AUTHORS: Josh Williams, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO 65211, USA; Lisa Webb, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO 65211, USA; Jonathan Spurgeon, U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
ABSTRACT: During the 20th century, extensive flood control infrastructure was built along many US rivers, separating mainstem river channels from floodplains and altering floodplain wetland structure and function. Wetland restoration often occurs in locations where levees have disconnected the floodplain from the mainstem river channel. Disconnected wetlands can experience reduced nutrient exchange, habitat heterogeneity, biodiversity, and hazard mitigation compared to wetlands in connected floodplains. Understanding the effects of river-floodplain connectivity on wetland restoration efforts has been limited—in part—by brief time periods between restoration and evaluation. The Agricultural Conservation Easement Program – Wetland Reserve Easements (ACEP-WRE) program, established in 1990, is a voluntary program that provides landowners with technical assistance and financial incentives to restore marginal farmland to historic wetland conditions. Our objective is to compare abiotic and biotic metrics in ACEP-WRE wetlands along a gradient of restoration age (6 to 29 years) and degree of connectivity between the Missouri River and the adjacent floodplain. Hydrological connectivity was categorized based on wetland proximity to an adjacent levee system (landward or riverward) and quantified using continuous temperature logging units, level of local mainstem channel incision, and historical river stage data. At each ACEP-WRE site (riverward sites n = 26, landward sites n = 24), water, soil, and algae samples were collected along with surveys of vegetation, macroinvertebrate, fish, amphibian, and bird assemblages. We compare metrics for riverward and landward sites with six reference and six control sites to elucidate whether river-floodplain connectivity affects the time needed to achieve ACEP-WRE restoration goals.
