Land use legacies affect early tropical forest succession in Mexico

Summary

Questions: Agricultural expansion is one of the dominant drivers of forest and biodiversity loss, and shifting cultivation is the most widely used form of agriculture in many tropical forest regions. Where forests have been cleared, they have the potential to recover once the land is abandoned. However, legacies of land use are often overlooked in successional studies, and a deeper understanding of this legacy effect is needed to define efficient restoration practices using natural or assisted regeneration. Here, we analysed how land-use history affects soil properties and early succession on abandoned agricultural fields in two contrasting Mexican socio-ecological systems. Location: Mexico, Oaxaca and Chiapas. Methods: We sampled soil and monitored vegetation for 2 years after agricultural abandonment, and interviewed landowners about their land-use practices. Results: Land-use practices were clearly influenced by landowners’ social context (residence time, rural or urban origin), and topography and soil type also constrained or facilitated land-use practices. Soil characteristics were strongly affected by three land-use practices: mechanical tillage decreased soil N and K; frequent herbicide and pesticide use increased N and K; and for pasture systems, stocking density increased soil bulk density and decreased pH and N. High-intensity land management practices, specifically use of machinery, had the highest impact on early forest succession. When machinery was not used, the frequency of land-use practices, particularly weeding frequency, is the main factor influencing tree cover and sapling diversity. Conclusions: To facilitate post-agricultural forest recovery, we recommend restoration efforts using natural regeneration in areas with low previous land-use intensity and frequency.