Search

Ecosystem management policies increasingly emphasize provision of multiple, as opposed to single, ecosystem services. Management for such "multifunctionality" has stimulated research into the role that biodiversity plays in providing desired rates of multiple ecosystem processes. Positive effects of biodiversity on indices of multifunctionality are consistently found, primarily because species that are redundant for one ecosystem process under a given set of environmental conditions play a distinct role under different conditions or in the provision of another ecosystem process. Here we show that the positive effects of diversity (specifically community composition) on multifunctionality indices can also arise from a statistical fallacy analogous to Simpson's paradox (where aggregating data obscures causal relationships). We manipulated soil faunal community composition in combination with nitrogen fertilization of model grassland ecosystems and repeatedly measured five ecosystem processes related to plant productivity, carbon storage, and nutrient turnover. We calculated three common multifunctionality indices based on these processes and found that the functional complexity of the soil communities had a consistent positive effect on the indices. However, only two of the five ecosystem processes also responded positively to increasing complexity, whereas the other three responded neutrally or negatively. Furthermore, none of the individual processes responded to both the complexity and the nitrogen manipulations in a manner consistent with the indices. Our data show that multifunctionality indices can obscure relationships that exist between communities and key ecosystem processes, leading us to question their use in advancing theoretical understanding--and in management decisions--about how biodiversity is related to the provision of multiple ecosystem services.

Land capability systems have been designed to evaluate and communicate biophysical constraints on land use, including climatic limitations. By grading land quality, the resulting information is particularly relevant for planners and managers, and for land valuation. Higher-grade land is more flexible and has more options for land use. Using Scotland as a case study, a widely-used land capability system was adapted to investigate the influence of recent and future climate change on land-use potential. The adapted method was applied to both interpolated gridded weather station data and to future climate change scenarios derived from the HadRM3 climate model. At a national scale, differing regional patterns of land capability were recognised, with changes in these patterns occurring in recent decades and projected to occur on a more substantial scale into the future. In general, climate change is acting to enhance land-use potential in Scotland, mainly in the drier east, while the west remains constrained by its wetter climate. These results demonstrate the key control directed by soil moisture values on land-use options, in addition to temperature change. Shifts in land-use potential have implications for both strategic resource planning and for developing anticipatory climate change adaptation actions. The land capability assessment highlights not only potential changes in agriculture and other productive land uses, but also repercussions for biodiversity and terrestrial carbon stocks. Various amendments are suggested to the land capability procedures to reflect existing or emerging climate-related issues that were not considered necessary in the original system, notably excessive soil moisture deficits. [ABSTRACT FROM AUTHOR]