Intra-annual variability and environmental controls over transpiration in a 58-year-old even-aged stand of invasive woody Juniperus virginiana L. in the Nebraska Sandhills, USA

Tala Awada, Rita El-Hage, Makram Geha, David A. Wedin, Julie A. Huddle, Xinhua Zhou, Joseph Msanne, Robert A. Sudmeyer, Derrel L. Martin, James R. Brandle

Research output: Contribution to journalArticlepeer-review

Abstract

We investigated the intra-annual variability and environmental controls over transpiration (E) in a planted, even-aged (58years; 537 treesha-1), experimental forest of invasive native Juniperus virginiana in the Nebraska Sandhills, with three canopy classes (dominant, co-dominant, and suppressed) by using sap flux techniques, in a year where drought was absent (2008, 34% above average precipitation). Daily E was closely linked to growing-season length and variability in the environment. Minimum and average daily air temperatures, photosynthetically active radiation, and precipitation explained the majority of the intra-annual daily variability in E. Vapour pressure deficit was a significant factor in spring and summer, shallow volumetric soil water content (VSWC 0·2m) was important during summer particularly June, and deep VSWC (0·6m) was a significant factor in January and August. E was highest in the dominant trees and contributed to the majority (~77%) of stand transpiration (Ec) on site because of their larger canopy size, greater tree density, more leaf area, and accessibility to water resources compared with the co-dominant and suppressed tree canopies, which contributed to 16% and 7%, respectively. Ec averaged ~413mmyear-1, corresponding to ~24% of potential evapotranspiration. Soils were significantly drier in the J. virginiana stand than in adjacent C4-dominated grasslands, which could be due to the longer growing season over which physiological activity extends in J. virginiana compared with C4-dominated grasslands in the region and precipitation interception by the canopy and forest floor, which evaporates before reaching the soil.

Original languageEnglish (US)
Pages (from-to)731-740
Number of pages10
JournalEcohydrology
Volume6
Issue number5
DOIs
StatePublished - Oct 2013

Keywords

  • Ecohydrology
  • Granier-type sensor
  • Great Plains
  • Sap flux
  • Soil moisture
  • Warm-season grasslands
  • Woody species invasion

ASJC Scopus subject areas

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

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