Designing Land-Based Biodiversity Policy: A Spatially Resolved Economic Analysis

Global conservation initiatives, including the Kunming–Montreal Global Framework's 30×30 target, require policy instruments that determine not only how much land is protected, but also where protection occurs. Yet most economic assessments of conservation policies rely on highly aggregated representations of land use that cannot capture spatial heterogeneity in ecosystem value, agricultural productivity, or opportunity costs. As a result, they provide limited insight into how alternative conservation designs influence land-use displacement, trade, and economic outcomes. This paper evaluates the economic and land-use consequences of alternative spatial conservation policies using a high-resolution gridded equilibrium model of global agriculture. We implement a set of land-conversion taxes within SIMPLE-G, a spatially explicit modeling framework that represents agricultural production, consumption, trade, and land allocation across 2.3 million grid cells worldwide. All policy scenarios achieve the same conservation objective, maintaining at least 30 percent natural land within each region-biome, but differ in their degree of spatial targeting. We compare uniform taxes applied broadly across landscapes with priority-targeted and differentiated tax schemes that concentrate conservation efforts in ecologically valuable locations. The results demonstrate that the spatial design of conservation policy is a first-order determinant of economic and environmental outcomes. Priority-targeted policies achieve conservation goals more efficiently by concentrating land withdrawal in high-value areas, but they also generate greater leakage through the relocation of agricultural production and land-use change to non-target regions. Uniform policies reduce leakage by spreading adjustments more broadly, although at higher aggregate economic cost. We further show that intermediate policy designs defined at the biome-region level capture much of the efficiency gain associated with highly targeted interventions while reducing implementation complexity. These findings highlight the importance of explicitly accounting for spatial heterogeneity and market-mediated feedbacks when evaluating large-scale conservation policies. More broadly, they demonstrate that conservation outcomes depend not only on the extent of protection but also on the spatial allocation of conservation effort within an interconnected global food system.