| Popis: |
The tundra ecosystem, with its frost-molded landscape and large peat reserves, is vulnerable to climate change. Thus, any increase in temperature due to global warming will cause changes in above-and belowground biota. Understanding the linkage between these biotas will help make prediction of the biodiversity and ecosystem functioning when global change phenomena occur, and consequently aid in making management strategies. The role of nematodes in nutrient cycling and decomposition, among many other attributes, make them useful organisms to study soil processes. Associations between plant and nematode communities, from six sites (Berm Face, Berm Crest, Tundra Heath, Polygon, Hummock and Forest) and from within a young, visually homogeneous tundra heath field site, were examined in the subarctic environment of Churchill, Manitoba. The study also provided nematofaunal information, which is very limited in this region. Multivariate analyses of nematode taxa abundance revealed four distinct groupings: Berm Face, Berm Crest, heaths (Tundra Heath, Polygon and Hummock) and Forest. The result showed a parallel relationship between nematode and vegetation assemblages, and thus, a seeming interdependency between above-ground and below-ground biota. Conversely, association between nematode and plant assemblages within a visually homogeneous tundra site was not as obvious. At this fine scale, the heterogeneous nature of edaphic factors and not plant assemblages is hypothesized to influence within-site nematode communities. The thesis also provided results to improve nematofaunal analysis to enhance their utility as bioindicators of soil food webs. |
