4月19日：Mass-conservative self-organization and the resilience of patchy ecosystems

主 讲 人：Koen Siteur
主 持 人：刘权兴 教授
开始时间：2018年4月19日上午10：30
讲座地址：闵行校区 资环楼435会议室

摘要：Spatial self-organization is the process where large-scale ordered spatial patterns emerge out of disorder. Spatial self-organization is an important phenomenon in ecology, enabling organisms to cope with harsher environmental conditions. Furthermore, self-organized patterns are suggested as indicator ecosystem resilience against environmental changes. Scale-dependent feedbacks provide the predominant conceptual framework for self-organized spatial patterns, including the regular patterns observed in arid ecosystems, peatlands and musselbeds. In this presentation I highlight a different category of self-organized patterns, that form through density-dependent aggregation of a mass conservative ecosystem component, such as nutrients, sediment or herbivores, rather than scale-dependent feedbacks. The patterns resulting from mass-conservative self-organization have fundamentally different dynamics and resilience properties, that can be described and understood using physics theory. I demonstrate that both localized disturbances and global changes beyond a critical threshold can result in redistribution of the conserved component. Finally, I show that physics concepts, such as Ostwald ripening, provide indicators that can help identify these tipping points and subsequent ecosystem degradation, including fractional cover and patch-size distributions.