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Despite a wealth of published research on the nature of woodland soils, little is known about the nature of soils on sites that have supported woodland for many hundreds of years, namely ancient woodland. The properties and variability of soils in three ancient woods; one in the New Forest. Hampshire and two in Berkshire, were compared with those under recent woods. The acidity of ancient and recent woodland soils was high and remarkably similar. Only where cultivation of soils had preceded woodland establishment was soil acidity lower. The quantity of carbon in the soils studied was inversely related to soil acidity and the ancient woods had accumulated larger quantities of carbon than their recent counterparts. The quantities of Ca?', M&+ and K + were larger in the ancient woods except where prior cultivation had taken place. Total and organic phosphate contents of the ancient woodland soils were also consistently larger. The nature and pattern of soil variability in ancient woodland soils was quite distinct from that found in recent woods. Overall, the variability of soil acidity, carbon content and organic phosphate was larger in the ancient woodland soils but the pattern of variability differed between the soil properties. No clear association existed between the pattern of soil acidity and individual trees. At the surface of some of the woodland soils, however, carbon distribution appeared to be associated with individual trees. At depth in the ancient woodland soils, the association with the existing vegetation cover was not so clear. It is probable that the ancient woodland soils retained relict features of previous vegetation cover. Organic phosphate distribution was very strongly associated with the present vegetation cover. The pattern of distribution of organic phosphate appeared to be stronger than that of soil acidity and carbon content.

PedologyUnderstanding the potential of soil to store soil organic carbon (SOC) is important for potential climate change mitigation strategies and assessing soil health issues. We examined the factors controlling SOC storage in eastern Australian soils and how these vary with depth. Models were developed using a set of readily interpreted covariates to represent key soil forming factors together with multiple linear regression (

Aggregates play a key role in protecting soil organic carbon (SOC) from microbial decomposition. The objectives of this study were to investigate the influence of pore geometry on the organic carbon decomposition rate and bacterial diversity in both macro- (250–2000 μm) and micro-aggregates (53–250 μm) using field samples. Four sites of contrasting land use on Alfisols (i.e. native pasture, crop/pasture rotation, woodland) were investigated. 3D Pore geometry of the micro-aggregates and macro-aggregates were examined by X-ray computed tomography (μCT). The occluded particulate organic carbon (oPOC) of aggregates was measured by size and density fractionation methods. Micro-aggregates had 54% less μCT observed porosity but 64% more oPOC compared with macro-aggregates. In addition, the pore connectivity in micro-aggregates was lower than macro-aggregates. Despite both lower μCT observed porosity and pore connectivity in micro-aggregates, the organic carbon decomposition rate constant (Ksoc) was similar in both aggregate size ranges. Structural equation modelling showed a strong positive relationship of the concentration of oPOC with bacterial diversity in aggregates. We use these findings to propose a conceptual model that illustrates the dynamic links between substrate, bacterial diversity, and pore geometry that suggests a structural explanation for differences in bacterial diversity across aggregate sizes.