Development of vegetation patterns in early primary succession

Abstract

Question: We investigated colonisation filters in early plant community development on a glacial outwash plain. We asked if these were related to seed limitation or to a lack of safe sites, if topographical heterogeneity affected species patchiness and how species life cycles influence successional trajectories. Location: An outwash plain (Skeiðarársandur) in southeast Iceland. Methods: We identified surface heterogeneity at two different scales, ca. 10–15 cm (larger stones and established plants) and ca. 50 m (shallow depressions representing dry river beds) at two study sites. We quantified species cover, flowering plant density, seed production, seed rain, seed bank density, seedling emergence and seedling survival from June 2005 to June 2007 for the whole plant community, and measured seed production for five species. Results: Mean vegetation cover was <2.5% at the sites. Low emergence rates and high seedling mortality were the two main recruitment filters. Only 1.4% of seedlings emerging in 2005 survived into the 2007 growing season. Topographical heterogeneity had little effect on plant colonisation. High annual variation was recorded, and the two study sites (ca. 2 km apart) differed in their colonisation success. Of the five species, establishment of Cerastium alpinum and Silene uniflora was most limited by lack of seeds, whereas establishment of Luzula spicata, Poa glauca and Rumex acetosella was most limited by safe sites. Conclusions: We conclude that colonisation processes and patterns in early primary succession on Skeiðarársandur were largely influenced by stochastic factors.

Between ice and ocean; soil development along an age chronosequence formed by the retreating Breiðamerkurjökull glacier, SE-Iceland

“…Further, the unstable surfaces of the outwash plains in SE-Iceland have shown to reduce seedling survival rates (Marteinsdóttir et al, 2010). There are several signs of eolian activity throughout the chronosequence at Breiðamerkurjökull; the retreating glacier constantly leaves behind finely ground material that is removed from the surface through wind and water erosion, deposited in vegetated surfaces or transported to water bodies.…”

Accumulation of nitrogen and organic matter during primary succession of &lt;i&gt;Leymus arenarius&lt;/i&gt; dunes on the volcanic island Surtsey, Iceland

“…As some vegetation cover establishes on the pristine surfaces, organic matter (OM) and soil organic nitrogen (SON) start to accumulate, which again improves the growing conditions for later successional species (Whittaker et al, 1989). Such "autogenic" (internal) factors are expected to determine the course of succession by traditional succession theory (Walker and del Moral, 2003), but "allogenic" (external) or stochastic factors (such as distance to potential colonists) also play an important role in some cases (del Moral et al, 2009;Marteinsdottir et al, 2010).…”

Construction of energy landscapes can clarify the movement and distribution of foraging animals

“…For example, although it is widely accepted that many birds enhance their flight capacities by making use of predictable sources of rising air [5] and that terrestrial animals expend more energy moving over soft substrate than hard [6], general consideration of the energetic costs of animals moving through their variable landscapes is minimal (but see [7]). Landscapes vary in character in both space and time with, for example, heterogeneous vegetation landscapes changing during succession [8,9] and over the growing season [10], becoming correspondingly more problematic for animals to move through [11]. Indeed, the degree of variation in the landscape (e.g.…”