| Abstract | Evidence for solum recarbonation following forest invasion of a grassland soil. Calcareous organic-matter~rjch Black Chernozemic soils often persist under poplar forests in Saskatchewan, not acquiring the Ae horizons and related properties more characteristic of Gray Luvisol soils. These are Rego Black Chemozems, locally tenned "Wooded Calcareous" because of the occurrence ofa dark. calcareous horizon (AC) at depths of 10 to 30 em. We hypothesize that dark, calcareous horizons are fonner 8m horizons that have been recarbonated because of intense biocycling of Ca by aspen (Popu/us tremu/oides). The comparatively small amounts of carbonate occur mainly in the fine silt and clay fractions, and are dominantly calcite, indicating secondary origin, in comparison to the carbonate minerals of the Ck horizons where both calcite and dolomite occur, the latter more common in coarse fractions. The ol3C values of the carbonate minerals indicate that virtually all the carbonate in fine fractions of the upper horizons of the Wooded Calcareous soil is pedogenic. The dominance of pedogenic carbonate in the Ahk and AC horizons of the Wooded Calcareous soil is consistent with a secondary enrichment, a probable result of increased biocycling of Ca where aspen grows on sites with large amounts of soluble Ca in the subsoil. High concentrations of soluble Ca2+ and 5°42- in the LFH of the Wooded Calcareous are consistent with increasing biocycling of these ions. from a gypsum |
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