School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510641, China.
School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510641, China.
Sci Total Environ. 2018 Oct 15;639:237-247. doi: 10.1016/j.scitotenv.2018.05.155. Epub 2018 May 19.
Land use and land cover patterns in mainland China have substantially changed in the recent decades under the economic reform policies of the government. The terrestrial carbon cycle, particularly the net primary productivity (NPP), has been substantially changed on both local and national scales. With the growing concern over the effects of the terrestrial carbon cycle on global climate changes, the impacts of land use and cover change (LUCC) on NPP need to be understood. In this study, variations in NPP caused by LUCC (e.g., urbanization and conversion of other land use to forest and grassland) in mainland China from the late 1980s to 2015 were evaluated based on land cover datasets and NPPs simulated from the Carnegie-Ames-Stanford Approach model. The results indicate that the national total losses in NPP attributed to urbanization reached 1.695 TgC between the late 1980s and 2015. A large proportion (63.02%) of the total losses was due to the transformation from cropland to urban land. Urban expansion decreased the monthly and total NPPs over southern China, which includes the South China Region, Southwest China Region, and the middle and lower regions of the Yangtze River. However, the total NPP increased in the majority of urbanized areas in Northern China, including the Huang-Huai-Hai Region, Inner Mongolia Region (MGR), Gan-Xin Region (GXR), and Northeast China Region; monthly NPP in GXR and MGR increased throughout the year. By contrast, the conversion to grassland or forestland increased the monthly and total NPPs of Northern China, suggesting that returning to forestland and grassland could increase the carbon sequestration capacity of terrestrial ecosystems in mainland China. Among the sub-regions, the Loess Plateau Region contributed the largest increase in NPP, which was prompted by the conversion to grassland and forestland.
在政府经济改革政策的推动下，近几十年来，中国大陆的土地利用和土地覆盖格局发生了巨大变化。陆地碳循环，特别是净初级生产力（NPP），在地方和国家尺度上都发生了重大变化。随着人们对陆地碳循环对全球气候变化影响的关注日益增加，需要了解土地利用和土地覆盖变化（LUCC）对 NPP 的影响。本研究基于土地覆盖数据集和 Carnegie-Ames-Stanford 方法模型模拟的 NPP，评估了 20 世纪 80 年代末至 2015 年中国大陆因 LUCC（如城市化和其他土地利用向森林和草地的转化）而导致的 NPP 变化。结果表明，城市化导致的全国 NPP 总损失在 20 世纪 80 年代末至 2015 年期间达到 1.695TgC。总损失的很大一部分（63.02%）是由于耕地向城市用地的转化。城市扩张降低了中国南方（包括华南地区、西南地区和长江中下游地区）的月和年 NPP。然而，包括黄淮海地区、内蒙古地区（MGR）、甘新区（GXR）和东北地区在内的中国北方大部分城市化地区的总 NPP 都有所增加，GXR 和 MGR 的月 NPP 全年都在增加。相比之下，向草地或林地的转化增加了中国北方的月和年 NPP，这表明退耕还林还草可以提高中国陆地生态系统的碳固存能力。在各分区域中，黄土高原地区因向草地和林地的转化而对 NPP 的贡献最大。
