Identifying Agricultural Frontiers for Modeling Global Cropland Expansion

Felix Eigenbrod,Michael Beckmann,Sebastian Dunnett,Laura Graham,Robert A Holland,Patrick Meyfroidt,Ralf Seppelt,Xiao-Peng Song,Rebecca Spake,Tomáš Václavík,Peter H Verburg

doi:10.1016/j.oneear.2020.09.006

Abstract

SummaryThe increasing expansion of cropland is major driver of global carbon emissions and biodiversity loss. However, predicting plausible future global distributions of croplands remains challenging. Here, we show that, in general, existing global data aligned with classical economic theories of expansion explain the current (1992) global extent of cropland reasonably well, but not recent expansion (1992–2015). Deviations from models of cropland extent in 1992 (“frontierness”) can be used to improve global models of recent expansion, most likely as these deviations are a proxy for cropland expansion under frontier conditions where classical economic theories of expansion are less applicable. Frontierness is insensitive to the land cover dataset used and is particularly effective in improving models that include mosaic land cover classes and the largely smallholder-driven frontier expansion occurring in such areas. Our findings have important implications as the frontierness approach offers a straightforward way to improve global land use change models.

Highlights

In general, existing global data, which are aligned with classical theories of agricultural expansion, explain the current global extent of cropland reasonably well, but do not explain most recent cropland expansion well
Our findings have important implications for global land use change models, as they show both that the dependence of these models of classical theories of agricultural expansion is problematic, and that they can be improved using the frontierness approach we demonstrate here
Standard Theories Explain Extent Better Than Expansion In general, independent global predictor variables aligned with classical theories of cropland expansion (Table 1; Figure 1 and Model 1; Experimental Procedures) explained the 1992 extent of cropland globally well, but not recent expansion (1992– 2015)

Summary

Introduction

The increasing appropriation of land by humans is a major driver of global environmental change.[1,2] Cropland expansion is a particular issue, given the projected increase in demand for agricultural products driven by changing dietary patterns of a growing population, increased demand for land-based climate solutions,[3] and the potential threat such expansion has for high-biodiversity tropical areas.[4,5,6] While intensification of agriculture on existing agricultural lands can reduce the need for expansion into uncultivated areas,[7,8] the rate of global yield gains per area is decreasing,[9] and the rate of agricultural. 504 One Earth 3, 504–514, October 23, 2020 a 2020 The Authors.

Results

Discussion

Conclusion