Geodiversity-biodiversity relationships in alpine environments: a biogeomorphic perspective

Recent research has shown that landforms promote biodiversity (Bailey et al., 2018), making landform distribution an Essential Geodiversity Variable (EGV) (Schrodt et al., 2019). However, the processes and mechanisms underlying these geodiversity-biodiversity relationships are still poorly understood (Alahuhta et al., 2020). In alpine environments, biogeomorphic research showed that feedbacks between plants and geomorphic processes can create landforms and landscape patterns with closely linked geomorphic and ecologic properties (Eichel et al., 2013, 2017). Thus, biogeomorphic feedbacks could be an important driver of geodiversity-biodiversity relationships in alpine environments and could help to refine geomorphic EGVs.

Based on geomorphic and ecological plot data and detailed maps from glacier forelands and turf-banked solifluction lobes in the Swiss Alps and Southern Alps, New Zealand, we investigate alpine geodiversity-biodiversity relationships in time and space. Our initial results show that alpine geodiversity-biodiversity relationships are (i) especially evident at fine, sub-landform scales, (ii) dynamic due to geomorphic and ecological processes; and (iii) can be caused by biogeomorphic feedbacks. In particular, (i) on lateral moraine slopes, species richness is variable due to different degrees of geomorphic activity, while on solifluction lobes, species richness varies between landform elements (tread, riser, ridge) with different microtopography and dynamics. (ii) Geodiversity and species richness in glacier forelands change in time due to linked paraglacial adjustment and vegetation succession following glacier retreat. At solifluction lobes, geodiversity and species richness change with changing solifluction movement and vegetation colonization. (iii) Alpine ecosystem engineering can create solifluction landforms, landform elements and geomorphic-ecologic landscape patterns during biogeomorphic succession. Therefore, biogeomorphic feedbacks can be responsible for small scale, dynamic alpine geodiversity-biodiversity relationships.

Our results suggest that landforms, and their distribution, often considered on a meso scale (hectares), might not sufficiently represent geomorphic geodiversity. Additional geomorphic EGVs, such as landform elements and geomorphic-ecologic properties within landforms (e.g. geomorphic activity) are needed as additional essential variables accounting for geodiversity.

 

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