Campus Evenstad, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Inland Norway University of Applied Sciences, Koppang, Norway.
PLoS One. 2020 Mar 27;15(3):e0230509. doi: 10.1371/journal.pone.0230509. eCollection 2020.
Vegetative parts of bilberry (Vaccinium myrtillus) are important forage for many boreal forest mammal, bird and insect species. Plant palatability to insects is affected by concentration of nutrients and defense compounds in plants. We expected that palatability of bilberry leaves to insect herbivores is influenced by light availability and soil productivity (both affecting nitrogen concentration and constitutive carbon-based defense compound concentration) and herbivory by mammals (affecting nitrogen concentration and induced carbon-based defense compound concentration). We studied bilberry leaf herbivory under different light availability, soil productivity and mammalian herbivory pressure in small sampling units (1m x 1m) in boreal forest in Norway. We used generalized linear mixed models and generalized additive mixed models to model insect herbivory on bilberry leaves as a function of shade, soil productivity and mammalian herbivory. Observed insect herbivory on bilberry leaves increased with increasing shade levels. Predicted insect herbivory increased with increasing previous mammalian herbivory at high shade levels and this response was magnified at higher soil productivity levels. At low to intermediate shade levels, this response was only present under high soil productivity levels. Our results indicate that light availability is more important for variation in bilberry leaf palatability than soil nutrient conditions.
越橘（Vaccinium myrtillus）的营养体部分对许多北方森林哺乳动物、鸟类和昆虫物种来说是重要的饲料。植物对昆虫的适口性受植物中营养物质和防御化合物浓度的影响。我们预计，越橘叶对昆虫食草动物的适口性受光照条件和土壤生产力（均影响氮浓度和组成性基于碳的防御化合物浓度）以及哺乳动物食草作用（影响氮浓度和诱导性基于碳的防御化合物浓度）的影响。我们在挪威的北方森林中，在小采样单元（1m x 1m）中研究了不同光照条件、土壤生产力和哺乳动物食草压力下的越橘叶食草作用。我们使用广义线性混合模型和广义加性混合模型，将越橘叶上昆虫食草作用建模为阴影、土壤生产力和哺乳动物食草作用的函数。观察到的越橘叶上昆虫食草作用随遮荫水平的增加而增加。在高遮荫水平下，预测的昆虫食草作用随先前哺乳动物食草作用的增加而增加，而在较高的土壤生产力水平下，这种反应更为显著。在低至中等遮荫水平下，这种反应仅在高土壤生产力水平下存在。我们的结果表明，光照条件对越橘叶适口性的变化比土壤养分条件更为重要。
