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| Titel |
Changes in growth of pristine boreal North American forests from 1950 to 2005 driven by landscape demographics and species traits |
| VerfasserIn |
M. P. Girardin, X. J. Guo, P. Y. Bernier, F. Raulier, S. Gauthier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 7 ; Nr. 9, no. 7 (2012-07-11), S.2523-2536 |
| Datensatznummer |
250007184
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| Publikation (Nr.) |
 copernicus.org/bg-9-2523-2012.pdf |
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| Zusammenfassung |
| In spite of the many factors that are occurring and known
for positively affecting the growth of forests, some boreal forests across
North America have recently felt the adverse impacts of environmental
changes. Knowledge of causes for productivity declines in North American
boreal forests remains limited, and this is owed to the large spatial and
temporal scales involved, and the many plant processes affected. Here, the
response of pristine eastern boreal North American (PEBNA) forests to
ongoing climatic changes is examined using in situ data, community ecology
statistics, and species-specific model simulations of carbon exchanges
forced by contemporary climatic data. To examine trends in forest growth, we
used a recently acquired collection of tree-ring width data from 252 sample
plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.]
B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree
growth data highlight a dominating forest growth decline in overmature
forests (age > 120 years) from 1950 to 2005. In contrast, improving growth
conditions are seen in jack pine and mature (70–120 years) black spruce
stands. Multivariate analysis of climate and growth relationships suggests
that responses of PEBNA forests to climate are dependent on demographic and
species traits via their mediation of temperature and water stress
constraints. In support of this hypothesis, the simulation experiment
suggests that in old-growth black spruce stands the benefit to growth
brought on by a longer growing season may have been low in comparison with
the increasing moisture stress and respiration losses caused by warmer
summer temperatures. Predicted increases in wildfire frequency in PEBNA
forests will likely enhance the positive response of landscape-level forest
growth to climate change by shifting the forest distribution to younger age
classes while also enhancing the jack pine component. |
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