Ecological and hydrological response of farmlands abandoned for different lengths of time: Evidence from the Loess Hill Slope of China

• Two-phase mosaic structure forms, and moss coverage increases on abandoned land.
• Runoff increases but loss of sediment decreases after farmland abandonment.
• The wastage of soil organic matter and most nutrients decreases on abandoned slopes.

As a widely distributed land use type, abandoned farmland has become a research focus due to its complex ecological and hydrological responses. Most recent studies have focussed on the interactions between the ecological and hydrological responses in degradation processes, whilst little research has focussed on the recovery of the ecosystem. Moreover, some in-depth analyses are required to further elucidate their interactive on abandoned farmland. In addition, although runoff generation and soil erosion on abandoned farmland have been investigated, few reports have investigated nutrient transport in runoff and eroded sediments.This study investigated the vegetation and soil composition and carried out a 2 year monitoring experiment to monitor the runoff and soil erosion of farmlands abandoned for different lengths of time (4, 12, 22 and 50 years) on a mountain slope located in the Loess Plateau of China. It is found that after farmland abandonment, vegetation holds a positive succession. A two-phase mosaic structure forms, and the moss coverage increases on the inter-vascular plant. From 4 to 50 years in abandoned farmland, the average accumulated runoff increases from 9698.2 ml to 38,605.3 ml in a 5 × 2 m runoff plot. Additionally, the average accumulated sediment loss decreases from 2019.5 g to 387.7 g in a same plot. Furthermore, the wastage of soil organic matter and most nutrients also decreases on slopes after farmland abandonment because the nutrients are mainly lost in the eroded sediments.