International Arid Lands Consortium investigates biological degradation and restoration of arid and semi-arid lands

Physically active soil organic matter: Key factor in arid land reclamation?

July 26, 2000 (Tucson, AZ)-- International Arid Lands Consortium (IALC) is conducting research on land degradation and restoration in arid and semi-arid regions of the world. Livestock grazing and growth of cities have lead to major changes in vegetation and soil conditions. These changes significantly impact biological diversity, land productivity, water movement and quality, and soil erosion potential. Such impacts have both ecological and economic implications.

The interaction between historic livestock impact and periodic drought conditions in arid and semiarid regions is thought to be the major factor which has caused widespread degradation of many natural grasslands, according to Dr. Simon Bird, a postdoctoral research associate based at the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) Jornada Experimental Range in New Mexico. However, the ecological processes involved in both degradation and recovery are poorly understood. In order to develop ways of effectively and sustainably managing arid and semiarid rangeland, these processes need to be understood and reliably monitored.

A research team from University of Illinois, USDA-ARS Jornada Experimental Range in New Mexico, and Bar-Ilan University in Israel is investigating how the relationship between soil stability and vegetation change. Soil aggregation (the formation of larger soil particles from smaller primary particles) is very important for soil fertility, water movement, and soil aeration, and greatly influences plant growth. Increased formation and stability of large soil particles decrease the risk of soil erosion from wind and water action.

Researchers are measuring soil aggregate stability in an area of semi-arid rangeland in the Chihuahuan Desert of New Mexico, USA. They are investigating how stability changes through time and over space in areas of rangeland in different stages of degradation. In this way, they are able to test the potential of aggregate stability as an indicator of overall rangeland condition and further understand the response of the soil to shifts in vegetation cover.

The two-year project, titled, "Physically active soil organic matter: Key factor in arid land reclamation?" also attempts to determine which parts of soil organic matter are most important for increasing soil aggregation. Soil organic matter is mostly made up of the products of decomposed plant and animal material, and material exuded from plant roots and soil microbes. Measurements of soil organic matter will lead to the identification of the most effective strategies that land managers can use to restore degraded rangeland soils and slow degradation in threatened areas.

"Our research has also allowed us to test different methods of measuring soil stability," says Dr. Bird. "Land managers in arid and semi-arid rangelands are in need of reliable tools for monitoring ecosystem condition and performing impact assessments. We are currently determining which soil stability methods have most utility for these purposes."

"Given the importance of soil aggregation and soil organic matter to the prevention of soil erosion, regulation of water movement, soil aeration, and plant growth, this research has broad implications for rangeland monitoring and management," says Dr. Bird. "Our long-term goal is to develop sustainable management guidelines and practices for semi-arid rangeland based on ecological processes, the exploitation of the natural spatial and temporal variability within these systems, and manipulation of soil inputs."

Other researchers on the team include Dr. Jeff Herrick, Soil Scientist at the USDA-ARS Jornada Experimental Range in New Mexico, and Dr. Michelle Wander, Assistant Professor of Soil Fertility/Ecology at the Department of Natural Resources and Environmental Sciences at the University of Illinois Urbana-Champaign. Israeli scientists from Bar Ilan University include Hanoch Lavee, Professor in the Department of Geography and Sarah Pariente, Research Associate.



The International Arid Lands Consortium (IALC) is an independent nonprofit organization dedicated to exploring the problems and solutions unique to arid and semiarid regions. IALC promotes cooperative research and practical application of new knowledge to develop sustainable ecological practices. The member institutions and their affiliates share a mission to enable people of arid lands to improve the quality of life for future generations. IALC members include the University of Arizona, Desert Research Institute-Nevada, the University of Illinois, Jewish National Fund, New Mexico State University, South Dakota State University, Texas A&M University-Kingsville, and the Higher Council for Science & Technology-Jordan. The Ministry of Agriculture & Land Reclamation-Egypt is an affiliate member.

Project Addressed in this News Release:
  • 00D-03 Management of Semi-arid Watersheds - Phase 2: Decision-Making Tools and Technology Transfer (The University of Arizona, USDA Forest Service)