Human and climate impact on15N natural abundance of plants and soils in high-mountain ecosystems: a short review and two examples from the Eastern Pamirs and Mt. Kilimanjaro

High-mountain ecosystems, vital for millions yet threatened by population pressure and climate change, show distinct nitrogen cycle disruptions linked to human activity and environmental shifts. Research reveals that intensively grazed pastures in the Eastern Pamirs exhibit a 3.5‰ enrichment in ^15N compared to less-exploited areas, indicating soil degradation, volatile nitrogen losses, and leaching. Similarly, degraded savanna soils on Mt. Kilimanjaro's foothills display highly positive δ^15N values (~6.5‰), while undisturbed montane forests show depleted ^15N, suggesting a closed nitrogen cycle. However, the upper montane forest zone near the subalpine transition exhibits elevated δ^15N, likely due to climate-induced fires pushing the rainforest boundary downward. The study demonstrates that ^15N natural abundance serves as an effective indicator for detecting land-use or climate change-driven soil degradation and nitrogen cycle alterations in high-mountain environments.

Zech, M., Bimüller, C., Hemp, A., Samimi, C., Broesike, C., Hörold, C., & Zech, W. (2011). Human and climate impact on¹⁵N natural abundance of plants and soils in high-mountain ecosystems: a short review and two examples from the Eastern Pamirs and Mt. Kilimanjaro. Isotopes in Environmental and Health Studies, 47(3), 286–296. https://doi.org/10.1080/10256016.2011.596277