Published online in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/eco.81 Ecohydrology Bearings—Invited Commentary

As the earth becomes a quilt of managed patches, ecohydrologists need to move from describing to predicting the consequences of human activities, using knowledge to improve human well-being. We highlight three current opportunities in ecohydrology. The first is the need for stronger research in arid and semi-arid ecosystems, where water is scarce and a tight coupling exists between hydrology and ecology. The second is to build better predictive frameworks for understanding the consequences of vegetation change. The new framework we propose here combines landscape connectivity, through recharge and discharge dynamics, with global climate. In systems where annual precipitation and evapotranspiration are similar, the evapotranspirative differences of altered vegetation can quickly tip the water balance between positive and negative, fundamentally altering water flows and biogeochemistry. The third opportunity is to use simplified agricultural systems to build and test ecohydrological theory. Such systems function under the same biophysical rules but are often better controlled and replicated than more natural ecosystems. Resolving today’s controversies requires sound ecohydrological science in a world where the influences of people are increasingly universal. Copyright 2009 John Wiley & Sons, Ltd. KEY WORDS ecohydrology; climate change; crop yields; groundwater dynamics; plant transpiration; salinity; vegetation change; water uptak