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WATER RESOURCES RESEARCH, VOL. 44, W03430, doi:10.1029/2006WR005595, 2008

Vegetation-hydrology dynamics in complex terrain of semiarid areas: 2. Energy-water controls of vegetation spatiotemporal dynamics and topographic niches of favorability

Valeriy Y. Ivanov

Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
Center for the Environment, Harvard University, Cambridge, Massachusetts, USA


Rafael L. Bras

Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA


Enrique R. Vivoni

Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico, USA


Abstract

Ecosystems of dry climates are a particularly interesting subject for ecohydrological studies, as water is generally considered to be the key limiting resource. This work focuses on vegetation-water-energy dynamics occurring on the complex terrain of a semiarid area characteristic of central New Mexico. The study employs a mechanistic model of coupled interactions to construct a set of numerical experiments carried out for two small-scale synthetic domains that exhibit particular hillslope curvatures. The linkages between terrain attributes and patterns of C4 grass productivity and water balance components are examined for three generic soil types. It is argued that in conditions of negligible moisture exchange, aspect and slope are the key determinants of both the hydrologic behavior and the degree of site “favorability” to vegetation. Certain topographic locations are more favorable to vegetation, as compared to a flat horizontal surface not influenced by lateral effects. These locations are associated with sites of northerly aspect with surface slopes within a narrow range of magnitudes. Contributions from both rainfall and radiation forcings are discussed to explain the existence of these topographic niches. The sensitivity of results is investigated by modifying the dominant mechanism of lateral water transfer. Two additional controlling topographic features are explored, corresponding to the contiguous and global terrain convergence levels. It is argued that their effects on vegetation-hydrology dynamics at a given location are characteristically superimposed with the impact of site-specific terrain attributes. Furthermore, the results lead to a conceptual relationship linking vegetation-hydrology quantities at different landscape locations.

Received 4 October 2006; accepted 4 January 2008; published 29 March 2008.

Keywords: hydrology; ecohydrology; vegetation dynamics.

Index Terms: 1813 Hydrology: Eco-hydrology; 1804 Hydrology: Catchment; 1852 Hydrology: Plant uptake; 1866 Hydrology: Soil moisture.

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 9742534 bytes)

Citation: Ivanov, V. Y., R. L. Bras, and E. R. Vivoni (2008), Vegetation-hydrology dynamics in complex terrain of semiarid areas: 2. Energy-water controls of vegetation spatiotemporal dynamics and topographic niches of favorability, Water Resour. Res., 44, W03430, doi:10.1029/2006WR005595.