Linking ecohydrology and ecosystem functioning: from examples to current challenges.

SALA, OSVALDO; BRESHEARS, DAVID; YAHDJIAN, LAURA

Portland, Oregon, USA

Simposio; 89th Annual Meeting of the ESA; 2004

Ecological Society of America

Here, we provide a closing synthesis for a symposium titled "Ecohydrology: Towards an Ecologically Meaningful Water Budget". The symposium focuses on the importance of water in terrestrial ecosystems and emerging interfaces between the disciplines of ecology and hydrology. We highlight how improvement in understanding ecosystem water dynamics relates to key aspects of ecosystem functioning. We provide a case study relating profiles of water and nitrogen in arid and semiarid ecosystems. Nitrogen availability sharply declines with soil depth in most arid and semiarid ecosystems, whereas patterns of water availability in the soil profile vary significantly. When water pulses are larger, such as in association with winter precipitation or during wetter years, the water availability in deep soil layers increases and the overlap with the N distribution decreases. Second, we evaluate the effects of water inputs on carbon and nitrogen cycling. Water inputs were linearly related to primary production and mass loss from litter, whereas N mineralization was not affected by water availability even when inputs were substantially reduced. These results help explain temporal and spatial relationships between precipitation and productivity across sites, and more generally highlight the important linking between ecohydrology and ecosystem functioning. Building on this case study and previous presentations in the symposium, we highlight future research issues and opportunities in ecohydrology.