Nitrogen and carbon dynamics of a foliar biotrophic fungal parasite in fertilized Douglas‐fir

El‐Hajj, Zeina; Kavanagh, Kathleen L.; Rose, Cathy L.; Kanaan-Atallah, Zahi

doi:10.1111/j.1469-8137.2004.01102.x

Cited by 21 publications

(13 citation statements)

References 31 publications

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“…Phaeocryptopus gaeumannii, the causal agent of Swiss needle cast disease in Douglas fir, responds to host nutrient status; high nitrogen and carbon availability inside Douglas fir needles is associated with increased fungal fruiting and thus disease severity (El-Hajj et al 2004). In the current study, the root total carbon and nitrogen contents of ammonium-grown plants were significant higher than nitrate-grown plants ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Plant Primary Metabolism Regulated by Nitrogen Contributes to Plant–Pathogen Interactions

Wang

et al. 2018

Plant and Cell Physiology

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Section: Discussionmentioning

confidence: 99%

Plant Primary Metabolism Regulated by Nitrogen Contributes to Plant–Pathogen Interactions

Wang

et al. 2018

Plant and Cell Physiology

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“…v www.esajournals.org fir foliage typically accumulates as free amino acids (El-Hajj et al 2004), and if also present in litter, should be biologically available. Leaf morphological changes resulting from high N are unlikely to have influenced decomposition rates given that specific leaf area is not related to tissue %N in these Douglas-fir forests (r 2 ¼ 0.03, n ¼ 22, from data in Perakis et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin‐rich conifer litter

Perakis¹,

Matkins²,

Hibbs³

2012

Ecosphere

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Abstract. High tissue nitrogen (N) accelerates decomposition of high-quality leaf litter in the early phases of mass loss, but the influence of initial tissue N variation on the decomposition of lignin-rich litter is less resolved. Because environmental changes such as atmospheric N deposition and elevated CO 2 can alter tissue N levels within species more rapidly than they alter the species composition of ecosystems, it is important to consider how within-species variation in tissue N may shape litter decomposition and associated N dynamics. Douglas-fir (Pseudotsuga menziesii ) is a widespread lignin-rich conifer that dominates forests of high carbon (C) storage across western North America, and displays wide variation in tissue and litter N that reflects landscape variation in soil N. We collected eight unique Douglas-fir litter sources that spanned a two-fold range in initial N concentrations (0.67-1.31%) with a narrow range of lignin (29-35%), and examined relationships between initial litter chemistry, decomposition, and N dynamics in both ambient and N fertilized plots at four sites over 3 yr. High initial litter N slowed decomposition rates in both early (0.67 yr) and late (3 yr) stages in unfertilized plots. Applications of N fertilizer to litters accelerated early-stage decomposition, but slowed late-stage decomposition, and most strongly affected low-N litters, which equalized decomposition rates across litters regardless of initial N concentrations. Decomposition of N-fertilized litters correlated positively with initial litter manganese (Mn) concentrations, with litter Mn variation reflecting faster turnover of canopy foliage in high N sites, producing younger litterfall with high N and low Mn. Although both internal and external N inhibited decomposition at 3 yr, most litters exhibited net N immobilization, with strongest immobilization in low-N litter and in N-fertilized plots. Our observation for lignin-rich litter that high initial N can slow decomposition yet accelerate N release differs from findings where litter quality variation across species promotes coupled C and N release during decomposition. We suggest reevaluation of ecosystem models and projected global change effects to account for a potential decoupling of ecosystem C and N feedbacks through litter decomposition in lignin-rich conifer forests.

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“…, El‐Hajj et al. ). Declines in foliar Ca associated with high N that reduce foliar membrane integrity may also increase susceptibility to Swiss needle cast (Perakis et al.…”

Section: Mechanism Of Effect From Atmospheric Deposition On Treesmentioning

confidence: 99%

Mechanisms of nitrogen deposition effects on temperate forest lichens and trees

et al. 2017

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Abstract. We review the mechanisms of deleterious nitrogen (N) deposition impacts on temperate forests, with a particular focus on trees and lichens. Elevated anthropogenic N deposition to forests has varied effects on individual organisms depending on characteristics both of the N inputs (form, timing, amount) and of the organisms (ecology, physiology) involved. Improved mechanistic knowledge of these effects can aid in developing robust predictions of how organisms respond to either increases or decreases in N deposition. Rising N levels affect forests in micro-and macroscopic ways from physiological responses at the cellular, tissue, and organism levels to influencing individual species and entire communities and ecosystems. A synthesis of these processes forms the basis for the overarching themes of this paper, which focuses on N effects at different levels of biological organization in temperate forests. For lichens, the mechanisms of direct effects of N are relatively well known at cellular, organismal, and community levels, though interactions of N with other stressors merit further research. For trees, effects of N deposition are better understood for N as an acidifying agent than as a nutrient; in both cases, the impacts can reflect direct effects on short time scales and indirect effects mediated through long-term soil and belowground changes. There are many gaps on fundamental N use and cycling in ecosystems, and we highlight the most critical gaps for understanding potential deleterious effects of N deposition. For lichens, these gaps include both how N affects specific metabolic pathways and how N is metabolized. For trees, these gaps include understanding the direct effects of N deposition onto forest canopies, the sensitivity of different tree species and mycorrhizal symbionts to N, the influence of soil properties, and the reversibility of N and acidification effects on plants and soils. Continued study of how these N response mechanisms interact with one another, and with other dimensions of global change, remains essential for predicting ongoing changes in lichen and tree populations across North American temperate forests.

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Nitrogen and carbon dynamics of a foliar biotrophic fungal parasite in fertilized Douglas‐fir

Cited by 21 publications

References 31 publications

Plant Primary Metabolism Regulated by Nitrogen Contributes to Plant–Pathogen Interactions

Plant Primary Metabolism Regulated by Nitrogen Contributes to Plant–Pathogen Interactions

Interactions of tissue and fertilizer nitrogen on decomposition dynamics of lignin‐rich conifer litter

Mechanisms of nitrogen deposition effects on temperate forest lichens and trees

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