SELECTIVE FORAGING AND ECOSYSTEM PROCESSES IN BOREAL FORESTS

We suggest that selective foraging alters feedbacks between plants and decomposers and between plants and herbivores. Plant tissue chemistry is an important link between herbivores and decomposers. Plants that produce easily decomposable litter are also heavily browsed, because the same chemical properties that determine litter decay also determine digestibility. This trait links theories of food webs and nutrient cycles by posing a role of herbivores as functional switches determining both plant community composition and the array of litters returned to the soil. This role appears to be particularly strong in boreal forests, where nutrient availability is low and limits productivity and determines successional pathways, where effects of herbivores are strong and long lasting, and where the same plant traits that determine herbivore preference and response to browsing also determine interactions with soil nutrient availability. Such feedbacks cause the effects of herbivores on ecosystems to persist even after the herbivores are no longer present.