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.