Year-Round Transpiration Dynamics Linked With Deep Soil Moisture in a Warm Desert Shrubland

D. J. Szutu, Shirley Papuga

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Ecohydrological processes in semiarid shrublands and other dryland ecosystems are sensitive to discrete pulses of precipitation. Anticipated changes in the frequency and magnitude of precipitation events are expected to impact the spatial and temporal distribution of soil moisture in these drylands, thereby impacting their ecohydrological processes. Recent field studies have shown that in dryland ecosystems, transpiration dynamics and plant productivity are largely a function of deep soil moisture available after large precipitation events, regardless of where the majority of plant roots occur. However, the strength of this relationship and how and why it varies throughout the year remains unclear. We present eddy covariance, soil moisture, and sap flow measurements taken over an 18-month period in conjunction with an analysis of biweekly precipitation, shallow soil, deep soil, and stem stable water isotope samples from a creosotebush-dominated shrubland ecosystem at the Santa Rita Experimental Range in southern Arizona. Within the context of a hydrologically defined two-layer conceptual framework, our results support that transpiration is associated with the availability of deep soil moisture and that the source of this moisture varies seasonally. Therefore, changes in precipitation pulses that alter the timing and magnitude of the availability of deep soil moisture are expected to have major consequences for dryland ecosystems. Our findings offer insights that can improve the representation of drylands within regional and global models of land surface atmosphere exchange and their linkages to the hydrologic cycle.

Original languageEnglish (US)
JournalWater Resources Research
DOIs
StatePublished - Jan 1 2019

Fingerprint

shrubland
transpiration
desert
soil moisture
ecosystem
sap flow
shallow soil
flow measurement
eddy covariance
conceptual framework
temporal distribution
land surface
moisture
stem
isotope
spatial distribution
productivity
atmosphere
soil
water

Keywords

  • creosotebush
  • ecohydrology
  • evapotranspiration
  • plant water use
  • transpiration
  • water-use strategies

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

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abstract = "Ecohydrological processes in semiarid shrublands and other dryland ecosystems are sensitive to discrete pulses of precipitation. Anticipated changes in the frequency and magnitude of precipitation events are expected to impact the spatial and temporal distribution of soil moisture in these drylands, thereby impacting their ecohydrological processes. Recent field studies have shown that in dryland ecosystems, transpiration dynamics and plant productivity are largely a function of deep soil moisture available after large precipitation events, regardless of where the majority of plant roots occur. However, the strength of this relationship and how and why it varies throughout the year remains unclear. We present eddy covariance, soil moisture, and sap flow measurements taken over an 18-month period in conjunction with an analysis of biweekly precipitation, shallow soil, deep soil, and stem stable water isotope samples from a creosotebush-dominated shrubland ecosystem at the Santa Rita Experimental Range in southern Arizona. Within the context of a hydrologically defined two-layer conceptual framework, our results support that transpiration is associated with the availability of deep soil moisture and that the source of this moisture varies seasonally. Therefore, changes in precipitation pulses that alter the timing and magnitude of the availability of deep soil moisture are expected to have major consequences for dryland ecosystems. Our findings offer insights that can improve the representation of drylands within regional and global models of land surface atmosphere exchange and their linkages to the hydrologic cycle.",
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AB - Ecohydrological processes in semiarid shrublands and other dryland ecosystems are sensitive to discrete pulses of precipitation. Anticipated changes in the frequency and magnitude of precipitation events are expected to impact the spatial and temporal distribution of soil moisture in these drylands, thereby impacting their ecohydrological processes. Recent field studies have shown that in dryland ecosystems, transpiration dynamics and plant productivity are largely a function of deep soil moisture available after large precipitation events, regardless of where the majority of plant roots occur. However, the strength of this relationship and how and why it varies throughout the year remains unclear. We present eddy covariance, soil moisture, and sap flow measurements taken over an 18-month period in conjunction with an analysis of biweekly precipitation, shallow soil, deep soil, and stem stable water isotope samples from a creosotebush-dominated shrubland ecosystem at the Santa Rita Experimental Range in southern Arizona. Within the context of a hydrologically defined two-layer conceptual framework, our results support that transpiration is associated with the availability of deep soil moisture and that the source of this moisture varies seasonally. Therefore, changes in precipitation pulses that alter the timing and magnitude of the availability of deep soil moisture are expected to have major consequences for dryland ecosystems. Our findings offer insights that can improve the representation of drylands within regional and global models of land surface atmosphere exchange and their linkages to the hydrologic cycle.

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