On the observed ecohydrologic dynamics of a semiarid basin with aspect-delimited ecosystems

Abstract

[1] In semiarid complex terrain, the combination of elevation and aspect promotes variations in the water and energy balance, resulting in slopes with distinct ecologic and hydrologic properties. Quantifying the differential energy and water dynamics of opposing slopes can provide essential information on the potential effects of climate variability on landscapes. In this study, we use observations from a network of hydrologic sensors deployed on the slopes of a semiarid catchment in central New Mexico, USA, to quantify the ecohydrologic dynamics of two coexisting and contrasting ecosystems : a juniper (Juniperus monosperma) savanna on a north facing slope (NFS) and a creosote (Larrea tridentata) shrubland on a south facing slope (SFS). Our analyses show that: (1) energy loads exert a first-order control on the dynamics of evapotranspiration and soil moisture residence times in the catchment, with vegetation imposing a second-order control at the onset of the growing season; (2) soils exhibit a characteristic progression of moisture and temperature along the slope-aspect continuum that is preserved throughout the year, going from a wetter and cooler NFS to a drier and warmer SFS; (3) there are remarkable differences in the runoff dynamics among the catchment slopes, with a smaller precipitation threshold triggering larger SFS runoff amounts than at its NFS counterpart; and (4) seasonal water balances of the NFS and SFS follow opposite trajectories in the year and point to distinct soil water pools for evapotranspiration demands. The results of this study have important implications for understanding landscape changes in areas of complex topography under current and future climate variability.

Assessing a Multi-Platform Data Fusion Technique in Capturing Spatiotemporal Dynamics of Heterogeneous Dryland Ecosystems in Topographically Complex Terrain

“…Similar studies in water-limited ecosystems have also found similar aspect-dependent distributions of vegetation type [49][50][51][52]. For that reason, there is some reason to suspect that errors in STARFM-derived images might be correlated with topographic aspect both in the study area and more broadly in the water-limited ecosystems being studied.…”

Closing the water balance with cosmic-ray soil moisture measurements and assessing their relation to evapotranspiration in two semiarid watersheds

“…Semiarid watersheds with heterogeneous vegetation in the southwestern United States (Gibbens and Beck, 1987;Browning et al, 2014) exhibit variations in soil moisture that challenge our ability to quantify land-atmosphere interactions and their role in hydrological processes (Dugas et al, 1996;Small and Kurc, 2003;Scott et al, 2006;Gutiérrez-Jurado et al, 2013;Pierini et al, 2014). Moreover, accurate measurements of soil moisture over scales relevant to land-atmosphere interactions in watersheds are difficult to obtain.…”

Field comparison of methods for estimating groundwater discharge by evaporation and evapotranspiration in an arid-zone playa

“…Historical data at Territory Grape Farm, located approximately 75 km from Stirling Swamp, shows an average of 56 rain days per year over 124 years of record (1889-2013Station 015643;BOM, 2014). Groundwater recharge has been estimated at between 0.1 and 500 mm/y, with a median of 0.9 mm/y (Harrington et al, 2002).…”