Catchment-scale patterns of geomorphic activity and vegetation distribution in an alpine glacier foreland (Kaunertal Valley, Austria)

Abstract

The interaction between geomorphological and ecological processes plays a significant role in determining landscape patterns in glacier forelands. However, the spatial organization of this biogeomorphic mosaic remains unclear due to limited catchment-scale data. To address this gap, we used a multi-proxy analysis to map potential geomorphic activity related to surface changes induced by sediment transport on drift-mantled slopes and a glaciofluvial plain. High-resolution vegetation data were used to generate a catchment-scale map delineating vegetation cover and stability thresholds. The two maps were integrated, and an exploratory regression analysis was conducted to investigate the influence of geomorphic activity on vegetation colonization. The multi-proxy analysis resulted in an accurate mapping of catchment-wide geomorphic activity, with a validation accuracy ranging from 75.3% through field mapping to 85.9% through plot sampling. Through vegetation cover mapping, we identified biogeomorphic stability thresholds, revealing a mosaic of vegetation distribution. Distinct colonization patterns emerged across different geomorphic process groups, influenced by process magnitude and the time since the last disturbance event. The exploratory regression analysis showed that vegetation distribution is significantly affected by geomorphic processes. Based on the overlay of results regarding geomorphic activity and vegetation distribution, we suggest an age-independent framework that indicates four potential situations of biogeomorphic succession.

Structural shifts in plant functional diversity during biogeomorphic succession: Moving beyond taxonomic investigations in an alpine glacier foreland

“…The study area's landforms are dominated by lateral and terminal moraine complexes, talus slopes, debris flow channels and fans, glaciofluvial incisions and floodplains (Baewert & Morche, 2014), which were formed during and after paraglacial adjustment. Periglacial landforms, such as thermokarst, solifluction lobes and an active rock glacier, are present, yet surface changes in the area are primarily characterized by water-mediated sediment transport, as indicated by the geomorphological mapping of Haselberger et al (2023). The moraine and till material is poorly sorted, with grain sizes ranging from silt to boulders, and the proglacial area has weakly developed soils (Temme et al, 2016).…”

“…Geomorphic influence was determined based on geomorphological processes that frequently occur in proglacial areas and affect vegetation succession by moving sediment, namely rock fall, debris flows, fluvial process and slope wash. Given the limited occurrence of peri-glacial processes in the catchment, we adopted an a priori approach by excluding areas featuring peri-glacial landforms based on the geomorphological map by Haselberger et al (2023). Additionally, we excluded locations displaying signs of peri-glacial activity during our fieldwork.…”

“…To test trait spectra differences during biogeomorphic succession, we classified vegetation plots into four groups representing specific stages during biogeomorphic succession, which were conceptualized by Haselberger et al (2023). The groups were determined by two factors: a plant cover gradient (low: <35% plant cover; high: >35% plant cover) and absence and presence of geomorphic influence.…”