The bright and shaded side of duneland life: the photosynthetic response of lichens to seasonal changes is species-specific

Abstract

Terricolous lichens are relevant associates of biological soil crusts in arid and semiarid environments. Dunes are ecosystems of high conservation interest, because of their unique, vulnerable and threatened features. The function of lichens is affected by the changing seasons and different microhabitat conditions. At the same time, inland dunes are less investigated areas from the terricolous lichens point of view. We explored the effect of seasonal variation and different micro-environmental conditions (aspect) on the metabolic activity of five terricolous lichen species, representing various growth forms, in temperate semiarid grasslands. Populations of Cladonia foliacea, C. furcata, C. pyxidata group, Diploschistes muscorum and Thalloidima physaroides were investigated. Thalli sampled from the south-west and north-east facing microhabitats were studied by chlorophyll fluorescence analysis for 2 years. The present study aims to understand how changing climate (during the year) and aspect affect photosynthetic activity and photoprotection. Microclimatic data were also continuously recorded to reveal the background of the difference between microhabitat types. As a result, the air temperature, photosynthetically active radiation, soil temperature and vapour pressure deficit were significantly higher on south-west than on north-east facing microsites, where relative humidity and water content of soil proved to be considerably higher. Higher photosynthetic activity, as well as a higher level of photoprotection, was detected in lichens from north-east-oriented microsites compared with south-west populations. In addition, the difference between sun and shade populations varied seasonally. Since a species-specific response to both aspect and season was detected, we propose to investigate more than one species of different growth forms, to reveal the response of lichens to the changing environment in space and time.

Factors at multiple scales influence the composition of terricolous lichen communities in temperate semi-arid sandy grasslands

“…Our results showed that the site had higher explanatory power than dune side. Since we could not find any significant difference in the climate between the two study site (Veres et al 2020) history could also play an important role in developing different lichen communities.…”

“…The list of terricolous lichen species at the Bugacpusztaháza (BU) and Fülöpháza (FH) sites according to previous authors and collectors (Gallé 1973;Lőkös & Verseghy 2001) Sampling was carried out in late autumn and during wintertime because it was more advantageous to estimate the cover of the different lichen growth forms than in summer when they are usually in a dry condition. Our previous long-term study (Veres et al 2020) revealed a significant difference in microclimate between the north-east (NE) and south-west (SW) facing dune sides or aspect of the sites. The more exposed, SW-facing slopes are considered arid; the NE-facing sides are considered less arid (hereafter 'humid') dune sides.…”

Global diversity and ecological drivers of lichenised soil fungi

“…Consequently, the net effect of competition and facilitation is the co‐occurrence of lichen symbiosis and vascular plants. Competitive effects are important for structuring lichen communities at a global scale, as lichen symbiosis may confer a competitive advantage and promote stability (Rogers, 1971; Bowker et al ., 2016; van Zuijlen et al ., 2020; Veres et al ., 2020). However, drought conditions may favour lichen development over vascular plants in drylands and give greater tolerance by lichens to extreme dryness, light and temperature (Belnap, 2006; Ding & Eldridge, 2020).…”

“…For example, pH is important in predicting the relative abundance of Verrucaria and Endocarpon , but not Rinodina . We found that precipitation seasonality is a potential predictor of Rinodina , suggesting that it is sensitive to changes in seasonal precipitation, similar to lichenised fungi in general (Bowker et al ., 2016; Veres et al ., 2020). While fluctuations in seasonal precipitation might favour some lichenised taxa (Lange, 1953; Rogers, 1971), high levels of hydration, particularly at high temperatures, are known to reduce photosynthetic levels of lichen symbiosis despite their high respiration (Rogers, 1971).…”

Resilience of Epiphytic Lichens to Combined Effects of Increasing Nitrogen and Solar Radiation

“…Finally, we hypothesized that species belonging to more tolerant functional groups would show a higher capacity to recover after the stress exposure than sensitive species. To test our hypotheses, we used chlorophyll a fluorescence as a sensitive but non-destructive method for assessing the response of photosynthetic organisms to environmental changes [ 33 ]. Understanding the response of these sensitive elements of ecosystems to multiple environmental stressors is a primary goal to improve the use of lichens as indicators for environmental protection and predict the potential consequences of global change on ecosystem functioning.…”