| The overall goal of this research was to quantify carbon and water fluxes in three sagebrush communities present along an elevation gradient and dominated by different speciesand subspeciesof sagebrush. We examined difference in diurnal and seasonal water and carbon fluxes and compared environmental drivers of these fluxes. Additionally, we aimed to quantify the variability in water-regulation strategies and carbon-regulation strategies among sub-/species.Our results indicated that ecosystem level CO2(Net ecosystem exchange; NEE) and water (Evapotranspiration; ET) fluxes differed among three communities, with being greater at the highest elevation (snow-dominated) site during the growing season (June-August, 2016) compared to lower elevation sites. Similarly, greater transpiration and shrub hydraulic conductivity werealso observed in Artemisia tridentate spp. vaseyanaat the highest elevation (snow-dominated) site. However, the long-term water flux (monthly and annual scales) calculated using sap flow sensors were greater at the lowest and rain dominated site due to comparativelylonger growing season at that site. At rain-dominated sites,NEE and ET were moisture limited and associated with atmospheric vapor pressure deficit (VPD) and shallow soil moisture. At the snow-dominated site, NEE and ET were constrained by deep soil moisture and air temperature. Therefore, the data contribute to our understanding of how environmental parameters that controlled daytime NEE, ET and sap flux varied among three sites. This research also verifies thatwater regulation varied with respect to sagebrush sub-species. A.t.vaseyanaacted as isohydric species that was indicated by greater stomatal sensitivity to atmospheric VPD and smaller hydroscapecompared to A.t. wyomingensis, which acted like anisohydric species. In spite of all thesedifferences observed in water-carbon relations among threesagebrush
xvicommunities, R:A (autotrophic respiration to gross photosynthesis) ratiowas maintained between three sites, along the growing season and at both leaf and shrub scales.Overall, this study demonstrated that there are fundamental differences in CO2and water relations among the component shrub communities that constitute the vast, but not homogeneous sagebrush landscapes, and ecosystem and climate models should account these differencesfor better predictions of how sagebrush sub-/species will respond in near future.KeyWords: Sagebrush, Net ecosystem exchange, Evapotranspiration, Transpiration, Sap flux, Reynolds creek critical zone observatory |