Abstract
Abstract. Grassland ecosystems play important roles in the global carbon cycle. The net primary productivity (NPP) of grassland ecosystems has become the hot spot of terrestrial ecosystems. To simulate grassland NPP in southern China, a new model using productivity coupled with hydrothermal factors (PCH) was built and validated based on data recorded from 2003 to 2014. The results show a logarithmic correlation between grassland NPP and mean annual temperature and a linear positive correlation between grassland NPP and mean annual precipitation in southern China, both highly significant relationships. There was a highly significant correlation between simulated and measured NPP (R2 = 0. 8027). Both RMSE and relative root mean square error (RRMSE) were relatively low, showing that the simulation results of the model were reliable. The NPP values in the study area had a decreasing trend from east to west and south to north. Mean NPP was 471.62 g C m−2 from 2003 to 2014. Additionally, the mean annual NPP of southern grassland presented a rising trend, increasing 3.49 g C m−2 yr−1 during the past 12 years. These results document performance and use of a new method to estimate the grassland NPP in southern China.
Highlights
Grassland is one of the major biological communities in the world
Sun et al.: Application of a new model using productivity coupled with hydrothermal factors practical significance for evaluating the environmental quality of terrestrial ecosystems, regulating ecological processes, and estimating the terrestrial carbon sink to master the interannual variation rule of terrestrial Net primary productivity (NPP) (Cao et al, 2013; Richardson et al, 2012; Picard et al, 2005; Zhang et al, 2011; Xu et al, 2012)
Grassland NPP is a joint result of the regional light, temperature, precipitation, soil, and other natural conditions, which reflects the ability of using natural environmental resources (Gang et al, 2015)
Summary
Grassland is one of the major biological communities in the world It covers more than 40 % of the total land area on the planet and plays an important role in the global biogeochemical cycle and energy transformation process (Chen and Zhang, 2000; Mosier et al, 1991). Changes in NPP directly reflect the response of ecosystems to climatic conditions; it can be used as a research index in the relationship between ecosystem function and climate change (Zhou et al, 2014).
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