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Assessing Biogeochemical Process in Dryland Ecosystems: Potential Impacts of Climate Change

  • Author(s): Dintwe, Kebonyethata
  • Advisor(s): Okin, Gregory
  • et al.
Abstract

Drylands are drought-prone biomes in which precipitation is less than the potential evapotranspiration for the whole year, or for the most part of it. They include grasslands, shrublands, savannas, Mediterranean and deserts. Drylands cover 6.3 billion hectares (Bha) or 47% of the earth’s land surface, and are home to 30% of the global human population. Collectively, drylands highly productive, contributing 30% of the global net primary productivity. Although dryland soils contain low organic carbon at local scale, globally they contain 20% of the global soil organic carbon. Furthermore, dryland are fire-prone ecosystems, with more than 80% of global wildfires occurring in drylands. The biogeochemical processes, such as soil carbon sequestration and fire regime are highly regulated by precipitation, and to some extent surface temperature.

Climate models, on the other hand, show that drylands would experience a decrease in mean annual precipitation, and an increase in surface temperature. The secondary effects of climate change include frequent extreme weather events such as strong winds, lighting and droughts. The predicted climate change and associated secondary effects are likely to alter and modify biogeochemical processes in drylands, a process that could lead drylands to become either net carbon source or sink depending on the magnitude of climate change. In light of the relationship between climate change and dryland functions, it is imperative to assess and evaluate the magnitude of the potential impacts of climate change in biogeochemical processes in drylands.

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