Carbon and nitrogen dynamics in forest floor during short-term laboratory incubations

Harris, M. M.; Riha, Susan J.

doi:10.1016/0038-0717(91)90040-q

Cited by 25 publications

(6 citation statements)

References 32 publications

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“…Carbon mineralization was not different among the three forest floors; therefore, the differences in net N mineralization among species were not related to differences in rates of C mineralization or microbial activity. Other researchers have suggested that N availability is not necessarily related to decomposition rates (Harris and Riha 1991;Hart et al 1994) and is strongly influenced by immobilization, through microbial assimilation or chemical binding to humic substances (Haynes 1986). As a result, C mineralization is likely to be strongly related to gross N transformations (Hart et al 1994) but not necessarily to net N mineralization.…”

Section: Discussionmentioning

confidence: 98%

Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality

Thomas¹,

Prescott²

2000

Can. J. For. Res.

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Forest floor samples from a 25-year-old plantation of three tree species (Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), and paper birch (Betula papyrifera Marsh.)) growing on the same site were incubated (aerobically) in the laboratory for 29 days. Rates of N mineralization in the forest floors of Douglas-fir (165.1 µg/g) was significantly greater than either birch (72.9 µg/g) or lodgepole pine (51.2 µg/g). Douglas-fir forest floors also had the highest N concentration, lowest C/N ratio, and highest NH 4 -N concentrations, followed by paper birch and lodgepole pine. Douglas-fir forest floors also mineralized more N per unit of either N or C than the other species. There were no differences in rates of CO 2 -C mineralization in forest floors among the three species. Nitrogen mineralization rates were positively correlated with the N concentration of the forest floor (r 2 = 0.81) and also with the C/N and NH 4 -N concentration of the forest floor. Nitrogen concentration, C/N, and lignin/N of foliar litter were poor predictors of N mineralization rates resulting from Douglas-fir litter having the lowest N concentrations in litter but the highest rates of net N mineralization in the forest floor. Nitrogen mineralization in the forest floor was negatively correlated (r 2 = 0.67) with the lignin concentration in foliar litter. Douglas-fir litter had low lignin concentrations, which may allow more of the mineralized N to remain in inorganic forms rather than being bound in humus. Our results suggest that a component of Douglas-fir might improve N availability in coniferous forest floors.Résumé : Des échantillons de la couverture morte prélevés dans une plantation âgée de 25 ans, où croissent sur le même site trois espèces d'arbres, le douglas de Menzies (Pseudotsuga menziesii (Mirb.) Franco), le pin lodgepole (Pinus contorta Dougl. var. latifolia Engelm.) et le bouleau blanc (Betula papyrifera Marsh.), ont été incubés en condition aérobique au laboratoire pendant 29 jours. Le taux de minéralisation de N dans la couverture morte du douglas de Menzies (165,1 µg/g) était significativement plus élevé que ceux de la couverture morte du bouleau (72,9 µg/g) ou du pin lodgepole (51,2 µg/g). La couverture morte de douglas de Menzies avait également la concentration en azote la plus élevée, le plus faible rapport C/N et la concentration en N-NH 4 la plus élevée suivi du bouleau blanc et du pin lodgepole. La couverture morte de douglas de Menzies minéralisait également plus de N par unité de N ou de C que celle des autres espèces. Il n'y avait pas de différence dans le taux de minéralisation de C-CO 2 entre les couvertures mortes des trois espèces. Le taux de minéralisation de N était positivement corrélé avec la concentration de N dans la couverture morte (r 2 = 0,81) et également avec le rapport C/N et la concentration de N-NH 4 de la couverture morte. La concentration de N, les rapports C/N et lignine/N de la litière de feuilles ne permettent pas de prédire le...

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Section: Discussionmentioning

confidence: 98%

Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality

Thomas¹,

Prescott²

2000

Can. J. For. Res.

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“…Rates of net N mineralization in the forest floors during the laboratory incubation were not related to the soil N capital whereas turnover rates of C were, indicating a weak relationship between C and net N mineralization rates. Poor relationships between rates of C mineralization and net N mineralization are commonly observed during laboratory incubations (Harris and Riha 1991), and is explained as the effect of N immobilization into microbial biomass. Rates of gross N mineralization are correlated with rates of C mineralization, but a very substantial proportion of the mineralized N is re-immobilized into microbial biomass.…”

Section: Discussionmentioning

confidence: 99%

Nitrogen Turnover in Forest Floors of Coastal Douglas-Fir at Sites Differing in Soil Nitrogen Capital

Prescott

Chappell

Vesterdal³

2000

Ecology

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Nitrogen cycling is generally considered to be more rapid on sites with high availability of N; this is usually associated with differences in tree species composition. We tested whether N cycling in stands of a single tree species increased with increasing mineral soil nitrogen capital. Rates of N cycling in nine stands of Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) were estimated by measuring annual N input in litter, N content of the forest floor, and net N mineralization rate in the forest floor. Rates of C and N turnover were estimated from the litterfall:forest floor ratio. The amount of N returned in litter increased as soil N capital increased. The increase in litter N content resulted from both increased litter mass (C content) and increased N concentration in litter. Despite the greater litter input, forest floor mass was smaller at N‐rich sites, indicating more rapid turnover of the forest floor on N‐rich sites. There was a positive relationship between fractional annual loss of N from the forest floor and soil N capital. Therefore, even without changes in tree species composition, sites with greater soil N capital returned more N in annual litterfall and had faster turnover of N in the forest floor. Fractional annual loss of C also increased with increasing soil N capital, indicating faster decomposition on N‐rich sites. The rate of net N mineralization during laboratory incubations of the forest floor was not correlated with soil N capital or N concentrations of litter, but was related to the C:N ratio of the forest floor. Net N mineralization was appreciable only at two sites where forest floor C:N ratios were <35. The rate of net N mineralization or C:N ratio of the forest floor were not good indicators of N availability at these sites. The results of this study are consistent with the hypothesis that rates of N cycling are faster on N‐rich sites, and that this effect can occur in the absence of changes in tree species composition.

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“…Over a 1-year period, Grace (1986) found that insect defoliation increased litterfall N from 31 kg N/ha in non-defoliated forests to 52 kg N/ha in defoliated forests. This input of fresh organic matter with high N and labile C may accelerate microbial activity and produce flushes of NO 3 -and NH 4 + release (Harris and Riha 1991;Lovett and Ruesink 1995). However, Lovett and Ruesink (1995) found that frass from gypsy moth caterpillars (Lymantria dispar L.) increased microbial immobilization of N, thereby reducing, at least temporarily, the possibility of N losses from the ecosystem.…”

Section: Introductionmentioning

confidence: 94%

The fate of nitrogen in gypsy moth frass deposited to an oak forest floor

et al. 2002

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Forest defoliation by insects can lead to severe disruptions of the nitrogen (N) cycle resulting in elevated NO levels in stream water. To trace the movement of insect-mobilized N in a forest soil, N-labeled gypsy moth frass orN-labeled oak leaf litter was added to trenched plots in an oak forest over 29 months. Nitrogen movement from the frass or litter was measured in the available, mineralizable, microbial and total soil pools. Uptake of N by oak seedlings and inorganic N leaching losses were also measured. No significant differences were found between the frass or leaf treatments for total N in any of the pools. Significant differences were found among the treatments in the distribution of theN tracer. Forty percent of the N added as frass became incorporated in the soils, with less than 1% found in oak seedlings. Almost 80% ofN added as leaves remained in the undecomposed leaf material after 2 years. Less than 0.001% of the added N was leached in both treatments. Our data indicate that N in frass is mobilized more quickly than N in leaf litter. However, this frass N may be largely unavailable to plants and microorganisms as little of it was found in the extractable, microbial, or readily mineralizable pools.

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Carbon and nitrogen dynamics in forest floor during short-term laboratory incubations

Cited by 25 publications

References 32 publications

Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality

Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality

Nitrogen Turnover in Forest Floors of Coastal Douglas-Fir at Sites Differing in Soil Nitrogen Capital

The fate of nitrogen in gypsy moth frass deposited to an oak forest floor

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