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| Titel |
Transitions and coexistence along a grazing gradient in the Eurasian steppe |
| VerfasserIn |
Haiyan Ren, Friedelm Taube, Yingjun Zhang, Yongfei Bai, Shuijin Hu |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138686
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| Publikation (Nr.) |
 EGU/EGU2017-1789.pdf |
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| Zusammenfassung |
| Ecological resilience theory has often been applied to explain species coexistence and range
condition assessment of various community states and to explicate the dynamics of
ecosystems. Grazing is a primary disturbance that can alter rangeland resilience by causing
hard-to-reverse transitions in grasslands. Yet, how grazing affects the coexistence
of plant functional group (PFG) and transition remains unclear. We conducted a
six-year grazing experiment in a typical steppe of Inner Mongolia, using seven grazing
intensities (0, 1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 sheep/ hectare) and two grazing systems
(i.e. a continuous annual grazing as in the traditional grazing system, and a mixed
grazing system combining grazing and haymaking), to examine grazing effects on
plant functional group shifts and species coexistence in the semi-arid grassland
system.
Our results indicate that the relative richness of dominant bunchgrasses and forbs had a
compensatory coexistence at all grazing intensities, and the richness of rhizomatous grasses
fluctuated but was persistent. The relative productivity of dominant bunchgrasses and
rhizomatous grasses had compensatory interactions with grazing intensity and grazing
system. Dominant bunchgrasses and rhizomatous grasses resist grazing effects by using their
dominant species functional traits: high specific leaf area and low leaf nitrogen content. Our
results suggest that:
1. Stabilizing mechanisms beyond grazing management are more important in
determining plant functional group coexistence and ecological resilience.
2. Plant functional group composition is more important in influencing ecosystem
functioning than diversity.
3. Ecosystem resilience at a given level is related to the biomass of dominant PFG, which
is determined by a balanced shift between dominant species biomass. The relatively even
ecosystem resilience along the grazing gradient is attributed to the compensatory interactions
of dominant species in their biomass variations. Community stability may rely on constantly
regulating internal PFGs composition to maintain functional stability in grassland
ecosystems.
In the semi-arid grassland system, environmental factors mediate grazing effects
on PFG transition, leading to homogeneous grassland dominated by bunchgrass. |
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