Climate Change-Induced Shift of Tree Growth Sensitivity at a Central Himalayan Treeline Ecotone
Niels Schwab 1,*
, Ryszard J. Kaczka 2, Karolina Janecka 3, Jürgen Böhner 1, Ram P. Chaudhary 4, Thomas Scholten 5 and Udo Schickhoff 1
, Ryszard J. Kaczka 2, Karolina Janecka 3, Jürgen Böhner 1, Ram P. Chaudhary 4, Thomas Scholten 5 and Udo Schickhoff 1
1
Physical Geography, Center for Earth System Research and Sustainability (CEN), University of Hamburg, 20146 Hamburg, Germany
2
Faculty of Earth Sciences, University of Silesia in Katowice, 41-200 Sosnowiec, Poland
3
Institute of Botany and Landscape Ecology, University of Greifswald, 17489 Greifswald, Germany
4
Research Centre for Applied Science and Technology (ReCAST), Tribhuvan University, Kirtipur 44618, Nepal
5
Department of Geosciences, Chair of Soil Science and Geomorphology, University of Tübingen, 72070 Tübingen, Germany
*
Author to whom correspondence should be addressed.
Forests 2018, 9(5), 267; https://doi.org/10.3390/f9050267
Received: 4 April 2018 / Revised: 2 May 2018 / Accepted: 10 May 2018 / Published: 13 May 2018
(This article belongs to the Special Issue Tree-Ring Records of Climatic Impacts on Forests)
Abstract
Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth–climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause–effect relationships and to solve this attribution problem. View Full-TextKeywords:
Blue Intensity; climate warming; Himalayan Silver Fir (Abies spectabilis), Nepal Himalaya; temporal dynamics; tree growth–climate correlation; treeline ecotone; tree-ring width
▼
Figures
Figure 1
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
Share & Cite This Article
MDPI and ACS Style
Schwab, N.; Kaczka, R.J.; Janecka, K.; Böhner, J.; Chaudhary, R.P.; Scholten, T.; Schickhoff, U. Climate Change-Induced Shift of Tree Growth Sensitivity at a Central Himalayan Treeline Ecotone. Forests 2018, 9, 267.
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.