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RESPONSES OF SALIX GOODDINGII AND TAMARIX RAMOSISSIMA TO FLOODING
Citation:
TallentHalsell, N G. AND L. M. Walker. RESPONSES OF SALIX GOODDINGII AND TAMARIX RAMOSISSIMA TO FLOODING. WETLANDS 22(4):776-785, (2003).
Impact/Purpose:
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Description:
Impoundments create artificial shorelines that differ from natural lake shorelines in patterns of water-level fluctuations, flow, sediment transport, and shoreline vegetation dynamics. Shoreline plant communities in the American Southwest often become dominated by mature, senescent Populus and Salix, with few if any seedlings. The failure of native plant community replacement is exacerbated by the fact that Tamarix, a prolific invader, is abundant on regulated rivers and occupies extensive areas along the shores of impoundments. Efforts to replant natives within the often-flooded drawdown zone surrounding Lake Mohave, a lower Colorado River impoundment bordering Nevada and Arizona, have not been successful. A greenhouse experiment was designed to examine the responses of cuttings of a native species, Salix
gooddingii (Goodings willow), and the invasive species, Tamarix ramosissima (salt cedar), to
different water levels comparable to those influencing Lake Mohave riparian plant communities
High survival and rapid growth under saturated but not flooded soil conditions demonstrated that both Salix and Tamarix cuttings can prosper in soils within the exposed drawdown zone,
provided the shoots are not submerged. However, particularly rapid growth in Tamarix under
conditions favorable to the native Salix also indicates that Tamarix invasion will have to be
controlled. Revegetation efforts must include matching the natural hydrodynamics of the
waterway to the requirements of native plant species.