Fertilization Effects on Carbon Pools in Loblolly Pine Plantations on Two Upland Sites
- Zakiya H. Leggetta and
- Daniel L. Kelting *b
A study was conducted in loblolly pine (Pinus taeda L.) plantations on sandy and clayey upland sites, with and without the addition of 250 kg ha−1 of diammonium phosphate (DAP) applied at planting, to estimate the effects of fertilization on ecosystem C storage. Soil C pools were inventoried before planting and in the 11th year of stand development. Tree inventory data were used to convert stand volume to accumulated biomass. During the 11 yr of stand development, total ecosystem C increased by 24.2 Mg ha−1 on average across sites, averaging 2.2 Mg C ha−1 yr−1 Fertilization increased accretion by 25.3 Mg ha−1, or 2.3 Mg C ha−1 yr−1, with the majority of increase (65%) occurring in biomass. The clayey site averaged 64% more total ecosystem C than the sandy site. With the exception of a 12 Mg ha−1 loss in mineral soil C for the 10- to 20-cm depth in nonfertilized (control) plots on the sandy site, soil C in the surface 20 cm did not change during the 11 yr of stand development, suggesting that the mineral soil C is a minor sink in these aggrading pine plantations. The loss in mineral soil C observed in control plots on the sandy site may be explained by the macroporosity of this coarse-textured sandy soil creating an environment conducive to oxidation and in turn optimal for respiration and C losses following site preparation, and a disadvantaged opportunity for C accumulation owing to higher soil temperatures. Fertilization may have improved the opportunity for C accumulation on the plots having been fertilized on the sandy site in early years by creating a cooler soil as a result of more rapid canopy closure and forest floor accumulation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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