Two broad but contrasting strategies have been proposed to provide food for people whilst conserving biodiversity: (1) embedding productive lands into native ecosystems (land sharing), or (2) isolating these two types of land covers (land sparing). There is empirical evidence supporting both approaches, but they are two ends of a continuum, and we still do not know where, and to what extent we should focus on one approach, or to what extent both can be combined. Thus, the debate is still open.

 

Brief description

 

How to simultaneously provide food and energy for people whilst conserving biodiversity and ecosystem services is one of the most important questions facing ecologists and conservation biologists in the 21st Century. Of particular concern is whether biodiversity will benefit more from natural ecosystems embedded into, or isolated from productive (agricultural and pastoral) lands. The former strategy, usually termed ‘land sharing’, involves the retention of small elements of native ecosystems in the agricultural mosaic. This can enable some biodiversity to be maintained within the agricultural landscape, but, some argue that it is often lower-yielding, thus requiring a larger area of farmland to produce a given amount of food. The latter strategy, termed ‘land sparing’, requires farming at higher yields on a smaller area of land, potentially preventing the conversion (or enabling restoration) of natural ecosystems. The relative effectiveness of the two approaches for biodiversity conservation depends on how individual species respond to changes in agricultural management. If species are relatively resilient to habitat conversion, but are highly sensitive to practices that increase yields of livestock and crops, they will do least badly with a land sharing approach that limits intensification at the potential cost of increased habitat conversion. Alternatively, if species are highly sensitive to habitat conversion (e.g. forest loss) a land sparing approach will be more effective as it maximizes natural habitat conservation whilst concentrating production elsewhere. Because the land sparing approach usually requires a smaller area of land to attain the same yield, and therefore leaves greater areas of natural habitat untouched, it may have the best potential to preserve net biodiversity. Yet, increasing per-hectare productivity, especially in large-scale monocultures, is not likely to solve the hunger and malnutrition in the world, which is largely a consequence of limited access to food and not the overall quantity of food available. Furthermore, increasing yields can often result in a ‘rebound effect’, accelerating rather than slowing down deforestation, at least locally. Thus, there are still many issues that need to be clarified, and the debate is still open. Some propose that both land sparing and land sharing are needed to promote biodiversity conservation, but others counter that this perspective downplays the clear tension between the two strategies. Is this win-win vision little more than wishful thinking, or can we really combine both?