The Interaction of Habitat Fragmentation, Plant, and Small Mammal Succession in an Old Field

Abstract

We compared the density and spatial distribution of four small mammal species (Microtus ochrogaster, Peromyscus maniculatus, Sigmodon hispidus, and P. leu-copus) along with general measures of an old field plant community across two successional phases (1984-1986 and 1994-1996) of an experimental study of fragmentation in eastern Kansas. During the early phase the plant community was characterized by little spatial or temporal variance across patch size, consistent with spatially neutral models of succession. In contrast, there was a strong, species-specific effect of patch size on small mammal species distribution and abundance. The lack of variance in vegetation structure across patch size during the early seres suggests that small mammal distributions were responding in large part to features of the system other than variance in vegetation structure and composition across patch size. As succession proceeded, the colonization of the system by woody plant species precipitated a series of patch size effects on plant community composition. Differential habitat selection by small mammals at the patch scale tracked these changes in plant distribution. For example, M. ochrogaster and S. hispidus shifted their distributions away from less fragmented patches toward smaller patches, where retarded plant succession had maintained an earlier sere. P. leucopus successfully colonized and maintained high densities only on large patches, where plant succession had progressed most rapidly toward a woody-species-dominated community. Our results highlight the role of landscape structure in long-term community dynamics and indicate that some of the complexity observed in successional systems may result from the structure and composition of the landscape mosaic. In general, our results suggest that to fully understand long-term change within communities, the influence of landscape structure on patterns of heterogeneity in both vegetation and consumer dynamics must be understood. Moreover, the long-term and landscape-scale perspectives afforded by our study provide insight into community dynamics that might otherwise be missed.

The Interaction of Habitat Fragmentation, Plant, and Small Mammal Succession in an Old Field

“…Interstitial area was assumed to be a completely hostile matrix and this area was not incorporated into any of our density estimation procedures (Foster and Gaines 1991, Gaines et al 1992a, b, Diffendorfer et al 1995a, b, 1996. However, recent evidence (Schweiger 1998, Wilson 1998; J. Foster, personal communication; R. Anderson and W. Schweiger, unpublished data) suggests that certain small mammal species use interstitial habitat for foraging and even nesting and that densities calculated using only patch area may be inflated.…”

Role of Landscape Scale in the Distribution of Rodents in an Agroecosystem of Argentina

“…These changes may cause the disappearance or fragmentation of habitats, which in turn affect the composition, structure and function of communities and landscapes (Mc Garigal & Mc Comb, 1995;Schweiger, Diffendorfer, Holt, Pierotti, & Gaines, 2000).…”

Comparison of Three Plot Selection Methods for Estimating Change in Temporally Variable, Spatially Clustered Populations.

“…These distributional changes were correlated with habitat changes, namely, pond hydroperiod and forest canopy cover. Schweiger et al (2000) reported a shift in spatial distributions in populations Microtus ochrogaster and Sigmodon hispidis in Kansas over a 12-year period, apparently in response to changes in patch size and plant seral stage. Conversely, the population of Peromyscus leucopus in the same study area maintained high densities in larger patches of later seral vegetation throughout the time period.…”

“…A sample that is initially representative may lose this quality if there are shifts in population numbers and/or distribution during later time periods that are no longer captured by the original sampled units Stehman 1996, Wikle andRoyle 1999). These population shifts across time could be generated by a number of factors, such as changes in habitat due to anthropomorphic influences (e.g., see Schweiger et al 2000, Coppedge et al 2001 or succession (e.g., see Ballinger andWatts 1995, Skelly et al 1999). This situation exemplifies how an unbiased sample may not necessarily equate to a representative one.…”