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| Titel |
Field 13CO2 pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a Kobresia meadow |
| VerfasserIn |
J. Zou, L. Zhao, S. Xu, X. Xu, D. Chen, Q. Li, N. Zhao, C. Luo, X. Zhao |
| 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 ; 11, no. 16 ; Nr. 11, no. 16 (2014-08-20), S.4381-4391 |
| Datensatznummer |
250117554
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| Publikation (Nr.) |
 copernicus.org/bg-11-4381-2014.pdf |
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| Zusammenfassung |
| Livestock exclosure has been widely used as an approach for grassland
restoration. However, the effects of exclosures on grasslands are controversial
and can depend on many factors, such as the grassland ecosystem types,
evolutionary history and so on. In this study, we conduct field experiments
to investigate the variations of the ecosystem function in response to livestock
exclosure in a Kobresia humilis meadow with 6 years of grazing
exclosure on the Qinghai–Tibetan Plateau. We focused on two ecosystem
functions: plant community structure and ecosystem carbon cycling. The
plant aboveground productivity, plant diversity and the composition of plant
functional groups of the meadow were addressed as the indicators of the plant
community structure. The 13C isotope pulse labeling technique was
applied to evaluate the alterations of ecosystem carbon cycling during a
short term. The results showed that the plant community structure was changed
after being fenced in for 6 years, with significantly decreased aboveground
productivity, species loss and varied composition of the four plant
functional groups (grasses, sedges, legumes and forbs). Using the pulse
labeling technique, we found a lower cycling rate of 13C in the
plant–soil system of the fenced plots compared with the grazed sites during
the first 24 h after labeling. A higher proportion of recovered 13C in
the plant–soil system migrated into the soil as root exudates immediately
after labeling at both fenced and control grazed sites, with a significantly
lower proportion in the fenced site, coinciding with the lower proportion
of 13C lost from soil respiration. Thirty-two days after labeling,
37% of the recovered 13C remained in the soil of the fenced plots, with
significant differences compared to in the grazed plots (47%). In addition,
less 13C (5 vs. 7%) was lost by soil respiration in the
fenced plots during the chase period of 32 days. Overall, our study suggests that
livestock exclosures have negative effects on the plant community structure
and partitioning patterns of the photoassimilated carbon in the
Kobresia meadow, and the effects on photoassimilated carbon cycling
are likely to result from the variations of community structures in the
ecosystem. |
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