Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (4): 305-319.DOI: 10.17521/cjpe.2018.0241

• Research Articles • Previous Articles     Next Articles

Spatiotemporal distribution changes in alpine desert belt in Qilian Mountains under climate changes in past 30 years

ZHANG Fu-Guang,ZENG Biao(),YANG Tai-Bao   

  1. College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
  • Received:2019-02-11 Revised:2019-04-17 Online:2019-04-20 Published:2019-05-30
  • Contact: ZENG Biao ORCID:0000-0002-3398-0741
  • Supported by:
    Supported by the National Natural Science Foundation of China(41871075);the Fostering Talents Project in National Basic Science(J1210065)

Abstract:

AimsAlpine desert, as the top part of the vertical vegetation spectrum of the Qinghai-Xizang Plateau, is widely distributed in the high altitude zones in the Qilian Mountains (QLM). Its distribution and growth conditions are different from the surrounding area. It is more sensitive to climate change but rarely being studied. In this study, we focused on the dynamic changes and spatiotemporal differences of the alpine desert belt in the QLM under the warming climates from the 1990s to the 2010s.
MethodsThe distribution changes in the alpine desert belt in the QLM during the past three decades were obtained from the thematic mapper and the operational land imager remote sensing digital images by using the decision tree classification and artificial visual interpretation. Spatiotemporal differences of the alpine desert distribution were studied by the overlay analysis. Meanwhile, the relationships between the changes and climates were explored using correlation analysis.
Important findings The results indicated that the alpine desert shrank gradually and lost its area by approximately 348.3 km2·a-1 in the QLM with climate warming in the past 30 years. The amplitude of the shrinkage increased from east to west. However, its areas expanded in some sections. Collectively, the low boundary of the alpine desert belt moved upwards to higher altitudes at a velocity of 15 m per decade. The maximum upward-‌shifting amplitude lied in the western QLM, followed by the eastern and middle QLM. The vertical zonal shifting was modulated by topography-induced difference in local hydrothermal conditions. The distribution shifts in the alpine desert belt were mainly concentrated in the gentle slope regions. Because of the differences of hydrothermal background, the position shifts were greater in the sunny aspects than in the shady aspects in the eastern and middle QLM, while opposite in the western QLM. The differences in the hydrothermal conditions and regional topography led to the spatiotemporal change differences of the alpine desert distribution. The correlation between the normalized differential vegetation index and climate factors in the transition zone showed that temperature was the main factor affecting the dynamics and spatial differences of the alpine desert belt in the QLM, and climate warming facilitated the alpine meadow below the alpine desert belt by releasing the low temperature limitation on the vegetation growth.

Key words: alpine desert belt, spatiotemproal difference, climate change, remote sensing monitor, Qilian Mountains