RESUMO
Center Pivot Irrigation system (CPIs) is widely used in newly exploited arable land in sandy lands. These sandy lands are currently stable because of climate change and ecological restoration efforts since the beginning of the 21st century in northern China. The exploitation of these fixed sandy lands to arable land with CPIs may affect the soil wind erosion, yet it remains unknown. The temporal changes of CPIs and its effect on wind erosion module were analyzed and modeled from 2000 to 2020 in Mu-Us sandy land using satellite images and Revised Wind Erosion Equation (RWEQ). The establishment of CPIs started from 2010, boomed in 2015 and peaked in 2020. They were mainly transformed from woodland, grassland, and barren land near rivers in east and southeast, and from cropland in inter-dunes in west and southwest of Mu-Us sandy land. The temporal and spatial pattern of CPIs well aligns with the land consolidation and requisition-compensation balance policies. In most of the Mu-Us sandy land, the annual erosion module is <25 t ha-1 a-1. Despite great variation, the annual, Winter and Spring erosion module of the Mu-Us sandy land or in Otog Qian and Yuyang, the CPIs concentrated counties, all decreased during 2000-2019. Although, wind erosion module in CPIs was lower than the surrounding area, it increased in 2019 given the same climate conditions as in 2010. Our results suggest 1) the establishment of CPIs in Mu-Us sandy land greatly depends on the local policy and natural endowment, and 2) although the set-up of CPIs showed no impact on the wind erosion with CPIs accounting for <1 % of Mu-Us sandy land, post-harvest of CPIs should be carefully concerned to prevent soil wind erosion.
RESUMO
Intensive and frequent climate change events (e.g., droughts or extreme weather) significantly affect vulnerable water-limited ecosystems. Until now, the ecosystem stability against climate changes in regional scale sandy lands remain unclear. In this study, the AutoRegression (ARx) model was combined with time-series Net Primary Productivity (NPP) data to extract stability metrics (e.g., temporal stability, resilience, drought-resistance, and temperature-resistance) to evaluate the stability of the main sandy land regions of Northern China. Strong correlations among ecosystem stability metrics were found in the study area, such as the significant negative correlation between resilience and resistance (r = -0.49, p < 0.01), the strong positive correlation between drought-resistance and temperature-resistance, (r = 0.81, p < 0.01), except for the uncorrelation between resilience and temporal stability. Meanwhile, more unstable regions were found in the western low- or moderate-cover sandy grassland. Due to the differences of factors (e.g. hydrothermal conditions, vegetation species composition, and other disturbances or anthropogenic impacts), the unstable grasslands and barren regions, Otindag and Hulun Buir sandy lands, and slightly desertified area (SL) presented more resilience but less resistance and variance than the forest and cropland, Horqin Sandy Land, and Moderate (M) or Severe desertified areas (S), respectively. Thus, the unstable low-or moderate-cover grassland and SL area should be paid much more attention to meet the challenges of more intense climate extremes in the future.
