An integrative study using Landsat TM data, century model output, and a digital elevation model to quantify climatic effects on high plains vegetation related to sand dune stability

Sand dunes were episodically active in central North America during the Holocene, suggesting less dune-stabilizing vegetation cover from more severe and/or longer droughts than the High Plains drought of the 1930s. These dunes may be susceptible to reactivation if the climate becomes more arid. Use of Landsat TM imagery, a nutrient cycling model, and a digital elevation model may help in assessing High Plains sand dune stability.; A suite of CENTURY model experiments examined the effects of drought, grazing, fire, and erosion on dune vegetation dynamics. The impact of 1 mm soil erosion per year is the equivalent of 30 percent less precipitation than the 1930s drought. Local hydrologic factors may also influence High Plains vegetation. Use of a digital elevation model illustrates the surface hydrology of a region and shows water accumulation zones, which can influence the ability of vegetation to survive a prolonged drought.; The Normalized Difference Vegetation Index (NDVI) from Landsat TM imagery is useful for monitoring vegetation changes throughout a growing season and between years that receive differing amounts of precipitation. Vegetation responses in some areas are more climatically sensitive than others'. TM data may be used to assess some changes in grasslands but it has serious limitations in its applicability for more arid shrublands. These limitations result largely from sparse green vegetation cover.; Local hydrologic influences will cause less correlation between NDVI and biomass at smaller scales, such as dune ridges, when sampled at TM's 30-meter resolution. What may be considered “wet” for one region may be “dry” for another. Drier regions will be more susceptible to change, which will be detected earlier. Covariance between wet and dry regions, however, will give early clues for potential dune mobilization across entire regions. Dune reactivation in the past must have started locally in “dry” regions and then spread outwards, as erosion increases the impact of local drought.