Ecological Determinants of Species Composition of Biological Soil Crusts on a Landscape Scale

The species composition of algae from biological soil crusts (biocrusts) on the surface of sand dunes (Black Sea coast, Primorske, Izmail District, Odesa Region, Ukraine) was investigated. Samples were collected from three coastal localities: Katranivska Spit, Zhebryianska Bay and Zhebryianska Ridge. The latter two localities are in the territory of the Danube Delta Biosphere Reserve. The samples were investigated by direct microscopy, followed by a culture approach. 60 species from Chlorophyta (32), Cyanobacteria (16), Streptophyta (7) and Ochrophyta (5) were identified. Representatives of the cyanobacterial genera Microcoleus Desmazières ex Gomont, Coleofasciculus M.Siegesmund, J.R.Johansen & T.Friedl, Nostoc Vaucher ex Bornet & Flahault, Hassallia Berkeley ex Bornet & Flahault, and streptophytes from the genus Klebsormidium P.C.Silva, Mattox & W.H.Blackwell dominated in the studied biocrusts. Phylogenetic analyses based on 16S/18S rRNA as well as 16S-23S ITS/ITS-1,2 regions were undertaken for some strains of cyanobacteria and eukaryotic algae. As a result, species identification and their position in respective phylogeny was refined, as well as aiding the discovery of some interesting and rare species. New genera and species were described (Streptosarcina arenaria Mikhailyuk & Lukešová and Tetradesmus arenicola Mikhailyuk & P.Tsarenko); with two genera (Nodosilinea R.B.Perkerson & D.A.Casamatta and Pleurastrosarcina H.J.Sluiman & P.C.J.Blommers) and four species reported for the first time for the flora of Ukraine (Nodosilinea epilithica Perkerson & Casamatta, Pseudomuriella aurantiaca (W.Vischer) N.Hanagata, Pleurochloris meiringensis Vischer, Pleurastrosarcina terriformae Darienko, W.J.Kang, Orzechowski & Pröschold). Comparison of the results from this study with similar investigations at Cape Kazantip (Sea of Azov, Ukraine) and at two islands of the Baltic Sea (Rügen, Usedom, Germany) revealed that sand composition and texture, as well as climate type of the respective region, are the main factors determining species composition of algae and cyanobacteria in biocrusts of maritime dunes.

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Unassisted establishment of biological soil crusts on dryland road slopes

Web Ecology ◽

10.5194/we-19-39-2019 ◽

2019 ◽

Vol 19 (1) ◽

pp. 39-51 ◽

Cited By ~ 3

Author(s):

Laura Concostrina-Zubiri ◽

Juan M. Arenas ◽

Isabel Martínez ◽

Adrián Escudero

Keyword(s):

Species Composition ◽

Soil Properties ◽

Vascular Plant ◽

Plant Cover ◽

Critical Role ◽

Biological Soil Crusts ◽

Functional Structure ◽

Ecosystem Recovery ◽

Natural Habitats ◽

Soil Crusts

Abstract. Understanding patterns of habitat natural recovery after human-made disturbances is critical for the conservation of ecosystems under high environmental stress, such as drylands. In particular, the unassisted establishment of nonvascular plants such as biological soil crusts or biocrust communities (e.g., soil lichens, mosses and cyanobacteria) in newly formed habitats is not yet fully understood. However, the potential of biocrusts to improve soil structure and function at the early stages of succession and promote ecosystem recovery is enormous. In this study, we evaluated the capacity of lichen biocrusts to spontaneously establish and develop on road slopes in a Mediterranean shrubland. We also compared taxonomic and functional diversity of biocrusts between road slopes and natural habitats in the surroundings. Biocrust richness and cover, species composition, and functional structure were measured in 17 road slopes (nine roadcuts and eight embankments) along a 13 km highway stretch. Topography, soil properties and vascular plant communities of road slopes were also characterized. We used Kruskal–Wallis tests and applied redundancy analysis (RDA) to test the effect of environmental scenario (road slopes vs. natural habitat) and other local factors on biocrust features. We found that biocrusts were common in road slopes after ∼20 years of construction with no human assistance needed. However, species richness and cover were still lower than in natural remnants. Also, functional structure was quite similar between roadcuts (i.e., after soil excavation) and natural remnants, and topography and soil properties influenced species composition while environmental scenario type and vascular plant cover did not. These findings further support the idea of biocrusts as promising restoration tools in drylands and confirm the critical role of edaphic factors in biocrust establishment and development in land-use change scenarios.

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