Evapotranspiration and water yield of a pine‐broadleaf forest are not altered by long‐term atmospheric [CO2] enrichment under native or enhanced soil fertility |
| |
| Authors: | Eric J Ward Ram Oren Hyun Seok Kim Dohyoung Kim Pantana Tor‐ngern Brent E Ewers Heather R McCarthy Andrew Christopher Oishi Diane E Pataki Sari Palmroth Nathan G Phillips Karina V R Schäfer |
| |
| Institution: | 1. Division of Environmental Science and Policy, Nicholas School of the Environment, Duke University, Durham, North Carolina;2. Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee;3. Department of Forest Sciences, University of Helsinki, Helsinki, Finland;4. Department of Civil and Environmental Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina;5. Department of Forest Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, Korea;6. Institute of Future Environmental and Forest Resources, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea;7. National Center for Agro‐Meteorology, Seoul, Korea;8. Interdisciplinary Program in Agriculture and Forest Meteorology, Seoul National University, Seoul, Korea;9. Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana;10. Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand;11. Department of Botany and Program in Ecology, University of Wyoming, Laramie, Wyoming;12. Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma;13. USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory, Otto, North Carolina;14. Department of Biology, University of Utah, Salt Lake City, Utah;15. Department of Earth and Environment, Boston University, Boston, Massachusetts;16. Department of Biological Sciences, Rutgers University, Newark, New Jersey |
| |
| Abstract: | Changes in evapotranspiration (ET) from terrestrial ecosystems affect their water yield (WY), with considerable ecological and economic consequences. Increases in surface runoff observed over the past century have been attributed to increasing atmospheric CO2 concentrations resulting in reduced ET by terrestrial ecosystems. Here, we evaluate the water balance of a Pinus taeda (L.) forest with a broadleaf component that was exposed to atmospheric CO2] enrichment (ECO2; +200 ppm) for over 17 years and fertilization for 6 years, monitored with hundreds of environmental and sap flux sensors on a half‐hourly basis. These measurements were synthesized using a one‐dimensional Richard's equation model to evaluate treatment differences in transpiration (T), evaporation (E), ET, and WY. We found that ECO2 did not create significant differences in stand T, ET, or WY under either native or enhanced soil fertility, despite a 20% and 13% increase in leaf area index, respectively. While T, ET, and WY responded to fertilization, this response was weak (<3% of mean annual precipitation). Likewise, while E responded to ECO2 in the first 7 years of the study, this effect was of negligible magnitude (<1% mean annual precipitation). Given the global range of conifers similar to P. taeda, our results imply that recent observations of increased global streamflow cannot be attributed to decreases in ET across all ecosystems, demonstrating a great need for model–data synthesis activities to incorporate our current understanding of terrestrial vegetation in global water cycle models. |
| |
| Keywords: | |
|
|
