UBC Theses and Dissertations
Experimental evidence that reserves benefit yield : a test in a natural microcosm Venter, Katsky
No-take reserves, in addition to protecting biodiversity, may ensure the maintenance of harvested species. It has been proposed that reserves can both directly limit harvesting (by decreasing the area available for extraction), and increase yield through dispersal into harvestable areas. Although theory and observational evidence generally support such claims, experimental evidence indicating that reserves can provide yield to surrounding areas remains scarce primarily because large scale experiments are prohibitive. We employed a moss-based microarthropod community to experimentally compare the effects of reserve presence, size, and number on yield. We found that no-take reserves increased the density, biovolume, and species richness of microarthropods in non-reserve areas, regardless of the spatial arrangement of reserves. Treatments with reserves had equal or greater total harvests (abundance or biovolume) than treatments without reserves, despite the loss in harvestable area due to reserve establishment. Partitioning the harvested microarthropods into broad taxonomic groups indicated that all taxa exhibited the same ranked effects of treatments even though taxa exhibited different trends in abundances through time. No differences between having a single large reserve or three small reserves (whose combine area was equivalent the single large reserve) were detected. The absence of an effect of reserve number may be a product of high dispersal or differences in densities between small and large reserves. These results provide strong evidence that reserves are capable of functioning as sustainable management tool, and that reserve size, but not number is important for increasing yield.
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