植物生态学报 ›› 2019, Vol. 43 ›› Issue (4): 305-319.DOI: 10.17521/cjpe.2018.0241

• 研究论文 • 上一篇    下一篇

气候变化背景下近30年祁连山高寒荒漠分布时空变化

张富广,曾彪(),杨太保   

  1. 兰州大学资源环境学院, 兰州 730000
  • 收稿日期:2019-02-11 修回日期:2019-04-17 出版日期:2019-04-20 发布日期:2019-05-30
  • 通讯作者: 曾彪 ORCID:0000-0002-3398-0741
  • 基金资助:
    国家自然科学基金(41871075);国家基础科学人才培训资助项目(J1210065)

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)

摘要:

高寒荒漠作为青藏高原植被带谱的顶端类型广泛分布于祁连山高海拔地区, 其生长和分布条件与周边区域差异明显, 对气候变化的响应更为敏感, 且研究较少。该文利用1990年以来的Landsat TM、OLI数据, 采用决策树分类和人工目视解译方法, 提取了祁连山高寒荒漠的分布范围。结合气候变化情况, 综合分析了气候变化背景下近30年祁连山高寒荒漠分布的动态变化及其时空差异。结果表明: (1)近30年增温气候变化过程中, 祁连山高寒荒漠分布范围呈萎缩趋势, 萎缩速率约为348.3 km 2·a -1, 萎缩变化幅度表现为西段>中段>东段, 局部地段上存在扩张现象。上述现象导致高寒荒漠下界平均海拔以每10年约15 m的平均速率向更高海拔推进, 向上推进幅度为西段>东段>中段; (2)受水热条件控制, 近30年祁连山高寒荒漠分布动态变化集中分布在低坡度地区。由于水热背景条件的空间差异, 祁连山东段和中段阳坡上高寒荒漠分布动态变化大于阴坡, 而在祁连山西段表现相反; (3) 1990年以来, 祁连山增温显著, 降水量微弱增加。在气候变化以及区域地形限制共同影响下, 祁连山高寒荒漠分布变化时空差异明显, 且过渡带上归一化植被指数与气温相关性高于降水量。以上结果表明, 气候变化影响祁连山高寒荒漠分布动态变化及其空间差异, 但气温是主要的影响因子, 增温促进了高寒荒漠下接植被带主体高寒草甸的生长。

关键词: 高寒荒漠, 时空差异, 气候变化, 遥感监测, 祁连山

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