Soils as Components of Ecosystems

Witkamp, M.

doi:10.1146/annurev.es.02.110171.000505

Cited by 82 publications

(32 citation statements)

References 32 publications

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“…Switzer decline, sensu Covington (1981) and Mattson and et al (1979), in a study of upland forests in Smith (1993), was not described, but sites less eastern Mississippi, reported an aggrading forest than 15 years were not studied. Decreases in forest floor mass immediately following harvest are documented (Witkamp, 1971;Marks and Bormann, 1972;Aber et al, 1978;Johnson et al, 1985), and usually are attributed to greater decomposition rates from increases in soil temperature, moisture content, and nutrient availability (Covington, 1981). Despite the overriding hydrologic influences in floodplains, our analyses suggest that the pattern of development of the forest floor during floodplain succession is similar to that found in forested uplands.…”

Section: Forest Floorsupporting

confidence: 51%

Soil organic matter formation and sequestration across a forested floodplain chronosequence

Wigginton

Lockaby

Trettin

2000

Ecological Engineering

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Successional changes in soil organic matter formation and carbon sequestration across a forested floodplain chronosequence were studied at the Savannah river site, National Environmental Research Park, SC, US. Four floodplain sites were selected for study, three of which are in various stages of recovery from impact due to thermal effluent discharge. The fourth is a minimally disturbed reference site. Forest floor organic matter increases rapidly during early secondary succession, with a maximum of 657 g, " ' and decreasing to 338 g/m' during the later seral stages. Carbon content in the forest floor also reflected this pattern. with levels greatest during early succession and declining thereafter. Changes in carbon pools of the forest floor are primarily driven by changing levels of forest floor biomass in the various stages of succession, rather than element concentrations. The composition of the forest floor from the various stages differed markedly. The percent herbaceous material declined during succession from 74% in an early stage to < IO<) in the latest seral stage. Conversely. the amount of woody foliage increased from 6.7 to more than 70% in late succession. Measures of the degree of transformation of forest floor litter to soil organic matter using the lignocellulose index (LCI) did not differ between stages of succession. Percent lignin and percent cellulose of the forest floor were similar between stages and ranged from 13. 8-16.3, and 30.4-31.5'X~ respectively. Carbon content of the mineral soil increased with successional stage of the floodplain chronosequence. Soil carbon content ranged from 15.6 kg;"' per 0.7 m in the earliest stage of succession to 55.9 kg, m7 in late succession. Regression analyses indicated that it may take over 50 years for carbon levels to reach 73" of that of the reference site. The evidence also suggests that soil structure was disrupted by the disturbance, producing a greater proportion of microaggregates in early seral stages. The formation of soil macroaggregate structure. which may facilitate the accrual of carbon, appears to be occurring slowly. 0 2000 Elsevier Science B.V. All rights reserved.

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Section: Forest Floorsupporting

confidence: 51%

Soil organic matter formation and sequestration across a forested floodplain chronosequence

Wigginton

Lockaby

Trettin

2000

Ecological Engineering

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“…Most of the demand for P in natural forests can be met by rapid cycling of P in organic matter (Attiwill and Adams 1993;Turner and Engelbrecht 2011) and fine roots growing into the organic horizons acquire P directly from decomposing litter as it is mineralized (Herrera and others 1978;Stark and Jordan 1978;Tobon and others 2004), bypassing the mineral soil (Witkamp 1971). The increase in P uptake despite the lack of change in soil extractable P pools in the double-litter plots suggests that most of the plant demands for P were met by direct cycling from the forest floor.…”

Section: Phosphorusmentioning

confidence: 99%

Variable Responses of Lowland Tropical Forest Nutrient Status to Fertilization and Litter Manipulation

et al. 2012

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Predicting future impacts of anthropogenic change on tropical forests requires a clear understanding of nutrient constraints on productivity. We compared experimental fertilization and litter manipulation treatments in an old-growth lowland tropical forest to distinguish between the effects of inorganic nutrient amendments and changes in nutrient cycling via litterfall. We measured the changes in soil and litter nutrient pools, litterfall, and fine root biomass in plots fertilized with nitrogen (N), phosphorus (P), or potassium (K), and in litter addition and litter removal treatments during 7 years. Soil inorganic N and litter N increased in double-litter plots but not in N-fertilized plots. Conversely, fitter P and soil pools of P and K increased in fertilized plots but not in the double-litter plots. Soil and litter pools of N and K decreased in the no-litter plots.Changes in litterfall with added nutrients or litter were only marginally significant, but fine root biomass decreased with both the litter and the K addition. Differences between the two experiments are mostly attributable to the coupled cycling of carbon and nutrients in litter. Increased nutrient inputs in litter may improve plant uptake of some nutrients compared to fertilization with similar amounts. The litter layer also appears to play a key role in nutrient retention. We discuss our findings in the context of possible impacts of anthropogenic change on tropical forests.

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“…It had long been asserted, but without experimental tests, that increased moisture and temperature following logging should accelerate decomposition rates (Lutz and Chandler 1946;Moller 1954;Hart 1961;Witkamp 1971). However, litter decomposition experiments following the 1981 publication of the Covington curve instead found the opposite.…”

Section: Accelerated Decompositionmentioning

confidence: 99%

Soil Carbon Dynamics after Forest Harvest: An Ecosystem Paradigm Reconsidered

2003

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In one of the most influential studies in the recent history of forest ecology, W. W. Covington (1981) described a pattern in organic matter storage in the forest floors of northern hardwood stands as a function of date of harvest. We review the history of the use and misuse of Covington's curve, describe the studies that tested and failed to support early interpretations of the curve, and provide some alternate interpretations. The curve suggested that forest floor organic matter declines by 50% within 20 years after harvest, and this decline was attributed to accelerated decomposition and changes in litter inputs after harvest. Subsequent studies showed that decomposition rates of surface litter generally decrease after clear-cutting, but accelerated decomposition remains possible in the Oe and Oa horizons. Changes in litter inputs are still difficult to evaluate, because the rate at which woody debris enters the forest floor is unknown. Although Covington attempted to minimize variation due to mechanical disturbance during logging, a reasonable alternative explanation for low organic matter in the forest floor of young stands is that surface material is mixed into mineral soil during harvesting operations. The pattern of forest floor organic matter in stands of different ages may be partly due to changes over time in logging technology and the intensity of biomass removal, in addition to successional effects. It is important to distinguish between mechanisms that release carbon to the atmosphere and those that transfer it to the mineral soil before making inferences about nutrient cycling and carbon sequestration.

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Soils as Components of Ecosystems

Abstract: Research sponsored by the US Atomic Energy Commission under contract with the Union Carbide Corporation. 85

Cited by 82 publications

References 32 publications

Soil organic matter formation and sequestration across a forested floodplain chronosequence

Soil organic matter formation and sequestration across a forested floodplain chronosequence

Variable Responses of Lowland Tropical Forest Nutrient Status to Fertilization and Litter Manipulation

Soil Carbon Dynamics after Forest Harvest: An Ecosystem Paradigm Reconsidered

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