Expanding agriculture destroys more habitat than any other factor

M Lambertini/BirdLife The past 40 years have seen dramatic increases in global production of soya, palm oil and other tropical export commodities Zoom In

The single most important cause of habitat loss is the expansion of agriculture, which represents one of the greatest threats to the world’s remaining biodiversity. Tropical forests are particularly threatened.

Agricultural expansion is severe in biodiversity hotspots

Agriculture has been expanding since the domestication of crop plants 10,000 years ago. But in the past three centuries, exponential human population growth has led to a 500% expansion in the extent of cropland and pasture world-wide (see box 1, figure a). In Europe and North America, unchecked agricultural development has already transformed many natural habitats and depleted their biodiversity. Similar transformation is now underway in the tropics, where most of the world’s biodiversity is found, with huge implications for both wildlife populations and ecosystem functioning. Endemic Bird Areas (EBAs), globally important centres of biodiversity, are under above-average threat from agricultural expansion (box 1, figure b). As tropical forests are the predominant natural habitat in EBAs, this tells us that they too are particularly threatened by agriculture.

Demand for tropical commodities is a major cause of current agricultural expansion

The cultivation of agricultural export commodities has expanded rapidly within the developing world during the past half-century, notably for coffee, cocoa, sugar and (more recently) palm oil and soya (box 2). Increased production of such commodities is causing unprecedented levels of habitat loss, particularly of tropical forests.

Agricultural expansion is increasingly threatening species

In the past, over-hunting and alien invasive species were responsible for most bird species extinctions. Today, the greatest threat to biodiversity is habitat loss, particularly as a result of agricultural expansion, which is now threatening previously widespread and common birds (box 3).

The potential impacts of genetically modified organisms remain unclear

Genetic modification is already producing plants, animals and micro-organisms that can overcome the current limits on their growth and ranges. Such organisms could have big impacts on biodiversity, but this will depend on how they are used, in agriculture and other natural-resource sectors. For instance, they could reduce pressure for new habitat clearance by making already degraded land more productive. By contrast, they could allow agriculture to intensify to the detriment of those species that inhabit farmed land, and could also facilitate its expansion into today’s agriculturally .marginal. but biologically important habitats, such as boreal forests and drylands.

Boxes: case studies and scientific analyses

Download SOWB pp.32–33 (PDF, 296 KB) containing the following:

1. Agricultural land has expanded six-fold since 1700 and EBAs have suffered disproportionately
a) The timing and expansion of agricultural land from 1700 to 1990
b) Over 300 years substantially more land in EBAs has been converted to cropland and pasture than in the rest of the world

2. The past 40 years have seen dramatic increases in global production of soya, palm oil and other tropical export commodities
The global extent of several major tropical crops expanded markedly between 1961 and 2000

3. Agricultural expansion is a major threat to birds, and appears to be increasing in importance
Hunting and alien invasive species were the most frequent threats (61% of threats) for Extinct birds whereas for Near Threatened birds, habitat loss through agricultural expansion is the most frequently listed threatening process (57% of threats)