Abstract
The rapid urbanization process has threatened the ecological environment. Net primary productivity (NPP) can effectively indicate vegetation growth status in an urban area. In this paper, we evaluated the change in NPP in China and China’s urban lands and assessed the impact of temperature, precipitation, the sunshine duration, and vegetation loss due to urban expansion on NPP in China’s three fast-growing urban agglomerations and their buffer zones (~5–20 km). The results indicated that the NPP in China exhibited an increasing trend. In contrast, the NPP in China’s urban lands showed a decreasing trend. However, after 1997, China’s increasing trend in NPP slowed (from 9.59 Tg C/yr to 8.71 Tg C/yr), while the decreasing trend in NPP in China’s urban lands weakened. Moreover, we found that the NPP in the Beijing–Tianjin–Hebei urban agglomeration (BTHUA), the Yangtze River Delta urban agglomeration (YRDUA), and the Pearl River Delta urban agglomeration (PRDUA) showed a decreasing trend. The NPP in the BTHUA showed an increasing trend in the buffer zones, which was positively affected by temperature and sunshine duration. Additionally, nonsignificant vegetation loss could promote the increase of NPP. In the YRDUA, the increasing temperature was the main factor that promoted the increase of NPP. The effect of temperature on NPP could almost offset the inhibition of vegetation reduction on the increase of NPP as the buffer zone expanded. In PRDUA, sunshine duration and vegetation loss were the main factors decreasing NPP. Our results will support future urban NPP prediction and government policymaking.
Highlights
The Chinese land-use/cover dataset (CLUD) is based on a variety of multispectral satellite data, including data from the Landsat multispectral scanner (MSS), thematic mapper (TM), enhanced thematic mapper plus (ETM+), operational land imager (OLI), and the Huanjing-1 (HJ-1) satellite
We evaluated the importance of the annual cumulative precipitation, the the average annual cumulative precipitation in the Beijing–Tianjin–Hebei urban agglomeration (BTHUA) was less than in other urban annual average air temperature, the annual cumulative sunshine duration, and the proagglomerations
We confirmed that the range of the annual Net primary productivity (NPP) in China is between 2751 and 3343 Tg C, which is consistent with previous studies [37,38]
Summary
More than 50% of the world’s total population lives in urban areas. According to the World Population Prospects revised by the United Nations in 2017, the world’s urban population will grow to approximately 8.5 billion by 2030 [1]. Population growth and rapid economic development are important factors contributing to the urbanization process, which has become a common phenomenon around the world [2,3,4]. Previous studies have demonstrated that Asia and North America have the most newly urbanized areas. Europe has already been highly urbanized, and the increase in urban area there is the smallest [5]
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