The quantity and nature of the forest floor and topsoil under some indigenous forests and nearby areas converted toPinus radiataplantations in South Island New Zealand

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Abstract
In a comparative study, the quantity of accumulated organic matter in, and the nutrient composition of the forest floor and topsoil (0–20 cm) of indigenous (beech or podocarp) forests and nearby Pinus radiata plantations in five widely separated forest sites in the South Island of New Zealand were measured. Total mass of forest floors in native and radiata plantation stands ranged from 25 to 464 and 9 to 79 t/ha, respectively. Native forest stands apparently accumulated larger amounts than nearby radiata pine stands, especially in the West Coast forests. In exotic plantations, the nett accumulation was modified by management practices such as burning, during the process of converting native forests to pine plantations, and stand thinning. Except in Nelson forests, forest floors in native stands had larger contents of carbon and nutrients than those of nearby radiata pine sites. No consistent differences were found in carbon and nutrient concentrations in topsoils of native and exotic forests except in the 9-year-old radiata pine stand in the Hochstetter forest, where they were lower than those under the native forest. However, levels of exchangeable cations and Bray-P in top-soils under radiata pine stands were higher than those of native stands. Concentrations of ether-extractable components (lipids), water-soluble carbohydrates and polyphenols in the forest floors under native forest were generally higher than those under radiata pine stands. Consistent differences between concentrations of lipid components and polyphenols in the topsoil under native and exotic forest were not found.