Mapping cropping systems and their effects on ecosystem functioning and services in the Argentine Pampas

Abstract

The agricultural expansion and intensification modify the structure and functioning of ecosystems, which alter their capacity to provide ecosystem services (ES). An adequate analysis of these changes requires an exhaustive characterization of land use and land cover. In the Rio de La Plata Grassland (RPG), most of these characterizations are limited in terms of spatial or conceptual resolution since they generally differentiate coarse classes, such as winter and summer crops instead of crop types, at more than 30 m. In this work, we propose to map crop types and cropping systems in one of the most productive agricultural areas of the RPG and assess their effects on ecosystem functioning and services. We combined remote sensing data based on optical and microwave sensors provided by Sentinel 1 and 2 satellites (10 m resolution) and used a Random Forest algorithm to map crop types and cropping systems. Also, we used Landsat 8 images to characterize changes in albedo, Land Surface Temperature (LST) and evapotranspiration (ET) to analyze the environmental impacts of agriculture. Furthermore, we used Sentinel 2 to estimate the Normalized Difference Vegetation Index (NDVI), a proxy of primary production, and the Ecosystem Services Supply Index (ESSI), a synoptic indicator that estimates provision and regulating ES related to water and carbon dynamics based on annual NDVI dynamics. We identified 14 crop types with an overall precision between 0.85 and 0.95. Winter crops were identified with a better precision than summer crops. Compared to native grasslands, the different cropping systems generated an increase in albedo and land surface temperature while evapotranspiration tended to be higher in systems that had more than one crop per year. The productivity (NDVI) and ecosystem services supply (ESSI) were the variables that showed the greatest variability. Schemes based on summer crops with cover crops and pastures would allow maintaining ecosystem functioning, which suggest the need to preserve and expand the area covered by production systems that keep the soil covered for much of the year. This work allowed us to evaluate the effect of cropping systems on ecosystem functioning and services supply, and provide information of interest for the future design, planning and implementation of sustainable productive development schemes.