Community structure of corticolous microalgae within a single forest stand: evaluating the effects of bark surface pH and tree species

Abstract

Community structure of corticolous macro-epiphytes, such as lichens and mosses, usually strongly correlates with bark characteristics related to the taxonomic identity of the host tree. However, the reasons for the occurrence of similar patterns of microalgal corticolous biofilms are unclear and have rarely been investigated. In this study, we surveyed aerial phototrophic biofilms growing on the bark of Acer, Alnus, Fagus, Fraxinus and Picea trees in a single stand of a temperate forest. A flathead electrode was used to measure and evaluate the effect of bark surface pH on microalgal species richness and composition. In total, 47 distinct morphotypes were found, chiefly consisting of various coccoid green algae belonging to Trebouxiophyceae and Chlorophyceae. In addition, members of the Bacillariophyceae, Eustigmatophyceae, Streptophyta, Trentepohliales, Xanthophyceae and Cyanobacteria were also found. Bark pH and species richness of the samples were positively correlated; in the most acidic samples (from Picea and Alnus trees), only green algae occured. Aerial diatoms, Cyanobacteria, Xanthophyceae and Trentepohlia sp. were only found in the more basic samples. The species composition was significantly structured by the separated effects of host tree species, the bark pH and the sampling season. The observed non-random differences in community structure of the biofilms among host tree species indicated possible effects of deterministic processes, such as species sorting of microalgae along the environmental gradients.

Molecular characterization of eukaryotic algal communities in the tropical phyllosphere based on real-time sequencing of the 18S rDNA gene

“…Many of Trebouxiophycean algae are reported from terrestrial environments or as symbionts and endosymbionts with independent evolutions, i.e., Lunachloris , Choricystis , Trebouxia , Symbiochloris and Xylochloris [19, 43–45]. Molecular phylogenies of this class recovered four orders (Chlorellales, Trebouxiales, Prasiolales, Microthamnionales) and several not well-defined clades, i.e., Neocystis - Coenocystis clade, Apatococcus clade, Coccobotrys clade, Choricystis - Botryococcus - Coccomyxa clade, Elliptochloris clade, Eremochloris clade, Xylochloris clade and Watanabea clade [11, 22, 45, 46].…”

Small‐scale variation of corticolous microalgal covers: Effects of microhabitat, season, and space

“…Therefore, we used the standard Bold Basal Medium (Andersen ), which has originally been designed for culturing terrestrial green microalgae (Bischoff & Bold ). This medium has also been proven to be suitable for culturing multiple subaerial coccoid and filamentous microalgae (e.g., Ettl & Gärtner ; Flechtner ; Lewis & Flechtner ; Freystein et al ; Neustupa & Škaloud , ; Štifterová & Neustupa ).…”

“…On larger spatial scales (such as among regions), the geographic distance, correlated with the differences in temperature and humidity, seems to be the most important factor for the distribution of major microalgal taxa (Rindi & Guiry ; Neustupa & Štifterová ). On an intermediate scale (i.e., meters to tens of kilometers within a single region), the physicochemical factors related to different substrata, such as pH, nutrients, or water‐holding capacity, seem to determine the community composition of the microalgal biofilms (Hoffmann ; Lukešová & Hoffmann ; Mataloni & Tell ; Freystein et al ; Neustupa & Štifterová ; Kulichová et al ; Marmor & Degtjarenko ; Nováková & Neustupa ; Štifterová & Neustupa ). Other important factors that correlate with microalgal distribution in subaerial microhabitats include local irradiance, sample orientation, or age of substrata (Hedenås et al ; Neustupa & Škaloud , ; Neustupa & Štifterová ).…”

“…Other important factors that correlate with microalgal distribution in subaerial microhabitats include local irradiance, sample orientation, or age of substrata (Hedenås et al ; Neustupa & Škaloud , ; Neustupa & Štifterová ). The observed prominence of the environmental factors on this scale, presumably coupled with frequent dispersal of microalgal propagules (Sharma et al ), suggests the probable strong effects of deterministic processes, such as species sorting along the environmental gradients (Jones & McMahon ; Štifterová & Neustupa ). Previous studies that have shown considerably lower heterogeneity of biofilm community structure on this spatial scale were typically focused on a single type of a homogeneous substrate and, thus, the observed homogeneity of phototrophic microcommunities might have reflected the local homogeneity of environmental conditions (Mataloni et al ; Cutler et al ).…”

The Aerophytic Diatom Assemblages Developed on Mosses Covering the Bark of Populus alba L.

“…Hickman, Vitt 1973, Van de Vijver, Beyens 1997, Gremmen et al 2007). Until now, the algological studies of tree barks have focused mainly on the green and bluegreen algae in tropical zones (Foerester 1971, Mrozińska 1990, Thompson, Wujek 1997, Salleh, Milow 1999, Neustupa 2003, 2005, Neustupa, Škaloud 2008, Kharkongor, Ramanujam 2014, Štifterová, Neustupa 2015, while diatoms were noted rarely, usually mentioned only in the lists of species (Lakatos et al 2004, Geissler et al 2006, Neustupa, Škaloud 2010, Kharkongor, Ramanujam 2014, Štifterová, Neustupa 2015, Qin et al 2016. In Poland, no studies on the diatom assemblages developing among mosses on the tree barks have been conducted so far.…”