Wang Zhi Peng, Zhang Xian Zhou, He Yong Tao, Li Meng, Shi Pei Li, Zu Jia Xing, Niu Ben
Lhasa Plateau Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jan;29(1):75-83. doi: 10.13287/j.1001-9332.201801.014.
Precipitation change is an important factor in the inter-annual variation of grassland growth on the Tibetan Plateau. The total amount, distribution pattern and concentration time are three basic characteristics of precipitation change. The temporal and spatial characteristics of precipitation change were analyzed based on climate data of 145 meteorological stations on the Tibetan Plateau and nearby areas from 2000 to 2015. The total precipitation amount was characterized by annual precipitation, distribution pattern of precipitation during the year was characterized by improved precipitation concentration index (PCI), and precipitation centroid (PC) was defined to indicate the change in precipitation concentrated time. To better illustrate the response of grassland to precipitation change, vegetation growth status was characterized by the maximum value of normalized difference vegetation index (NDVI). Results indicated that the annual precipitation and PCI had an apparent gradient across the whole plateau and the latest PC occurred in the southern plateau. NDVI of alpine shrub grassland was significantly correlated with the change of PCI,increased with even distribution of precipitation during growth period, and limited by the total annual precipitation. Alpine meadow did not show significantly correlations with these three indices. The inter-annual variability of NDVI of steppe was controlled by both PCI and PC. NDVIof alpine desert grassland was mainly controlled by annual precipitation. In addition to annual total amount of precipitation, the distribution characteristics of precipitation should be further considered when the influence of precipitation change on different types of vegetation on the Qinghai Tibet Plateau was studied.
降水变化是青藏高原草地生长年际变化的一个重要因素。降水量、分布格局和集中期是降水变化的三个基本特征。基于2000年至2015年青藏高原及周边地区145个气象站的气候数据，分析了降水变化的时空特征。年降水量表征年总降水量，降水集中指数（PCI）改进后表征年内降水分布格局，定义降水重心（PC）来指示降水集中时间的变化。为了更好地说明草地对降水变化的响应，用归一化植被指数（NDVI）最大值表征植被生长状况。结果表明，年降水量和PCI在整个高原上有明显梯度，最新的PC出现在高原南部。高寒灌丛草地的NDVI与PCI变化显著相关，随生长季降水均匀分布而增加，受年总降水量限制。高寒草甸与这三个指数均无显著相关性。草原NDVI的年际变率受PCI和PC共同控制。高寒荒漠草地的NDVI主要受年降水量控制。在研究降水变化对青藏高原不同植被类型的影响时，除了年降水量总量外，还应进一步考虑降水的分布特征。
