Even in the expected tradeoff between crop production and water quality, the researchers found something unexpected.
"There is a strong tradeoff between crop production and surface and groundwater quality," Qiu says. "But despite this, there are still some locations that can be high for all three services exceptions that can produce high crop yield and good water quality in general."
Preliminary analysis of these "win-win" areas suggests that factors like flat topography, a deep water table, less field runoff, soil with high water-holding capacity, more adjoining wetlands and proximity to streams with riparian vegetation may contribute to maintaining both crop production and good water quality.
The results also show that nearly all of the land in the watershed provides a high level of at least one of the measured services but that they are not uniformly distributed. Most areas offer a high level of just one or two services. But a few, termed "hotspots" and making up just three percent of the watershed (largely parks and protected areas), provide high levels of at least six of the measured services.
"A single piece of land can provide different kinds of services simultaneously but you cannot expect that this land can provide all of the benefits," Qiu says.
The work was undertaken as part of a larger project to improve water sustainability in a mixed urban and agricultural landscape, supported by the Water Sustainability and Climate Program of the National Science Foundation (NSF).
"This paper is an initial assessment that gives us a picture of the spatial distribution of ecosystem services in contemporary times, a starting point for comparison," says Chris Kucharik,
|Contact: Jiangxiao Qiu|
University of Wisconsin-Madison