Abstract
ABSTRACT Lichens play a key role in natural ecosystems, as they can function as primary producers, recycle minerals and fix nitrogen. Despite their environmental importance, little is known about lichen ecology in Brazil, and especially about how abiotic factors may influence their spatial distribution. In this study, we aimed to verify how the cover and richness of corticolous lichens on Araucaria angustifolia trunks vary between two different habitats (Forest and Grassland). The photoquadrat sampling method was applied to A. angustifolia trunks. The Coral Point Count software with Excel extensions (CPCe) was used to analyze photographs for lichen cover and richness. Additionally, a redundancy analysis was conducted to estimate how five abiotic and two biotic variables affected the spatial distribution of lichens. Twenty-five morphospecies were identified, none of them occurring exclusively in the Grassland habitat. Canopy openness, air humidity and tree trunk rugosity were important parameters influencing lichen distribution; therefore, spatial segregation of growth forms can be explained by environmental selectivity. Foliose lichens require more air humidity, which explains their predominance in the Forest habitat. Canopy openness in Grassland habitat favors fruticose lichens, which depend on factors such as wind for reproduction.
Highlights
Lichens are symbiotic organisms formed by the association of one or more fungi (Ascomycota and/ or Basidiomycota) and microalgae (Cianophyceae or Chlorophyta groups; Beck et al 1998; Marcelli 2006; Spribille et al 2016)
This study aimed to evaluate the influence of abiotic factors on the cover and richness of lichen morphospecies and growth forms associated with A. angustifolia in two different habitats in Mixed Ombrophilous Forest (Forest and Grassland)
We verified that the cover and richness of corticolous lichens on A. angustifolia trunks are determined by the environment in which the tree is growing, as a consequence of abiotic variables that can influence the selectivity of lichens for substrate type
Summary
Lichens are symbiotic organisms formed by the association of one or more fungi (Ascomycota and/ or Basidiomycota) and microalgae (Cianophyceae or Chlorophyta groups; Beck et al 1998; Marcelli 2006; Spribille et al 2016). Lichens develop close interactions with living surfaces, such as tree trunks (Brodo 1973). These biological substrates provide favorable environmental conditions for lichen growth, such as substrate complexity and light conditions that are generally adequate for physiological responses by lichens (Brodo 1973; Nascimbene et al 2009). The structural complexity of tree trunks, considering tree age and size, influence lichen richness, as older tree trunks tend to be rougher and favor establishment (Nascimbene et al 2009)
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