Colonization processes on a central Alpine glacier foreland

Abstract

Questions: What are the colonization trends in vegetated vs. bare‐ground plots over a 10‐year period in a central Alpine glacier foreland? What are the long‐term effects of artificial seed addition to these plots? Location: Glacier foreland of the Rotmoosferner in the Central Alps, Obergurgl, Tyrol, Austria, 2380 – 2400 m a.s.l. Methods: A total of 40 permanent plots were established on moraines ice‐free for 35 and 50 years on vegetated and bare‐ground areas. Half of them were treated with a seed mixture in 1996 and 1997. Number and cover of the species were recorded in 1996 and from 2002/2003 to 2006. Results: Species richness doubled in the control plots and tripled in seeded plots on the 35‐year‐ice‐free moraine. On the 50‐year‐ice‐free moraine the increase in species number was more modest. Significant site, seeding and time effects were found. Seed addition had no effects in the bare‐ground plots on the older moraine and low effects in those on the younger moraine. All plots showed significant changes in cover of single species. The pioneer species decreased significantly in both moraines, in the control as well as in the seeded plots. A disappearance during the next years is predicted. Conclusions: Colonization in bare‐ground plots is limited by a lack of safe sites, whereas vegetated plots facilitate recruitment and establishment. Colonization on the glacier foreland is also dispersal limited. Seed addition enhanced the presence of already established species, and late successional species were newly introduced.

Vegetation diversity and selected abiotic factors influencing the primary succession process on the foreland of Gåsbreen, Svalbard

“…Micranthes nivalis seems to have an especially strong capacity of germinating from the seed bank (Cooper et al 2004). A so-called cascade effect, as observed on glacier forelands in the central Alps (Erschbamer et al 2008), is also possible when germination takes place faster in places already overgrown by vegetation in contrast to areas lacking plant cover. Further research is needed to gain deeper insight into this subject.…”

Dispersal and microsite limitation of a rare alpine plant

“…Indeed, our seed addition experiment indicates that C. thyrsoides is strongly dispersal limited, since adding seeds to unoccupied habitats resulted in successful germination and survival of seedlings. In a seed sowing experiment with several plant species on a glacier foreland in the Eastern Alps, it was suggested that dispersal limitation might be a common feature of alpine plant species (Erschbamer et al 2008).…”

Succession of vascular plants in front of retreating glaciers in central Spitsbergen

“…Cooper 1939;Boggs et al 2010), the Alps (e.g. Burga et al 2010;Erschbamer et al 2008) and the Scandinavian Mountains (e.g. Matthews and Whittaker 1987).…”