Herbivores modify palatability of Silica–rich grasses
Silica–rich grasses are often abundant in pastures. The silica content causes these grasses to have low palatability, yet to what extent herbivores themselves modify the silica-content and the nutrient content of these grasses is uncertain. Here we ask to what extent small rodents and reindeer can modify Silicon (Si), Nitrogen (N) and Phosphorous (P) contents in Si–rich grasses over a summer season in the sub–arctic tundra. Within an experimental exclosure setup, we studied impacts of small rodents or reindeer or the combined effect of the two different sized herbivores on the nutrient responses in Si–rich grasses in meadow habitats. Leaves of three common Si–rich grasses, Nardus stricta, Calamagrostis spp. and Deschampsia cespitosa, were sampled every second week, from late June to mid September in 2015, after which samples were analysed for their Si, N and P content. The small rodents winter activity significantly improved the N and P content in the Si–rich grasses and had no effect on the Si content, whereas reindeer summer grazing significantly decreased the Si content late in the season, but with no effect on N and P content. However, the combined effect of small rodents winter activity and summer reindeer activity showed the opposite pattern, with lower N and P leaf content and a higher Si content in the Si–rich grasses.
ForlagUiT Norges arktiske universitet
UiT The Arctic University of Norway
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