REU: Patch Size, Herbivory, and Secondary Succession: An Experimental Study

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The study of secondary succession in old fields has largely emphasized the causal role of life history strategies and interspecific competition. Yet the rate or pattern of succession may be influenced by the size of the area undergoing succession and herbivory. Given that herbivory is important, the intensity of herbivory should also vary systematically with successional patch size. A conceptual model will be tested which predicts that given a trade-off between colonizing and competitive abilities, succession should be slower on small patches and that mammal herbivores should be less abundant and diverse on small patches, and biased toward small-bodied species. The experimental study will use an archipelago of successional patches in eastern Kansas. The patches span two orders of magnitude in area and are kept isolated through regular mowing. Immigration, population growth or decline, spatial patterns, and species turnover for plants and small mammals will be documented. The effects of small mammals on plant succession will be gauged using exclosures. Patch size may also indirectly affect plant and animal succession through effects on resource availability (e.g., small patches are relatively more wind-exposed and may be drier than large patches). The availability of water and nitrogen in the system will be monitored.