Abstract
Large herbivores can by their selective feeding change structure and species composition of the plant community. These changes can further affect other animal assemblages and fundamental ecosystem processes. From the Swedish perspective it is important to reveal how different population densities of cervids affect the ecosystem. To study this, a new, completely experimental research project was started, where impact (browsing, defecation, urination) of 4 different moose densities was simulated in 8 exclosures in young forest stands along a habitat productivity gradient. The moose food plants are clipped in quantities corresponding to the different densities both summer and winter, and dung and urine are added. The results so far clearly show that moose significantly can affect the ecosystem, especially at higher densities. There are clear effects on growth and productivity of trees, litterfall, abundance and species richness of vascular plants, ground and soil living invertebrates. Also soil temperature and soil respiration rates have been affected. Effect further depends on habitat productivity, and the same moose density can give opposite effects in poor and rich habitats. The exclosures now have the optimal age to do further studies on biodiversity of plants, mosses, lichens, tree and ground living invertebrates, biochemical soil processes and microclimate. The results will also be used to develop ecological models on how changes in one process affects other.
Sweden