Empirical prediction models for Vaccinium myrtillus and V. vitis-idaea berry yields in North Karelia, Finland

Abstract

Forest berries and the outdoor experiences related to berry collection are important goods and services provided by Finnish forests. Consequently, there is a need for models which facilitate the prediction of the impacts of alternative forest management options on berry yields. Very few such models are available. In particular, empirical models are lacking. Models used in forest management should express the effect of variables altered in forest management such as stand density and mean tree size. This study developed empirical models for bilberry and cowberry yields in North Karelia. The data consisted of 362 measurements of 40 m 2 sample plots. The plots were located in clusters. The same plot was measured over 1 to 4 years. Besides berry yield some site and growing stock characteristics of each plot were measured. A random parameter model was used to express the berry yield as a function of site fertility, growing stock characteristics, and random parameters. The random part of the models accounted for the effect of plot, measurement year, and cluster. The fixed predictors of the model for bilberry were stand age and forest site type. Stand basal area, mean tree diameter and forest site type were used to predict cowberry yields. The most significant random parameter was the plot factor. The fixed model part explained only a few per cent of the variation in berry yields. The signs of regression coefficients were logical and the model predictions correlated rather well with the predictions of earlier models.

Variations of yield and utilisation of bilberries (Vaccinium myrtillus L.) and cowberries (V. vitis-idaea L.) in Finland

“…The average weights of ripe berries on medium and more fertile site types (w M ) and on rather poor and poorer site types (w P ) were determined on the basis of earlier studies (Kuchko 1988, Ihalainen et al 2003. In the case of bilberry, they were 0.36 g and 0.32 g respectively, and in the case of cowberry, they were 0.25 g and 0.23 g respectively.…”

Empirical models for predicting the production of wild mushrooms in Scots pine (Pinus sylvestris L.) forests in the Central Pyrenees

“…To integrate mushrooms and other NWFP and services in forest planning, models based on empirical studies that can predict production or function and are applicable to planning parameters are needed. However, other than empirical models to predict the yield of wild berries in Finland [11][12][13], very few empirical models have been developed to predict productions of NWFP for use in forest planning. No models were found in the literature for predicting the production of wild mushrooms in forest planning.…”

Modelling the coverage and annual variation in bilberry yield in Finland

“…Thirdly, Turtiainen et al (2011) andSalo (2015) calculated mean annual bilberry yields (kg ha -1 ) using the method described by Turtiainen et al (2011), which used average weights of ripe bilberries on different site fertilities. The weights were obtained from earlier studies by Kuchko (1988) and Ihalainen et al (2003). However, one can question whether the weights used were accurate enough (cf.…”

“…In Finland, several models for the yields of bilberry and cowberry (V. vitis-idaea L.) have been developed (Ihalainen and Pukkala 2001;Ihalainen et al 2002Ihalainen et al , 2003Ihalainen et al , 2005Miina et al 2009;Turtiainen et al 2013). All these models have been prepared for forest planning purposes.…”