Once lost is lost

Wetlands lost to agriculture can be reclaimed with relative ease, but they will not regain their former flora and fauna without a huge effort, according to research conducted at the University of Minnesota, in the US. Susan Galatowitsch, associate professor and a colleague found that restored prairie potholes were quickly colonised by waterfowl-dispersed plants but were slow to acquire a diverse plant community resembling the original wetlands. They found that although nitrates transported to wetlands are soon converted to nitrogen gas by soil bacteria, the early nitrate load could tip the balance in favor of weeds (www.newswise.com , August 18).