Woody Plant Invasion Into the Freshwater Marl Prairie Habitat of the Cape Sable Seaside Sparrow
Woody Plant Invasion into the Freshwater Marl Prairie Habitat of the Cape Sable Seaside Sparrow Southeast Environmental Research Center Florida International University Authors: Erin Hanan, Michael Ross, Jay Sah, Pablo L Ruiz, Susana Stoffella, Nilesh Timilsina, David Jones, Jose Espinar and Rachel King A Final Report submitted to: U.S. Fish and Wildlife Services Grant Agreement No: 401815G163 February 19, 2009 Summary In the fall of 2005, U.S. Fish and Wildlife Services (USFWS) contracted with Florida International University (FIU) to study the physical and biological drivers underlying the distribution of woody plant species in the marl prairie habitat of the Cape Sable Seaside Sparrow (CSSS). This report presents what we have learned about woody plant encroachment based on studies carried out during the period 2006-2008. The freshwater marl prairie habitat currently occupied by the Cape Sable seaside sparrow (CSSS; Ammodramus maritimus mirabilis) is a dynamic mosaic comprised of species-rich grassland communities and tree islands of various sizes, densities and compositions. Landscape heterogeneity and the scale of vegetative components across the marl prairie is primarily determined by hydrologic conditions, biological factors (e.g. dispersal and growth morphology), and disturbances such as fire. The woody component of the marl prairie landscape is subject to expansion through multiple positive feedback mechanisms, which may be initiated by recent land use change (e.g. drainage). Because sparrows are known to avoid areas where the woody component is too extensive, a better understanding of invasion dynamics is needed to ensure proper management. Through an integrated ground-level and remote sensing approach, we investigated the effects of hydrology, seed source and (more indirectly) fire on the establishment, survival and recruitment of woody stems.
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