Assessing the impact of reindeers grazing on tundra vegetation and their influence on carbon and nitrogen cycles in Svalbard Islands

Climate change impacts plant physiology and the carbon (C) and nitrogen (N) cycles in Arctic ecosystems, which contain about 50% of the world’s underground organic carbon. The Arctic tundra is experiencing significant changes due to global warming and permafrost thaw, leading to increased CO₂ and CH₄ emissions. Herbivores, like reindeers, play an important role in these dynamics by influencing vegetation structure and composition, thereby altering the C and N cycles through grazing and soil modification. Because reindeer populations experience considerable fluctuations with changing climate, understanding the role of grazing in Arctic tundra dynamics is essential for predicting the ecological responses to climate change in the Arctic This study investigates the effects of reindeer grazing on the tundra by comparing areas with and without big grazers (through fences) on Svalbard Islands. It focuses on the interaction between grazing, plant composition, microbial activity, and C and N cycles. A multifaceted methodological approach includes alongside vegetation monitoring, its functional performance with CO₂ flux measurements, elemental and isotopic analysis under natural abundance to characterize WUE and nutrients cycling (δ¹³C, δ¹⁵N) and isotope labeling to track N allocation dynamics. The aim is to clarify how grazing influences the Arctic carbon balance and its long-term consequences for climate and land management. By understanding the complex interactions between vegetation, soil, and herbivores, the findings will improve climate models and support efforts to mitigate climate change impacts through better land management practices