西藏NPP时空格局与气候因子的关系

根据2000-2012年1 km MOD17A3 NPP遥感数据和气温、降水等气象资料,在GIS支撑下,结合多种统计计算方法,对西藏NPP时空格局与气候因子的关系进行研究。结果表明:2000-2012年间西藏陆地植被的NPP为119.3～148.4 g·m^-2·a^-1,平均为135.2 g·m^-2·a^-1;近年来西藏NPP呈不显著上升趋势,NPP总体上由东南向西北逐渐变小。13年来西藏NPP在总体不变(面积占61.11%)的基础上略有增加(面积占10.7%);不同植被类型中阔叶林的NPP最大,为1 185.2～1 430.2 g·m^-2·a^-1,其次是混交林,为535.1～741.2 g·m^-2·a^-1,其后依次是稀树草原、针叶林、农用地、草地和灌丛;西藏NPP与气温、降水因子分别有较好的正、负相关性。所有植被类型都与年均气温呈正相关,其中草地的NPP与年均气温的相关系数达0.88,其次是针叶林为0.76,相关性最差为热带稀树草原0.13;与年降水量的相关性,除了热带稀树草原正相关(0.26),其余都负相关,草地、针叶林的相关系数分别为-0.79、-0.73。

Spatial and Temporal Pattern of NPP and Its Relationship with Climate Factors in Tibet,China

Based on MOD17A3 NPP remote sensing data and meteorological data such as temperature, precipitation, the spatiotemporal distribution and variation characteristics of vegetation net primary productivity (NPP) and their relationships with climate factor was studied in Tibet from 2000-2012 by using of GIS and statistical methods. The results show that the NPP of vegetation in Tibet varies from 119.3 to 148.4 gC·m^-2·a^-1, with an average of 135.2 gC·m^-2·a^-1; anomaly analysis shows that the NPP was not significant upward trend in recent years, and its value is gradually decreasing from the southeast to the northwest on the whole based on the Tibet. The NPP slightly increases for almost 10.70% and remain unchanged which occupied 61.11% of total region during the past 13 years. Considering the NPP of different vegetation types, broadleaved forest has the largest value ranging from 1 185.2 gC·m^-2·a^-1 to 1 430.2 gC·m^-2·a^-1, then mixed forest with varies from 535.1 gC·m^-2·a^-1 to 741.2 gC·m^-2·a^-1, followed by savannas, coniferous forest, farmland, grassland and shrub. The NPP over Tibet has a better positive and negative relation with the annual mean temperature and the annual precipitation respectively. All vegetation types were positively correlated with mean annual temperature, which grassland NPP and the average annual temperature correlation coefficient of 0.88, followed by coniferous forest was 0.76, the worst correlation is savanna(r=0.13). The correlation analysis indicates that the NPP of different vegetation types are negatively related to the annual precipitation except the NPP of savanna (r=0.26), where the grass maximum correlation coefficient (r=-0.79), followed by coniferous forest (r=-0.73).