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Shrub facilitation promotes selective tree establishment beyond the climatic treeline.
Journal article

Shrub facilitation promotes selective tree establishment beyond the climatic treeline.

  • Chen J Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China; Department of Environmental Systems Science, Swiss Federal Institute of Technology Zurich, Universitätstrasse 2, Zurich 8092, Switzerland. Electronic address: chenjianguo@mail.kib.ac.cn.
  • Yang Y Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China. Electronic address: yangyang@mail.kib.ac.cn.
  • Wang S School of Life Sciences, Yunnan University, Kunming 650091, Yunnan, China.
  • Sun H Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China. Electronic address: sunhang@mail.kib.ac.cn.
  • Schöb C Department of Environmental Systems Science, Swiss Federal Institute of Technology Zurich, Universitätstrasse 2, Zurich 8092, Switzerland. Electronic address: christian.schoeb@usys.ethz.ch.
  • 2019-12-03
Published in:
  • The Science of the total environment. - 2020
Climate warming
Ecosystem engineer
Growth rate
Hengduan mountains
Seedling performance
Species interactions
Treeline ecotone
China
Ecosystem
Picea
Seedlings
Trees
English The alpine treeline is shifting upward due to climate warming. However, the treeline species composition and the pace of its upward migration can be mediated by ecological interactions. In particular, so-called ecosystem engineers, i.e. species that modulate the microscale environmental conditions, at the treeline may play a crucial role. We conducted a three-year seedling transplant experiment at the alpine treeline ecotone in southwest China to study how the shrub Rhododendron rupicola modifies the microscale physical and biotic environments and thus influences the establishment and performance of the two treeline species Larix potaninii and Picea likiangensis. Seedlings were transplanted to the current timberline and treeline, as well as above the current treeline in order to determine the responses of the two tree species to the shrub with respect to the current tree distribution. R. rupicola modified the microenvironment by increasing soil moisture and nutrient contents, buffering soil temperature fluctuations, and by increasing richness and changing the composition of root-associated fungi. As a result, tree seedlings planted under shrubs had significantly higher survival, growth rates and nutrient accumulations than those planted in open ground. Furthermore, seedlings planted at lower elevations performed better than those planted at higher elevations. Beyond the treeline, seedling survival was very low on open ground but strongly facilitated by the shrub. Finally, facilitation effects were species-specific, with Larix benefitting more from the shrub than Picea, while Picea had less mortality than Larix in the absence of the shrub. This study demonstrates that shrubs, through the amelioration of physical and biotic microenvironmental conditions, can act as stepping stones for the establishment of selective tree species beyond the current treeline. This suggests that biotic interactions can strongly modify the treeline species composition and push the treeline beyond its current climatic limits, thereby facilitating the upward shift with ongoing climate warming.
Language
  • English
Open access status
closed
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Persistent URL
https://sonar.ch/global/documents/185302
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