Effect of greentree reservoir management on the vegetative and breeding bird communities on the Montezuma National Wildlife Refuge (New York).

摘要

Greentree reservoir (GTR) management is a successful waterfowl enhancement technique used in both the northeastern and southeastern United States. However, numerous years of flooding a forest community can cause changes in the forest composition and structure, and the breeding bird community. I studied the effects of GTR management at the Montezuma National Wildlife Refuge in central New York, comparing vegetation in permanent plots in 2 GTRs and a natural forested wetland over 30 years (pre-flood and 2 years and 18 years after flood cessation), and vegetation and breeding birds over 2 years (pre- and post-flooding).; Although the vegetative composition remained relatively unchanged over 30 years, long-term effects of GTR management were detected 18 years after flood cessation. Red maple and green ash remained the dominant overstory species, however, suppression of green ash regeneration during flooding was evidenced by the higher density of saplings in a natural forested wetland compared to the 2 GTRs. Green ash seedling mortality in 1996 was highest in GTR flooded for 1 year versus an unflooded GTR and a natural forested wetland. Overall, shrub density was resilient after cessation of flooding, but several species had lower densities than a natural forested wetland. Diversity and richness of herbaceous species were similar among all sites 18 years after flood cessation. However, 2 species of fern remained at lower densities while 3 other herbaceous species remained at higher densities 18 years after flood cessation as compared to pre-flood densities and densities in a natural forested wetland. I conclude that although it is unknown after which year of flooding these changes occur, 12 years of GTR management can cause long-term impacts on the forest community. (Abstract shortened by UMI.)