Session S10, continued (part 2)
The second part of session S10 started with the question if particular plant traits may favor or restrain species declines/extinction on mountain summits. Aino Kulonen showed, on basis of recent and historical summit data across Europe, which plant traits lead to a higher probability of disappearance. Interestingly, species with the highest demand for temperature, which are taller growing and are good competitors were among the ones commonly extirpated. This suggests that disappearance during the past decade has been driven by environmental filtering rather than by competition. The upper range margin of more warm-demanding species seems to be repeatedly pushed back and forth with climatic oscillations.
The implementation of a remarkable “multi-organism groups” GLORIA target region in the Sierra Famatina (Argentina) was shown by Mariana Musicante. Being South America’s highest mountain range outside the Andes, the number of narrow-range endemics is especially high at higher elevations. The GLORIA summits extend over an elevation gradient of over 2500m (2574 to 5110m), where both vascular and non-vascular plants were recorded as well as different animal organism groups such as insect and vertebrate groups. The site, further, links to the monitoring network MARAS for arid and semiarid regions in the continent’s south.
The GLORIA master site Schrankogel (also part of the LTER Tyrolean Alps) started in 1994 and focuses on the alpine-nival ecotone. Andrea Lamprecht presented results on changing species composition during the past 20 years, which include an increase in species losses at constant colonization rates as well as an acceleration of a thermophilisation process during the past decade. High elevation species showed a decline in species cover and are now more often among those disappearing. New elevation transects for soil microbial patterns and selected arthropod groups were established parallel to the vegetation transects, where baseline data showed strikingly rich biodiversity patterns above the alpine grasslands.
Several studies of Jalil Noroozi et al. (presented by proxy by Harald Pauli) show the impressive degree of vascular plant endemism increasing with elevation as well as very distinct alpine-nival scree communities in the mountains of Iran. Iran’s extremely small and highly fragmented “low-temperature islands” at high elevations host a flora and plant communities being extraordinarily vulnerable to impacts of global warming.
An alternative approach to permanent plot studies, either through historical summits or at GLORIA sites, is the use of phytosociological relevés for determining vegetation changes over time and relating shifts in species composition to climatic changes, as presented by Sabine Rumpf. Counteracting to difficulties such as variable sampling sizes and differences in the information on location and abiotic habitat conditions is the benefit of a large number of relevé data accumulated during the 20th century in the Alps. This, however, such as conducted in the current study across the Eastern Alps, implies a laborious effort in resurveying a large number of plots and of species, where functional trait data need to be collected or extracted from existing sources.
Another study uses exhaustive plant inventories of a range of different plant communities from subalpine to alpine belts in Switzerland, such as various grassland types and snowbeds. Magali Matteodo showed that alpha-diversity increased throughout, probably due to recent colonization, whereas the overall composition remained rather stable in grasslands, irrespectively of the bedrock type. In contrary, snowbed communities experienced pronounced vegetation changes indicating dryer conditions.
The final presentation, presented by Elisabet Safont, focused on a monitoring approach on highly isolated table mountains in Venezuelan Guayana. The baseline study, conducted on the best-explored table mountain of the region, tepui Roraima, showed a high degree of very local endemism (35% of species restricted to this single mountain) and several new species to science. Given the very restricted species ranges, an especially high risk of biodiversity losses due to global warming is assumed.
On Thursday, October 8, session S10 was thematically followed by a very stimulatory post-conference workshop on joint data analyses of European historical/resurvey summits and European GLORIA data, organized by Sonja Wipf. The workshop continued the sUMMITDIV project commencing in Leipzig in autumn 2014.