Lichen traits responding to aridity

Abstract

Summary1. Climate change is expected to cause several impacts at the global scale, and drylands will be amongst the most affected areas. Thus, investigating how these changes will affect the composition, structure and functioning of dryland ecosystems has become a priority. From an ecological indicator point of view, several works have shown that functional diversity is better than species richness to understand ecosystem functioning or response to environmental factors. However, most of these works focus on plants, while those of other organisms remain largely unknown. Lichens are amongst the ecosystem components more sensitive to climatic changes due to several physiological and ecological characteristics. Their poikilohydric nature (therefore highly dependent on the atmosphere for water supply) and their ubiquity on terrestrial ecosystems underlie their potential as indicators of climate. Nonetheless, works specifically aiming to identify lichen functional traits that respond to aridity remain poorly explored, particularly in drylands.2. We proposed to identify lichen functional traits and respective functional groups responding to aridity in a Mediterranean drylands ecosystem.3. Lichen diversity was sampled in open holm oak woodlands along an aridity gradient in SW Europe (Iberian Peninsula). Lichen functional traits that could be easily identified and related to water uptake were selected to be tested: type of photobiont, growth form and reproduction strategy. 4.Lichen species composition was related to the aridity gradient. The three traits chosen were related with the community's response to aridity, but with contrasting responses in different functional groups. More specifically crustose and fruticose lichens, isidiate species and the ones with Trentepohlia as photobiont were related to the less arid part of the gradient. Foliose species and cyanolichens, on the contrary, were associated with the most arid areas.5. Synthesis. We were able to identify lichen traits responding to aridity. Type of photobiont was particularly responsive, with Trentepohlia and cyanobacteria functional groups, responding clearly in contrasting ways to aridity in this drylands ecosystem. This work emphasizes functional diversity role on understanding and assessing the response to environmental factors, namely to climate. It also highlights the potential use of lichen functional groups as ecological indicators of climate change.

Estrutura da comunidade de liquens corticícolas em área urbana e rural no município de Novo Hamburgo, Rio Grande do Sul, Brasil

“…A presença de liquens fruticosos está associada a locais mais úmidos (Giordani et al 2013, Käffer & Martins 2014, Matos et al 2015. Segundo MartinsMazzitelli et al (2006), os liquens fruticosos são os mais sensíveis à poluição atmosférica, sendo os primeiros a desaparecerem em áreas muito degradadas, podendo-se sugerir que no ambiente rural amostrado as condições microclimáticas associado às características ambientais da região estavam mais favoráveis para a ocorrência destes espécimes quando comparado à área urbana analisada.…”

“…Este gênero tem sido citado como indicador de ecossistemas florestais preservados, com alta continuidade ecológica (Campbell & Fredeen 2004, Liira & Sepp 2009, Gjerde et al 2012. De outro lado o baixo índice de liquens que portam cianobactéria nas áreas I e II (5,5%) pode estar atribuído ao fato de que estes organismos estarem normalmente relacionados a ambientes úmidos e sombreados (Sierk 1964, Giordani et al 2013, Matos et al 2015. Neste estudo houve apenas a ocorrência de uma espécie do gênero Collema e duas espécies do gênero Leptogium.…”

“…Na área rural 40,62% das espécies pertencem aos liquens que portam cianobactéricas (Leptogium e Collema) ou são do grupo morfológico fruticoso (Ramalina, Usnea e Teloschistes), além dos gêneros Crocodia e Ricasolia que também não foram constatados na área urbana. Espécies liquênicas do tipo fruticoso, assim como aquelas associadas às cianobactérias são mais suscetíveis as alterações ambientais, especialmente pelas variações nos fatores climáticos, como temperatura, umidade e luminosidade ocorrentes em ambientes urbanos (Martins-Mazzitelli et al 2006, Giordani et al 2013, Matos et al 2015. Embora a riqueza de espécies obtida neste trabalho tenha sido inferior ao inventariado em outras pesquisas para a região metropolitana de Porto Alegre, este estudo vem a contribuir para o conhecimento da micota liquenizada corticícola para o trecho inferior da Bacia do Rio dos Sinos, no estado do Rio Grande do Sul.…”

Community dynamics of stabilized dune xerophytic shrubs

“…Functional diversity was assessed using three functional indices described by Villéger et al (2008), namely functional richness, functional evenness and functional divergence, as well as Rao's quadratic entropy (Botta-Dukát 2005). The functional responses through successional gradients were analysed by performing Spearman correlations between functional groups and traits and NMS axes and overlaying the signifi-cant variables onto the community ordination (Matos et al 2015). Generalized Additive Models (GAMs; Wood 2006) were used to model both the community dynamics and the variations of functional indices across environmental gradients.…”

Fire affects the functional diversity of epilithic lichen communities

“…Consequently, functional diversity is often quantified as the functional richness of the traits present in the community and the dissimilarity of functional composition between communities (Vill eger et al, 2011). In the case of lichens, functional diversity has been used for assessing the effects of several natural and anthropogenic disturbances, such as short-and long-range nitrogen depositions (Pinho et al, 2012;Giordani et al, 2014a, c) or aridity (Concostrina-Zubiri et al, 2014;Matos et al, 2015). However, these works mainly focused on functional a-diversity (Spitale and Nascimbene, 2012), whereas the connection between various components of lichen diversity in terms of functionality is still poorly investigated (Giordani et al, 2014c).…”