Mycorrhizal associations of dominant trees influence nitrate leaching responses to N deposition

Midgley, Meghan G.; Phillips, Richard P.

doi:10.1007/s10533-013-9931-4

Cited by 67 publications

(58 citation statements)

References 76 publications

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“…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.…”

Section: Resultsmentioning

confidence: 67%

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

Chen

Koide

Adams

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

278

258

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Photosynthesis by leaves and acquisition of water and minerals by roots are required for plant growth, which is a key component of many ecosystem functions. Although the role of leaf functional traits in photosynthesis is generally well understood, the relationship of root functional traits to nutrient uptake is not. In particular, predictions of nutrient acquisition strategies from specific root traits are often vague. Roots of nearly all plants cooperate with mycorrhizal fungi in nutrient acquisition. Most tree species form symbioses with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. Nutrients are distributed heterogeneously in the soil, and nutrient-rich "hotspots" can be a key source for plants. Thus, predicting the foraging strategies that enable mycorrhizal root systems to exploit these hotspots can be critical to the understanding of plant nutrition and ecosystem carbon and nutrient cycling. Here, we show that in 13 sympatric temperate tree species, when nutrient availability is patchy, thinner root species alter their foraging to exploit patches, whereas thicker root species do not. Moreover, there appear to be two distinct pathways by which thinner root tree species enhance foraging in nutrient-rich patches: AM trees produce more roots, whereas EM trees produce more mycorrhizal fungal hyphae. Our results indicate that strategies of nutrient foraging are complementary among tree species with contrasting mycorrhiza types and root morphologies, and that predictable relationships between below-ground traits and nutrient acquisition emerge only when both roots and mycorrhizal fungi are considered together. mycorrhizal fungi | plant traits | root proliferation | soil heterogeneity | symbioses

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Section: Resultsmentioning

confidence: 67%

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

Chen

Koide

Adams

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

278

258

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“…The previous meta‐analysis was consistent with our results with ECM forests having higher average soil C/N ratios than AM forests (Averill et al, ; Lin et al, ). AM forests with lower soil C/N ratios tend to dominate in warm and wet habitats (Table ), where nitrogen mineralization and nitrification processes are rapid (Midgley & Phillips, ). Increased soil C/N ratios indicate nitrogen limitation of decomposer activity and, thus, low mineralization rates, which can explain subsequent accumulation of larger amounts of fine root necromass (Leuschner et al, ) and lower fine root B/N ratios in AM forest as shown in the present study (Figure a).…”

Section: Discussionmentioning

confidence: 99%

The Responses of Forest Fine Root Biomass/Necromass Ratio to Environmental Factors Depend on Mycorrhizal Type and Latitudinal Region

et al. 2018

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Fine root (≤2 mm in diameter) biomass/necromass (B/N) ratio, representing many dynamic key root parameters, can serve as a powerful measure of root vitality. Based on a global synthesis of fine root biomass and necromass in forest ecosystems, we describe a framework for recognizing responses of B/N ratio to biotic (e.g., mycorrhizal type) and abiotic (e.g., latitudinal region) characteristics. Arbuscular mycorrhiza (AM) and ectomycorrhiza (ECM) forests had similar average B/N ratios (3.28 versus 3.23). AM forest B/N ratio decreased with increasing altitude, stand density, tree age, and soil carbon/nitrogen ratio (C/N) but increased with soil pH. In contrast, ECM forest B/N ratio increased with increasing mean annual precipitation (MAP), altitude, and stand density but decreased with tree age. The average B/N ratio was higher in temperate forests (4.39) than in tropical (2.97) and boreal forests (2.40). The B/N ratio was relatively stable in temperate forests irrespective of changes in biotic and abiotic factors. In tropical forest, the B/N ratio was sensitive to mean annual temperature, altitude, soil C/N ratio, and pH, whereas in boreal forests, it was more sensitive to MAP, stand density, and tree age. The late‐successional forest B/N ratio was closely aligned with biotic and abiotic factors. Our analysis revealed that the relationships of B/N ratio with climate, topography, edaphic, and stand characteristics were dependent on mycorrhizal types and latitudinal regions. These findings provide a basis for large‐scale prediction of fine root dynamics and for better understanding of belowground processes of global forest ecosystems in a changing world.

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“…In contrast, ECM trees generally have more slowly decomposing leaf litter (Cornelissen et al, 2001;Hobbie et al, 2006), and a greater proportion of nutrients in organic forms that are re-acquired by plants via ectomycorrhizal mycelium that produce extracellular enzyme to mine nutrients from SOM. A consequence of these dynamics is that ECM-dominated forests tend to cycle C and nutrients more conservatively than AM-dominated forests, and contribute to differential rates of soil C retention (Vesterdal et al, 2012;Averill et al, 2014) and N leaching losses (Midgley and Phillips, 2014).…”

Section: Introductionmentioning

confidence: 99%

Root-induced changes in nutrient cycling in forests depend on exudation rates

Yin

Wheeler

Phillips

2014

Soil Biology and Biochemistry

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191

120

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a b s t r a c t(1) While it is well-known that trees release carbon (C) to soils as root exudates, the factors that control the magnitude and biogeochemical impacts of this flux are poorly understood.(2) We quantified root exudation and microbially-mediated nutrient fluxes in the rhizosphere for four 80 year-old tree species in a deciduous hardwood forest, Indiana, USA. We hypothesized that trees that exuded the most carbon (C) would induce the strongest rhizosphere effects (i.e., the relative difference in nutrient fluxes between rhizosphere and bulk soil). Further, we hypothesized that tree species that associate with ectomycorrhizal (ECM) fungi would exude more C than tree species that associate with arbuscular mycorrhizal (AM) fungi, resulting in a greater enhancement of nutrient cycling in ECM rhizospheres.(3) Mass-specific exudation rates and rhizosphere effects on C, N and P cycling were nearly two-fold greater for the two ECM tree species compared to the two AM tree species (P < 0.05). Moreover, across all species, exudation rates were positively correlated with multiple indices of nutrient cycling and organic matter decomposition in the rhizosphere (P < 0.05). Annually, we estimate that root exudation represents 2.5% of NPP in this forest, and that the exudate-induced changes in microbial N cycling may contribute~18% of total net N mineralization.(4) Collectively, our results indicate that the effects of roots on nutrient cycling are consequential, particularly in forests where the C cost of mining nutrients from decomposing soil organic matter may be greatest (e.g., ECM-dominated stands). Further, our results suggest that small C fluxes from exudation may have disproportionate impacts on ecosystem N cycling in nutrient-limited forests.

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Mycorrhizal associations of dominant trees influence nitrate leaching responses to N deposition

Cited by 67 publications

References 76 publications

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

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

The Responses of Forest Fine Root Biomass/Necromass Ratio to Environmental Factors Depend on Mycorrhizal Type and Latitudinal Region

Root-induced changes in nutrient cycling in forests depend on exudation rates

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