Pasture degradation modifies the water and carbon cycles of the Tibetan highlands

authored by

W. Babel, T. Biermann, H. Coners, E. Falge, E. Seeber, J. Ingrisch, P. M. Schleuß, T. Gerken, J. Leonbacher, T. Leipold, S. Willinghöfer, K. Schützenmeister, O. Shibistova, L. Becker, S. Hafner, S. Spielvogel, X. Li, X. Xu, Y. Sun, L. Zhang, Y. Yang, Y. Ma, K. Wesche, H. F. Graf, C. Leuschner, G. Guggenberger, Y. Kuzyakov, G. Miehe, T. Foken

Abstract

The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.

Organisation(s)

Institute of Soil Science
Section Soil Chemistry

External Organisation(s)

University of Bayreuth
Lund University
University of Göttingen
Johann Heinrich von Thünen Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries
State Museum of Natural History Görlitz
University of Innsbruck
Pennsylvania State University
University of Koblenz-Landau
Russian Academy of Sciences (RAS)
Lanzhou University
Chinese Academy of Sciences (CAS)
University of Cambridge
Kazan Volga Region Federal University
Philipps-Universität Marburg
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig

Type

Article

Journal

BIOGEOSCIENCES

Volume

11

Pages

6633-6656

No. of pages

24

ISSN

1726-4170

Publication date

02.12.2014

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Ecology, Evolution, Behavior and Systematics, Earth-Surface Processes

Sustainable Development Goals

SDG 13 - Climate Action, SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.5194/bg-11-6633-2014 (Access: Open)