title: Soil microbial communities influence seedling growth of a rare conifer independent of plant-soil feedback.
abstract: Plant-soil feedback, the reciprocal relationship between a plant and its associated microbial communities, has been proposed to be an important driver of plant populations and community dynamics. While rarely considered, understanding how plant-soil feedback contributes to plant rarity may have implications for conservation and management of rare species. Wollemi pine (Wollemia nobilis) is a critically endangered species, of which fewer than 100 trees are known to exist in the wild. Seedling survival within the first year after germination and subsequent recruitment of Wollemi pine is limited in the wild. We used a plant-soil feedback approach to investigate the functional effect of species-specific differences previously observed in the microbial communities underneath adult Wollemi pine and a neighboring species, coachwood (Ceratopetalum apetalum), and also whether additional variation in microbial communities in the wild could impact seedling growth. There was no evidence for seedling growth being affected by tree species associated with soil inocula, suggesting that plant-soil feedbacks are not limiting recruitment in the natural population. However, there was evidence of fungal, but not bacterial, community variation impacting seedling growth independently of plant-soil feedbacks. Chemical (pH) and physical (porosity) soil characteristics were identified as potential drivers of the functional outcomes of these fungal communities. The empirical approach described here may provide opportunities to identify the importance of soil microbes to conservation efforts targeting other rare plant species and is also relevant to understanding the importance of soil microbes and plant-soil feedbacks for plant community dynamics more broadly.
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Rigg
authors.affiliation: Australian PlantBank, Royal Botanic Gardens and Domain Trust, Australian Botanic Garden Mount Annan, Sydney, New South Wales, 2587, Australia.
authors.forename: Cathy A
authors.initials: CA
authors.lastname: Offord
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia.|Global Centre for Land-Based Innovation, Western Sydney University, Penrith, New South Wales, 2751, Australia.
authors.forename: Brajesh K
authors.initials: BK
authors.lastname: Singh
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia.
authors.forename: Ian
authors.initials: I
authors.lastname: Anderson
authors.affiliation: NSW Parks and Wildlife Services, Office of Environment and Heritage, Sydney, New South Wales, 2000, Australia.
authors.forename: Steve
authors.initials: S
authors.lastname: Clarke
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia.
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Powell
mesh_terms: D056727:Endangered Species; D018517:Plant Roots / Q000254:growth & development* / Q000382:microbiology; D036226:Seedlings / Q000254:growth & development* / Q000382:microbiology; D012988:Soil Microbiology; D064028:Tracheophyta / Q000254:growth & development*
keywords: Wollemi pine; coachwood; conservation; critically endangered; plant-soil feedback; soil microbial community; structural equation modelling