Earth’s Critical Zone (CZ), the near-surface layer where rock is weathered and landscapes co-evolve with life, is profoundly influenced by the type of underlying bedrock. Previous studies employing the CZ framework have focused primarily on landscapes dominated by silicate rocks. However, carbonate rocks crop out on approximately 15% of Earth’s ice-free continental surface and provide important water resources and ecosystem services to ~1.2 billion people. Unlike silicates, carbonate minerals weather congruently and have high solubilities and rapid dissolution kinetics, enabling the development of large, interconnected pore spaces and preferential flow paths that restructure the CZ. Here we review the state of knowledge of the carbonate CZ, exploring parameters that produce contrasts in the CZ in different carbonate settings and identifying important open questions about carbonate CZ processes. We introduce the concept of a carbonate-silicate CZ spectrum and examine whether current conceptual models of the CZ, such as the conveyor model, can be applied to carbonate landscapes. We argue that, to advance beyond site-specific understanding and develop a more general conceptual framework for the role of carbonates in the CZ, we need integrative studies spanning both the carbonate-silicate spectrum and a range of carbonate settings.

Land-use decisions and ecosystem characteristics affect the amounts of nutrients that end up in water bodies and the ability of the land to provide ecosystem services. Water quality is also highly valued by Florida forest landowners and managers. So, understanding the role of land use and forest cover and types, management practices, and conservation programs in reducing nutrient pollution will allow landowners, forest managers, and policy makers to make informed and better management decisions. In this 6-page fact sheet, we present the results of a study that used easily available models and information to assess the role of forests in providing ecosystem services, including water quality improvement or purification. Specifically, this assessment used available geospatial data and the InVEST Water Purification model to estimate how forest vegetation and soils purify water through the retention, and subsequent export, of nitrogen and phosphorus polluted runoff. Written by Sonia Delphin, Francisco J. Escobedo, Amr Abd-Elrahman, Alison E. Adams, Jackie Martin, Ronald Cademus, and published by the UF Department of School of Forest Resources and Conservation, January 2014. FOR317/FR385: Stewardship Ecosystem Services Study Series: Assessing Forest Water Yield and Regulation Ecosystem Services in the Lower Suwannee River Watershed, Florida (ufl.edu)