Factors Influencing Vegetation Trends in Dryland Zones

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

Land degradation is a significant threat that can reduce agricultural production and cause extreme human suffering. This is particularly true in drylands where climate, soils, and human activities interact to produce desertification, the reduction or loss of ecosystem services in arid and semi-arid regions that negatively affect people, animals, and plants. Nearly the entire western half of the United States is considered a dryland and our country's Dust Bowl of the 1930s is often cited a classic large-scale example of desertification. Severe droughts, inappropriate agricultural practices, and fragile soils caused widespread dust storms and enormous crop and cattle losses in the southern Great Plains. Severe droughts and attending famines in semi-arid Africa and parts of Asia have also been linked to desertification. Because it affects a huge portion of the globe's population, there is a United Nations Convention to Combat Desertification (UNCCD), which was signed in 1994. Despite these historical events and global concern, desertification remains a poorly understood and often controversial environmental process. Basic questions concerning its rate, extent and severity at local, regional and global scales are frequently examined in scientific studies but rarely definitively answered. One of the largest of these questions concerns whether or not desertification, once started, can be reversed and, if so, how? This study uses a test case where droughts in the 1970s and 1980s initiated widespread desertification and where recent satellite images suggest large-scale clusters of increased vegetation, or potentially desertification in reverse. Dr. Colin West and Dr. Aaron Moody of the University of North Carolina at Chapel Hill will explore what factors drive vegetation trends in the greening of dryland zones. This study would test the hypothesis that local land-use practices drive regional vegetation trends. The research would take place in northern Burkina Faso, where one of the researchers has conducted long-term anthropological work since 2002. With previous support from the National Science Foundation, the research team has assembled a time series of satellite images that show distinct areas of both greening (where desertification may be in reverse) and browning (where desertification may be accelerating). Using these results as a guide, they seek to ground-truth these patterns by asking local farmers and herders about their perceptions of environmental change. The anthropologist, his graduate students, and local collaborators will conduct workshops using high-resolution satellite images in areas considered greening, browning and mixed. Using remote sensing procedures, other students will process and analyze these images to measure the amount of vegetation in the three zones. The study predicts that green zones will have more trees than brown zones and that the mixed zone will be intermediate. Workshops will local resource users will also seek their perspectives on how climate, land-use practices, and soils interact to produce these patterns. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.