Long-term Monitoring of Two Subpopulations of the Federally Threatened Aeschynomene virginica (Sensitive Joint-vetch) in Maryland

Abstract

Abstract The largest Maryland population of the federally threatened tidal freshwater wetlands legume, Aeschynomene virginica (Sensitive Joint-vetch), is comprised of two subpopulations in the Manokin River watershed. To provide baseline data fundamental to understanding annual fluctuations and long-term trends, annual censuses began in 1991 and 1994 for Taylor Branch and Manokin River subpopulations, respectively, and continued through 2009. In addition, distributional limits, phenology, average plant height, associated plant species, and muskrat activity were recorded to better understand plant and habitat characteristics. Large annual fluctuations in size were common to both subpopulations. The Manokin River subpopulation (2 km in extent) averaged 1,867 ± 268 plants (n = 16), ranged from 715–4,394 plants, and inhabited marshes (56%) and banks (44%). Subpopulation size increased significantly during the survey period. June rainfall may have contributed to a tripling in subpopulation size from 2005 to ...