Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6413861 | Journal of Hydrology | 2012 | 10 Pages |
SummaryArid and semi-arid ecosystems represent a dynamic but poorly understood component of global carbon, water, and energy cycles. We studied a semi-arid mountain big sagebrush (Artemisia tridentata var. vaseyana; hereafter, “sagebrush”) dominated ecosystem to quantify the (1) relative control of surface (0-15 cm) versus deep (15-45 cm) soil moisture on leaf transpiration (EL) and stomatal conductance (gS); (2) response of EL and gS to light and soil and atmospheric drought; and (3) physiological mechanisms underlying these responses. The physiological mechanisms were tested using a simple plant hydraulic model for gS based on homeostatic regulation of minimum leaf water potential (ΨLmin) that was originally developed for trees. Our results showed that a combination of atmospheric and surface soil drought controlled EL, whereas gS was mainly driven by atmospheric drought. Sagebrush displayed greater reference conductance [gS@1 kPa vapor pressure deficit (D), gSR] and greater sensitivity (âm) of gS to D than mesic trees, reflecting the high average light intensity within the shrub canopy. The slope of âm/gSR was similar to mesic trees (â¼0.6), indicating an isohydric regulation of ΨLmin, but different than previously published values for semi-arid shrubs (â¼0.4). Isohydric behavior of sagebrush indicates that well-known forest ecosystem models with greater gSR and âm can be used for modeling water, energy and carbon cycles from sagebrush and similar ecosystems.
⺠We tested a plant hydraulic model in a semi-arid sagebrush ecosystem. ⺠We quantified transpiration and stomatal conductance response to climate. ⺠Sagebrush displayed an isohydric regulation of minimum leaf water potential. ⺠Sagebrush is different than previously published values for semi-arid shrubs.