Go or grow? An interdisciplinary ‘biogeomorphic balance’ concept linking moving mountain slopes and shifting mountain plants

High mountains are hotspots of climate and global environmental change. Mountain biodiversity is threatened by quickly rising temperatures which cause vegetation shifts, such as upslope migration. At the same time, natural hazards develop as mountain slopes become increasingly unstable due to permafrost degradation and changes in rain and snowfall regimes. Resulting slope movements, such as rockfalls and debris flows, can limit colonization by plants. However, plants that manage to colonize mountain slopes can stabilize them through their roots and above ground biomass. Therefore, we believe that an interdisciplinary approach linking ecology and geomorphology is needed as a next step to better understand how climate change affects high mountain landscapes and ecosystems. Combining results from previous geomorphic, ecological and palaeoecological studies, we show that the response of high mountain environments to climate change can depend on the balance between slope movement intensity and the trait-dependent ability of plants to colonize and stabilize moving slopes. For this ‘biogeomorphic balance’ we envisage three possible scenarios: (1) Intensifying slope movements impede vegetation shifts, amplifying instability. (2) Ecosystem engineer species, adapted to moving slopes, stabilize slopes and facilitate shifts for less movement-adapted species. (3) Competitive trees and tall shrubs, shifting on stable slopes, reduce instability but potentially diminish biodiversity. Given the disparate rates of ecological and geomorphic responses to climate change, coupled with high environmental heterogeneity and elevational gradients in in mountains, we anticipate that future biogeomorphic balances will be variable and heterogeneous in both space and time. To unravel these intricate biogeomorphic balances, we advocate for collaborative research between mountain geomorphologists and ecologists and propose three distinct future directions that combine advancing field measurement, remote sensing techniques and modeling approaches. We believe that by recognizing high mountains as 'biogeomorphic ecosystems', shaped by the interplay of geomorphic and ecological processes, we can improve our ability to safeguard people, infrastructure and ecosystems in mountain environments around the world.   References: Eichel J, Stoffel M, Wipf S. 2023. Go or grow? Feedbacks between moving slopes and shifting plants in high mountain environments. Progress in Physical Geography: Earth and Environment 47 : 967–985. DOI: 10.1177/03091333231193844