Summary
The authors developed a model they call HILDA + (Historic Land Dynamics Assessment) to examine the gains and losses in major land use/cover (LUC) categories (i.e., urban, cropland, pasture/rangeland, forest, unmanaged grass/shrubland, sparse/no vegetation) around the globe. The HILDA+ model combines multiple, high-resolution remote sensing data with long-term statistical data streams from 1960-2019.
Overall, HILDA+ revealed that nearly a third of the world’s land surface has experienced a land change event over the last six decades. Globally, there was a net loss of 0.8 million square kilometers of forest area concurrent with an increase in cropland (1.0 million square kilometers) and pasture/rangeland (0.9 million square kilometers). Agricultural expansion accounted for the LUC for 48% of areas that underwent a single change event and 86% that underwent multiple changes. Examples of this expansion include pastureland in China and tropical deforestation in the Amazon.
Regionally, the Global North (including China) gained forest areas, whereas the Global South lost such areas. In contrast, cropland areas decreased in the Global North and increased in the Global South. The hemispheric pattern is less obvious for pasture/rangeland change given the expansion of this land use in China and Brazil, each in a different hemisphere.
The authors note that a strength of the HILDA+ model is that errors in single datasets have less influence on the results given the combination of multiple “heterogeneous datasets”. In terms of limitations, the authors acknowledge that the deviations among datasets were larger for agricultural LUC categories cropland and pasture/rangeland.
An Animal Data Project summary specifically for the HILDA+ project dataset can be found here.
Quantifying the dynamics of land use change is critical in tackling global societal challenges such as food security, climate change, and biodiversity loss. Here we analyse the dynamics of global land use change at an unprecedented spatial resolution by combining multiple open data streams (remote sensing, reconstructions and statistics) to create the HIstoric Land Dynamics Assessment + (HILDA +). We estimate that land use change has affected almost a third (32%) of the global land area in just six decades (1960-2019) and, thus, is around four times greater in extent than previously estimated from long-term land change assessments. We also identify geographically diverging land use change processes, with afforestation and cropland abandonment in the Global North and deforestation and agricultural expansion in the South. Here, we show that observed phases of accelerating (~1960–2005) and decelerating (2006–2019) land use change can be explained by the effects of global trade on agricultural production.