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Modelling the carrying capacity and coexistence of pika and livestock in the mountain steppe of the South Gobi, Mongolia

Title data

Retzer, Vroni ; Reudenbach, Christoph:
Modelling the carrying capacity and coexistence of pika and livestock in the mountain steppe of the South Gobi, Mongolia.
In: Ecological Modelling. Vol. 189 (2005) Issue 1-2 . - pp. 89-104.
ISSN 0304-3800
DOI: https://doi.org/10.1016/j.ecolmodel.2005.03.003

Abstract in another language

Forage competition between small mammals and livestock is of crucial importance in most semi-arid and arid regions of the world. In order to improve the forage availability for livestock small mammals have been the target of eradication worldwide. However, in most of these regions the ecosystems are governed by non-equilibrium processes which have overwhelming influence on livestock densities. Due to these ecosystems' highly variable natural environment, field observations are usually insufficient to describe the whole system as they usually are too short to cover all significant states. Thus we used field information on processes and additional literature information to drive a dynamic model simulating forage competition between the Mongolian pika (Ochotona pallasi) and livestock in the Mongolian South-Gobi. The regulatory mechanisms of pika's territoriality and herders' migration strategy as implemented in the model proved to be sufficient to keep the densities of both herbivore groups within the observed and denoted limits. Both groups can coexist because each has exclusive access to a forage resource unavailable to the other group: pika have the ability to bite down the vegetation deeper than livestock can while the herders drive livestock to better pasture grounds out of reach of the pika when forage is scarce. Nevertheless, both groups react to the frequent periods of forage scarcity and thus indirectly interact via forage competition. The model shows that the large increase in livestock numbers after the Mongolian socio-economic transformation cannot be singularly explained by favourable weather conditions during that period. Only a change in herding strategies with higher livestock densities can explain the observed increase in numbers. However, the larger numbers were short-lived as the risky strategy succumbed to to adverse weather conditions in the late 1990s and livestock numbers crashed in reality as well as in the model. This indicates that in the non-equilibrium system livestock numbers are regularly forced well below the average carrying capacity. Thus, livestock densities are largely controlled by the variability of the abiotic conditions – namely precipitation – and previous levels of livestock densities cannot be increased in the long term as herding strategies are already optimised.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER29532
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Biogeography
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 29 Jun 2015 06:10
Last Modified: 07 Sep 2015 07:37
URI: https://eref.uni-bayreuth.de/id/eprint/15553