Estimating net primary production of natural grassland and its spatio-temporal distribution in China.
Estimating net primary production of natural grassland and its spatio-temporal distribution in China.
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DOI：
10.1016/j.scitotenv.2016.02.106
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发表时间：
2016-05
期刊：
影响因子：
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通讯作者：
Meiling Zhang;R. Lal;Youyi Zhao;Wenlan Jiang;Quangong Chen
中科院分区：
文献类型：
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作者：
Meiling Zhang;R. Lal;Youyi Zhao;Wenlan Jiang;Quangong Chen
草地净初级生产力（NPP）在很大程度上决定了陆地碳（C）汇，在全球碳循环中起着重要作用。草原综合序列分类系统（Comprehensive and sequential classification system of grasslands，CSCS）是一个独特的植被分类系统（主要用于草原），它依赖于定量测量指标[> 0 °C年积温（K θ）和湿度指数（K值）]。基于CSCS的定量分类与草地NPP的关系，采用CASA模型对2004 - 2008年中国草地NPP进行了预测，并分析了其时空分布特征。NPP估算值与实测值的散点图表明，估算值与实测值之间的相关系数为0.896（P< 0.05）。2004 - 2008年中国草地年平均净初级生产力介于443.23 - 554.40 g C m− 2 yr.−1之间。NPP也表现出时空变化。由于植被的地带性分布，NPP有从西北向东南逐渐增加的趋势。从月变化趋势来看，NPP的累积主要发生在4 ~ 10月。从4月到10月的7个月平均NPP为482.19 g C m− 2，约占全年总量的88.78%。这一时空变化趋势表明，水热状况对草地NPP的影响是重要的，即水热状况是草地生产力的关键限制因子，聚类分析也证实了这一点。不同K值和不同θ值草地类型的年平均NPP和年NPP总量差异显著。结果表明，草地NPP与CSCS中的类/超类实现了最佳耦合。
The net primary production (NPP) of grassland largely determines terrestrial carbon (C) sinks, and thus plays an important role in the global C cycle. Comprehensive and sequential classification system of grasslands (CSCS) is a unique vegetation classification system (mainly for grassland) that is dependent on quantitative measurement indices [> 0 °C annual cumulative temperature (Σθ) and moisture index (K-value)]. Based on the relationship of the quantitative classification of CSCS and grassland NPP, a modified model of Carnegie–Ames–Stanford Approach (CASA) was used to predict the grassland NPP and its temporal and spatial distribution in China from 2004 to 2008. The scatter plot of the estimated NPP and the observed NPP showed that the estimated data can be accepted with correlation coefficient of 0.896 (P< 0.05). The average annual NPP of grassland from 2004 to 2008 in China ranged from 443.23 to 554.40 g C m− 2yr.−1. The NPP also showed spatial–temporal variations. There existed an increasing trend of NPP from the northwest to southeast due to the zonal distribution of vegetation. From the trend of monthly variations, it can be drawn that the NPP accumulation primarily occurred between April and October. The average NPP over seven months from April to October was 482.19 g C m− 2, or about 88.78% of the annual total. The spatial–temporal trend suggests the importance of water and thermal regimes in determining the grassland NPP (i.e. water and thermal are key limited factors for the grassland production), which is also confirmed by a cluster analysis. The mean annual NPP and the total annual NPP differed significantly among grassland classes corresponding with different Σθ and K-value. The results demonstrate that the grassland NPP and the classes/super-classes in CSCS achieve the optimum coupling.