Biotic and abiotic plant–soil feedback depends on nitrogen‐acquisition strategy and shifts during long‐term ecosystem development

Abstract

Feedback between plants and soil is an important driver of plant community structure, but it remains unclear whether plant–soil feedback (PSF): (i) reflects changes in biotic or abiotic properties, (ii) depends on environmental context in terms of soil nutrient availability, and (iii) varies among plant functional groups. As soil nutrient availability strongly affects plant distribution and performance, soil chemical properties and plant nutrient‐acquisition strategies might serve as important drivers of PSF. We used soils from young and old stages of a long‐term soil chronosequence to represent sites where productivity is limited by nitrogen (N) and phosphorus (P) availability, respectively. We grew three N‐fixing and three non‐N‐fixing plant species in soils conditioned by co‐occurring conspecific or heterospecific species from each of these two stages. In addition, three soil treatments were used to distinguish biotic and abiotic effects on plant performance, allowing measurements of overall, biotic, and abiotic PSF. In young, N‐poor soils, non‐N‐fixing plants grew better in soils from N‐fixing plants than in their own soils (i.e., negative PSF). However, this difference was not only associated with improved abiotic conditions in soils from N‐fixing plants but also with changes in soil biota. By contrast, no significant PSF was observed for N‐fixing plants grown in young soils. Moreover, we did not observe any significant PSF for either N‐fixing or non‐N‐fixing plants growing in old, P‐impoverished soils. Synthesis. The direction and strength of plant‐soil feedback (PSF) varied among N‐acquisition strategies and soils differing in nutrient availability, with stronger plant‐soil feedback in younger, N‐poor soils compared to older, P‐impoverished soils. Our results highlight the importance of considering soil nutrient availability, plant‐mediated abiotic and biotic soil properties, and plant nutrient‐acquisition strategies when studying plant‐soil feedback, thereby advancing our mechanistic understanding of plant‐soil feedback during long‐term ecosystem development.

Toward more robust plant–soil feedback research: Comment

“…, Png et al. ). Indeed, it is widely recognized that it is generally only the build‐up of high densities of specialized soil pathogens that causes significant effects on plant growth and survival (Bever et al.…”

Phosphorus‐ and nitrogen‐acquisition strategies in two Bossiaea species (Fabaceae) along retrogressive soil chronosequences in south‐western Australia

“…We did so to maximise the chances that the inoculum interacts with roots of very small seedlings following emergence. The use of inoculum as top‐soil only was effective in previous studies in our group (Png ). The field soil was a 1:1 mix of soil collected under B. eriocarpa and B. aquifolium .…”

“…The plants accumulated less than 1 g of dry weight in 5 months, even at the highest nutrient supply. Co‐occurring legumes from the same stages, Acacia pulchella and Jacksonia floribunda , accumulated up to 5 g at similar nutrient supplies (50 mg P kg −1 soil, 25 mg N kg −1 soil) and up to 10 g at higher N supplies (300 mg N kg −1 soil) in 6 months (Png ). The slow growth of Bossiaea reveals a very conservative nutrient‐use strategy.…”

How anthropogenic shifts in plant community composition alter soil food webs

“…For example, plant species differ in their effects on soil moisture, either directly through differences in water uptake or indirectly through effects of shading. Plants can also influence soil organisms through their effects on soil chemistry (for example, through nutrient depletion, nutrient mobilization, or the addition of allelopathic chemicals) 40 – 42 . Although each of these three pathways has been studied for individual plant species, these plant-mediated mechanisms are less well understood for plant communities 22 , 43 , 44 .…”