Wetland Vegetation Response to Groundwater Pumping and Hydrologic Recovery

Abstract

AbstractAn investigation of wetland vegetation response to groundwater alteration was conducted at the J.B. Starkey Wilderness Park, a large municipal wellfield in the area of west Florida, USA. Decades of historic groundwater withdrawal had created a gradient of impacted wetlands on the wellfield, after which time the groundwater pumping rates were reduced. Nineteen cypress dome wetlands were grouped, based on their hydrologic histories, as either most-altered (least inundation), marginally-altered (intermediate inundation), or least-altered (near-normal inundation). Annual species–level monitoring data were used to evaluate understory plant community response to the hydrologic recovery that resulted from reduced groundwater pumping. Species richness, cover, prevalence index (PI), and species importance percentages were assessed during pre- (2005–2007) and post- (2012–2014) hydrologic recovery periods. The vegetation in marginally- and most-altered wetlands responded to hydrologic recovery with increased species richness and lower PI values (i.e., greater hydrophytic character). However, species importance percentages indicated greater variation in the recovery of most-altered wetlands, where species composition often remained different from least-altered wetlands. Although reductions in groundwater pumping caused sufficient passive hydrologic recovery to elicit a vegetation response, further reductions and/or more time may be needed before the vegetation of some altered wetlands can become comparable to that of least-impacted wetlands.