In natural ecosystems around the world herbivores play an important role in ecosystem processes. Herbivores affect plant community structure and dynamics in many ways. Although herbivory may kill small plants instantly, the more common effect is a reduction in growth and resource uptake and changes in plant chemistry and morphology. This affects competitive hierarchies between plants and thus vegetation composition and dynamics as well as nutrient cycling and herbivory.
Much research has been conducted on large herbivores. Small mammalian and insect herbivores may be affected by large herbivores through changes in plant species composition, nutrient content, chemical and morphological defences and through vegetation structure. Although less recognised, herbivory and related behavior (winter food hoarding, disturbance etc.) by small herbivores itself might be of importance for vegetation dynamics, interactions between herbivores and soil nutrient cycling processes.
Plants can respond to herbivory in several ways, both morphologically as well as chemically. The responses of plants following herbivory might give rise to huge impacts on herbivores, and have been suggested to drive small mammal cycles, and also influence vegetation composition and dynamics, by altering competitive hierarchies between plants. All these herbivory-induced responses by plants, vegetation and ecosystems imply interactions between herbivores that are mediated by modification of habitat (e.g., cover for small mammals) and/or food availability/quantity and/or quality, facilitation or inhibition.
The effects of herbivory by small mammal herbivores like voles on bilberry, an abundant plant species in the understory of many forest types in the boreal forest region in Scandinavia, and other herbivore species, remain unclear to a large extent. To solve some of the questions, this research project is conducted.
Smit, R., J. Bokdam, J. den Ouden, H. Olff, H. Schot-Opschoor &M. Schrijvers. 2001. Effects of introduction and exclusion of large herbivores on small rodent communities. Plant Ecology 155:119-127. (pdf)