Work in progress: Lichen substrate ecology of the Barberton Greenstone Belt, South Africa Ian D. Medeiros1, Alan M. Fryday2, Nathaniel Pope3, Arnold Frisby4, Marthie Coetzee5, Stefan Siebert5 and Nishanta Rajakaruna5,6 1Department of Biology, Duke University, United States of America; 2Department of Plant Biology, Michigan State University, United States of America; 3School of Biological Sciences, University of Texas-Austin, United States of America; 4Department of Plant and Soil Sciences, University of Pretoria, South Africa; 5Unit for Environmental Sciences and Management, North-West University-Potchefstroom, South Africa; 6Biological Sciences Department, California Polytechnic State University, United States of America Introduction Plans for Analysis The Barberton Greenstone Belt in Mpumalanga, South Africa, comprises intermixed formations of ultramafic and non-ultramafic rock. This region (Figure 1) has received geobotanical attention as a source of nickel hyperaccumulators and floristic diversity (Williamson and Balkwill 2015), but, as with much of South Africa, the saxicolous lichens have received little focused study. In the present study, we aim to characterise how moisture availability moderates the influence of substrate on lichen community structure. As a prelude to the project, AMF prepared a new checklist for the lichens of South Africa (Fryday 2015). Fieldwork was conducted in February 2016, and taxonomic work on our collections is ongoing. Here, we present an outline of the project and discuss some early findings. Because the taxonomic understanding of South Africa's saxicolous lichens is rudimentary, taxonomic study must precede ecological analyses of our data. For example, we collected ca. 50 specimens referable to the genus Buellia that are anatomically similar but differ in thalline morphology and could represent anywhere from 5 to 25 distinct species (Figure 4). Without determining species boundaries, we cannot compare lichen diversity between sites. Figure 1. Location of study area. Figure 2. Elevation of study sites. Graph does not indicate horizontal distance between sites. Figure 4. Four Buellia collections with identical apothecial anatomy and thalline chemistry. Sampling Methodology We will use multivariate methods to characterise ecological differentiation of lichen communities across edaphic and climatic gradients. The edaphic variables include chemical and physical measurements of the rock substrates from which lichens were collected; we will use dimension reduction to reduce these to a small subset of synthetic variables that capture the major gradients in our study region. We will then use dissimilarity modeling and variance partitioning to relate turnover in lichen communities to substrate and climatic dissimilarity and geographic distance. To characterise general patterns of alpha diversity across substrates and climates, we will use rarefaction to estimate per-site species richness, and then use weighted regression to model average species richness as a function of environment and geography. We sampled lichen communities on ultramafic and non-ultramafic lithologies along an elevation gradient (Figure 2), a proxy for rainfall. At each site, lichen diversity and abundance were measured in 10 to 16 25×25 cm quadrats positioned randomly on boulders and bedrock to document a variety of aspects and slopes (Figure 3). In each quadrat, the identities and cover percentages of lichen morphospecies were recorded; voucher specimens were collected to positively identify these field-delimited morphospecies. Except for morphospecies that were obviously the same across sites, voucher specimens were collected from the same morphospecies present at different sites to confirm (or refute) morphological classifications made in the field. Preliminary Findings Casual field observations suggest that high elevation sites in the “mist belt” support a diverse assemblage of lichens that are relatively undifferentiated across substrates, and that at lower elevations, the relatively harsh conditions on rock surfaces result in an overall decrease of lichen diversity and a partitioning of the lichen community across distinct substrates. From our work in South Africa we have found several species new to science and several new to South Africa, although only one of the latter—Agonimia opuntiella—was found at the sites visited for this particular project. Literature Cited Fryday, A. M. 2015. A new checklist of lichenised, lichenicolous and allied fungi reported from South Africa. Bothalia 45(1): Art. #148. http://dx.doi. org/10.4102/abc.v45i1.148 Williamson, S. D. and K. Balkwill. 2015. Plant census and floristic analysis of selected serpentine outcrops of the Barberton Greenstone Belt, Mpumalanga, South Africa. South African Journal of Botany 97: 133–142. Acknowledgements Figure 3. Quadrats. Clockwise from upper left: crustose lichens on felsic/intermediate rock; Acarospora sp. and Caloplaca sp. on felsic/intermediate rock; Caloplaca sp. on serpentine rock; Diploschistes actinostomus on serpentine rock. This research was funded by a grant from the National Geographic Society (award #9774-15). We thank herbarium staff at PUC, MSC, and HCOA for their assistance with this project.