• Aubinet, M., and Coauthors, 2000: Estimates of the annual net carbon and water exchange of forests: The EUROFLUX methodology. Adv. Ecol. Res., 30 , 113175.

    • Search Google Scholar
    • Export Citation
  • Austin, T. A., and Coauthors, 2004: Water pulses and biogeochemical cycles in arid and semiarid ecosystems. Oecologia, 141 , 221235.

  • Baldocchi, D., , and Meyers T. , 1998: On using eco-physiological, micrometeorological and biogeochemical theory to evaluate carbon dioxide, water vapor and trace gas fluxes over vegetation: A perspective. Agric. For. Meteor., 90 , 125.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Blanken, P. D., and Coauthors, 1997: Energy balance and canopy conductance of a boreal aspen forest: Partitioning overstory and understory components. J. Geophys. Res., 102 , 2891528927.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Caldwell, M. M., 1985: Physiological ecology of North American plant communities. Cold Desert, B. F. Chabot and H. A. Mooney, Eds., Chapman and Hall, 198–212.

    • Search Google Scholar
    • Export Citation
  • Dobrowolski, J. P., , Caldwell M. M. , , and Richards J. H. , 1990: Basin hydrology and plant root systems. Plant Biology of the Basin and Range, C. B. Osmond, L. F. Pitelka, and G. M. Hidy, Eds., Ecological Studies, Vol. 80, Springer-Verlag, 243–292.

    • Search Google Scholar
    • Export Citation
  • Donovan, L., , and Ehleringer J. R. , 1994: Water stress and use of summer precipitation in a Great Basin shrub community. Funct. Ecol., 8 , 289297.

  • Ehleringer, J. R., , Schwinning S. , , and Gebauer R. , 1999: Water-use in arid land ecosystems. Plant Physiological Ecology, M. C. Press, J. D. Scholes, and M. G. Barker, Eds., Blackwell, 347–365.

    • Search Google Scholar
    • Export Citation
  • Emmerich, W. E., 2003: Carbon dioxide fluxes in a semiarid environment with high carbonate soils. Agric. For. Meteor., 116 , 91102.

  • Finnigan, J. J., , and Belcher S. E. , 2004: Flow over a hill covered with a plant canopy. Quart. J. Roy. Meteor. Soc., 130 , 129.

  • Flanagan, L. B., , Ehleringer J. R. , , and Marshall J. D. , 1992: Differential uptake of summer precipitation among co-occurring trees and shrubs in a pinyon-juniper woodland. Plant Cell Environ., 15 , 831836.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Flanagan, L. B., , Wever L. A. , , and Carlson P. J. , 2002: Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland. Global Change Biol., 8 , 599615.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Goulden, M. L., , Daube B. C. , , Fan S. M. , , Sutton D. J. , , Bazzaz A. , , Munger J. W. , , and Wofsy S. C. , 1997: Physiological responses of a black spruce forest to weather. J. Geophys. Res., 102 , 2898728996.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hastings, S. J., , Oechel W. C. , , and Muhlia-Melo A. , 2005: Diurnal, seasonal and annual variation in the net ecosystem CO2 exchange of a desert shrub community (Sarcocaulescent) in Baja California, Mexico. Global Change Biol., 11 , 927939.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Huxman, T. E., , Cable J. M. , , Ignace D. D. , , Eilts J. A. , , English N. B. , , Weltzin J. , , and Williams D. G. , 2004a: Response of net ecosystem gas exchange to a simulated precipitation pulse in a semi-arid grassland: The role of native versus non-native grasses and soil texture. Oecologia, 141 , 295305.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Huxman, T. E., and Coauthors, 2004b: Precipitation pulses and carbon fluxes in semiarid and arid ecosystems. Oecologia, 141 , 254268.

  • Ivans, C. Y., , Leffler A. J. , , Spaulding U. , , Stark J. M. , , Ryel R. J. , , and Caldwell M. M. , 2003: Root responses and nitrogen acquisition by Artemisia tridentata and Agropyron desertorum following small summer rainfall events. Oecologia, 134 , 317324.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ivans, S., 2005: Response of water vapor and CO2 fluxes in semi-arid plant communities to variations in precipitation. Ph.D. dissertation, Utah State University, 119 pp.

  • Leffler, A. J., , and Caldwell M. M. , 2005: Shifts in depth of water extraction and photosynthetic capacity inferred from stable isotope proxies across an ecotone of Juniperus osteosperma (Utah juniper) and Artemisia tridentata (big sagebrush). J. Ecol., 93 , 783793.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Leffler, A. J., , Ryel R. J. , , Hipps L. , , Ivans S. , , and Caldwell M. M. , 2002: Carbon acquisition and water use in a northern Utah Juniperus osteosperma (Utah juniper) population. Tree Physiol., 22 , 12211230.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Loik, M., , Breshears D. D. , , Lauenorth W. K. , , and Belnap J. , 2004: A multi-scale perspective of water pulses in dryland ecosystems: Climatology and ecohydrology of the western USA. Oecologia, 141 , 269281.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lowe, T. M., 1999: Soil–vegetation relationships in a Juniper community on an Alluvian fan, western Utah. M.S. thesis, Department of Range Science, Utah State University, 180 pp.

  • Martens, S. N., , Breshears D. D. , , and Meyer C. W. , 2000: Spatial distributions of understory light along the grassland/forest continuum: Effects of cover, height, and spatial patterns of tree canopies. Ecol. Model., 126 , 7993.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Massman, W. J., , and Lee X. , 2002: Eddy covariance flux corrections and uncertainties in long-term studies of carbon and energy exchanges. Agric. For. Meteor., 113 , 121144.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ryel, R. J., , Leffler A. J. , , Peek M. S. , , Ivans C. Y. , , and Caldwell M. M. , 2004: Water conservation in Artemisia tridentata through redistribution of precipitation. Oecologia, 141 , 335345.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saetre, P., , and Stark J. M. , 2005: Microbial dynamics and carbon and nitrogen cycling following re-wetting of soils beneath two semi-arid plant species. Oecologia, 142 , 247260.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saigusa, N., , Oikawa T. , , and Liu S. , 1998: Seasonal variations of the exchange of CO2 and H2O between a grassland and the atmosphere: An experimental study. Agric. For. Meteor., 89 , 131139.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schwinning, S., , and Ehleringer J. R. , 2001: Water use trade-offs and optimal adaptations to pulse-driven ecosystems. J. Ecol., 89 , 464480.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schwinning, S., , and Sala O. E. , 2004: Hierarchy of responses to resource pulses in arid and semi-arid ecosystems. Oecologia, 141 , 211220.

  • Unland, H. E., , Houser P. R. , , Shuttleworth W. J. , , and Yang Z. L. , 1996: Surface flux measurement and modeling at a semi-arid Sonoran Desert site. Agric. For. Meteor., 82 , 119153.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Veenendaal, E. M., , Kolle O. , , and Lloyd J. , 2004: Seasonal variation in energy fluxes and carbon dioxide exchange for a broad-leaved semi-arid savanna (Mopane woodland) in southern Africa. Global Change Biol., 10 , 318328.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Webb, E. K., , Pearman G. I. , , and Leuning R. , 1980: Correction of flux measurements for density effects due to heat and water vapor transfer. Quart. J. Roy. Meteor. Soc., 106 , 85100.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wever, L. A., , Flanagan L. B. , , and Carlson P. J. , 2002: Seasonal and interannual variation in evapotranspiration, energy balance and surface conductance in a northern temperate grassland. Agric. For. Meteor., 112 , 3149.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Whitford, W. G., 2002: Ecology of Desert Systems. Academic Press, 327 pp.

  • Wilczak, J. M., , Oncley S. P. , , and Stage S. A. , 2001: Sonic anemometer tilt correction algorithms. Bound.-Layer Meteor., 99 , 127150.

  • Wilson, K. B., , and Baldocchi D. D. , 2000: Seasonal and interannual variability of energy fluxes over a broadleaved temperate deciduous forest in North America. Agric. For. Meteor., 100 , 118.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yan, S., , Wan C. , , Sosebee R. E. , , Wester D. B. , , Fish E. B. , , and Zartman R. E. , 2000: Responses of photosynthesis and water relations to rainfall in the desert shrub creosote bush (Larrea tridentata) as influenced by municipal biosolids. J. Arid Environ., 46 , 397412.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 53 53 16
PDF Downloads 15 15 4

Response of Water Vapor and CO2 Fluxes in Semiarid Lands to Seasonal and Intermittent Precipitation Pulses

View More View Less
  • 1 Campbell Scientific, Inc., Logan, Utah
  • 2 Department of Plants, Soils, and Biometeorology, Utah State University, Logan, Utah
  • 3 Ecology Center, Utah State University, Logan, Utah, and Louisiana Tech University, Ruston, Louisiana
  • 4 Ecology Center, Utah State University, Logan, Utah
© Get Permissions
Restricted access

Abstract

Precipitation pulses are important in controlling ecological processes in semiarid ecosystems. The effects of seasonal and intermittent precipitation events on net water vapor and CO2 fluxes were determined for crested wheatgrass (Agropyron desertorum), juniper (Juniperus osteosperma), and sagebrush (Artemisia tridentata) ecosystems using eddy covariance measurements. The measurements were made at Rush Valley, Utah, in the northern Great Basin of the United States. Data were evaluated during the growing seasons of 2002 and 2003. Each of these communities responds to precipitation pulses in all seasons, but these responses vary among season and ecosystem, and differ for water vapor and CO2. The degree and direction of response (i.e., net uptake or efflux) depended upon the timing and amount of precipitation. In early spring, both evapotranspiration (ET) and CO2 fluxes responded only slightly to precipitation pulses because soils were already moist from snowmelt and spring rains. As soils dried later in the spring, ET response to rainfall increased. The summer season was very warm and dry in both years, and both water and CO2 fluxes were generally reduced as compared to fluxes in the spring. Water vapor fluxes increased during and immediately after periodic summer rain events at all sites, especially at juniper, followed by the sagebrush and crested wheatgrass sites. Net CO2 exchange changed significantly at the juniper and sagebrush sites but changed very little at the crested wheatgrass site due to senescence of this grass. However, in the wetter summer of 2003, the grass species maintained physiological activity and responded to rain events. In the fall of both years, responses of ET and CO2 fluxes to precipitation were very similar for all three communities, with only small changes, presumably due to significantly lower temperatures in the fall. This research documents the importance of the temporal distribution of rainfall on patterns of ET and CO2 fluxes and suggests that soil moisture and stand-level leaf area index (LAI) are critical factors governing ET and CO2 responses to precipitation in these communities.

Corresponding author address: Sasha Ivans, Campbell Scientific, Inc., 815 West 1800 North, Logan, UT 84321-1784. Email: sasha@campbellsci.com

Abstract

Precipitation pulses are important in controlling ecological processes in semiarid ecosystems. The effects of seasonal and intermittent precipitation events on net water vapor and CO2 fluxes were determined for crested wheatgrass (Agropyron desertorum), juniper (Juniperus osteosperma), and sagebrush (Artemisia tridentata) ecosystems using eddy covariance measurements. The measurements were made at Rush Valley, Utah, in the northern Great Basin of the United States. Data were evaluated during the growing seasons of 2002 and 2003. Each of these communities responds to precipitation pulses in all seasons, but these responses vary among season and ecosystem, and differ for water vapor and CO2. The degree and direction of response (i.e., net uptake or efflux) depended upon the timing and amount of precipitation. In early spring, both evapotranspiration (ET) and CO2 fluxes responded only slightly to precipitation pulses because soils were already moist from snowmelt and spring rains. As soils dried later in the spring, ET response to rainfall increased. The summer season was very warm and dry in both years, and both water and CO2 fluxes were generally reduced as compared to fluxes in the spring. Water vapor fluxes increased during and immediately after periodic summer rain events at all sites, especially at juniper, followed by the sagebrush and crested wheatgrass sites. Net CO2 exchange changed significantly at the juniper and sagebrush sites but changed very little at the crested wheatgrass site due to senescence of this grass. However, in the wetter summer of 2003, the grass species maintained physiological activity and responded to rain events. In the fall of both years, responses of ET and CO2 fluxes to precipitation were very similar for all three communities, with only small changes, presumably due to significantly lower temperatures in the fall. This research documents the importance of the temporal distribution of rainfall on patterns of ET and CO2 fluxes and suggests that soil moisture and stand-level leaf area index (LAI) are critical factors governing ET and CO2 responses to precipitation in these communities.

Corresponding author address: Sasha Ivans, Campbell Scientific, Inc., 815 West 1800 North, Logan, UT 84321-1784. Email: sasha@campbellsci.com

Save