TY - JOUR

T1 - Carbon pools and fluxes in a Tibetan alpine Kobresia pygmaea pasture partitioned by coupled eddy-covariance measurements and 13CO2 pulse labeling

AU - Ingrisch, Johannes

AU - Biermann, Tobias

AU - Seeber, Elke

AU - Leipold, Thomas

AU - Li, Maoshan

AU - Ma, Yaoming

AU - Xu, Xingliang

AU - Miehe, Georg

AU - Guggenberger, Georg

AU - Foken, Thomas

AU - Kuzyakov, Yakov

N1 - Funding information: Supplementary data is available at http://doi.org/10.1594/PANGAEA.833208 . This work was supported by the German Research Council (DFG) DFG Fo 226/18-1.2, DFG KU 1184/14, MI 338/7-2; WE 2601/4-2;(SPP1372 ) within the Priority Program 1372 “Tibetan Plateau: Formation, Climate, Ecosystems” (TiP). Access to the “ Naqu Ecological and Environmental Observation and Research Station ” was granted by the Tibet University, Lhasa and the Institute of Tibetan Plateau Research (ITP), Chinese Academy of Sciences. Furthermore, the authors would like to thank everybody who participated in the collection of the data on the Tibetan plateau. We also are thankful to the Centre for Stable Isotope Research and Analysis (KOSI) of Göttingen University and the Laboratory of Isotope Biogeochemistry of the Bayreuth Center of Ecology and Environmental Research (BayCEER) for the ? 13 C analysis. Appendix A

PY - 2015/2/1

Y1 - 2015/2/1

N2 - The Tibetan highlands host the largest alpine grassland ecosystems worldwide, bearing soils that store substantial stocks of carbon (C) that are very sensitive to land use changes. This study focuses on the cycling of photoassimilated C within a Kobresia pygmaea pasture, the dominating ecosystems on the Tibetan highlands. We investigated short-term effects of grazing cessation and the role of the characteristic Kobresia root turf on C fluxes and belowground C turnover. By combining eddy-covariance measurements with 13CO2 pulse labeling we applied a powerful new approach to measure absolute fluxes of assimilates within and between various pools of the plant-soil-atmosphere system. The roots and soil each store roughly 50% of the overall C in the system (76MgCha-1), with only a minor contribution from shoots, which is also expressed in the root:shoot ratio of 90. During June and July the pasture acted as a weak C sink with a strong uptake of approximately 2gCm-2 d-1 in the first half of July. The root turf was the main compartment for the turnover of photoassimilates, with a subset of highly dynamic roots (mean residence time 20days), and plays a key role for the C cycling and C storage in this ecosystem. The short-term grazing cessation only affected aboveground biomass but not ecosystem scale C exchange or assimilate allocation into roots and soil.

AB - The Tibetan highlands host the largest alpine grassland ecosystems worldwide, bearing soils that store substantial stocks of carbon (C) that are very sensitive to land use changes. This study focuses on the cycling of photoassimilated C within a Kobresia pygmaea pasture, the dominating ecosystems on the Tibetan highlands. We investigated short-term effects of grazing cessation and the role of the characteristic Kobresia root turf on C fluxes and belowground C turnover. By combining eddy-covariance measurements with 13CO2 pulse labeling we applied a powerful new approach to measure absolute fluxes of assimilates within and between various pools of the plant-soil-atmosphere system. The roots and soil each store roughly 50% of the overall C in the system (76MgCha-1), with only a minor contribution from shoots, which is also expressed in the root:shoot ratio of 90. During June and July the pasture acted as a weak C sink with a strong uptake of approximately 2gCm-2 d-1 in the first half of July. The root turf was the main compartment for the turnover of photoassimilates, with a subset of highly dynamic roots (mean residence time 20days), and plays a key role for the C cycling and C storage in this ecosystem. The short-term grazing cessation only affected aboveground biomass but not ecosystem scale C exchange or assimilate allocation into roots and soil.

KW - Alpine grassland

KW - Carbon cycle

KW - Grazing

KW - Land use changes

KW - Tibetan-Plateau

UR - http://www.scopus.com/inward/record.url?scp=84915746497&partnerID=8YFLogxK

U2 - 10.1016/j.scitotenv.2014.10.082

DO - 10.1016/j.scitotenv.2014.10.082

M3 - Article

C2 - 25461119

AN - SCOPUS:84915746497

VL - 505

SP - 1213

EP - 1224

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

ER -