COS 76-10 - Spatial insurance in a moss-microarthropod ecosystem

Wednesday, August 10, 2011: 4:40 PM
9C, Austin Convention Center
Gennifer E. Meldrum, Zoology Department, University of British Columbia, Vancouver, BC, Canada and Diane S. Srivastava, Zoology, University of British Columbia, Vancouver, BC, Canada

Habitat loss and fragmentation threaten biodiversity worldwide, which may have serious consequences for the functioning and stability of ecosystems. Dispersal between remnant habitat patches can alleviate the loss of biodiversity in fragmented landscapes and can facilitate community recovery from disturbance. However, the ‘spatial insurance hypothesis’ suggests that these effects will be strongest at intermediate dispersal rates and when environmental conditions vary heterogeneously across the landscape. As landscape-scale manipulation is often difficult to perform and replicate, experimental evidence for this hypothesis is lacking. We used a moss-microarthropod ecosystem to assess how dispersal rate and synchronicity of disturbance across the landscape affect biodiversity, community biomass, and resilience at local and metacommunity scales. We fragmented a contiguous area of moss into moss “islands” with a cement matrix. We created two-patch metacommunities that were connected by no, one, or two moss corridors and disturbed both patches simultaneously (both in May or both in August) or asynchronously (one in May and one in August) using Tulgren funnel extraction. We compared disturbed systems to undisturbed controls as an indication of resilience. All systems were sampled by Tulgren funnel extraction 6 months after fragmentation and the mites and collembolans were sorted to morphospecies under a dissection scope. 


Preliminary results suggest that species richness did not differ greatly between connectivity and disturbance treatments but that microarthropod abundance was generally greater in connected systems. Systems disturbed synchronously in May tended to have lower micoarthropod abundance than undisturbed or asynchronously disturbed metacommunities. Higher abundance in connected and asynchronously disturbed systems, as compared to synchronously disturbed systems, is consistent with the spatial averaging effect predicted by the spatial insurance hypothesis.

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