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Soil mosses are among the most widely distributed organisms on land. Experiments and observations suggest that they contribute to terrestrial soil biodiversity and function, yet their ecological contribution to soil has never been assessed globally under natural conditions. Here we conducted the most comprehensive global standardized field study to quantify how soil mosses influence 8 ecosystem services associated with 24 soil biodiversity and functional attributes across wide environmental gradients from all continents. We found that soil mosses are associated with greater carbon sequestration, pool sizes for key nutrients and organic matter decomposition rates but a lower proportion of soil-borne plant pathogens than unvegetated soils. Mosses are especially important for supporting multiple ecosystem services where vascular-plant cover is low. Globally, soil mosses potentially support 6.43 Gt more carbon in the soil layer than do bare soils. The amount of soil carbon associated with mosses is up to six times the annual global carbon emissions from any altered land use globally. The largest positive contribution of mosses to soils occurs under perennial, mat and turf mosses, in less-productive ecosystems and on sandy soils. Our results highlight the contribution of mosses to soil life and functions and the need to conserve these important organisms to support healthy soils.

Soils are the foundation of all terrestrial ecosystems1. However, unlike for plants and animals, a global assessment of hotspots for soil nature conservation is still lacking2. This hampers our ability to establish nature conservation priorities for the multiple dimensions that support the soil system: from soil biodiversity to ecosystem services. Here, to identify global hotspots for soil nature conservation, we performed a global field survey that includes observations of biodiversity (archaea, bacteria, fungi, protists and invertebrates) and functions (critical for six ecosystem services) in 615 composite samples of topsoil from a standardized survey in all continents. We found that each of the different ecological dimensions of soils—that is, species richness (alpha diversity, measured as amplicon sequence variants), community dissimilarity and ecosystem services—peaked in contrasting regions of the planet, and were associated with different environmental factors. Temperate ecosystems showed the highest species richness, whereas community dissimilarity peaked in the tropics, and colder high-latitudinal ecosystems were identified as hotspots of ecosystem services. These findings highlight the complexities that are involved in simultaneously protecting multiple ecological dimensions of soil. We further show that most of these hotspots are not adequately covered by protected areas (more than 70%), and are vulnerable in the context of several scenarios of global change. Our global estimation of priorities for soil nature conservation highlights the importance of accounting for the multidimensionality of soil biodiversity and ecosystem services to conserve soils for future generations.

ABSTRACTPhylogenetic relationships of 12 species in Aleurodiscussensu lato (Stereaceae, Russulales) described from the Patagonian forests of Chile and Argentina were investigated based on sequences of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and the D1–D2 domains of nuc 28S rDNA (28S). A new genus and a new species are presented, and 10 new combinations proposed. The genus Gloeosomais shown to be phylogenetically well supported and morphologically circumscribed; it includes G. vitellinum(type species), G. mirabile, comb. nov., G. zealandicum, comb. nov., and Gloeosoma decorticans, sp. nov., which is newly described from Chile. The new genus Stereodiscusis proposed to accommodate a group of taxa characterized by an austral distribution and morphologically by smooth, thin-walled, amyloid basidiospores and a lack of gloeocystidia and acanthocystidia; three species develop Stereum-like basidiomata and two species present discoid ones. The new genus includes the species formerly known as Aleurodiscus antarcticus, A. limonisporus, A. parmuliformis, A. patagonicus, and A. triviale. Specimens of Stereodiscus parmuliformis(A. parmuliformis) from New Zealand (where it was originally described) and southern Chile are shown to be phylogenetically conspecific, which confirms its presence in Patagonia. Gloeosomaand Stereodiscusare shown to be distantly related to Aleurodiscuss. str. and other genera in Stereaceae. The new combinations Aleurocystidiellum bernicchiae, Aleurocystidiellum hallenbergii, and Acanthobasidium quilaeare proposed based on morphology and phylogenetic analyses, and Aleurodiscus cerussatusis shown to be a cryptic species complex.

Genetic diversity within and among Chilean Araucaria araucanapopulations was estimated using allozyme variability. A total of 537 individuals were sampled from nine populations. Twelve loci were scored in all populations and used for analyses. In general, the genetic variability of A. araucanawere high as shown by mean expected heterozygosity (HE= 0.151), percentage of polymorphic loci (P= 91.7%), mean number of alleles per locus (A= 1.73) and mean number of alleles per polymorphic locus (AP= 2.4). Although the most of this genetic variation was within populations (HS= 0.151), an important proportion of the total genetic diversity (HT= 0.212) was among population (GST= 0.287). To analyze the relationships between populations we constructed a tree based on Nei’s genetic distances using UPGMA methods, and calculated FSTbetween population pairs. Our results showed complex patterns of genetic relationships among Chilean Araucaria araucanapopulations. Tree topology suggested the existence of three distinct groups of populations: The first group included populations from low-elevation central Andean range and Coastal range populations. The second group, included northern Andean populations. The third group of populations was composed of central high-elevation Andean populations. These patterns of population clustering are congruent with multiple glacial refugia hypothesis. In order to understand the present patterns of distribution of the genetic diversity and post-glacial colonization routes of Araucaria araucana, paleogeographical, paleoclimatic and biogeographical evidence is discussed.