Significance: Land-use intensification is a major threat to biodiversity. So far, however, studies on biodiversity impacts of land-use intensity (LUI) have been limited to a single or few groups of organisms and have not considered temporal variation in LUI. Therefore, we examined total ecosystem biodiversity in grasslands varying in LUI with a newly developed index called multidiversity, which integrates the species richness of 49 different organism groups ranging from bacteria to birds. Multidiversity declined strongly with increasing LUI, but changing LUI across years increased multidiversity, particularly of rarer species. We conclude that encouraging farmers to change the intensity of their land use over time could be an important strategy to maintain high biodiversity in grasslands.

Biocrusts are associations of various prokaryotic and eukaryotic microorganisms in the top millimeters of soil, which can be found in every climate zone on Earth. They stabilize soils and introduce carbon and nitrogen into this compartment. The worldwide occurrence of biocrusts was proven by numerous studies in Europe, Africa, Asia and North America, leaving South America understudied. Using an integrative approach, which combines morphological and molecular characters (small subunit rRNA and ITS region), we examined the diversity of key biocrust photosynthetic organisms at four sites along the latitudinal climate gradient in Chile. The most northern study site was located in the Atacama Desert (arid climate), followed by open shrubland (semiarid climate), a dry forest region (Mediterranean climate) and a mixed broad leaved-coniferous forest (temperate climate) in the south. The lowest species richness was recorded in the desert (18 species), whereas the highest species richness was observed in the Mediterranean zone (40 species). Desert biocrusts were composed exclusively of single-celled Chlorophyta algae, followed by cyanobacteria. Chlorophyta, Streptophyta and cyanobacteria dominated semiarid biocrusts, whereas Mediterranean and temperate Chilean biocrusts were composed mostly of Chlorophyta, Streptophyta and Ochrophyta. Our investigation of Chilean biocrust suggests high biodiversity of South American biocrust phototrophs.

FortyKlebsormidiumstrains isolated from soil crusts of mountain regions (Alps, 600–3,000 m elevation) were analyzed. The molecular phylogeny (internal transcribed spacerrDNAsequences) showed that these strains belong to clades B/C, D, E, and F. Seven main (K. flaccidum,K. elegans,K. crenulatum,K. dissectum,K. nitens,K. subtile,andK. fluitans) and four transitional morphotypes (K. cf.flaccidum,K. cf.nitens,K. cf.subtile,andK. cf.fluitans) were identified. Most strains belong to clade E, which includes isolates that prefer humid conditions. One representative of the xerophytic lineage (clade F) as well as few isolates characteristic of temperate conditions (clades B/C, D) were found. Most strains of clade E were isolated from low/middle elevations (<1,800 m above sea level; a.s.l.) in the pine‐forest zone. Strains of clades B/C, D, and F occurred sporadically at higher elevations (1,548–2,843 m a.s.l.), mostly under xerophytic conditions of alpine meadows. Comparison of the alpineKlebsormidiumassemblage with data from other biogeographic regions indicated similarity with soil crusts/biofilms from terrestrial habitats in mixed forest in Western Europe, North America, and Asia, as well as walls of buildings in Western European cities. The alpine assemblage differed substantially from crusts from granite outcrops and sand dunes in Eastern Europe (Ukraine), and fundamentally from soil crusts in South African drylands. Epitypification of the known speciesK. flaccidum,K. crenulatum,K. subtile,K. nitens,K. dissectum,K. fluitans,K. mucosum,andK. elegansis proposed to establish taxonomic names and type material as an aid for practical studies on these algae, as well as for unambiguous identification of alpine strains. New combinationKlebsormidium subtile(Kützing) Mikhailyuk, Glaser, Holzinger et Karsten comb. nov. is made.

Most of the data on biodiversity, ecology and biogeography of microalgae and cyanobacteria are based on classical morphological approaches. However, morphological identification of these microorganisms is often possible only to higher taxonomic ranks such as genus, because of low morphological diversity and high variability along with the presence of cryptic taxa. This study compared the species composition of cyanobacteria, and green and streptophyte microalgae, isolated from biological soil crusts (BSCs) of maritime sand dunes (Baltic Sea, Germany) and identified through culture-dependent morphological methods combined with molecular phylogenetic data. Phylogenetic analyses (based on SSU rRNA and ITS-1,2 for microalgae, or the SSU-LSU ITS region for cyanobacteria) provided unambiguous identifications of 20 strains (37.7% of all strains investigated) to species level; the identifications had to be corrected after preliminary morphological determination of eight strains. For 27 strains (50.9%), identification with molecular markers was possible only to genus or group of closely related species, because a modern taxonomic revision of these taxa is preliminary, incomplete or non-existent. Identification to genus was problematic for six strains (11.3%). This combination of morphological and molecular methods (integrative approach) resulted in the discovery of rare, taxonomically or ecologically interesting taxa, and in the description of a new species of Tetradesmus (T. arenicola sp. nov.), a new combination for Chlamydomonas callunae (Heterochlamydomonas callunae comb. nov.), epitypification of the rare alga Actinochloris sphaerica and emendation of the recently described Eremochloris sphaerica. A microscopic culture-dependent method and an integrative approach provided similar results concerning the cyanobacterial and algal diversity of BSCs of Baltic sand dunes in general. However, this investigation using an integrative approach allowed us to precisely identify species of several important taxa (the most common and dominant species) in the community structure of BSCs, and also certain rare representatives.

Biological soil crusts (BSCs) are highly important communities in drylands and disturbed areas worldwide, where the higher vegetation is sparse, with a diverse microalgal community as the key component. They perform important ecological functions, such as stabilization of soil and nutrient enrichment. In temperate regions BSCs are also common, but generally less studied. Changes in land use and land use intensity strongly influence biodiversity per se and ecosystem processes, as can be seen particularly in densely populated regions like Europe. However, systematic studies on the effect of land use gradients, i.e., forest management intensity, on BSCs have been missing up to now. To close this knowledge gap and enhance the understanding of management effects on BSCs from pine and beech forests under different management regimes, key primary producers of these communities (eukaryotic microalgae and cyanobacteria) were studied. Phototrophic microorganisms were identified morphologically and categorized as either coccal taxa, which typically occur in high diversity, or filamentous taxa, which have the potential to initiate BSC formation. In total, 51 algal species were recorded, most of them from the phylum Chlorophyta, followed by Streptophyta and Stramenopiles, and only 1 cyanobacterial taxon. The most abundant crust-initiating filamentous algae were three species of Klebsormidium (Streptophyta), a ubiquitous genus regularly occurring in BSCs because of its broad ecophysiological tolerance. Increasing management intensity in the forests resulted in a higher number of algal species; especially the number of coccal taxa increased. Furthermore, the proportion of inorganic phosphorus showed tendencies towards a negative correlation with the number of algal species. Thus, management of forests has an impact on the diversity of phototrophic organisms in BSCs, which might in turn affect their biogeochemical P cycling.

Biological soil crusts (biocrusts) accommodate diverse communities of phototrophic and heterotrophic microorganisms. Heterotrophic protists have critical roles in the microbial food webs of soils, with Cercozoa and Endomyxa often being dominant groups. Still, the diversity, community composition, and functions of Cercozoa and Endomyxa in biocrusts have been little explored. In this study, using a high-throughput sequencing method with taxon-specific barcoded primers, we studied cercozoan and endomyxan communities in biocrusts from two unique habitats (subarctic grassland and temperate dunes). The communities differed strongly, with the grassland and dunes being dominated by Sarcomonadea (69%) and Thecofilosea (43%), respectively. Endomyxa and Phytomyxea were the minor components in dunes. Sandonidae, Allapsidae, and Rhogostomidae were the most abundant taxa in both habitats. In terms of functionality, up to 69% of the grassland community was constituted by bacterivorous Cercozoa. In contrast, cercozoan and endomyxan communities in dunes consisted of 31% bacterivores, 25% omnivores, and 20% eukaryvores. Facultative and obligate eukaryvores mostly belonged to the families Rhogostomidae, Fiscullidae, Euglyphidae, Leptophryidae, and Cercomonadidae, most of which are known to feed mainly on algae. Biocrust edaphic parameters such as pH, total organic carbon, nitrogen, and phosphorus did not have any significant influence on shaping cercozoan communities within each habitat, which confirms previous results from dunes.