Vegetation Expansion in the Subnival Hindu Kush Himalaya

Overview

Journal Glob Chang Biol

Specialties Biology
Environmental Health

Date 2020 Jan 10

PMID 31918454

Citations 11

Authors

Karen Anderson

Dominic Fawcett

Anthony Cugulliere

Sophie Benford

Darren Jones

Ruolin Leng

Affiliations

Soon will be listed here.

Abstract

The mountain systems of the Hindu Kush Himalaya (HKH) are changing rapidly due to climatic change, but an overlooked component is the subnival ecosystem (between the treeline and snow line), characterized by short-stature plants and seasonal snow. Basic information about subnival vegetation distribution and rates of ecosystem change are not known, yet such information is needed to understand relationships between subnival ecology and water/carbon cycles. We show that HKH subnival ecosystems cover five to 15 times the area of permanent glaciers and snow, highlighting their eco-hydrological importance. Using satellite data from the Landsat 5, 7 and 8 missions, we measured change in the spatial extent of subnival vegetation from 1993 to 2018. The Landsat surface reflectance-derived Normalized Difference Vegetation Index product was thresholded at 0.1 to indicate the presence/absence of vegetation. Using this product, the strength and direction of time-series trends in the green pixel fraction were measured within three regions of interest. We controlled for cloud cover, snow cover and evaluated the impact of sensor radiometric differences between Landsat 7 and Landsat 8. Using Google Earth Engine to expedite data processing tasks, we show that there has been a weakly positive increase in the extent of subnival vegetation since 1993. Strongest and most significant trends were found in the height region of 5,000-5,500 m a.s.l. across the HKH extent: R = .302, Kendall's τ = 0.424, p < .05, but this varied regionally, with height, and according to the sensors included in the time series. Positive trends at lower elevations occurred on steeper slopes whilst at higher elevations, flatter areas exhibited stronger trends. We validated our findings using online photographs. Subnival ecological changes have likely impacted HKH carbon and water cycles with impacts on millions of people living downstream, but the strength and direction of impacts of vegetation expansion remain unknown.

Citing Articles

Restoration of vegetation in the Yellow River Basin of Inner Mongolia is limited by geographic factors.

Wang S, Xing X, Wu Y, Guo X, Li M, Ma X Sci Rep. 2024; 14(1):14922.

PMID: 38942788 PMC: 11213893. DOI: 10.1038/s41598-024-65548-6.

Leaf carbon isotope tracks the facilitation pattern of legume shrubs shaped by water availability and species replacement along a large elevation gradient in Trans-Himalayas.

Ale R, Zhang L, Bahadur Raskoti B, Cui G, Pugnaire F, Luo T Ann Bot. 2023; 132(3):429-442.

PMID: 37632795 PMC: 10667008. DOI: 10.1093/aob/mcad117.

Himalayan alpine ecohydrology: An urgent scientific concern in a changing climate.

Leng R, Harrison S, Anderson K Ambio. 2022; 52(2):390-410.

PMID: 36324019 PMC: 9755440. DOI: 10.1007/s13280-022-01792-2.

Impacts of climate change and human activities on different degraded grassland based on NDVI.

Hou Q, Ji Z, Yang H, Yu X Sci Rep. 2022; 12(1):15918.

PMID: 36151254 PMC: 9508234. DOI: 10.1038/s41598-022-19943-6.

Assessment of climate change effects on vegetation and river hydrology in a semi-arid river basin.

Ougahi J, Cutler M, Cook S PLoS One. 2022; 17(8):e0271991.

PMID: 36037176 PMC: 9423654. DOI: 10.1371/journal.pone.0271991.

References

Tian F, Brandt M, Liu Y, Rasmussen K, Fensholt R . Mapping gains and losses in woody vegetation across global tropical drylands. Glob Chang Biol. 2016; 23(4):1748-1760. DOI: 10.1111/gcb.13464. View

Pritchard H . Asia's shrinking glaciers protect large populations from drought stress. Nature. 2019; 569(7758):649-654. DOI: 10.1038/s41586-019-1240-1. View

Gardner A, Moholdt G, Cogley J, Wouters B, Arendt A, Wahr J . A reconciled estimate of glacier contributions to sea level rise: 2003 to 2009. Science. 2013; 340(6134):852-7. DOI: 10.1126/science.1234532. View

Skowno A, Thompson M, Hiestermann J, Ripley B, West A, Bond W . Woodland expansion in South African grassy biomes based on satellite observations (1990-2013): general patterns and potential drivers. Glob Chang Biol. 2016; 23(6):2358-2369. DOI: 10.1111/gcb.13529. View

Keenan T, Riley W . Greening of the land surface in the world's cold regions consistent with recent warming. Nat Clim Chang. 2018; 8:825-828. PMC: 6180328. DOI: 10.1038/s41558-018-0258-y. View

Dolezal J, Dvorsky M, Kopecky M, Liancourt P, Hiiesalu I, Macek M . Vegetation dynamics at the upper elevational limit of vascular plants in Himalaya. Sci Rep. 2016; 6:24881. PMC: 4855180. DOI: 10.1038/srep24881. View

Vermote E, Justice C, Claverie M, Franch B . Preliminary analysis of the performance of the Landsat 8/OLI land surface reflectance product. Remote Sens Environ. 2020; Volume 185(Iss 2):46-56. PMC: 6999666. DOI: 10.1016/j.rse.2016.04.008. View

Roy D, Kovalskyy V, Zhang H, Vermote E, Yan L, Kumar S . Characterization of Landsat-7 to Landsat-8 reflective wavelength and normalized difference vegetation index continuity. Remote Sens Environ. 2020; Volume 185(Iss 1):57-70. PMC: 6999663. DOI: 10.1016/j.rse.2015.12.024. View

Anderson K, Fawcett D, Cugulliere A, Benford S, Jones D, Leng R . Vegetation expansion in the subnival Hindu Kush Himalaya. Glob Chang Biol. 2020; 26(3):1608-1625. PMC: 7078945. DOI: 10.1111/gcb.14919. View

10.

Gleick P, Palaniappan M . Peak water limits to freshwater withdrawal and use. Proc Natl Acad Sci U S A. 2010; 107(25):11155-62. PMC: 2895062. DOI: 10.1073/pnas.1004812107. View

11.

Chen H, Zhu Q, Wu N, Wang Y, Peng C . Delayed spring phenology on the Tibetan Plateau may also be attributable to other factors than winter and spring warming. Proc Natl Acad Sci U S A. 2011; 108(19):E93. PMC: 3093455. DOI: 10.1073/pnas.1100091108. View

12.

Li Z, Roy D, Zhang H, Vermote E, Huang H . Evaluation of Landsat-8 and Sentinel-2A aerosol optical depth retrievals across Chinese cities and implications for medium spatial resolution urban aerosol monitoring. Remote Sens (Basel). 2020; 11(2). PMC: 6999735. DOI: 10.3390/rs11020122. View

13.

Telwala Y, Brook B, Manish K, Pandit M . Climate-induced elevational range shifts and increase in plant species richness in a Himalayan biodiversity epicentre. PLoS One. 2013; 8(2):e57103. PMC: 3577782. DOI: 10.1371/journal.pone.0057103. View

14.

Brun F, Berthier E, Wagnon P, Kaab A, Treichler D . A spatially resolved estimate of High Mountain Asia glacier mass balances, 2000-2016. Nat Geosci. 2017; 10(9):668-673. PMC: 5584675. DOI: 10.1038/NGEO2999. View

15.

Myers-Smith I, Hik D . Shrub canopies influence soil temperatures but not nutrient dynamics: An experimental test of tundra snow-shrub interactions. Ecol Evol. 2013; 3(11):3683-700. PMC: 3810868. DOI: 10.1002/ece3.710. View

16.

Worni R, Huggel C, Stoffel M . Glacial lakes in the Indian Himalayas--from an area-wide glacial lake inventory to on-site and modeling based risk assessment of critical glacial lakes. Sci Total Environ. 2012; 468-469 Suppl:S71-84. DOI: 10.1016/j.scitotenv.2012.11.043. View

17.

Immerzeel W, Van Beek L, Bierkens M . Climate change will affect the Asian water towers. Science. 2010; 328(5984):1382-5. DOI: 10.1126/science.1183188. View

18.

Kaab A, Berthier E, Nuth C, Gardelle J, Arnaud Y . Contrasting patterns of early twenty-first-century glacier mass change in the Himalayas. Nature. 2012; 488(7412):495-8. DOI: 10.1038/nature11324. View

19.

Qiu J . Trouble in Tibet. Nature. 2016; 529(7585):142-5. DOI: 10.1038/529142a. View

20.

Bolch T, Kulkarni A, Kaab A, Huggel C, Paul F, Cogley J . The state and fate of Himalayan glaciers. Science. 2012; 336(6079):310-4. DOI: 10.1126/science.1215828. View