Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland
| Autor: | William J. Riley, Todd E. Dawson, Heath Powers, William T. Pockman, Nate G. McDowell, Clifton W. Meyer, J. H. Shim, Alexander Knohl |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0106 biological sciences
010504 meteorology & atmospheric sciences Vapour Pressure Deficit lcsh:Life Flux Juniperus monosperma 01 natural sciences lcsh:QH540-549.5 Water content Ecology Evolution Behavior and Systematics 0105 earth and related environmental sciences Earth-Surface Processes Transpiration Hydrology biology Chemistry Hydrologic control oxygen isotope semi-arid woodland lcsh:QE1-996.5 15. Life on land Oxygen isotope ratio cycle biology.organism_classification lcsh:Geology lcsh:QH501-531 13. Climate action Environmental chemistry Soil water lcsh:Ecology Ecosystem respiration 010606 plant biology & botany |
| Zdroj: | Biogeosciences, Vol 10, Iss 7, Pp 4937-4956 (2013) |
| ISSN: | 1726-4189 |
| Popis: | We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma) woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR). Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET) was significantly related to post-pulse δR enrichment because the leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET/ES). In contrast, the soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought. |
| Databáze: | OpenAIRE |
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