Warming, permafrost thaw and increased nitrogen availability as drivers for plant composition and growth across the Tibetan Plateau

• Published in: Soil biology & biochemistry Vol. 182; p. 109041
• Main Authors: Yun, Hanbo, Zhu, Qing, Tang, Jing, Zhang, Wenxin, Chen, Deliang, Ciais, Philippe, Wu, Qingbai, Elberling, Bo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.07.2023; Elsevier
• Subjects: Agricultural Science; Climate Research; Climate Science; Climate warming; Earth and Related Environmental Sciences; ENVIRONMENTAL SCIENCES; Geovetenskap och miljövetenskap; Geovetenskap och relaterad miljövetenskap; Jordbruksvetenskap; Klimatforskning; Klimatvetenskap; Natural Sciences; Naturgeografi; Naturvetenskap; Nitrogen; Permafrost thawing; Physical Geography; Sciences of the Universe; Tibetan plateau; Climate warming; Tibetan plateau; Nitrogen; Permafrost thawing; Nitrogen; Permafrost thawing; Climate warming; Tibetan plateau
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2023.109041

Permafrost-affected ecosystems are subject to warming and thawing, which can increase the availability of subsurface nitrogen (N) with consequences in otherwise N-limited tundra and alpine vegetation. Here, we quantify the extent of warming and permafrost thawing and the corresponding effects on nitrogen availability and plant growth based on a 20-year survey across 14 sites on the Tibetan Plateau. The survey showed that most sites have been subject to warming and thawing and that the upper permafrost zone across all sites was rich in inorganic N, mainly as ammonium. We further explore the efficiency of plants to utilize 15N-labelled inorganic N over five years following 15N addition at the permafrost table far below the main root zone. The 15N experiment showed that deep-rooted plant species were able to utilize the labelled N. A SEM model suggests that changes in vegetation can be explained by both active layer warming and permafrost thawing and the associated changes in inorganic nitrogen availability. Our results highlight a feedback mechanism of climate warming, in which released plant-available N may favour deep-rooted plants. This can explain important changes in plant composition and growth across the sites on the Tibetan Plateau. •Wide-spread permafrost thawing is observed on the Tibetan Plateau over two decades.•Across 14 sites, permafrost samples reveal a high content of N, mainly as ammonium.•An 15N experiment shows that deep–rooted plant species can utilize permafrost N.•Changes in vegetation can partly be explained by increased permafrost N availability.