三江源区植被净初级生产力时空特征及对气候变化的响应

Temporal and Spatial Characteristics of Vegetation Net Primary Productivity and Its Responses to Climate Change in Three-river Headwaters Region

三江源区是我国乃至亚洲重要的水源地,是高寒生态系统的脆弱区和敏感区。植被净初级生产力(Net Primary Productivity,NPP)是评价生态环境状况的重要指标。利用1961—2014年三江源区18个气象站的气象观测资料、11个监测点的草地生物量观测资料以及中国地区气候变化预估数据集的全球气候模式加权平均集合数据,通过5种估算植被NPP气候模型的对比验证,筛选出适用性好、精度高的模型构建该区植被NPP估算模型,并进行植被NPP的时空变化特征及对气候变化的响应分析。结果表明:周广胜模型对三江源区的植被NPP模拟结果有效且精度最高,故选用该模型模拟三江源区植被NPP。1961—2014年,三江源区植被NPP呈从东南向西北逐渐降低的空间分布特征,平均值为59.59 gC·m^(-2),其中黄河源区植被NPP的年际及空间波动高于长江源区和澜沧江源区;近54 a植被NPP整体呈显著增加趋势,但不同区域变化幅度有所差异。气温是影响三江源区植被NPP增加的主要气象因素;未来90 a三江源区植被NPP仍呈现持续增加态势。

The three-river headwaters region is an important water source in China,even in the Asia,which is a vulnerable and sensitive area of high-cold ecosystem. Net primary productivity（NPP） is one of the important indicators of ecological environment evaluation. For exploring the vegetation biomass to adapt climate change in the three-river headwaters region,based on the meterological observation data at 18 weather stations during 1961-2014,biomass observation data of grassland at 11 monitoring sites during 2003-2013 and prediction data set of climate change in China during 2011-2100 from the National Climate Center,the applicable and high precision model was selected to estimate vegetation NPP in three-river headwaters region by comparing the five climate estimation models of NPP. And on this basis that the temporal and spatial variation characteristics of vegetation NPP and its response to climate change in the three-river source area from 1961 to 2014 were analyzed and predicted. The results showed that Zhou Guang-sheng＇s model to estimate vegetation NPP in the three-river source region had good applicability and the highest precision,so the model was used to estimate NPP from 1961 to 2014. The spatial distribution of NPP decreased gradually from southeast to northwest in the three-river source region,the average was 59. 59 gC·m^-2,and the spatial and interannual fluctuations of NPP in the Yellow River source area was higher than in the Yangtze River and Lancangjiang River source areas during 1961-2014. NPP had an increasing trend in the past 54 years on the whole,but the change rates in different regions were obviously different. The temperature was an important factor to affect the increase of vegetation NPP in the three-river source region. In the future 90 years,NPP in three-river headwaters region still would continue to increase.