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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.
Bd. 189
(2005)
Heft 1-2
.
- S. 89-104.
ISSN 0304-3800
DOI: https://doi.org/10.1016/j.ecolmodel.2005.03.003
Abstract
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.
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| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Zusätzliche Informationen: | BAYCEER29532 |
| Institutionen der Universität: | Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Lehrstuhl Biogeographie Fakultäten Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften |
| Titel an der UBT entstanden: | Ja |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik |
| Eingestellt am: | 29 Jun 2015 06:10 |
| Letzte Änderung: | 07 Sep 2015 07:37 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/15553 |