Reflections on the Kansas long-term habitat fragmentation experiment: >30+ years, and counting
A large-scale, long-term experiment examining the interplay of habitat fragmentation and succession was established in the prairie-forest ecotone of eastern Kansas in the early 1980’s and maintained to the present day. The initial focus of the project was to meld the insights of island biogeography theory (area and distance effects on colonization and extinction) into the study of succession, another domain of ecology in which colonization and extinction are key processes. The original hypothesis was that habitat patch size and landscape position (proximity to woodland) should mediate dynamics of secondary succession by governing rates and/or trajectories of community change, due to both direct effects on plant colonization and extinction, and indirect effects such as the modulation of trophic interactions. Our methods consisted of intensive repeated sampling of the plant community, small mammals, and other components of the successional ecosystem in a grid of permanent sample stations.
Impacts of patch size appeared quickly for some species, but testing the original system-level hypothesis about succession required long time-series emerging from many years of sample. In the study, by the late 1990’s, plant succession started to strongly reflect patch size ‘signals’, particularly in patterns of woody plant colonization and herbaceous plant extinction. This highlights the value and essential need for maintaining long-term field experiments. Further, with the passage of time, the conceptual framework of the project matured and elaborated, with the crystallization of metacommunity concepts, a growing recognition of the importance of matrix-patch interactions, and the interplay of plant community ecology and ecosystem processes -- all of which are at play in the perturbations to ‘whole systems’ occurring in fragmentation, including in the Kansas experiment. Many puzzles remain, and a particular present challenge is to disentangle ongoing successional changes in communities from changes driven by temporally varying processes at larger scales such as climate change.