Details
| Original language | English |
|---|---|
| Pages (from-to) | 528-538 |
| Number of pages | 11 |
| Journal | Global change biology |
| Volume | 18 |
| Issue number | 2 |
| Publication status | Published - 23 Sept 2011 |
Abstract
Since the late 1950s, governmental rangeland policies have changed the grazing management on the Tibetan Plateau (TP). Increasing grazing pressure and, since the 1980s, the privatization and fencing of pastures near villages has led to land degradation, whereas remote pastures have recovered from stronger overgrazing. To clarify the effect of moderate grazing on the carbon (C) cycle of the TP, we investigated differences in below-ground C stocks and C allocation using in situ 13CO 2 pulse labeling of (i) a montane Kobresia winter pasture of yaks, with moderate grazing regime and (ii) a 7-year-old grazing exclosure plot, both in 3440 m asl. Twenty-seven days after the labeling, 13C incorporated into shoots did not differ between the grazed (43% of recovered 13C) and ungrazed (38%) plots. In the grazed plots, however, less C was lost by shoot respiration (17% vs. 42%), and more was translocated below-ground (40% vs. 20%). Within the below-ground pools, <2% of 13C was incorporated into living root tissue of both land use types. In the grazed plots about twice the amount of 13C remained in soil (18%) and was mineralized to CO 2 (20%) as compared to the ungrazed plots (soil 10%; CO 2 9%). Despite the higher contribution of root-derived C to CO 2 efflux, total CO 2 efflux did not differ between the two land use types. C stocks in the soil layers 0-5 and 5-15 cm under grazed grassland were significantly larger than in the ungrazed grassland. However, C stocks below 15 cm were not affected after 7 years without grazing. We conclude that the larger below-ground C allocation of plants, the larger amount of recently assimilated C remaining in the soil, and less soil organic matter-derived CO 2 efflux create a positive effect of moderate grazing on soil C input and C sequestration.
Keywords
- C pulse labeling, C allocation, Grazing exclosure experiment, Grazing intensity, Montane Kobresia pasture, Qinghai-Tibetan Plateau, Soil organic carbon
ASJC Scopus subject areas
- Environmental Science(all)
- Global and Planetary Change
- Environmental Science(all)
- Environmental Chemistry
- Environmental Science(all)
- Ecology
- Environmental Science(all)
- General Environmental Science
Sustainable Development Goals
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In: Global change biology, Vol. 18, No. 2, 23.09.2011, p. 528-538.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Effect of grazing on carbon stocks and assimilate partitioning in a Tibetan montane pasture revealed by 13CO 2 pulse labeling
AU - Hafner, Silke
AU - Unteregelsbacher, Sebastian
AU - Seeber, Elke
AU - Lena, Becker
AU - Xu, Xingliang
AU - Li, Xiaogang
AU - Guggenberger, Georg
AU - Miehe, Georg
AU - Kuzyakov, Yakov
PY - 2011/9/23
Y1 - 2011/9/23
N2 - Since the late 1950s, governmental rangeland policies have changed the grazing management on the Tibetan Plateau (TP). Increasing grazing pressure and, since the 1980s, the privatization and fencing of pastures near villages has led to land degradation, whereas remote pastures have recovered from stronger overgrazing. To clarify the effect of moderate grazing on the carbon (C) cycle of the TP, we investigated differences in below-ground C stocks and C allocation using in situ 13CO 2 pulse labeling of (i) a montane Kobresia winter pasture of yaks, with moderate grazing regime and (ii) a 7-year-old grazing exclosure plot, both in 3440 m asl. Twenty-seven days after the labeling, 13C incorporated into shoots did not differ between the grazed (43% of recovered 13C) and ungrazed (38%) plots. In the grazed plots, however, less C was lost by shoot respiration (17% vs. 42%), and more was translocated below-ground (40% vs. 20%). Within the below-ground pools, <2% of 13C was incorporated into living root tissue of both land use types. In the grazed plots about twice the amount of 13C remained in soil (18%) and was mineralized to CO 2 (20%) as compared to the ungrazed plots (soil 10%; CO 2 9%). Despite the higher contribution of root-derived C to CO 2 efflux, total CO 2 efflux did not differ between the two land use types. C stocks in the soil layers 0-5 and 5-15 cm under grazed grassland were significantly larger than in the ungrazed grassland. However, C stocks below 15 cm were not affected after 7 years without grazing. We conclude that the larger below-ground C allocation of plants, the larger amount of recently assimilated C remaining in the soil, and less soil organic matter-derived CO 2 efflux create a positive effect of moderate grazing on soil C input and C sequestration.
AB - Since the late 1950s, governmental rangeland policies have changed the grazing management on the Tibetan Plateau (TP). Increasing grazing pressure and, since the 1980s, the privatization and fencing of pastures near villages has led to land degradation, whereas remote pastures have recovered from stronger overgrazing. To clarify the effect of moderate grazing on the carbon (C) cycle of the TP, we investigated differences in below-ground C stocks and C allocation using in situ 13CO 2 pulse labeling of (i) a montane Kobresia winter pasture of yaks, with moderate grazing regime and (ii) a 7-year-old grazing exclosure plot, both in 3440 m asl. Twenty-seven days after the labeling, 13C incorporated into shoots did not differ between the grazed (43% of recovered 13C) and ungrazed (38%) plots. In the grazed plots, however, less C was lost by shoot respiration (17% vs. 42%), and more was translocated below-ground (40% vs. 20%). Within the below-ground pools, <2% of 13C was incorporated into living root tissue of both land use types. In the grazed plots about twice the amount of 13C remained in soil (18%) and was mineralized to CO 2 (20%) as compared to the ungrazed plots (soil 10%; CO 2 9%). Despite the higher contribution of root-derived C to CO 2 efflux, total CO 2 efflux did not differ between the two land use types. C stocks in the soil layers 0-5 and 5-15 cm under grazed grassland were significantly larger than in the ungrazed grassland. However, C stocks below 15 cm were not affected after 7 years without grazing. We conclude that the larger below-ground C allocation of plants, the larger amount of recently assimilated C remaining in the soil, and less soil organic matter-derived CO 2 efflux create a positive effect of moderate grazing on soil C input and C sequestration.
KW - C pulse labeling
KW - C allocation
KW - Grazing exclosure experiment
KW - Grazing intensity
KW - Montane Kobresia pasture
KW - Qinghai-Tibetan Plateau
KW - Soil organic carbon
UR - http://www.scopus.com/inward/record.url?scp=84855823731&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2486.2011.02557.x
DO - 10.1111/j.1365-2486.2011.02557.x
M3 - Article
AN - SCOPUS:84855823731
VL - 18
SP - 528
EP - 538
JO - Global change biology
JF - Global change biology
SN - 1354-1013
IS - 2
ER -