The Importance of Southern Hemisphere CZOs for Evaluating Spatial Patterns of Chemical Structure in the Critical Zone and Assisting Human Development

Abstract:

The US Critical Zone Exploration Network (CZEN) is a network of sites designed to provide a better understanding of the integrated Earth surface system. The capacity of the critical zone to withstand perturbations, whether driven by climate, land use change, or spread of invasive species, depends on its chemical composition and physical state, which in turn depends on the time evolution of the critical zone. Many temperate and/or tectonically active critical zones contain a relatively short history due to rapid erosion but tectonically quiescent, tropical regions of the planet contain much longer records that need to be understood to cover the full suite of critical zone processes. Southern Hemisphere Critical Zone Observatories such as those proposed for Kruger National Park (KNP) in South Africa and for portions of the Yilgarn Craton in Western Australa will allow us to extend our temporal understanding of development of spatial heterogeneity in the chemical and physical structure of the critical zone. In addition to considering Earth and climate boundary conditions, these sites incorporate the roles that humans play in driving critical zone processes. For instance along the edges of KNP there is strong evidence of soil erosions due to periurbanization and small-scale agriculture. The existence of KNP provides an important contrast between a “natural” and “human-dominated” landscape that can be exploited to evaluate human impacts on critical zone resources and to develop targeted mitigation strategies. Western Australia has an exploitive economy that relies on large-scale agriculture and mineral extraction, both are intensive users of water which is scarce. The proposed CZO there will be partly focused on managing water under intense economic pressures. It is evident that if funding can be found for these sites they will enhance both critical zone science and practical applied science.