Development and degradation of Kobresia root mats and their effects on C and N turnover and C sequestration

嵩草牧场是世界上最大的高山生态系统，维持着大量的家养和天然食草动物。嵩草根垫的特殊功能提供了独特的机制，即使在适度过度放牧的情况下也能防止退化，并导致大量的碳储存。然而，这些机制仍然是描述性的，部分是推测性的，因为它们从未在基于过程的研究中得到证实。通过解决嵩草根垫功能的潜在机制，我们将改变现有的范式，根垫是过度放牧强烈退化的负面特征。我们将应用一系列的形态学，年代学，同位素（13 C，15 N，炸弹-14 C）和生物标志物的方法来解释嵩草根垫功能和气候变化的机制。大多数研究将在KEMA实验站进行，包括13 C/15 N标记实验，以跟踪在操纵的水分和温度下，在个别根垫层的C和N周转。为了外推广泛的时空条件下的结果，嵩草植被在全新世的发展将研究青藏高原的沉积物档案中的代表性网站使用新的生物标志物技术。研究结果将有助于缓解气候变化下嵩草生态系统的过度放牧和土地退化。

Kobresia pastures represent the world’s largest alpine ecosystem sustaining huge herds of domestic and natural herbivores. Specific features of Kobresia root mats provide unique mechanisms protecting against degradation even by moderate overgrazing and leading to a large carbon storage. These mechanisms, however, remain descriptive and partly speculative because they were never proven in process-based studies. By addressing the underlying mechanisms of Kobresia root mat functioning we will change the existing paradigm that the root mats is the negative feature of strong degradation by overgrazing. We will apply an array of morphological, chronological, isotopic (13C, 15N, bomb-14C) and biomarker approaches to explain the mechanisms of Kobresia root mat functioning and their alteration by climate change. Most of the studies will be carried out at KEMA experimental station and include 13C/15N labelling experiments to trace C and N turnover in individual root mat horizons under manipulated moisture and temperature. To extrapolate the results for a broad range of spatio-temporal conditions, the development of the Kobresia vegetation during the Holocene will be studied for representative sites of the Tibetan Plateau in sediment archives using novel biomarker techniques. Results will help to mitigate pronounced overgrazing and land degradation of Kobresia ecosystems under changing climate.