Submitted to: Arid Soil Research And Rehabilitation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/1997
Publication Date: N/A
Interpretive Summary: Climate change will have major impacts on the ecosystems of the world. Any information relative to the nature and extent of such impacts would be of great value in mitigating these impacts. The Environmental Protection Agency ask a group of specialist to use their judgement as to which soil variables would be most impacted by five scenarios of climate change in the deserts of North America. These scenarios included no change but increased human impacts; changes in the variability of annual precipitation; a shifting of winter to summer precipitation; and a 2oC increase in mean annual temperature with a 20% increase and a 20% decrease in mean annual precipitation. Computer modeling was used to integrate and project interactive changes. All scenarios impacted the physical and chemical characteristics of the desert soils, usually in a negative direction, e.g., increased crusting, soil erosion, salinity, and reductions in organic carbon and nitrogen. Only slight changes in soil phosphorus, sulphur and trace elements are expected. Projections of potential impacts of climate change will assist government agencies to prepare mitigation strategies.
Technical Abstract: A group of specialists was asked by the EPA to use their judgement as to which soil variables would be most impacted by five scenarios of climatic change in deserts of North America that could occur over the next 40 years. The following soil characteristics were evaluated in terms of their potential for change: physical, chemical and biological crusts; the vesicular layer; soil organic matter; organic C and N content; the C/N ratio; carbonate pool; inorganic N, P, and S; salinity levels; micro-element content; microbial community composition; free-living microbial N fixation; denitrification; ammonia volatilization; salinization rates; water infiltration; evaporation; lateral flow and leaching; wind and water erosion; and litter decomposition. The Delphi approach was used to reach consensus on expected trends. Computer modeling was used to integrate and project interactive changes. Indicators of desert ecosystem "health" that we identified are relatively low albedo, patchiness of plant cover and interspace (trend depends on context), changes in drainage patters and microrelief, biological crusting, and ratios of microbial biomass C to total organic C.