Abstract
Mountain regions are experiencing more pronounced climate change than other global land areas. How have vegetation dynamics responded to these changes and what are the implications for hydrology? To answer these questions, we examine the impacts of changes in mean air temperature (Tmean ), precipitation (P) and winter snow cover extent (SCE) in the headwaters of the Yellow River basin (HYRB) on two important vegetation dynamic metrics: (i) the maximum growing-season greenness (represented by the monthly maximum NDVI); and (ii) the beginning of growing season (BGS). Satellite-derived NDVI and SCE, along with observation-based gridded climate data, show that during the past 34 years (1982-2015) the HYRB experienced widespread vegetation greening, while no significant trend in BGS was observed. Spring greenness and phenology were significantly affected by SCE change, highlighting the importance of snow-related process to spring vegetation activity. We observed a clear signal of elevation-dependent warming below 4300 m elevation, which is absent at higher elevations. Changes in NDVI and BGS are elevation-dependent, and trends in Tmean, P, and SCE with elevation play different roles in this dependence. Both observed and estimated watershed annual evapotranspiration series show increasing trends, suggesting that vegetation greening imposes positive effects on evaporative fluxes. Given steady-state and non-stationary hydrological conditions, increasing evapotranspiration should result in runoff reduction, which agrees with catchment-scale runoff observations across the HYRB. These findings represent new knowledge regarding the vegetation response to climate change in alpine environments which has important implications for the hydrology of the region and for other high-water yielding mountainous regions worldwide.
Original language | English (US) |
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Article number | 094005 |
Journal | Environmental Research Letters |
Volume | 15 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2020 |
Bibliographical note
Funding Information:Original content from this work may be used under the terms of the . Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Postgraduate Research & Practice Innovation Program 410 of Jiangsu Province KYCX18_0580 National Natural Science Foundation of China 51539003 Fundamental Research Funds for the Central Universities 2018B608X14 2019B80214 National Key R&D Program of China 2016YFC0402710 yes � 2020 The Author(s). Published by IOP Publishing Ltd Creative Commons Attribution 4.0 license
Publisher Copyright:
© 2020 The Author(s). Published by IOP Publishing Ltd.
Keywords
- elevation-dependent warming
- evapotranspiration
- mountainous region
- NDVI
- runoff
- vegetation phenology
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Environmental Science
- Public Health, Environmental and Occupational Health