Evapotranspiration partitioning in semiarid shrubland ecosystems: A two-site evaluation of soil moisture control on transpiration

Michelle L. Cavanaugh, Shirley Papuga, Russell L. Scott

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

Vegetation of dryland ecosystems is sensitive to precipitation pulses. Future climate scenarios suggest that the frequency and magnitude of precipitation events will change. How much and to what extent will these changes impact the hydrological cycle in creosotebush (Larrea tridentata) shrublands that dominate the three North American hot deserts? In this study, we examine the partitioning of precipitation inputs into bare soil evaporation (E) and transpiration (T) within creosotebush ecosystems at sites characterized by bimodal precipitation regimes: the Santa Rita Experimental Range (SRER) and the Walnut Gulch Experimental Watershed (WGEW). At both sites, during summer 2008, we measured evapotranspiration (ET) using eddy covariance, whole plant T using the heat-balance sap flow, and soil moisture at several depths. During the dry period preceding the summer monsoon, both ET and soil moisture were very low. With the onset of summer rains, E dominated ET; shrub transpiration did not respond to increases in soil moisture for approximately 3 more weeks. A series of large precipitation events increased moisture at deeper soil layers, and triggered T. Overall, ET was largely correlated to moisture levels in shallow soil layers typical of dryland ecosystems dominated by dry conditions, high evaporative demand, and poor soil infiltration. Under the current precipitation regime, characterized by many small storms and few large storms, soil moisture is low with most precipitation inputs lost as E. However, if climatic changes lead to less frequent but larger precipitation events, dryland communities could experience shifts in the partitioning of ET affecting the hydrologic budget of the ecosystem.

Original languageEnglish (US)
Pages (from-to)671-681
Number of pages11
JournalEcohydrology
Volume4
Issue number5
DOIs
StatePublished - Sep 2011

Fingerprint

shrubland
shrublands
transpiration
evapotranspiration
partitioning
soil moisture
soil water
arid lands
ecosystems
ecosystem
soil
summer
moisture
Larrea tridentata
sap flow
shallow soil
heat balance
hydrologic cycle
eddy covariance
hydrological cycle

Keywords

  • Acacia constricta
  • Creosotebush
  • Desert
  • Dryland
  • Eddy covariance
  • Larrea tridentata
  • Santa Rita Experimental Range
  • Sap flow
  • Walnut Gulch Experimental Watershed
  • Whitethorn acacia

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes
  • Ecology

Cite this

Evapotranspiration partitioning in semiarid shrubland ecosystems : A two-site evaluation of soil moisture control on transpiration. / Cavanaugh, Michelle L.; Papuga, Shirley; Scott, Russell L.

In: Ecohydrology, Vol. 4, No. 5, 09.2011, p. 671-681.

Research output: Contribution to journalArticle

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