Carbon storage and transport in fertilized loblolly pine (Pinus taeda) plantations on upland sandy and clayey soils.
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Date
2004-06-27
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Abstract
Fertilization and soil texture may function independently or interactively to have a positive effect on a forest ecosystem's carbon (C) storage. Fertilization has been identified as an effective management strategy for sequestering additional atmospheric CO2 by increasing biomass accumulation in loblolly pine plantations. Fertilization may increase soil C sequestration as a beneficial result of enhancing peak leaf area index, which results in increased biomass production and return of litter. The ability of the soil to sequester the additional C fixed is largely dependent on the soil's capacity to retain and protect the C from respiration and leaching loss. Well-drained finer textured soils (clayey soils) have a higher C retention capacity than coarse textured soils (sandy soils).
This study was conducted in 11-year old loblolly pine plantations on sandy and clayey soils with and without the addition of nitrogen and phosphorus fertilization applied at planting. Soil C pools were inventoried prior to planting and soil and forest floor C pools were inventoried 11 years after stand establishment. Tree heights and diameters were used to estimate above- and below-ground biomass. Dissolved organic carbon (DOC) from throughfall and forest floor leachate was measured in the 11th growing season. The chemical composition of DOC from the forest floor leachate was evaluated using liquid state proton nuclear magnetic resonance (1H NMR).
After 11 years of stand development total ecosystem C increased by 24 Mg/ha on average across both sites (soils). Fertilization increased accretion by 25.3 Mg C/ha with the majority of the increase occurring in the biomass. The clayey site averaged 64% more total ecosystem C than the sandy site. Statistically, the mineral soil C in the surface 20-cm did not change during the 11 years of stand development, except for the significant decrease in soil C within the 10-20cm depth on the control plots of the sandy site.
Fertilization did not have a significant effect on throughfall or forest floor leachate solution volume, DOC concentration, or DOC flux. The yearly flux of DOC that entered the forest floor and soil from throughfall (100 kg/ha/yr) and forest floor leachate (150 kg/ha/yr) was relatively small (6% of the sum of all fluxes evaluated). Based on the 1H NMR spectrum, fertilization may alter the chemistry of the DOC leaching from the forest floor by increasing the C constituents least resistant to microbial oxidation.
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Keywords
dissolved organic carbon, soil texture, carbon sequestration, forest soils, fertilization
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Degree
PhD
Discipline
Forestry
