DOI: 10.1016/j.foreco.2015.04.016
Scopus记录号: 2-s2.0-84939417356
论文题名: Spatial coherence and change of opposite white spruce temperature sensitivities on floodplains in Alaska confirms early-stage boreal biome shift
作者: Juday G.P. ; Alix C. ; Grant T.A.
刊名: Forest Ecology and Management
ISSN: 0378-1127
出版年: 2015
卷: 350 起始页码: 46
结束页码: 61
语种: 英语
英文关键词: Alaska
; Climate change
; Divergence
; Picea glauca
; Temperature sensitivity
; Tree ring
Scopus关键词: Climate change
; Floods
; Alaska
; Divergence
; Picea glauca
; Temperature sensitivity
; Tree rings
; Forestry
; biochronology
; biome
; boreal forest
; climate change
; coniferous tree
; divergence
; floodplain
; growth rate
; longitudinal gradient
; population structure
; spatial analysis
; spatiotemporal analysis
; temperature effect
; tree ring
; Alaska
; United States
; Picea glauca
英文摘要: Since the mid 1970s, Interior Alaska white spruce trees experienced markedly lower growth than during the 19th and early 20th centuries. This observation raises the question of forest persistence on certain sites of lowland central and eastern Alaska. We analyzed white spruce growth across a 36-site network (540 trees) on three major river floodplains in boreal Alaska along a longitudinal gradient from eastern Interior to the southwest tree limit to test for the presence of tree growth patterns and climate sensitivities. Chronologies are compared for temperature sensitivity at both stand and individual tree levels, using data from Bethel, McGrath, and Fairbanks NWS stations during the common period of 1952-2001. Cross-dated stand-level ring width chronologies indicate three regions of common signal in tree growth across the gradient. Temperature sensitivity of stand- and individual-tree chronologies is spatially coherent. Most downriver chronologies correlate positively with spring mean monthly temperatures (MMT) at Bethel, mid- and upriver chronologies correlate negatively with MMT of May and previous year July at either McGrath or Fairbanks, and an area in between is a mixed population of positive and negative responders. In downriver positive responders, recent increases from suboptimal cool temperatures accelerated tree growth, while in mid- and upriver negative responders, recent increases from optimal or above-optimal temperatures decreased growth. Fairbanks negative responders are also negatively correlated with a 200-yr index of recorded and reconstructed Fairbanks summer temperatures, and recent sustained record high summer temperatures are associated with the lowest relative growth. Until the 1940s, absolute growth rate of negative responders was greater than positive responders, but from the 1970s the positive responders grew more. These results explain why northern ring width samples can display opposite temperature sensitivity and contribute to understanding recent "divergence" or loss of temperature sensitivity in a changing climate. We find that July MMT and annual precipitation at Fairbanks are now outside the limits that previously characterized the North American distribution of white spruce, and are near the reported physiological limits of the species. Our results of the spatial and temporal change of white spruce temperature sensitivity provide strong empirical evidence of previously proposed early stage biome shift in boreal Alaska due to clear climatic causes. Already, western Alaska, previously extending to tree limit, has become the optimum climate region for the species. With modest additional warming widespread tree death will be unavoidable on warmer lowland interior sites, where persistence of white spruce is unlikely. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/65401
Appears in Collections: 影响、适应和脆弱性
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作者单位: School of Natural Resources and Extension, University of Alaska Fairbanks, P.O. Box 757140, Fairbanks, AK, United States; UMR 8096 Archéologie des Amériques, CNRS, Univ. Paris 1 Panthéon-Sorbonne, Maison de l'Archéologie et de l'Ethnologie, 21 allée de l'Université, Nanterre, France; Master in Environmental Management (MEM), Western State Colorado University, United States
Recommended Citation:
Juday G.P.,Alix C.,Grant T.A.. Spatial coherence and change of opposite white spruce temperature sensitivities on floodplains in Alaska confirms early-stage boreal biome shift[J]. Forest Ecology and Management,2015-01-01,350