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SAND FLUX IN THE NORTHERN CHIHUAHUAN DESERT, NEW MEXICO, USA, AND THE INFLUENCE OF MESQUITE-DOMINATED LANDSCAPES
Citation:
GILLETTE, D. AND A M. Pitchford. SAND FLUX IN THE NORTHERN CHIHUAHUAN DESERT, NEW MEXICO, USA, AND THE INFLUENCE OF MESQUITE-DOMINATED LANDSCAPES. JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 109:doi: 10.1029/2003JF0, (2004).
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:
This study was designed to test two hypotheses: (1) that land dominated by mesquite (Prosopis glandulosa) is the most important area for active sand movement at the Jornada Experimental Range, located in the northern part of the Chihuahuan desert, and (2) that the most active sand movement in the mesquite-dominated ecosystems takes place on elongated bare soil patches ( "streets") having sandy-textured soil texture between the mesquite plants oriented in the direction of the strongest winds. Both hypotheses were confirmed by the evidence discussed in this paper. To integrate the wind observations, vegetation mapping, and sand flux monitoring described in this paper, we modeled the spatial and temporal mean airborne sand mass flux. The model had the form of an expectation integral that used information on the following: the increase in sand flux with street length, a function for the horizontal mass flux based on friction velocity and threshold friction velocity, wind speed probability versus wind direction, probability of street length versus direction, and probability of friction velocity being exceeded. The model's calculations of mean sand flux movement showed fairly good proportionality with the observed mean sand fluxes at three sites dominated by mesquite vegetation.