Fundamental intra-specific differences in plant–water relations in a widespread desert shrub (Artemisia tridentata)

• Published in: Plant ecology 2020-10, Vol.221 (10), p.925-938
• Main Authors: Sharma, Harmandeep, Reinhardt, Keith, Lohse, Kathleen A.
• Format: Article
• Language: English
• Subjects: Analysis; Applied Ecology; Artemisia tridentata; Atmospheric models; Biodiversity; Biomedical and Life Sciences; Community & Population Ecology; Diurnal; Drought resistance; Droughts; Ecology; Ecosystems; Fluxes; Laws, regulations and rules; Life Sciences; Moisture availability; Plant Ecology; Regulations; Stomata; Strategic planning (Business); Terrestial Ecology; Transpiration; Vapor pressure; Water; Water management; Water potential; Water relations
• ISSN: 1385-0237; 1573-5052
• DOI: 10.1007/s11258-020-01051-y

Big sagebrush (Artemisia tridentata) is a widespread and locally dominant shrub that is a key driver of water fluxes and storage in western North America. There are several recognized subspecies of big sagebrush that occupy different microsites across the landscape according to moisture availability, yet little is known about how these subspecies vary in drought tolerance or water management strategies. We measured diurnal and seasonal (i.e., early-, mid-, and late summer) variation in water status and transport efficiency, transpiration, and stomatal regulations in two subspecies of big sagebrush (A.t. wyomingensis and A.t. vaseyana) at the Reynolds Creek Critical Zone Observatory in southwestern Idaho. We hypothesized that water status, transport efficiency, and stomatal regulations would be greater in A.t. vaseyana compared to A.t. wyomingensis, because the first subspecies occupies wetter microsites. Predawn and midday water potentials were up to 2× more negative in A.t. wyomingensis compared to A.t. vaseyana, and transpiration was up to ~ 4 × greater in A.t. vaseyana compared to A.t. wyomingensis. A.t. vaseyana was more isohydric with ~ 1.5 × greater stomatal sensitivity to atmospheric vapor pressure deficit and a smaller hydroscape, compared to A.t. wyomingensis. Our data demonstrate that there are fundamental differences in plant–water relations among these subspecies that constitute the vast, but not homogeneous sagebrush landscapes. These important differences can have implications for modeling water fluxes in big sagebrush-dominated communities at shrub to ecosystem scales.