Regulatory Mechanisms Under Alpine Grasslands Sensitivity To Climate Change On The Qinghai-Tibetan Plateau

The Qinghai-Tibetan Plateau serves as a critical barrier to China’s climate stability,water supply,biodiversity conservation,and carbon balance.However,under the dual interference of human activities and climate change,significant changes have occurred in the plateau ecosystems.Identifying the sensitivity of high-altitude ecosystems to climate change and revealing their physiological driving mechanisms are crucial for maintaining and protecting the ecological security barrier function of the Tibetan Plateau.This study investigated the regulatory mechanisms of plant functional traits,soil nutrient effectiveness,and fencing on the response of alpine grasslands to climate change,focusing on the desert shrubland in the Qaidam of Qinghai and the alpine grassland in the northwest Qiangtang plateau,through a combination of remote sensing monitoring and field measurements.The results are as follows:(1)The climate sensitivity index of desert shrub in the Qaidam Basin ranged from 0 to 20,with variations observed among different community types.Specifically,communities dominated by Haloxylon ammodendron and Tamarix chinensis exhibited higher climate sensitivity,while communities dominated by kalidium foliatum demonstrated lower climate sensitivity.The climate sensitivity of alpine grasslands in Tibet ranges from 10-30,with different ecological regions exhibiting different levels of climate sensitivity.More specifically,The desert steppe and alpine meadow show the lowest climate sensitivity,while the grasslands in mountainous areas exhibit higher climate sensitivity.(2)Climate sensitivity of the arid shrublands on the Qaidam mediated by plant nutrient traits and soil nutrient availability.Leaf carbon and soil nitrogen content affect the sensitivity to temperature change,while leaf carbon and soil phosphorus content affect the sensitivity to precipitation change.The climate sensitivity of alpine grasslands in northwest Tibet is regulated by leaf isotopes and soil major and trace elements.Leaf nitrogen isotopes,soil organic carbon,soil potassium,and soil zinc content affect the sensitivity to temperature change.Soil phosphorus and soil zinc content regulate the sensitivity to precipitation change,while leaf carbon isotopes,soil phosphorus,and soil copper affect the sensitivity to drought.(3)At the sampled sites level,fencing has no significant effect on the climate sensitivity of alpine grasslands.At the scale of grassland types,fencing only significantly reduces the climate sensitivity of alpine steppe.In conclusion,the sensitivity of alpine grasslands to climate change is regulated by both plant functional traits and soil nutrient effectiveness,while fencing only affects the climate sensitivity of alpine steppe.This study helps to understand and predict the response mechanisms of alpine grasslands to climate change and suggest that future grassland utilization and conservation policies should fully consider the spatial heterogeneity of climate sensitivity across different grassland types.