Study Species & Experimental Design
To measure the above- and belowground traits and mycorrhizal colonization of eucalypts associated with varying levels of rarity and relatedness, we reanalyzed data from a previously published study (Wooliver et al. 2018). Fourteen species of Tasmanian eucalypts belonging to subgenera Symphyomyrtus were used due to their known variation in above- and belowground functional traits and mycorrhizal associations. Ranging in above- and belowground functional traits representative of resource acquisition and use strategies, such as growth form, biomass, SLA, and leaf nutrient content (Wooliver et al. 2018; Liu et al. 2023), eucalypt species depend on belowground ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) communities for sufficient nutrient acquisition and growth (Adjoud et al. 1996; Qin & Yu 2021). Moreover, Tasmanian eucalypts not only vary in functional trait expression, but also in species rarity, in accordance with Rabinowitz (1981). Consequently, eucalypt species found in small ranges, endemic to Tasmania, favoring specific habitats, and occurring in small local populations are considered to be the most rare, while species found in large ranges across ubiquitous habitat, and large local populations are considered to be common. Based on these standards, 14 species of Tasmanian Eucalyptus were categorized into ordinally ranked levels of rarity using the percent of Tasmanian bioregions inhabited, as well as measures of range size and population aggregation in accordance with Williams & Potts (1996). Rarity types five and seven are not represented in the data due to a lack of seed availability and absence in the sampled arboretum (details below). Soil inoculum used in this study were collected under individuals in both an arboretum in northern Tasmania (41.2265S, 146.3022E) and a forestry trial in southeastern Tasmania (43.3350S, 146.9451E). Soil inocula were pooled within species replicates as well as across sampling locations. Wooliver et al. (2018) conducted a fully factorial common garden study constituting of species that were grown in soils conditioned by 1) conspecific (“monoculture”) soil, 2) same lineage (“closely related”) soil, and 3) opposite lineage (“distantly related”) soil, under varying levels of N enrichment and fungicide application. Performance traits such as aboveground, belowground, and total biomass were measured, along with the proportion of roots colonized by ECM and DSE fungi after five months of growth at the end of the experiment. See details of this experiment in Wooliver et al. (2018). Reanalysis of these data in the context of rarity allows for a deeper understanding of the strength and direction of plant-soil feedbacks in rare versus common species as well as the mechanisms driving these above-belowground feedbacks in rare species.