title: Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change.
abstract: Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems.
authors.affiliation: Environmental Studies Program and Department of Geography, University of Oregon, Eugene, OR 97403, USA.
authors.forename: Lucas C R
authors.initials: LC
authors.lastname: Silva
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Sichuan 610041, China.
authors.forename: Geng
authors.initials: G
authors.lastname: Sun
authors.affiliation: Department of Land, Air, and Water Resources, University of California, Davis, CA 95616, USA.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhu-Barker
authors.affiliation: College of Life Science, Sichuan University, Sichuan 610041, China.
authors.forename: Qianlong
authors.initials: Q
authors.lastname: Liang
authors.affiliation: Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Sichuan 610041, China.
authors.forename: Ning
authors.identifier: 0000-0002-8392-2961
authors.initials: N
authors.lastname: Wu
authors.affiliation: Department of Land, Air, and Water Resources, University of California, Davis, CA 95616, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Horwath
mesh_terms: D001272:Atmosphere; D002245:Carbon Dioxide / Q000737:chemistry*; D017753:Ecosystem; D065928:Forests; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen; D012987:Soil / Q000737:chemistry; D013696:Temperature; D014197:Trees / Q000254:growth & development* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen
keywords: Climatic change; dendrochronology; ecophysiology; soil-pant interactions; stable isotopes