van Hees,P.A.W., Jones,D.L., Jentschke,G. and Godbold,D.L.(2004): Mobilization of aluminium, iron and silicon by Picea abies and ectomycorrhizas in a forest soil. European Journal of Soil Science, 55, 101-111.

『森林土壌におけるヨーロッパトウヒおよび外菌根によるアルミニウム・鉄・ケイ素の移動』


(Abstract)
Summary

 Weathering of soil minerals is a key determinant of ground and surface water quality and is also important in pedogenic and rhizosphere processes. The relative importance of biotic and abiotic studies in mineral weathering, however, is poorly understood. We investigated the impact of Picea abies seedlings, an ectomycorrhizal fungus and humic acid on the solubilization of aluminium (Al), iron (Fe) and silicon (Si) in an E horizon forest soil over 10 months. Elemental budgets were constructed based upon losses in drainage water, accumulation in plants and changes in the pools of exchangeable ions. Plants and mycorrhizas or both had a significant effect on the total amounts of Al, Fe and Si mobilized from the soil. Significantly larger amounts of Al and Fe were recovered in plants than those lost in drainage water, whereas the opposite trend was true for Si. The continual addition of dissolved organic matter to the soil in the form of humic acid had an effect only on mobilization of Fe, which increased due to larger plant uptake and an increase in the exchangeable pool. The mobilization of Fe and Si were positively correlated with hyphal length, soil respiration and concentrations of oxalate in the soil solution, and mobilization of Al was strongly correlated with plant weight. Scanning electron microscopy revealed that most fungal hyphae were associated with mineral surfaces with little occupation of cracks and micropores within mineral grains. Evidently ectomycorrhizas have important impacts on mineral dissolution and the chemistry of forest soils.』

(要旨)
要約

 土壌鉱物の風化は、地下と地表の水質の鍵となる決定要素であり、土壌形成と根圏過程でも重要である。しかし、鉱物風化について生物的研究と非生物的研究の関連する重要性はあまり理解されていない。我々は、10ヶ月にわたり森林土壌E層でのアルミニウム(Al)・鉄(Fe)・ケイ素(Si)の溶解化に対するヨーロッパトウヒ・外生菌根菌・フミン酸の影響を調べた。元素収支は、排水での損失・植物への蓄積・交換性イオンのプールでの変化を基に組み立てた。植物および菌根または両者では、土壌から移動するAl・Fe・Siの全量にかなりの影響があった。かなり多量のAlとFeが、排水で失われた以上に植物に回収され、一方Siについては逆の傾向が見られた。フミン酸の形で土壌に連続的に加えられた溶存有機物はFeの移動しやすさにのみ影響を与えたが、これは植物の摂取の増加と交換性プールの増大により大きくなった。FeとSiの移動しやすさは菌糸の長さ・土壌呼吸・土壌溶液中のシュウ酸塩濃度と正に相関し、Alの移動しやすさは植物重量と強く相関した。走査原子顕微鏡では、大部分の菌糸は鉱物表面に伴っていたが、鉱物粒子内部の割れ目や微小孔を占めるのは少なかった。明らかに、外生菌根は鉱物溶解と森林土壌の化学的性質に重要な影響をあたえる。』

Introduction
Materials and methods
 Soil sampling and pretreatment
 Plant and mycorrhizal preculture
 Soil-sand culture system and sampling of drainage water
 Experimental design
 Analysis of plant material
 Selective extractions ad analysis
 Scanning electron microscopy (SEM) studies
 Calculations and statistics
Results and discussion
 Growth rate and Al, Fe and Si concentrations in plant tissue
 Mobilization of Al,Fe and Si in drainage water
 Accumulation of Al, Fe and Si in plants
 Soil extractions
 Total mobilization of Si, Fe ad Al and correlations
 Scanning electron microscopy (SEM) studies
 Impact of ectomycorrhizas on soil processes
Conclusions
Acknowledgements
References


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