The influence of afforestation on upland soils: the use of "bomb 14C' enrichment as a quantitative tracer for changes in organic status

Abstract

Soil samples were collected from five stands of Sitka spruce planted at recorded times. Within a comprehensive program of ecologic and biogeochemical analyses, natural 14C measurements on selected organic components of the 0 to 5cm soil horizons serve to quantify progressive changes induced in the organic carbon inventory and relative to that of the original grassland. Points of particular interest are: an enhanced input of fresh organic matter in the years immediately following planting this, in parallel with a net decrease in the total carbon content of the topsoil; this freshly introduced carbon predominates in the soil profile even after 30 years of afforestation; during the 15- to 30-year growth period, the soil carbon content remains constant but progressive changes occur in its biogeochemical composition and rate of turnover. -from Authors