Augusto,L., Ranger,J., Turpault,M.-P. and Bonnaud,P.(2001): Experimental in situ transformation of vermiculites to study the weathering impact of tree species on the soil. European Journal of Soil Science, 52, 81-92.


 Weathering of soil minerals under forest seems to depend on the species present. To study the influence of tree species we placed unweathered vermiculites in the soil and assessed the impact in terms of saturation index of earth-alkaline cations and cation exchange capacity in 64 forest stands, dominated by different species and growing side by side at 20 sites on acidic soils. The vermiculites were of two types, one with a large charge and the other with a small charge. Minerals were maintained in the soil for 1 and 3 years.
 The minerals placed in the topsoil and in soils with low buffering capacity were more acidified and weathered than those deeper in the soil and in less acid conditions. The vermiculites were transformed into hydroxylated interlayered vermiculites, and the formation of hydroxides in the interlayer space decreased the vermiculites' cation exchange capacities. The high-charge vermiculite had a grater affinity for aluminium than the low-charge variety. The effect of tree species was significant but small compared with factors such as soil type, depth and during of incubation. Nevertheless, we can rank the acidifying and weathering caused by the trees in the following order: Picea abies(ヨーロッパトウヒ), Abies alba(ヨーロッパモミ)>Pinus sylvestris(ヨーロッパアカマツ), Pseudotsuga menziesii(オレゴンパイン)>Quercus spp.(コナラ属), Fagus sylvatica(ヨーロッパブナ). This in situ experimental approach enable us to study potential trends in pedogenesis in few years.』

 表層土および緩衝容量の低い土壌中に置かれた鉱物は、土壌の深部および酸条件の弱い場合よりも、酸性化されかつ風化された。バーミキュライトは層間が水酸基化したバーミキュライトに転移し、層間スペースでの水酸化物の生成はバーミキュライトの陽イオン交換容量を減少させた。高電荷のバーミキュライトは、低電荷のものよりアルミニウムに対して高い親和力をもっていた。樹種の影響は有意ではあったが、土壌型・深さ・植栽期間のような要因と比べて小さかった。それでも、我々は以下の順序で樹種による酸性化と風化に順位をつけることができる:ヨーロッパトウヒ(Picea abies)、ヨーロッパモミ(Abies alba)>ヨーロッパアカマツ(Pinus sylvestris)、オレゴンパイン(Pseudotsuga menziesii)>コナラ属(Quercus spp.)、ヨーロッパブナ(Fagus sylvatica)。このような現場での実験的手法により、我々は数年間の土壌生成において起こりえる傾向を研究することが可能である。』

Materials and methods
 Changes in the vermiculites
 Effect of length of incubation on the test minerals
 Effect of incubation depth on the test minerals
 Effect of bedrock type on the test minerals
 Effect of vermiculite type on the test minerals
 Effect of tree species on the test minerals