Modelling the abundance and temporal variation in the production of bilberry (Vaccinium myrtillus L.) in Finnish mineral soil forests

Abstract

Empirical models for the abundance and berry yield of V. myrtillus were constructed using generalized linear mixed model (GLMM) techniques. The percentage coverage of bilberry was predicted as a function of site and stand characteristics using the permanent sample plots of the National Forest Inventory (NFI) in 1995. The number of bilberries was predicted as a function of percentage coverage and stand characteristics using a sub-sample of the NFI plots in North Karelia. The between-year variation in the bilberry yield was analysed using the permanent experimental plots (MASI) established in different areas of Finland and measured in [2001][2002][2003][2004][2005][2006][2007]. The highest coverage of bilberry was found on mesic heath sites; on sub-xeric and herb-rich heath sites the values were 62% of that for mesic sites. The decreasing effect of deciduous trees (compared to spruce) was significant only on herb-rich heath sites. The coverage increased along with stand development up to certain stand ages and basal areas. The bilberry yields were higher in pine-dominated stands than in spruce-dominated ones. In spruce stands, the coverage of bilberry and stand basal area significantly affected the number of berries, whereas in pine stands only the coverage was a significant predictor. In the MASI data, the bilberry yield of pine stands was two times higher than that of spruce stands; however, the between-year variation in bilberry yield was higher in the spruce than in the pine stands. The estimated models were used to predict the bilberry coverage and yield along with stand development. On mesic heath sites in southern Finland (1200 dd.), the predicted annual yield of bilberry was about 25 kg ha -1 (95% confidence interval 9-73 kg ha -1 ) in a mature pine stand and about 10 kg ha -1 (3-35 kg ha -1 ) in a mature spruce stand. The models can be included in stand simulators, where they would facilitate the prediction of bilberry abundance and yields for silvicultural and forest planning purposes.

Effect of fertilization, tiller cutting and environment on plant growth and yield of European blueberry (Vaccinium myrtillus L.) in Norwegian forest fields

“…In Finland it is shown, using recently developed yield models that were included in a stand growth simulator, that a joint production of timber and E. blueberry could give economical gain depending on price and discounting rate [30].…”

Modelling Non-Wood Forest Products in Europe: a review

“…In addition, the annual variation in bilberry yields was not included in the previous model. Therefore, Miina et al (2009) proposed a new empirical bilberry yield model that first predict the coverage of bilberry as a function of e.g. dominant tree species, site fertility, regeneration method, stand age and stand basal area.…”

“…In the simulations of Miina et al (2009Miina et al ( , 2010, 80% of the unripe berries were assumed to become ripe. The number of ripe berries was converted into the bilberry yield (kg ha -1 ) by multiplying it by the mean fresh weight (0.35 g) of one ripe berry.…”

“…The number of ripe berries was converted into the bilberry yield (kg ha -1 ) by multiplying it by the mean fresh weight (0.35 g) of one ripe berry. The recently developed empirical model of Miina et al (2009) considers also the effect of stand density -and consequently thinnings-on the bilberry yields. In Finland, optimization of timber production has been used to evaluate the silvicultural recommendations for forestry practice.…”

Exploring the potential of wild food resources in the Mediterranean region: natural yield and gathering pressure of the wild asparagus (Asparagus acutifolius L.)

“…The abundance and yield of these wild food resources have not been properly studied, with the exception of some wild berries (Kerns et al, 2004;Murray et al, 2005;Miina et al, 2009;Molina et al, 2011) and mushrooms (Martínez de Aragón et al, 2007;Bonet et al, 2008). However, there is a large set of wild-growing species used in traditional cuisines that deserve more attention (Pieroni et al, 2005;Tardío et al, 2006).…”