Abstract
Vegetative precipitation-use efficiency (PUE) is a key indicator for evaluating the dynamic response of vegetation productivity to the spatiotemporal variation in precipitation. It is also an important indicator for reflecting the relationship between the water and carbon cycles in a vegetation ecosystem. This paper uses data from MODIS Net Primary Production (NPP) and China’s spatial interpolation data for precipitation from 2000 to 2015 to calculate the annual value, multiyear mean value, interannual standard deviation, and interannual linear trend of Chinese terrestrial vegetative PUE over the past 16 years. Based on seven major administrative regions, eleven vegetation types, and four climate zones, we analyzed the spatiotemporal variation characteristics of China’s vegetative PUE. The research results are shown as follows: (1) China’s vegetative PUE shows obvious spatial variation characteristics, and it is relatively stable interannually, with an overall slight increasing trend, especially in Northwest and Southwest China. The vegetative PUE is higher, and its stability is declined in Xinjiang, western Gansu, and the southern Tibetan valley. The vegetative PUE is lower, and its stability is increased in northeastern Tibet and southwestern Qinghai. An increasing trend in vegetative PUE is obvious at the edge of the Tarim Basin, in western Gansu, the southern Tibetan valley, and northwestern Yunnan. (2) There is a significant difference in the PUEs among different vegetation types. The average PUE of Broadleaf Forest is the highest, and the average PUE of Alpine Vegetation is the lowest. The stability of the PUE of Mixed Coniferous and Broadleaf Forest is declined, and the stability of the PUE of Alpine Vegetation is increased. The increasing speed of the PUE of Grass-forb Community is the fastest, and the decreasing speed of the PUE of Swamp is the fastest. (3) There is a significant difference in the PUEs among different vegetation types in the same climate zone, the difference in vegetative PUE in arid and semiarid regions is mainly affected by precipitation, and the difference in vegetative PUE in humid and semihumid regions is mainly affected by soil factors. The PUEs of the same vegetation type are significantly different among climate zones. The average PUE of Cultural Vegetation has the largest difference, the stability of the PUE of Steppe has the largest difference, and the increasing speed of the PUE of Swamp has the largest difference.
Highlights
Introduction eEarth’s climate is strongly influenced by the characteristics of atmosphere and ground surface which is known as the ecological environment [1,2,3]. e human economic activities have been proved to have significant impact on the ecosystems
China, where the averages of multiyear mean values are 6.4 × 10−1 gC·m−2·mm−1, 6.23 × 10−1 gC·m−2·mm−1, and 5.89 × 10−1 gC·m−2·mm−1, respectively. ese averages are significantly higher than the national average, especially in northeastern Jilin, southeastern Liaoning, most of Xinjiang and Gansu, northwestern Qinghai, northern Ningxia, western Inner Mongolia and other regions, and the southern Tibetan valley in Southwest China. e vegetative precipitation-use efficiency (PUE) in South China is the lowest, where the average of the multiyear mean value is 4.37 × 10−1 gC·m−2·mm−1; it is significantly lower than the national average, especially in northeastern Guangxi, northwestern Guangdong, and other regions
The interannual spatial variation characteristics of the vegetative PUE are significant, with a minimum value of 2.8 × 10−3. It is mainly distributed in northern Xinjiang, southwest Qinghai, northeastern Tibet, southern Anhui and other regions in Northwest China, Southwest China, and East China; the maximum value is 7.734, mainly distributed in the edge area of the Tarim Basin in Northwest China. e vegetative PUE stability is declined in Northeast and Northwest China, where the interannual standard variations are 1.387 × 10−1 and 1.474 × 10−1, respectively, especially in northeastern Jilin, southern Liaoning, the edge of the Tarim Basin, and other regions. e stability of the vegetative PUE in central China is increased, where the interannual standard variation is 8.8 × 10−2, especially in the majority of Hunan, southern Hubei, and other regions
Summary
Introduction eEarth’s climate is strongly influenced by the characteristics of atmosphere and ground surface which is known as the ecological environment [1,2,3]. e human economic activities have been proved to have significant impact on the ecosystems. Earth’s climate is strongly influenced by the characteristics of atmosphere and ground surface which is known as the ecological environment [1,2,3]. E interactions and mutual adaptations of ecosystems and the environment are embodied by the response relationship between global climate change and the vegetation ecosystem [8,9,10]. After its reform and opening up, China’s ecological environment is worsening, leading to the degradation of vegetation, and vegetation degradation results from the interactions between climate change and human activities [11,12,13]. Climate change is the main reason for vegetative degradation, directly resulting in the decrease of vegetation, causing desertification. Human activities and climate change interact in complex ways [14, 15]
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