Reproductive strategy and the compositional dynamics of crustose lichen communities on aspen (Populus tremula L.) in Scotland

Abstract

Ecological studies are essential in understanding the response of crustose lichens to habitat dynamics and developing effective conservation strategy. While the combined response of individual crustose species within a community will be tremendously complex, the overall result of individualistic change can be simplified using trait-based analyses. In this paper we examine the response of crustose species with contrasting reproductive traits (predominantly sexual vs asexual reproduction) and which occur within a closely defined habitat (as epiphytes on the lower bole of aspen) to environmental drivers measured at two different scales, i.e. between and within aspen stands. Our results point to the important effect of tree age and subsequent shifts in bark quality (pH) on the composition of the crustose community. However, shifts in community composition putatively controlled by bark quality comprise a change from a community dominated by sexual species to a community with mostly asexual crusts. Our results suggest therefore that variation within this crustose community may be driven by the combined effects of allogenic change (tree age and bark quality) and autogenic processes that are related to a species' adaptive life-history traits.

Tree and stand level variables influencing diversity of lichens on temperate broad-leaved trees in boreo-nemoral floodplain forests

“…increased with the circumference of tree. Still, the effects of tree ageing and/or tree size on bark acidity are hard to generalize as reverse effects have been observed depending on analysed tree species (Bates and Brown 1981;Bates 1992;Hyvärinen et al 1992;Ellis and Coppins 2007b). We also noted that bark pH is higher in the case of trees with a more extensive cover of bryophytes.…”

Asymmetric Co-evolution in the Lichen Symbiosis Caused by a Limited Capacity for Adaptation in the Photobiont

“…In Parmeliaceae (heteromous thallus), Parmelia (sensu lato) species from personal observation are usually vegetatively reproducing on the trunks of trees and most of the spore reproducing species occurring on twigs. Ellis and Coppins (2007) have shown that the mix of crustose lichen species occurring on aspen bark are more likely to be spore reproducing on young twig bark but there is a vegetatively reproducing mix on older branch bark with a clear trend from one to the other as the bark ages. The hyphae from germinating lichen spores presumably find endophloeodal Trebouxia cells on, or, possibly more likely, in the dead epidermal cells which might be an enclosed habitat similar to that within a lichen thallus.…”

Bark Roughness as A Factor Affecting Cell Density Of Epiphytic Microalgae (Apatococcus Sp)

“…The rough bark is more efficient surface structure to grasp the water and moisture from rain and dew. In the past, [21] also found that it is often visually obvious that colonization is more extensive on rough and porous surfaces than smooth, non-porous ones. Lichen studies also showed the rough bark also provides a greater opportunity for thallus fragments of lichens to embed in its surface [22].…”