Abstract
Developers of renewable energy installations in Southern California must monitor the impacts of operations of new facilities on fragile desert ecosystems. This study is the first to use Landsat satellite spectral data to map changes in the distribution of biological soil crusts (BSCs) across federal lands of the Lower Colorado Desert. The coverage of BSCs comprising >33% pixel area totaled 4008 Km2 in 1990, and increased to 4841 Km2 by 2014. The proximity of changing areas of BSC cover between 1990 and 2014 to known river flow channels such as the Lower McCoy Wash, Riverside County, CA) implied that flash floods associated with heavy precipitation events are important agents of change for BSC cover. These results have an immediate application for mapping the potential impacts of flash flood events around developed urban areas and utility-scale solar energy installations in the deserts of Southern California.
Highlights
Knowledge of the ecological roles of biotic soils crusts (BSCs) in arid lands has advanced greatly over the past several decades and has transformed how managers of desert ecosystems understand biological processes that stabilize and fertilize desert soils [1]
Changes in BSC coverage Biological Soil Crusts Index (BSCI) maps generated for the years 1990, 2000, 2010, and 2014 across the Southern DRECP study area in the Lower Colorado Desert (Figure 2) showed the distribution of BSCs at >33% Landsat pixel cover, which fell within the BSCI value range of 2.7 to 4.75
Subtle changes in vegetation cover in the period after most Southern California solar energy developments were initiated could instead be attributed largely to topographic water flow pathways through canyons and desert washes, both in and around the solar energy Development Focus Areas (DFAs). To begin extending this analysis to include threats to BSC cover, the DFAs delineated as potential footprints of renewable energy development in the DRECP study area were overlaid on BSCIs cover types from 2010 to calculate the areas at risk for disturbance from energy development activities
Summary
Knowledge of the ecological roles of biotic soils crusts (BSCs) in arid lands has advanced greatly over the past several decades and has transformed how managers of desert ecosystems understand biological processes that stabilize and fertilize desert soils [1]. Generalizations about ecologic functions of BSCs are still difficult to make because of the great diversity life forms and species in soil crust communities, consisting variously of bacteria, lichens, and non-vascular plants such as mosses [4]. BSCs in these California deserts are patchily distributed and have less structural complexity and biological diversity than crust communities found in the better-studied and generally cooler Great Basin and Colorado Plateau arid lands [1,2]
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