title: Species interactions slow warming-induced upward shifts of treelines on the Tibetan Plateau.
abstract: The alpine treeline is commonly regarded as being sensitive to climatic warming because regeneration and growth of trees at treeline generally are limited by low temperature. The alpine treelines of the Tibetan Plateau (TP) occur at the highest elevations (4,900 m above sea level) in the Northern Hemisphere. Ongoing climatic warming is expected to shift treelines upward. Studies of treeline dynamics at regional and local scales, however, have yielded conflicting results, indicating either unchanging treeline elevations or upward shifts. To reconcile this conflict, we reconstructed in detail a century of treeline structure and tree recruitment at sites along a climatic gradient of 4 °C and mean annual rainfall of 650 mm on the eastern TP. Species interactions interacted with effects of warming on treeline and could outweigh them. Densification of shrubs just above treeline inhibited tree establishment, and slowed upward movement of treelines on a time scale of decades. Interspecific interactions are major processes controlling treeline dynamics that may account for the absence of an upward shift at some TP treelines despite continued climatic warming.
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China; liangey@itpcas.ac.cn.
authors.forename: Eryuan
authors.initials: E
authors.lastname: Liang
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;
authors.forename: Shilong
authors.initials: S
authors.lastname: Piao
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Lu
authors.affiliation: Instituto Pirenaico de Ecología, Consejo Superior de Investigaciones Científicas (IPE-CSIC), 50059 Zaragoza, Spain;
authors.forename: Jesús Julio
authors.initials: JJ
authors.lastname: Camarero
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Haifeng
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;
authors.forename: Liping
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Harvard Forest, Petersham, MA 01366;
authors.forename: Aaron M
authors.identifier: http://orcid.org/0000-0003-4151-6081
authors.initials: AM
authors.lastname: Ellison
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, Commissariat a l'Energie Atomique CNRS, l'Université de Versailles Saint-Quentin, 91191 Gif sur Yvette, France;
authors.forename: Philippe
authors.initials: P
authors.lastname: Ciais
authors.affiliation: CSIC, Global Ecology Unit Centre de Recerca Ecològica i Aplicacions Forestals (CREAF)-CSIC-UAB, Cerdanyola del Vallès, E-08193 Catalonia, Spain; CREAF, Cerdanyola del Vallès, E-08193 Catalonia, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Peñuelas
mesh_terms: D065928:Forests; D057232:Global Warming; D008954:Models, Biological; D028222:Picea / Q000502:physiology*; D018609:Tibet
keywords: Tibetan Plateau; alpine treeline; climate change; interspecific competition; treeline dynamics