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Highlights • We analyze the spatiotemporal pattern of the ECC on the Loess Plateau. • The average annual ECC is 577 ± 124 g C m−2 yr−1 during 1982–2012. • Due to revegetation, 26 counties have exceeded the ECC threshold. • 138 counties have water competition between ecosystems and socio-economic systems. • Under future climate change and growing water demand, ECC will increase by 6–36%. Abstract Revegetation, especially afforestation, has served as an important tool for controlling desertification. However, revegetation in water-limited regions will inevitably reduce the water available for socio-economic systems, which is poorly considered in decision-making on sustainable ecosystem management. This paper proposed a framework to determine the threshold of vegetation productivity (i.e., ecosystem carrying capacity), corresponding to available water resources for ecosystems (i.e., annual precipitation minus water demand for socio-economic systems) on the Loess Plateau. The average annual ecosystem carrying capacity (ECC) during 1982–2012 is 577 ± 124 g C m−2 yr−1, with spatial gradients increasing from northwest to southeast. Vegetation in rocky mountain areas has the largest value of 833 ± 200 g C m−2 yr−1. Factorial analysis suggests that changes in precipitation and human water use contributed to 55% and 45% of the multi-decadal changes in regional ECC, respectively. Meanwhile, due to revegetation, 26 counties on the Loess Plateau, mainly in the southeast and eastern parts, have exceeded the ECC threshold during the study period. An additional 138 counties have a high potential for water competition between the ecosystems and socio-economic systems. At the regional scale, there are 9 years (∼30% of the study period) during which the ECC threshold has been exceeded, especially after 1997. Considering the climate change in the future and the growing demand for water in socio-economic systems, the corresponding ECC threshold will increase by 6–36%. We believe that these findings can provide reference for policy-makers to make decisions towards ecosystem sustainability while meeting human needs for water resources. [ABSTRACT FROM AUTHOR]

Climate change will affect the future availability of water resources for agriculture. An understanding of the impact of future climate change on regional agricultural water use can provide a basis for regional agricultural production and water management. This paper evaluated the agricultural water demand under three future climate change scenarios in the Loess Plateau of northern Shaanxi (LPNS), China. The results showed that in the scenarios RCP2.6, RCP4.5, and RCP8.5, the temperature, effective precipitation, and relative humidity were on the rise, the wind speed decreased slightly, and the trend of sunshine duration was unclear. The irrigation water requirements of the main crops exhibited a downward trend under future climate change scenarios. The decreasing trend of the irrigation water requirement was highest in the RCP8.5 (−0.90%) scenario, followed by the RCP4.5 (−0.77%/year) and the RCP2.6 (−0.30%/year) scenarios. Based on the impact of the changes in the evapotranspiration of future crops and the effective precipitation in the RCP2.6 scenario, the irrigation water requirements of the agricultural industry showed a downward trend and decreased from 1.84 × 10 9 m 3 /year (2010–2014 average) to 1.29 × 10 9 m 3 /year (2040–2049 average); the irrigation water requirements of the agricultural industry showed a significant downward trend (P < 0.05) in the RCP4.5 and RCP8.5 scenarios, decreasing from 1.84 × 10 9 m 3 /year (2010–2014 average) to 1.20 × 10 9 m 3 /year (2040–2049 average) and 1.15 × 10 9 m 3 /year (2040–2049 average), respectively. Future research should be aimed at improving the regional climate downscaling and developing a better understanding of the responses of agriculture to regional climate change. [ABSTRACT FROM AUTHOR]