Vegetation discontinuities and altitudinal indicator species in mountains of West Greenland: finding the best positions and traits to observe the impact of climate warming in the Arctic

Authors


siegb@uni-muenster.de

Abstract

Aims

To delineate boundaries of vegetation belts, characterize these belts by indicator species, plant functional types and plant distribution types, and explore options for climate change monitoring.

Location

Three research sites in the continental inland of West Greenland.

Methods

Based on spatially constrained clustering of 147 vegetation relevés and 145 transect plots of plant communities, boundaries of altitudinal vegetation belts were assessed. Indicators for altitudinal sections were identified from 664 vegetation relevés among vascular plants, bryophytes, lichens and plant functional types using indicator species analysis. The performance of different plant groups along the altitudinal gradient was visualized with response curves.

Results

Boundaries of altitudinal vegetation belts were detected at 400, 800 and 1175 m a.s.l. on north-facing slopes and at 450, 900 and 1250 m a.s.l. on south-facing slopes. The resulting four vegetation belts were well defined by 99 indicator species and nine indicator plant functional types. Species, plant functional types and vascular plant distribution types showed clear sequences along the altitudinal gradient, which partly resemble their distribution along the latitudinal gradient.

Conclusions

As an easily observable expansion of shrubs and a decline of mosses and lichens is expected, the boundary at 400/450 m a.s.l. is particularly promising for climate change monitoring. The anticipated replacement of numerous cryophilous by thermophilous indicator species, as well as an obvious shift of plant functional types suggest several monitoring options at 800/900 m a.s.l. The summit areas above 1175/1250 m a.s.l., having a discontinuous plant cover, are considered to be especially vulnerable to fast invasion by species of lower altitudes such as woody plants and sedges. Due to steep gradients and short migration distances in mountains, it can be assumed that these anticipated changes in the study area will be stronger and faster than the already observed changes along the latitudinal gradient in lowland areas of the Arctic.

Ancillary