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.

A quantitative synthesis of soil microbial effects on plant species coexistence

“…This yielded 18 studies, which along with the studies from Crawford et al. ( 8 ) generated a total of 50 papers from which we extracted information ( 24 , 26 , 28 , 38 , 43 , 46 – 90 ). If a study had multiple experiments across different soil sources, resource gradients, or competition intensities, we compiled data separately for each experiment.…”

Biodiversity of arbuscular mycorrhizal fungi and ecosystem function

“…This latter approach appears to be heavily underutilized relative to studies of other groups of microbes (e.g. Rigg et al, 2016).…”

Variable species establishment in response to microhabitat indicates different likelihoods of climate-driven range shifts

“…There are no general trends, except for that diverse components of microhabitat are important for establishment (Table S1). With regards to climatic aspects of microhabitat, soil moisture and temperature, plant-height temperature, and snow duration can affect establishment in a myriad of ways (Szeicz & Macdonald, 1995;Thompson & Naeem, 1996;Yates et al, 1996;Graae et al, 2009;Santana et al, 2010;Rodríguez-García et al, 2011;Bullied et al, 2012;Moyes et al 2013;Caldeira et al, 2014;Mondoni et al, 2015;Renard et al, 2016;Kueppers et al, 2017;Andrus et al, 2018;Elliott & Petruccelli, 2018;Lett & Dorrepaal, 2018;Dolezal et al, 2021;Ósvaldsson et al, 2022) How early life stages respond to microhabitat variables not directly related to climate is also variable by species, with linear, unimodal, or no responses to canopy cover (Lloret et al, 2005;Käber et al, 2021), soil fungus and bacterial content (Rigg et al, 2016;van der Heijden et al, 2016;Tobias et al, 2017;Xi et al, 2018), soil carbon and nitrogen (Monaco et al, 2003;Pérez-Fernández et al, 2006;Li et al, 2011;Pröll et al, 2011;Bateman et al, 2017;Ko lodziejek et al, 2017;Zhong et al, 2019), and water holding capacity (Moser et al, 2017;Smithers, 2017;James et al, 2019;Khurana & Singh, 2000). However, studies examining responses to microhabitat beyond range edges are rare and can show inconclusive effects of microhabitat (Lee-Yaw ...…”