How many tree species are in the Himalayan treelines and how are they distributed?
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Tropical Ecology https://doi.org/10.1007/s42965-020-00093-7
RESEARCH ARTICLE
How many tree species are in the Himalayan treelines and how are they distributed? Surendra Pratap Singh1 · Surabhi Gumber2 · Ripu Daman Singh2 · Gajendra Singh3 Received: 31 October 2019 / Revised: 2 July 2020 / Accepted: 7 July 2020 © International Society for Tropical Ecology 2020
Abstract Increase in endemism with elevation is a common feature in Himalayas because of increased isolation of higher areas like treelines. To protect species of treeline, we at least need to record their numbers and distribution. We estimated that the total number of tree species in Himalayan treeline is 58, and they belong to 14 genera and 8 families. It is impressive, given that globally alpine treeline species richness is unlikely to be considerably higher than 100. While estimating the species number, we confronted uncertainties in some cases concerning synonyms of species, weak demarcation between species and incorrect identification. Because of a high species differentiation in the Hengduan Mountains and Western Sichuan Province in Tibet, the eastern part of the Himalayan arc (88°E and more) has much higher species richness than the western part (less than 88°E), despite similar number of genera. These areas of high species differentiation accounted for nearly half of the total species. The dominant genera in terms of geographical distribution are Juniperus, Abies, Rhododendron, and Betula. Among the families, Pinaceae, Cupressaceae, Ericaceae, Betulaceae, and Rosaceae were prominent. Because of global climatic change, species shifts are predicted to occur along an altitudinal gradient (representing temperature gradient) as well as along the 31º longitudinal range, representing a moisture gradient. The Himalayan treelines are relatively species-rich, largely because of variations in precipitation, topography, continentality, and cultural factors, among others along the eastto-west arc. There is a need to undertake additional taxonomic studies, using tools such as molecular techniques to provide solution to confusion relating to incorrect identification of some species. Keywords Betula utilis · Climate change · Himalayan treeline · Pinaceae · Treeline species richness
Introduction
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42965-020-00093-7) contains supplementary material, which is available to authorized users. * Surendra Pratap Singh [email protected] * Surabhi Gumber [email protected] 1
Central Himalayan Environment Association (CHEA), 179, Kalyan Kunj, Panditwari, Dehradun 248007, India
2
Department of Forestry and Environmental Science, Kumaun University, Nainital 263001, India
3
Uttarakhand Space Application Centre (USAC), 31, Phase‑II, Vasant Vihar, 248006 Dehradun, India
The upper elevational limit of life form tree in mountains, called treeline is a common feature of a mountain landscape, involving several large-scale ecological and physiological mechanisms. B
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