Changes in fire regime break the legacy lock on successional trajectories in Alaskan boreal forest

Predicting plant community responses to changing environmental conditions is a key element of forecasting and mitigating the effects of global change. Disturbance can play an important role in these dynamics, by initiating cycles of secondary succession and generating opportunities for communities o...

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Veröffentlicht in:	Global change biology Jg. 16; H. 4; S. 1281 - 1295
Hauptverfasser:	Johnstone, Jill F, Hollingsworth, Teresa N, Chapin, F. Stuart III, Mack, Michelle C
Format:	Journal Article
Sprache:	Englisch
Veröffentlicht:	Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.04.2010 Blackwell Publishing Ltd Wiley-Blackwell
Schlagworte:	Alaska Animal and plant ecology Animal, plant and microbial ecology Betula Betula neoalaskana Biological and medical sciences boosted regression trees Boreal forests Canopies Climate change composite burn index data analysis Deciduous trees disturbance regimes Ecological succession Ecosystem services Environmental changes Environmental conditions environmental factors Environmental impact fire regime fire severity Fires forest communities forest stands forest succession forest trees Forestry Forests Fundamental and applied biological sciences. Psychology General aspects General forest ecology Generalities. Production, biomass. Quality of wood and forest products. General forest ecology Global warming history Picea mariana Plant communities Populus tremuloides postfire succession Prescribed fire recruitment regression analysis seedling recruitment Seedlings stand composition stand structure statistical models topography Trees Alaska USA, Alaska boosted regression trees Plant juvenile growth stage Decision tree postfire succession Recruitment Dicotyledones Fires Topography Angiospermae Gymnospermae Alaska Picea mariana Betulaceae composite burn index Boreal forest Populus tremuloides Betula neoalaskana fire severity Woody plant Salicaceae Fire ecology Coniferales Spermatophyta Betula seedling recruitment
ISSN:	1354-1013, 1365-2486
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Zusammenfassung:	Predicting plant community responses to changing environmental conditions is a key element of forecasting and mitigating the effects of global change. Disturbance can play an important role in these dynamics, by initiating cycles of secondary succession and generating opportunities for communities of long-lived organisms to reorganize in alternative configurations. This study used landscape-scale variations in environmental conditions, stand structure, and disturbance from an extreme fire year in Alaska to examine how these factors affected successional trajectories in boreal forests dominated by black spruce. Because fire intervals in interior Alaska are typically too short to allow relay succession, the initial cohorts of seedlings that recruit after fire largely determine future canopy composition. Consequently, in a dynamically stable landscape, postfire tree seedling composition should resemble that of the prefire forest stands, with little net change in tree composition after fire. Seedling recruitment data from 90 burned stands indicated that postfire establishment of black spruce was strongly linked to environmental conditions and was highest at sites that were moist and had high densities of prefire spruce. Although deciduous broadleaf trees were absent from most prefire stands, deciduous trees recruited from seed at many sites and were most abundant at sites where the fires burned severely, consuming much of the surface organic layer. Comparison of pre- and postfire tree composition in the burned stands indicated that the expected trajectory of black spruce self-replacement was typical only at moist sites that burned with low fire severity. At severely burned sites, deciduous trees dominated the postfire tree seedling community, suggesting these sites will follow alternative, deciduous-dominated trajectories of succession. Increases in the severity of boreal fires with climate warming may catalyze shifts to an increasingly deciduous-dominated landscape, substantially altering landscape dynamics and ecosystem services in this part of the boreal forest.
Bibliographie:	http://hdl.handle.net/10113/40754 http://dx.doi.org/10.1111/j.1365-2486.2009.02051.x istex:ABB817734BA0E5D8AB47202D6000A423386B2D37 ArticleID:GCB2051 ark:/67375/WNG-9JGCCDXM-L SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2
ISSN:	1354-1013 1365-2486
DOI:	10.1111/j.1365-2486.2009.02051.x