Forums | HES 健康与环境科学

11 May 2023, 6:47 PM

Speaker: Li Li

Date: 2023-05-16

Time: 11:10-12am

Room: ES354

Title: "Reinforcing feedback and cross-scale interactions during grassland degradation process of the Qinghai-Tibetan Plateau"

Abstract:

A large body of literature tries to identify the ‘underlying causes’ of the extensive grassland degradation on the Qinghai-Tibetan Plateau (QTP). Taking the complex system perspective, I argue that the degradation process can be understood as locally formed bare-soil patches expanding to the landscape level. The upscaling process is driven by various biological-environmental feedbacks. For example, positive feedback can be identified between intensified yak grazing, reduced vegetation height and accelerated pika dispersal, and between intensified yak trampling, increased water stress in soil and replacement of grass and sedge by unpalatable plants. Such reinforcing mechanisms overweigh specific socio-ecological factor (e.g., stocking rate, pika density) to become the main driver of degradation state change. In this presentation, I will illustrate this state-and-transition process of grassland degradation of Nyanpo Yutse in the eastern QTP. I will also demonstrate that the up-scaling of the bare-soil patches can be simulated using cellular automata model considering both the cross-scale interactions and the variation of topography. I will also argue that instead of mitigating the ‘underlying cause’ of degradation, such as pika eradication, sustainable grassland management should aim at promoting timely management adaptation to system signals indicating detrimental reinforcing feedback.

We will keep onsite seminar and provide online choice via Tencent (ID: 979-2894-8794).