Xiao Xingyuan, Li Xiubin, Jiang Tao, Tan Minghong, Hu Minyue, Liu Yaqun, Zeng Wen
College of Geomatics Shandong University of Science and Technology Qingdao China.
Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China.
Ecol Evol. 2019 Mar 30;9(8):4651-4666. doi: 10.1002/ece3.5068. eCollection 2019 Apr.
Net primary production (NPP) supplies matter, energy, and services to facilitate the sustainable development of human society and ecosystem. The response mechanism of NPP to land use and climate changes is essential for food security and biodiversity conservation but lacks a comprehensive understanding, especially in arid and semi-arid regions. To this end, taking the middle-reaches of the Heihe River Basin (MHRB) as an example, we uncovered the NPP responses to land use and climate changes by integrating multisource data (e.g., MOD17A3 NPP, land use, temperature, and precipitation) and multiple methods. The results showed that (a) land use intensity (LUI) increased, and climate warming and wetting promoted NPP. From 2000 to 2014, the LUI, temperature, and precipitation of MHRB increased by 1.46, 0.58°C, and 15.76 mm, respectively, resulting in an increase of 14.62 gC/m in annual average NPP. (b) The conversion of low-yield cropland to forest and grassland increased NPP. Although the widespread conversion of unused land and grassland to cropland boosted both LUI and NPP, it was not conducive to ecosystem sustainability and stability due to huge water consumption and human-appropriated NPP. Urban sprawl occupied cropland, forest, and grassland and reduced NPP. (c) Increase in temperature and precipitation generally improved NPP. The temperature decreasing <1.2°C also promoted the NPP of hardy vegetation due to the simultaneous precipitation increase. However, warming-induced water stress compromised the NPP in arid sparse grassland and deserts. Cropland had greater NPP and NPP increase than natural vegetation due to the irrigation, fertilizers, and other artificial inputs it received. The decrease in both temperature and precipitation generally reduced NPP, but the NPP in the well-protection or less-disturbance areas still increased slightly.
净初级生产力（NPP）为人类社会和生态系统的可持续发展提供物质、能量和服务。NPP对土地利用和气候变化的响应机制对粮食安全和生物多样性保护至关重要，但目前仍缺乏全面的认识，尤其是在干旱和半干旱地区。为此，以黑河流域中游（MHRB）为例，我们通过整合多源数据（如MOD17A3 NPP、土地利用、温度和降水）和多种方法，揭示了NPP对土地利用和气候变化的响应。结果表明：（a）土地利用强度（LUI）增加，气候变暖和湿润促进了NPP。2000年至2014年，MHRB的LUI、温度和降水分别增加了1.46、0.58°C和15.76毫米，导致年平均NPP增加了14.62克碳/平方米。（b）低产农田向森林和草地的转变增加了NPP。虽然未利用土地和草地向农田的广泛转变提高了LUI和NPP，但由于巨大的水资源消耗和人类占用的NPP，这不利于生态系统的可持续性和稳定性。城市扩张占用了农田、森林和草地，降低了NPP。（c）温度和降水的增加总体上提高了NPP。温度下降<1.2°C时，由于降水同时增加，也促进了耐寒植被的NPP。然而，变暖引起的水分胁迫削弱了干旱稀疏草地和沙漠的NPP。由于灌溉、施肥和其他人工投入，农田的NPP和NPP增加幅度大于天然植被。温度和降水的下降通常会降低NPP，但在保护良好或干扰较小的地区，NPP仍略有增加。
