Response to Waller and Rooney: nature is changing in more ways than one

Abstract

Waller and Rooney [1xNature is changing in more ways than one. Waller, D.M and Rooney, T.P. Trends Ecol. Evol. 2004; 19: 6Abstract | Full Text | Full Text PDF | PubMed | Scopus (12)See all References[1] agree with our call [2xMeasuring the changing state of nature. Balmford, A et al. Trends Ecol. Evol. 2003; 18: 326–330Abstract | Full Text | Full Text PDF | Scopus (218)See all References[2] for the monitoring of habitats and species populations to be improved and synthesized to provide better information about rates of change of the state of wild nature. However, they make two main points of criticism: that existing syntheses of time series on population size are mostly of vertebrate animals and do not reveal what is happening to the rest of biodiversity, and that broad indicators based on syntheses of data on habitat area and population sizes of many species will miss changes in the species composition of ecological communities that would help to identify the causes of change.We agree wholeheartedly with the first point and add to it the fact that, as well as being taxonomically biased, existing indicators are unrepresentative in terms of habitat and geographical location. Like them, we advocated a substantial increase in the representativeness of coverage [2xMeasuring the changing state of nature. Balmford, A et al. Trends Ecol. Evol. 2003; 18: 326–330Abstract | Full Text | Full Text PDF | Scopus (218)See all References[2]. One route would involve the carefully targeted collection and synthesis of new data. A second would be to make best use of currently available information about non-vertebrate groups, and we would strongly encourage botanists (and indeed entomologists) to follow the lead shown by Waller and Rooney in synthesizing existing time-series data.As for Waller and Rooney's second point, we think that they have not recognized the main reason for having broad indicators of the state of wild nature based on a combination of population and habitat data. We agree with them that broad indicators might not be of much help in diagnosing the detailed causes of change. However, this need could be accommodated by designing indicators that are hierarchically arranged, such that detailed data on individual trends remain available. As for the broad composite indicators, their primary purpose is very different: to provide a summary of changes that is comprehensible to people whose decisions largely drive those trends, such as the business community, the public, and their elected representatives.For a long time, many conservationists and ecologists have thought that people ought to want such indicators, but only recently have governments asked for them. The World Summit on Sustainable Development in 2002 called for a significant reduction of the current rate of biodiversity loss at global, regional and national levels by 2010. Broad indicators at all of these levels are the only practical means for measuring progress toward this objective. To begin with, such indicators will inevitably be far from ideal in their scope, but we believe that they can still be valuable in educating people whose interests are affected by losses of biodiversity and wild nature. That means everyone [3xEconomic reasons for conserving wild nature. Balmford, A et al. Science. 2002; 297: 950–953Crossref | PubMed | Scopus (716)See all References[3].