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Knieskern's beaked-rush Listed: 7/18/1991 Status since listing: Unknown Typically, this obligate wetland plant is found in groundwater-influenced habitats created by human disturbances including areas such as the edges of clay, sand, or gravel pits; burrow pits functioning as vernal ponds; ditches; unimproved roads; and near railroads and powerline rights of way [1]. Some populations still occur on bog iron substrates, the beaked-rushes' assumed historical preferred habitat that generally occurs adjacent to slow-moving streams [1, 3]. Periodic disturbance, either natural or human-induced that maintains damp-to-wet sites in an early ecological successional stage are thought to be necessary for the beak-rushes= colonization, maintenance, and recruitment [1, 3]. As of 1997, there were 38 extant populations in New Jersey occurring in Atlantic, Burlington, Camden, Monmouth, and Ocean counties [1]. These populations vary widely in size, with the smallest site containing approximately a dozen plants and the largest population occurring in patches covering more than two acres [4]. Six of the known populations occur on bog-iron or other stream bank substrates considered to be naturally maintained without active management [3]. Because all six sites occur on State land they are thought to be relatively secure [3]. Surveys for the Knieskern=s beaked-rush were conducted in 1984 and 1985 and although during this time period the plant had been reduced due to severe drought, several previously unknown populations were discovered [1, 3]. In 1992, three of the populations surveyed in 1984-85 were revisited and although they were all extant, populations appeared to be less extensive [3]. Because populations of Knieskern's beaked-rush can vary dramatically year to year, however, especially as water levels fluctuate in the wetlands they inhabit, population levels of are difficult to estimate [4]. The beaked-rush is threatened by wetland loss and degradation, agricultural runoff, vegetative succession, off-road vehicles, trash dumping and roadside grading [1]. Presently, vegetative succession is a major factor threatening Knieskern's beaked-rush with 19 of 38 extant populations currently undergoing vegetative succession that could eliminate these populations [1]. Without periodic intervention to reverse successional trends, these sites will likely become unsuitable for the species in the future [1]. The 1993 federal recovery plan [3] recommends that delisting be initiated when: (1) Nine populations and their habitat are permanently protected, (2) the species is shown to be an efficient colonizer of newly disturbed sites and/or introduction of the species to suitable habitat is proven to be a feasible technique for species maintenance, (3) a post-delisting strategy for monitoring the species' population trends and/or supplementing natural colonization through introductions to suitable habitat is in place, and (4) no evidence of decline in the species' status is seen by 1996. [1] U.S. Fish and Wildlife Service. 1997. Knieskern's beaked-rush (Rhynchospora knieskernii): Region 5 species account. Website (www.fws.gov/northeast/njfieldoffice/Endangered/Knieskern's_beaked-rush.htm) accessed January 29, 2006. |
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