Whether China can achieve the United Nations’ Sustainable Development Goals (SDGs) largely depends on the ability of main food-producing areas to cope with multiple land use change challenges. Despite the fact that the Yangtze River basin is one of the key regions for China’s food security, the spatiotemporal dynamics of cropland abandonment and recultivation remain largely unexplored in this region. The present study assesses the evolution of the agricultural system within the Yangtze River basin between 2000 and 2020 by mapping cropland abandonment and recultivation using MODIS time series and multiple land cover products. The results highlight a widespread cropland abandonment process (i.e., 10.5% of the total study area between 2000 and 2020), predominantly in Western Sichuan, Eastern Yunnan, and Central Jiangxi. Although 70% of abandoned cropland is situated in areas with slopes less than 5°, the highest rates of abandonment are in mountainous regions. However, by 2020, 74% of this abandoned cropland had been recultivated at least once, whereas half of the abandoned croplands got recultivated within three years of their initial abandonment. Hence, as this is one of the first studies that unravels the complex interaction between cropland abandonment and recultivation in a spatiotemporal explicit context, it offers (i) scientists a novel methodological framework to assess agricultural land use issues across large geographical entities, and (ii) policy-makers new insights to support the sustainable transition of the agricultural sector.

Over the last decades, growing crop production across China has had far-reaching consequences for both the environment and human welfare. One of the emerging questions is “how to meet the growing food demand in China?” In essence, the consensus is that the best way forward would be to increase crop yield rather than further extend the current cropland area. However, assessing progress in crop production is challenging as it is driven by multiple factors. To date, there are no studies to determine how multiple factors affect the crop production increase, considering both intensive farming (using yield and multiple cropping index) and large-scale farming (using mean parcel size and number of parcels). Using the Logarithmic-Mean-Divisia-Index (LMDI) decomposition method combined with statistical data and land cover data (GlobeLand30), we assess the contribution of intensive farming and large-scale farming changes to crop production dynamics at the national and county scale. Despite a negative contribution from MPS (mean parcel size, ), national crop production increased due to positive contributions from yield (), MCI (multiple cropping index, ), as well as NP (number of parcels, ). This allowed China to meet the growing national crop demand. We further find that large differences across regions persist over time. For most counties, the increase in crop production is a consequence of improved yields. However, in the North China Plain, NP is another important factor leading to crop production improvement. On the other hand, regions witnessing a decrease in crop production (e.g., the southeast coastal area of China) were characterized by a remarkable decrease in yield and MCI. Our detailed analyses of crop production provide accurate estimates and therefore can guide policymakers in addressing food security issues. Specifically, besides stabilizing yield and maintaining the total NP, it would be advantageous for crop production to increase the mean parcel size and MCI through land consolidation and financial assistance for land transfer and advanced agricultural infrastructure.

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). References:1. Liang, X.; Jin, X.; Yang, X.; Xu, W.; Lin, J.; Zhou, Y. Exploring cultivated land evolution in mountainous areas of Southwest China, an empirical study of developments since the 1980s. Land Degradation & Development 2021, 32, 546-558.2. Long, Y.; Wu, W.; Wellens, J.; Colinet, G.; Meersmans, J. An In-Depth Assessment of the Drivers Changing China’s Crop Production Using an LMDI Decomposition Approach. Remote Sensing 2022, 14, 6399.3. Yan, J.; Yang, Z.; Li, Z.; Li, X.; Xin, L.; Sun, L. Drivers of cropland abandonment in mountainous areas: A household decision model on farming scale in Southwest China. Land Use Policy 2016, 57, 459-469.