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Moose population density and habitat productivity as drivers of ecosystem processes in northern boreal forests

Persson, Inga-Lill (2003). Moose population density and habitat productivity as drivers of ecosystem processes in northern boreal forests. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae. Silvestria, 1401-6230 ; 272
ISBN 91-576-6506-0
[Doctoral thesis]

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Abstract

Ungulates have traditionally been viewed as consumers of plants and prey for predators, but recent studies have revealed that they also can have a significant indirect impact on fundamental ecosystem processes and biodiversity. In my thesis, I focus on how moose (Alces alces) can affect the boreal forests ecosystem in Sweden. Because of its wide distribution and at present high population densities we can expect moose to be important. The outcome depends on moose density as well as habitat productivity, and we chose an experimental approach where we simulated browsing, defecation and urination of different moose population densities in exclosures situated along a forest productivity gradient. The simulation was based on a review of available literature. I found that moose can have a significant impact on the morphology and productivity of the main food plants in winter, Scots pine (Pinus sylvestris) and birch (Betula pubescens and B. pendula). The outcome was highly dependent on moose density. At “low” to “moderate” moose densities, small and non-significant effects were found, whereas the effects were large at higher moose densities. I concluded that both foraging efficiency and food availability can be affected at higher moose densities over extended time, and that food production may steadily decrease to a level where winter food is limiting. Habitat type also affected the results. At low productive sites both birch and pine had low productivity and thus compensatory ability to defoliation by moose. Birch and pine also seemed to respond differently to habitat productivity, and the explanation might have been that pines suffered from competition with deciduous trees at richer sites. The quantity and quality (species mix) of litter from the tree and shrub layers were affected by the level of simulated moose population density and habitat. Richer sites produced more high quality litter (i.e. lower proportion of conifer needles). The quantity decreased and the proportion of conifer needles increased with simulated moose density. Despite the high browsing pressure on Scots pine, the general outcome of moose at high population densities over extended time seems to be decreased quantity and quality of litter, and thus reduced nutrient cycling and habitat productivity in the long run. Decay rates of moose dung appeared to be rather low, suggesting that the fertilizing effect also was low. However, the dung disappeared fast at richer sites due to concealment by vegetation, and visibility was negatively correlated with litter production. The coprophilous community colonizing moose dung appeared to be species rich and poorly known, and the abundance and species richness are affected by interactions with other organisms as well as habitat type. In my thesis I show that moose can affect fundamental ecosystem processes and biodiversity in Swedish boreal forests, and act as an important ecosystem engineer. Productivity gradients are important to consider when studying effects on the ecosystem level. Based on my findings, I suggest that more studies should be done on other tree species, plants in the field and bottom layers, soil properties, microclimate, and organisms connected to faeces and urine.

Authors/Creators:Persson, Inga-Lill
Title:Moose population density and habitat productivity as drivers of ecosystem processes in northern boreal forests
Year of publishing :April 2003
Volume:272
Number of Pages:30
Papers/manuscripts:
NumberReferences
ALLI. Persson, I.-L., Danell, K. and Bergström, R. 2000. Disturbance by large herbivores in boreal forests with special reference to moose. Annales Zoologici Fennici 37, 251-263. II. Persson, I.-L., Danell, K. and Bergström, R. Effects of moose on morphology and productivity of Scots pine and birch: importance for foraging efficiency and food availability. (Manuscript). III. Persson, I.-L., Danell, K. and Bergström, R. How forest productivity affects growth responses of Scots pine and birch subjected to simulated browsing, defecation and urination of moose. (Manuscript). IV. Persson, I.-L., Pastor, J., Danell, K. and Bergström, R. Impact of moose population density and forest productivity on the production and composition of litter in boreal forests. (Manuscript). V. Persson, I.-L. Seasonal and habitat differences in visibility of moose pellets. (Manuscript submitted to Alces). VI. Nyberg, Å. and Persson, I.-L. 2002. Habitat differences of coprophilous fungi on moose dung. Mycological Research 106, 1360-1366.
Place of Publication:Umeå
ISBN for printed version:91-576-6506-0
ISSN:1401-6230
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F40 Plant ecology
Subjects:Not in use, please see Agris categories
Agrovoc terms:elks, biodiversity, betula pubescens, betula pendula, pinus sylvestris, boreal forests, browsing, faeces, plant litter, habitats, productivity, sweden
Keywords:Alces alces, biodiversity, birch, boreal forest, browsing, coprophilous organisms, food ecosystem processes, faeces, habitat, litterfall, moose, productivity, Scots pine, selective feeding, Sweden.
URN:NBN:urn:nbn:se:slu:epsilon-32
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-32
ID Code:252
Department:(S) > Institutionen för skoglig zooekologi
Deposited By: Inga-Lill Persson
Deposited On:24 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:03

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