Journal of Resources and Ecology ›› 2017, Vol. 8 ›› Issue (1): 50-56.doi: 10.5814/j.issn.1674-764x.2017.01.007

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Declining Precipitation Enhances the Effect of Warming on Phenological Variation in a Semiarid Tibetan Meadow Steppe

ZHAO Guangshuai1,2, SHI Peili1,2,*, ZONG Ning1, HE Yongtao1, ZHANG Xianzhou1,2, HE Honglin1, ZHANG Jing3   

  1. 1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China;
    3. College of Global Change and Earth System Sciences, Beijing Normal University, Beijing 100875, China
  • Received:2016-11-15 Online:2017-01-20 Published:2017-01-24
  • Contact: SHI Peili. E-mail: shipl@igsnrr.ac.cn.
  • Supported by:
    National Natural Science Foundation of China (41271067) and National key research and development program (2016YFC0502001)

Abstract: Vegetation phenology is a sensitive indicator of global warming, especially on the Tibetan Plateau. However, whether climate warming has enhanced the advance of grassland phenology since 2000 remains debated and little is known about the warming effect on semiarid grassland phenology and interactions with early growing season precipitation. In this study, we extracted phenological changes from average NDVI in the growing season (GNDVI) to analyze the relationship between changes in NDVI, phenology and climate in the Northern Tibetan Damxung grassland from 2000 to 2014. The GNDVI of the grassland declined. Interannual variation of GNDVI was mainly affected by mean temperature from late May to July and precipitation from April to August. The length of the growing season was significantly shortened due to a delay in the beginning of the growing season and no advancement of the end of the growing season, largely caused by climate warming and enhanced by decreasing precipitation in spring. Water availability was the major determinant of grass growth in the study area. Warming increased demand for water when the growth limitation of temperature to grass was exceeded in the growing season. Decreased precipitation likely further exacerbated the effect of warming on vegetation phenology in recent decades due to increasing evapotranspiration and water limitations. The comprehensive effects of global warming and decreasing precipitation may delay the phenological responses of semiarid alpine grasslands.

Key words: climate change, Damxung station, phenology, Qinghai-Tibetan Plateau, NDVI