EAGER: Analyzing the Long-Term Soil Biogeochemistry Impacts of Plantation Agriculture and Implications for the Anthropocene Through Community-Engaged Research and Education

Tropical forests store 37% of global terrestrial carbon (C) and contain up to two-thirds of the world’s biodiversity, but these important Earth system functions are increasingly threatened by deforestation and agricultural land-use change. The regeneration of secondary forests on abandoned agricultural land provides a promising avenue towards preserving these critical functions; however, secondary tropical forests exhibit high spatial variability in their recovery of soil C stocks, plant biomass, and plant community composition that cannot be fully explained by common environmental covariates (e.g., climate drivers, topography, forest age).

Modern land-use legacy effects account for an additional portion of this variation; however, most studies to-date have focused on land-use impacts of the last 50-100-years, ignoring a critical period of land-use change and intensive ecosystem disturbance within the Tropics: colonial plantation agriculture facilitated by the Transatlantic Slave Trade. This research aims to characterize the ecological legacy effects of colonial plantation agriculture on tropical soils of St.

Croix, U.S. Virgin Islands, a small Caribbean island that was almost completely deforested in the 18th and 19th centuries and transformed into a Danish colonial sugarcane colony. Using a strategic study design informed by ecological gradient analysis, and archival data and methods from historical and social science disciplines, the PI team will employ a sampling scheme across former plantation estates that span a gradient of disturbance intensity values, measuring total soil C stocks, metrics of soil C stability, and isotopic signatures of soil and plant leaf waxes.

From these measurements, the intensity and duration of plantation agriculture will be evaluated to see how it influenced soil carbon storage and stability, with potential feedbacks to forest successional trajectories and plant community composition.

Tropical forests store over a third of the Earth’s land carbon (C), preventing the release of climate-warming CO2 into the atmosphere. Forest clearing for agriculture is a major human land use activity that reduces the storage of forest C and contributes to global warming. Forest regeneration on abandoned agricultural lands appears to help sequester C and mitigate climate change; however, forests are not regenerating consistently across the Tropics.

Agricultural plantations dominated the tropical landscapes of the Caribbean and Latin American tropics from the 1700-1800s, and historical records suggest they caused widespread damage to soils and ecosystems of this region. This research project aims to evaluate how this historical form of landscape transformation may have affected past soil C storage and the ability of these forest soils to serve as C sinks in the present, and into the future.

Furthermore, this research is among the first to detect the biophysical legacy effects and present implications of an historical human land use activity that was underpinned by the long-term human rights abuses of the Trans-Atlantic Slave Trade. Minimizing losses of soil C and understanding where forest soils are most vulnerable to further C loss is significant for mitigating the health and security risks associated with current and future global climate change.

This project is co-supported by the RISE/GOLDEN and EAR/GLD Programs in the Directorate for Geosciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.