Seasonal variations in moisture use in a piñon–juniper woodland
- 19 June 2007
- journal article
- Published by Springer Science and Business Media LLC in Oecologia
- Vol. 153 (4), 787-798
- https://doi.org/10.1007/s00442-007-0777-0
Abstract
In water-limited environments of the intermountain region of North America, summer precipitation may play a role in the structure and function of aridland communities and ecosystems. This study examined the potential reliance on summer precipitation of two widespread, coexisting woody species in the southwestern United States, Pinus edulis Englmn. (Colorado piñon) and Juniperus osteosperma (Torr) Little (Utah juniper). The current distributions of P. edulis and J. osteosperma are highly suggestive of different dependencies on summer rainfall. We hypothesized that P. edulis was dependent on summer precipitation, utilizing summer precipitation even during extremely dry summers, whereas J. osteosperma was not dependent, using summer precipitation only when amounts were above some minimum threshold. Using sap flux and stable isotopic methods to assess seasonal water sources and water use efficiency, we examined the response of these two species to seasonal variations in moisture at a site located near the northern limits of the North American monsoon. Both sap flux and isotopic results indicated that P. edulis was responsive to summer rain, while J. osteosperma was not. Following summer rain events, sap flux density increased in P. edulis for several days, but not in J. osteosperma. Isotopic evidence indicated that P. edulis took up summer-derived moisture to a greater extent than J. osteosperma. Values of the natural abundance stable isotope ratio of carbon of leaf soluble carbohydrates increased over the summer for P. edulis, indicative of assimilation at higher water use efficiency, but were invariant for J. osteosperma. Our results supported the hypothesis that P. edulis and J. osteosperma are differentially sensitive to summer precipitation and are discussed in the light of potential changes in the seasonality of precipitation associated with climate change.Keywords
This publication has 56 references indexed in Scilit:
- Water extraction times for plant and soil materials used in stable isotope analysisRapid Communications in Mass Spectrometry, 2006
- Summer and winter drought in a cold desert ecosystem (Colorado Plateau) part II: effects on plant carbon assimilation and growthJournal of Arid Environments, 2005
- Combining sources in stable isotope mixing models: alternative methodsOecologia, 2005
- A multi-scale perspective of water pulses in dryland ecosystems: climatology and ecohydrology of the western USAOecologia, 2004
- Resource pulses, species interactions, and diversity maintenance in arid and semi-arid environmentsOecologia, 2004
- Source partitioning using stable isotopes: coping with too many sourcesOecologia, 2003
- Uncertainty in source partitioning using stable isotopesOecologia, 2001
- Limits to water transport inJuniperus osteospermaandPinus edulis: implications for drought tolerance and regulation of transpirationFunctional Ecology, 1998
- Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groupsOecologia, 1998
- Structure and Dynamics of the Arizona Monsoon BoundaryMonthly Weather Review, 1989