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| Titel |
Plant communities as drivers of soil respiration: pathways, mechanisms, and significance for global change |
| VerfasserIn |
D. B. Metcalfe, R. A. Fisher, D. A. Wardle |
| 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 ; 8, no. 8 ; Nr. 8, no. 8 (2011-08-03), S.2047-2061 |
| Datensatznummer |
250006069
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| Publikation (Nr.) |
 copernicus.org/bg-8-2047-2011.pdf |
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| Zusammenfassung |
Understanding the impacts of plant community characteristics on soil carbon
dioxide efflux (R) is a key prerequisite for accurate prediction of the
future carbon (C) balance of terrestrial ecosystems under climate change.
However, developing a mechanistic understanding of the determinants of R is
complicated by the presence of multiple different sources of respiratory C
within soil – such as soil microbes, plant roots and their mycorrhizal
symbionts – each with their distinct dynamics and drivers. In this review,
we synthesize relevant information from a wide spectrum of sources to
evaluate the current state of knowledge about plant community effects on
R, examine how this information is incorporated into global climate models,
and highlight priorities for future research. Despite often large variation
amongst studies and methods, several general trends emerge.
Mechanisms whereby plants affect R may be grouped into effects on belowground
C allocation, aboveground litter properties and microclimate. Within
vegetation types, the amount of C diverted belowground, and hence R, may be
controlled mainly by the rate of photosynthetic C uptake, while amongst
vegetation types this should be more dependent upon the specific C
allocation strategies of the plant life form. We make the case that plant
community composition, rather than diversity, is usually the dominant
control on R in natural systems. Individual species impacts on R may be
largest where the species accounts for most of the biomass in the ecosystem,
has very distinct traits to the rest of the community and/or modulates the
occurrence of major natural disturbances. We show that climate vegetation
models incorporate a number of pathways whereby plants can affect R, but that
simplifications regarding allocation schemes and drivers of litter
decomposition may limit model accuracy. We also suggest that under a warmer
future climate, many plant communities may shift towards dominance by fast
growing plants which produce large quantities of nutrient rich litter. Where
this community shift occurs, it could drive an increase in R beyond that
expected from direct climate impacts on soil microbial activity alone.
We identify key gaps in knowledge and recommend them as priorities for
future work. These include the patterns of photosynthate partitioning
amongst belowground components, ecosystem level effects of individual plant
traits, and the importance of trophic interactions and species invasions or
extinctions for ecosystem processes. A final, overarching challenge is how
to link these observations and drivers across spatio-temporal scales to
predict regional or global changes in R over long time periods. A more
unified approach to understanding R, which integrates information about plant
traits and community dynamics, will be essential for better understanding,
simulating and predicting patterns of R across terrestrial ecosystems and its
role within the earth-climate system. |
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