Treeline very-high-resolution remote sensing workshop, 2022 in Kochel am See. (Photo: Nishtha Prakash)

A synthesis workshop on very-high resolution remote sensing of treeline ecotones and alpine vegetation, organised by the University OF Marburg, Germany, and the University of Turku, Finland, with the support of the Mountain Research Initiative (MRI) took place from July 18 - 22 2022 in Kochel am See, at the northern edge of the Alps in Germany. It had a partially hybrid format to enable online access to the presentations and some of the discussions.

Key words: alpine vegetation, treeline ecotone, fine-scale vegetation mapping, remote sensing, machine learning, pattern analysis

Mountain plant populations are already observed to shift uphill due to climate change, with resulting changes in vegetation composition and functionality. In addition, local shifts to suitable microsites, functioning as local refugia, may reduce the overall risk of extinction for mountain species. Characterizing fine-scale spatial patterns in vegetation cover, emerging through microsite preferences and spatial ecological processes, is therefore important to understand alpine vegetation dynamics and to predict the future of the alpine zone. To characterize and monitor such patterns, very-high-resolution remote sensing (i.e. with spatial resolutions < 0.5 m) offers great promise, in particular in the fine-grained alpine vegetation above the closed forest. However, two big challenges need to be overcome before this potentially fantastic resource can be applied to map vegetation cover and to monitor change in mountains globally: the availability of and access to these data, and the analysis of the images in terms of recognizing and delineating vegetation types and, in the case of larger species like shrubs, trees, cushion plants and giant rosettes, individuals.

In this workshop the group addressed these two challenges by discussing the following questions:
1. What very-high-resolution data are available in different mountain areas of the world and how can we help to increase their accessibility?
2. What data sources (e.g. satellite-based vs. drone-based) and methods are most suitable to map small-scale patterns in vegetation cover from the treeline ecotone into the alpine zone? Additionally, in the absence of easily available fine-scale imagery, how can readily available coarser-scale data be used to learn more about the fine details of alpine vegetation patterns?
3. How can treeline researchers collaborate to map vegetation in alpine treeline ecotones in different parts of the world?

The program included presentations and lively discussions, as well as a one-day excursion to the treeline ecotone on the nearby Zugspitze range (highest mountain of Germany). There were 11 on-site participants from five countries (New Zealand, Italy, Switzerland, Norway, Finland, and Germany), or eleven countries if counting nationalities. Researchers from eight countries registered to attend the online sessions and contributed with questions and comments for the presenters of the talks. The additional diversity in career stages and research foci assured a rich and enriching workshop. The group will consolidate and share the findings of the workshop as well as further discussion in a research paper.

The organizing team: Nishtha Prakash, Maaike Bader (University of Marburg, Germany), Johanna Toivonen (University of Turku, Finland)

See also the MRI Website

Edited by Sonja Vospernik and Klaus Katzensteiner, submissions possible also past June 2022.
See the MDPI website for more information.