Phosphorus cycling in deciduous forest soil differs between stands dominated by ecto‐ and arbuscular mycorrhizal trees

Abstract

SummaryAlthough much is known about how trees and their associated microbes influence nitrogen cycling in temperate forest soils, less is known about biotic controls over phosphorus (P) cycling. Given that mycorrhizal fungi are instrumental for P acquisition and that the two dominant associations -arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi -possess different strategies for acquiring P, we hypothesized that P cycling would differ in stands dominated by trees associated with AM vs ECM fungi.We quantified soil solution P, microbial biomass P, and sequentially extracted inorganic and organic P pools from May to November in plots dominated by trees forming either AM or ECM associations in south-central Indiana, USA.Overall, fungal communities in AM and ECM plots were functionally different and soils exhibited fundamental differences in P cycling. Organic forms of P were more available in ECM plots than in AM plots. Yet inorganic P decreased and organic P accumulated over the growing season in both ECM and AM plots, resulting in increasingly P-limited microbial biomass.Collectively, our results suggest that P cycling in hardwood forests is strongly influenced by biotic processes in soil and that these are driven by plant-associated fungal communities.

Root morphology and mycorrhizal symbioses together shape nutrient foraging strategies of temperate trees

“…as soil carbon storage (34), nitrogen leaching (35), and phosphorus cycling (36). Here, we provide additional evidence that the relative dominance of AM or EM trees in a forest, as well as their root traits, may partly determine the response pathways (roots vs. hyphae) to fine-scale spatial heterogeneity of soil nutrients.…”

Mycorrhizal phosphorus economies: a field test of the MANE framework

“…The mycorrhizal symbiosis then both constrains plant growth but also prevents non‐mycorrhizal plants being able to invade such forests (Näsholm et al ., ; Franklin et al ., ). However, despite strong P limitation the forests described by Rosling et al . are surprisingly productive, to judge from data on annual litter fall.…”

“…Rosling et al . observed that in these forests ectomycorrhizal and arbuscular mycorrhizal tree growth was equally limited by P. There were no differences in plant P uptake from, or plant P return to, the soil. Both mycorrhizal forests harboured a similar microbial biomass (of symbiotic and saprotrophic microbiota), a pool that contained almost three times as much P as the annual P uptake by the vegetation.…”

Asymmetric patterns of global diversity among plants and mycorrhizal fungi

“…If this is the case, the frequency of the ECM plant type is expected to increase under future global change scenarios (Tedersoo, ). Thus, the correlation patterns identified here suggest that such a process would be accompanied by decreases in the diversity and abundance of AM fungal and plant species, which could have profound effects on ecosystem functioning, such as carbon, nitrogen and phosphorus cycling (Fernandez & Kennedy, ; Lin, McCormack, Ma, & Guo, ; Rosling et al, ; Treseder & Lennon, ). In the future, there is a need to complement correlative studies with empirical tests concerning the quadripartite competition between ECM and AM symbiotic partners, and interactions involving ERM and NM partners, in order to better understand the distribution of mycorrhizal types and predict their responses to global change.…”