Cropland abandonment across the Yangtze River Basin does provide only limited benefits for C sequestration

Abstract

Recent estimates from satellite imageries indicated that extensive cropland abandonment took place across China due to rural outmigration, agricultural policy and environment changes[1-3]. Cropland abandonment provides an opportunity for C sequestration, and therefore climate change mitigation, soil retention and food security. However, this depends on the duration of cropland abandonment, which lacks comprehensive research. In this study, we map cropland abandonment and recultivation across the Yangtze River Basin in central China using a series of annual land cover maps of the period 2000 - 2020. The InVEST model is used to study the spatial distribution of carbon storage. We found that cropland abandonment is widespread, but last on average only 5.5 years. In addition, over 50% of the abandoned croplands will be recultivated (i.e. back into cropland) or convert into impervious surfaces (i.e. urban) within 20 years, limiting its ability to provide ecosystem services, such as climate regulation, soil retention and food security, due to a relatively small capacity of C sequestration. More precisely, the combined effect of recultivation and conversion into impervious surfaces resulted in an accumulated loss of 75% of abandoned croplands and 41% of carbon as compared to a situation without recultivation or conversion into impervious surfaces. In conclusion, this study highlights the need for land policymakers to make careful reflections as regards the conversion of abandoned croplands in order to mitigate climate change and combat soil degradation. Hence, it could be interesting to set up incentives for ecological restoration in order to valorize opportunities that cropland abandonment may provide us with when aiming to achieve the UN Sustainable Development Goals (SDGs).