Speaker
Description
Glacial retreats represent a unique opportunity to study primary successional processes. The new exposed rock is a new material for the assembly of a new ecosystem. Soil formation after glacial retreat is strongly influenced by plant colonization, but this colonization depends on nutrient availability. An ongoing project in the forefront of the last Venezuelan glacier has established a chronosequence of four sites where the glacier retreated between 1910 and 2009. Recent results show a slow successional response during early seral stages. Soil microbial communities play then the key role on ecosystem development through chemical and physical soil modifications that allow subsequent plant colonization. Exploring the mechanisms that assist the establishment of a pioneer plant in these extreme conditions will further our understanding of how the microbiota influences colonization and local adaptation in a novel poor habitat created by glacial retreat. We characterized community structure and diversity of the root endospheres and rhizospheres communities of the pioneer vascular plant in two stages of primary succession of this system (22 and 68 years of ecosystem development). Interestingly, we found that primary succession in belowground communities, as shown for aboveground communities, is also slow. Root-associated bacterial communities are very similar regardless of transect age, suggesting that the environment may be driving these communities, for instance limited initial colonization or severe environmental filtering. Alternatively, community-function in the host-microbiome relationship might be constraining taxonomic diversity. These results highlight the crucial role of host-microbiota mutualisms in the colonization by pioneer species of regions with extreme and quickly changing environmental conditions.
