Large, connected floodplain forests prone to flooding best sustain plant diversity

作者：Sarah E. Johnson, Kathryn L. Amatangelo, Philip A. Townsend, Donald M. Waller · 发表于：Ecology · 年份：2016 · DOI：10.1002/ecy.1556 · 被引用次数：41 · 研究领域：Ecology and Vegetation Dynamics Studies、Fire effects on ecosystems、Hydrology and Sediment Transport Processes

Dams, levees, and water withdrawals disrupt hydrologic regimes and associated floodplain forests. Because these forests are also responding to changes in land use, species invasions, and climate change, the relative effects of these factors are hard to disentangle. Most studies of floodplain forests lack historic data, requiring us to rely on recent data or contemporary spatial relationships to these drivers to infer those causes of vegetation dynamics. Here, we use survey data from the 1950s to reconstruct plant community changes across 40 floodplain forests in Wisconsin. We applied two partial least squares regression (PLS) models to evaluate how current site and landscape scale conditions and changes in these conditions since the 1950s influence contemporary patterns of community diversity and composition. Local site variables were among the most important in explaining current composition metrics and their changes, but historic landscape variables and changes in these were also important. Current local diversity (α) was the highest at sites prone to frequent flooding, even at sites in fragmented landscapes. Sites along sinuous rivers in large watershed areas with more contiguous forest had the highest abundance of wetland indicator plants in the re-survey and had the largest increases in α diversity since the 1950s, despite having the highest presence of exotic species then. These same sites have converged in composition, reflecting increases in wetland indicator plants a...