Indirect effects of moose on the birds and the bees
Doctoral thesis
Permanent lenke
http://hdl.handle.net/11250/132014Utgivelsesdato
2011Metadata
Vis full innførselOriginalversjon
Mathisen, K.M. (2011). Indirect effects of moose on the birds and the bees. Umeå : Swedish University of Agricultural SciencesSammendrag
Large herbivores are important drivers of ecosystem processes, affecting plant species
richness and composition, primary productivity, habitat structure as well as nutrient
cycling. Large herbivore activities may therefore have important indirect effects on
other plants and animals in the same ecosystem. The effect of herbivore activity on
ecosystem processes varies with habitat productivity, herbivore selectivity, herbivore
density and may be modified by different wildlife management practices. Therefore
indirect effects of herbivores may also vary with these factors. In this thesis, I focus
on indirect effects of moose (Alces alces) on plants and animals in the boreal forest
and how these effects are modified by moose density, habitat productivity and
supplementary winter feeding of moose. I studied effects of moose density and
habitat productivity on species composition, growth and reproduction in the field
layer vegetation and on abundance and family richness of flower-visiting insects. I
also studied effects of a gradient in moose density around supplementary winter
feeding stations for moose on bird species richness, abundance and reproduction.
Selective moose browsing on preferred species affected species composition in the
field layer vegetation, increasing abundance and reproduction in unbrowsed plant
species, and decreasing abundance and reproduction in browsed species. Moose
browsing in the tree canopy increased light availability and flowering in the field
layer as well as family richness of Hymenoptera at sites with high productivity.
Moose winter browsing around supplementary feeding stations led to reduced
species richness and abundance of insectivorous birds and birds nesting at browsing
height. Furthermore, high moose densities led to lower reproduction and food
availability for great tits (Parus major), and higher reproduction and food availability
for pied flycatchers (Ficedula hypoleuca). Supplementary feeding stations for moose
brought nutrients into the system and had a positive effect on species richness and
abundance of insectivorous birds, and the size of insect prey. These results show
that moose activity can have indirect effects on plants and animals through changed
resource availability and habitat structure, and that these effects are modified by
habitat productivity and supplementary feeding of moose.
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