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| Titel |
Moderate forest disturbance as a stringent test for gap and big-leaf models |
| VerfasserIn |
B. Bond-Lamberty, J. P. Fisk, J. A. Holm, V. Bailey, G. Bohrer, C. M. Gough |
| 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 ; 12, no. 2 ; Nr. 12, no. 2 (2015-01-27), S.513-526 |
| Datensatznummer |
250117786
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| Publikation (Nr.) |
 copernicus.org/bg-12-513-2015.pdf |
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| Zusammenfassung |
| Disturbance-induced tree mortality is a key factor regulating the carbon
balance of a forest, but tree mortality and its subsequent effects are
poorly represented processes in terrestrial ecosystem models. It is thus
unclear whether models can robustly simulate moderate (non-catastrophic)
disturbances, which tend to increase biological and structural complexity
and are increasingly common in aging US forests. We tested whether three
forest ecosystem models – Biome-BGC (BioGeochemical Cycles), a classic big-leaf model, and the
ZELIG and ED (Ecosystem Demography) gap-oriented models – could reproduce the resilience to moderate
disturbance observed in an experimentally manipulated forest (the Forest
Accelerated Succession Experiment in northern Michigan, USA, in which 38%
of canopy dominants were stem girdled and compared to control plots). Each
model was parameterized, spun up, and disturbed following similar protocols
and run for 5 years post-disturbance. The models replicated observed
declines in aboveground biomass well. Biome-BGC captured the timing and
rebound of observed leaf area index (LAI), while ZELIG and ED correctly
estimated the magnitude of LAI decline. None of the models fully captured
the observed post-disturbance C fluxes, in particular gross primary
production or net primary production (NPP). Biome-BGC NPP was correctly
resilient but for the wrong reasons, and could not match the absolute
observational values. ZELIG and ED, in contrast, exhibited large, unobserved
drops in NPP and net ecosystem production. The biological mechanisms
proposed to explain the observed rapid resilience of the C cycle are
typically not incorporated by these or other models. It is thus an open
question whether most ecosystem models will simulate correctly the gradual
and less extensive tree mortality characteristic of moderate disturbances. |
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