91社区

Canadian and Swedish researchers probe links between agriculture and environmental degradation like toxic algae blooms

Modern agriculture and land-use practices may lead to major disruptions of the world鈥檚 water flows, with potentially sudden and dire consequences for regions least able to cope with them researchers at the Stockholm University-affiliated Stockholm Resilience Centre and 91社区 have warned.

In a paper published April 1 in the journal Trends in Ecology and Evolution, Dr. Line J. Gordon of the Stockholm Resilience Centre and the Stockholm Environment Institute and Dr. Garry Peterson and Dr. Elena Bennett of 91社区 argue that global water management has been focused too much on the 鈥渂lue water鈥� side of the hydrological cycle, neglecting the largely invisible changes humanity has had on so-called 鈥済reen water.鈥�

鈥淏lue water is the part of the cycle we can see, like streams and rivers,鈥� said Gordon, an assistant professor at the Stockholm Resilience Centre and the Stockholm Environment Institute. 鈥淭his is as opposed to 鈥榞reen water鈥� in soil moisture, or evapotranspiration from plants, which agriculture can affect in significant ways.鈥�

鈥淩esilience鈥� describes the capacity of social-ecological systems to withstand climactic or economic shocks, and to then rebuild and renew themselves. In their paper, the researchers look at the likelihood of that vital resilience being lost in the aftermath of catastrophic changes to the hydrological cycle that could be caused by agriculture and land-use practices.

鈥淥ur main point is that these effects aren鈥檛 necessarily going to result in gradual change,鈥� explained Peterson, 91社区鈥檚 Canada Research Chair in Social-Ecological Modelling, and assistant professor in the Department of Geography and the 91社区 School of Environment. 鈥淭hey can result in surprising, dramatic changes, what we call 'ecosystem flips' or 'ecosystem regime changes,' which can be very difficult or even impossible to reverse.鈥�

According to Peterson, recent outbreaks of toxic algae blooms in Quebec lakes and off Sweden鈥檚 Baltic Sea coast are prime examples of ecosystem flips, the consequence of nutrients from fertilizers permeating the soil and running off into streams, lakes and oceans.

鈥淎s you get more and more nutrients in the soil you eventually get to a point where you can even completely stop farming and all the nutrients will still be there,鈥� explained Bennett, an assistant professor at 91社区's Department of Natural Resource Sciences and the School of Environment. 鈥淵ou go past a tipping point where it鈥檚 very difficult to reverse.鈥�

Ecosystem flips can have significant and sometimes devastating effects on human well-being, as global populations suddenly lose resources they are dependent on, said the researchers. Some of the most vulnerable areas on Earth are places like the drylands of sub-Saharan Africa.

鈥淚n some of these regions we risk two types of ecosystem flips, one that causes rapid soil degradation with dramatic effects on yields and farmers' livelihoods, and another that affects rainfall and therefore also vegetation growth,鈥� Gordon said.

鈥淭hese are the places where populations are growing the fastest, people have the least amount of water per capita and are the poorest of any of the biomes of the world. They are also the regions most likely to be affected by climate change,鈥� Peterson added.

As global demands for agriculture and water continue to grow, concluded the authors, it is increasingly urgent for scientists and managers to develop new ways to build resilience by anticipating, analyzing and managing changes in agricultural landscapes. Managing the green water component of the hydrological cycle is also important, as well as encouraging more diverse agricultural practices.

Regime shifts 鈥� a key issue at the Resilience2008 Conference

The risk of catastrophic ecosystem regime shifts and the need for resilience-building are key issues at the upcoming international science and policy conference in Stockholm titled 鈥淩esilience, adaptation and transformation in turbulent times - preparing for change in social-ecological systems.鈥�

Dr. Line J. Gordon and Dr. Garry Peterson will present their research at the conference. Keynote speakers include the father of resilience theory, Buzz Holling, leading political scientist Elinor Ostrom and renowned ecologist Steve Carpenter, to name a few. The last day of the conference will be devoted to a high-level policy forum on the implications of resilience science.

Resilience2008 is organized by the Resilience Alliance, in collaboration with the Royal Swedish Academy of Sciences and the International Council for Science (ICSU). Local organizers are the Stockholm Resilience Centre at Stockholm University, the Stockholm Environment Institute (SEI) and the Beijer Institute of Ecological Economics.

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Webcasting: A number of presentations and panel discussions will be available via streaming , an environmentally-friendly service provided by Qbrick.