Global projections of future cropland expansion to 2050 and direct impacts on biodiversity and carbon storage

Abstract

Cropland expansion threatens biodiversity by driving habitat loss and impacts carbon storage through loss of biomass and soil carbon (C). There is a growing concern land-use change (LUC) to cropland will result in a loss of ecosystem function and various ecosystem services essential for human health and well-being. This paper examines projections of future cropland expansion from an integrated assessment model IMAGE 3.0 under a "business as usual" scenario and the direct impact on both biodiversity and C storage. By focusing on biodiversity hotspots and Alliance for Zero Extinction (AZE) sites, loss of habitat as well as potential impacts on endangered and critically endangered species are explored. With regards to C storage, the impact on both soil and vegetation standing C stocks are examined. We show that if projected trends are realized, there are likely to be severe consequences for these resources. Substantial loss of habitat in biodiversity hotspots such as Indo-Burma, and the Philippians is expected as well as 50% of species in AZE sites losing part of their last remaining habitat. An estimated 13.7% of vegetation standing C stocks and 4.6% of soil C stocks are also projected to be lost in areas affected with Brazil and Mexico being identified as priorities in terms of both biodiversity and C losses from cropland expansion. Changes in policy to regulate projected cropland expansion, and increased measures to protect natural resources, are highly likely to be required to prevent these biodiversity and C losses in the future.

Keywords: biodiversity; carbon storage; cropland expansion; ecosystem services; land use change.

Figure 1

Graphic showing various steps taken in the methodology to produce results

Figure 2

Biodiversity hotspots (red) and their outer limit (red line) (Mittermeier et al., 2011)

Figure 3

Global forecasts of cropland expansion into biodiversity hotspots from 2010 to 2050 under SSP2 as predicted by the IMAGE model

Figure 4

Areas affected by concentrated, high percentages of conversion of habitat to cropland

Figure 5

Areas affected by widespread, low percentages of conversion to cropland

Figure 6

Count of all species for Critically Endangered (CR) and Endangered (EN) status in AZE sites for classes most affected by cropland expansion (Amphibia, Aves and Mammalia)

Figure 7

Panel showing spatial patterns of carbon lost a) from soil and b) from vegetation biomass

Figure 8

Estimated sum of carbon lost from soil and vegetation biomass per region (Gt C = billions of tonnes C)

Figure 9

Comparison of impacts of cropland expansion for each region on carbon storage for both soil and standing vegetation stocks and AZE species, Endangered (EN) and Critically Endangered (CR)