Hydrology and fire regulate edge influence on microclimate in wetland forest patches

Abstract

Differences in temperature, relative humidity, and vapor pressure deficit (VPD) were observed within small patches of pondcypress (Taxodium distichum var. imbricarium) compared with adjacent, largely treeless, vegetation communities. These patches, locally called cypress domes, displayed increasing differences in microclimate between their exterior or edges and interiors with increasing distance toward their centers. We sought to assess whether seasonal inundation of these small swamps results in a hydrologic switch in which the presence of standing water overwhelms the effects of edge distance on microclimate variation. Hydrology does appear to exert substantial control over the edge effect on microclimate, but the effects of distance from the edge remained discernable during periods of inundation. We also studied the effects of a wildfire that occurred 2 y before data collection. We expected to find warmer and drier conditions in domes affected by recent fire. Contrary to our expectations, previously burned domes were either similar to unburned domes or, in some cases, cooler and more humid than unburned domes, possibly because of vigorous regrowth after fire in these highly productive, fire-adapted subtropical ecosystems.