989 resultados para United States. National Park Service.


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Transpiration-driven nutrient accumulation has been identified as a potential mechanism governing the creation and maintenance of wetland vegetation patterning. This process may contribute to the formation of nutrient-rich tree islands within the expansive oligotrophic marshes of the Everglades (Florida, United States). This study presents hydrogeochemical data indicating that tree root water uptake is a primary driver of groundwater ion accumulation across one of these islands. Sap flow, soil moisture, water level, water chemistry, and rainfall were measured to identify the relationships between climate, transpiration, and groundwater uptake by phreatophytes and to examine the effect this uptake has on groundwater chemistry and mineral formation in three woody plant communities of differing elevations. During the dry season, trees relied more on groundwater for transpiration, which led to a depressed water table and the advective movement of groundwater and dissolved ions, including phosphorus, from the surrounding marsh towards the centre of the island. Ion exclusion during root water uptake led to elevated concentrations of all major dissolved ions in the tree island groundwater compared with the adjacent marsh. Groundwater was predominately supersaturated with respect to aragonite and calcite in the lower-elevation woody communities, indicating the potential for soil formation. Elevated groundwater phosphorous concentrations detected in the highest-elevation woody community were associated with the leaching of inorganic sediments (i.e. hydroxyapatite) in the vadose zone. Understanding the complex feedback mechanisms regulating plant/groundwater/surface water interactions, nutrient dynamics, and potential soil formation is necessary to manage and restore patterned wetlands such as the Everglades.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

One goal of Gray’s Reef National Marine Sanctuary (NMS) is to protect the unique community found within the Sanctuary’s boundaries. An understanding of the ecological interactions, including trophic structure, among these organisms is necessary to realize this goal. Therefore, diet information for 184 fish species was summarized from 113 published studies. Among the fish included are 84 fish species currently known to reside in Gray’s Reef NMS. The locations of these studies ranged from the Atlantic Ocean off the coast of the northeast United States to northern Brazil, the Gulf of Mexico, and the Caribbean. All of the species described in this bibliography occur in the southeast United States and are, therefore, current or potential residents of Gray’s Reef National Marine Sanctuary. Each entry includes the objectives, brief methods, and conclusions of the article. The bibliography is also indexed by species. (PDF contains 64 pages.)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Salt River Bay National Historical Park and Ecological Preserve (hereafter, SARI or the park) was created in 1992 to preserve, protect, and interpret nationally significant natural, historical, and cultural resources (United States Congress 1992). The diverse ecosystem within it includes a large mangrove forest, a submarine canyon, coral reefs, seagrass beds, coastal forests, and many other natural and developed landscape elements. These ecosystem components are, in turn, utilized by a great diversity of flora and fauna. A comprehensive spatial inventory of these ecosystems is required for successful management. To meet this need, the National Oceanic and Atmospheric Administration (NOAA) Biogeography Program, in consultation with the National Park Service (NPS) and the Government of the Virgin Islands Department of Planning and Natural Resources (VIDPNR), conducted an ecological characterization. The characterization consists of three complementary components: a text report, digital habitat maps, and a collection of historical aerial photographs. This ecological characterization provides managers with a suite of tools that, when coupled with the excellent pre-existing body of work on SARI resources, enables improved research and monitoring activities within the park (see Appendix F for a list of data products).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The 1982–1994 National Long-Term Care Surveys indicate an accelerating decline in disability among the U.S. elderly population, suggesting that a 1.5% annual decline in chronic disability for elderly persons is achievable. Furthermore, many risk factors for chronic diseases show improvements, many linked to education, from 1910 to the present. Projections indicate the proportion of persons aged 85–89 with less than 8 years of education will decline from 65% in 1980 to 15% in 2015. Health and socioeconomic status trends are not directly represented in Medicare Trust Fund and Social Security Administration beneficiary projections. Thus, they may have different economic implications from projections directly accounting for health trends. A 1.5% annual disability decline keeps the support ratio (ratio of economically active persons aged 20–64 to the number of chronically disabled persons aged 65+) above its 1994 value, 22:1, when the Hospital Insurance Trust Fund was in fiscal balance, to 2070. With no changes in disability, projections indicate a support ratio in 2070 of 8:1—63% below a cash flow balance.