and very young stands, on the  one hand, and in sparsely populated stands of large and old trees, on  the other hand. In pine swamps, the yields are best on rather poor  sites. Increasing basal area of deciduous trees decreases cowberry  yields.