ESJ58 一般講演（ポスタ-発表） P3-092

Is Mongolian rangeland non-equilibrium or disequilibrium? Co-existence of mobility modes introduces multi-scale density-dependency in key resources

岡安智生, *大黒俊哉, **ウンダルマ・ジャムサラン, *武内和彦 *東大・農 *モンゴル国立農業大学

Tomoo Okayasu*, Toshiya Okuro*, Undarmaa Jamsran** and Kazuhiko Takeuchi*

* The University of Tokyo

** Mongolian State University of Agriculture

Tropical arid rangelands are as mosaics with different levels of animal?vegetation density-dependence due to the intermittent density-dependent destruction of animal populations. However, arid rangelands in northern Asia frequently suffer from extreme cold events, which cause density-independent population destruction. Thus arid rangelands in northern Asia are predicted to be less vulnerable to land degradation from the theory. We demonstrate that relaxing two of the assumptions, full mobility of herders or animals and spatially homogeneous precipitation over an entire region introduce localized but frequent density-dependence of less mobile flocks which has a significant impact on the overall outcome, by using a published multi-agent model, taking Mongolian rangeland as an example. This study suggests that, depending on the social setting, it is premature to conclude that arid rangelands in northern Asia are less vulnerable to land degradation. To determine the expected degree of density-dependence and location of key resources, the spatial scale of animal mobility should be taken into account.