Zhang Renping, Guo Jing, Yin Gang
College of Resource and Environment Sciences, Key Laboratory of Oasis Ecology, Xinjiang University, Urumqi, China.
Xinjiang Academy Forestry, Urumqi, China.
PeerJ. 2021 Apr 30;9:e10650. doi: 10.7717/peerj.10650. eCollection 2021.
Determining the relationship between net primary productivity (NPP) and grassland phenology is important for an in-depth understanding of the impact of climate change on ecosystems. In this study, the NPP of grassland in Xinjiang, China, was simulated using the Carnegie-Ames-Stanford approach (CASA) model with Moderate Resolution Imaging Spectroradiometer (MODIS) grassland phenological (MCD12Q2) data to study trends in phenological metrics, grassland NPP, and the relations between these factors from 2001-2014. The results revealed advancement of the start of the growing season (SOS) for grassland in most regions (55.2%) in Xinjiang. The percentage of grassland area in which the end of the growing season (EOS) was delayed (50.9%) was generally the same as that in which the EOS was advanced (49.1%). The percentage of grassland area with an increase in the length of the growing season (LOS) for the grassland area (54.6%) was greater than that with a decrease in the LOS (45.4%). The percentage of grassland area with an increase in NPP (61.6%) was greater than that with a decrease in NPP (38.4%). Warmer regions featured an earlier SOS and a later EOS and thus a longer LOS. Regions with higher precipitation exhibited a later SOS and an earlier EOS and thus a shorter LOS. In most regions, the SOS was earlier, and spring NPP was higher. A linear statistical analysis showed that at various humidity () levels, grassland NPP in all regions initially increased but then decreased with increasing LOS. At higher levels of , when NPP gradually increased, the LOS gradually decreased.
确定净初级生产力（NPP）与草地物候之间的关系，对于深入理解气候变化对生态系统的影响至关重要。在本研究中，利用卡内基-埃姆斯-斯坦福方法（CASA）模型和中分辨率成像光谱仪（MODIS）草地物候数据（MCD12Q2），模拟了中国新疆草地的NPP，以研究2001 - 2014年期间物候指标、草地NPP的变化趋势以及这些因素之间的关系。结果表明，新疆大部分地区（55.2%）草地生长季开始时间（SOS）提前。生长季结束时间（EOS）推迟的草地面积百分比（50.9%）与EOS提前的百分比（49.1%）基本相同。生长季长度（LOS）增加的草地面积百分比（54.6%）大于LOS减少的百分比（45.4%）。NPP增加的草地面积百分比（61.6%）大于NPP减少的百分比（38.4%）。温暖地区SOS较早，EOS较晚，因此LOS较长。降水量较高的地区SOS较晚，EOS较早，因此LOS较短。在大多数地区，SOS较早，春季NPP较高。线性统计分析表明，在不同湿度（）水平下，所有地区的草地NPP最初随LOS增加而增加，但随后下降。在较高的水平下，当NPP逐渐增加时，LOS逐渐下降。
