Coping with water scarcity: Lessons from giant cacti of the Americas
A public lecture by David Williams, Professor of Botany, University of Wyoming and Institute of Advanced Studies Visiting Fellow.
Drylands cover almost half of Earth’s land surface, and climate warming is likely to intensify drought conditions globally. Human strategies to cope with water scarcity generally focus on improving the capture and efficient use of limited water supplies, and in many circumstances storage of fresh water in large surface reservoirs for future use. Here we can learn much from nature’s designs. The masters of drought adapted plants, and certainly the most charismatic, are the giant columnar cacti. The more than 70 species of giant columnar cacti, members of the large and highly diverse cactus family, a New World group of plants, are noted for their exaggerated structural forms and capacity to thrive in the harshest desert environments on Earth. Survival and ecological success of giant cacti are dependent on rapid capture of water from infrequent precipitation events, storage of water in specialized tissues within highly modified stems, sometimes on a very massive scale, and deployment of CAM photosynthesis which amplifies efficiency of photosynthetic water use by an order of magnitude over plants with other more common photosynthetic pathways.
This talk will explore the physiological, structural and ecological diversity of giant cacti from the deserts of the Americas noting especially the functional tradeoffs associated with extreme water storage capacity. Lessons can be applied to the design of food production and agricultural practices, and to conservation of biodiversity in fragile desert landscapes in the face of climate change.
David Williams is Professor and former Head of Botany at the University of Wyoming. He conducts fundamental and applied research in the areas of ecohydrology, biogeochemistry and plant ecophysiology in dryland environments. He founded and serves as Faculty Director of the University of Wyoming Stable Isotope Facility. Professor Williams received his PhD at Washington State University in 1992. After spending three years as a postdoctoral research fellow at the University of Utah with Professor James Ehleringer, Professor Williams joined the faculty at the University of Arizona in as an assistant professor. He earned tenure and promotion to associate professor at the University of Arizona in 2001 and then spent one year as Senior Fulbright Fellow at Paul Sabatier University in Toulouse France. Professor Williams moved to his current position at the University of Wyoming in 2003 to start and lead a new research program in isotope ecology. He has published over 120 refereed journal articles and book chapters, supervised 13 masters and 13 doctoral students, and mentored 10 postdoctoral researchers. He currently serves on the editorial board for the journals Ecology and Ecological Monographs and is an invited editor of a forthcoming special issue on CAM Biology in the Journal of Experimental Botany.