This paper presents quantitative descriptions of the vegetation plus associated vascular flora and soils on a sequence of ten marine terraces that extend from a Holocene raised beach a few metres above sea level to a terrace remnant at an elevation of630 m some 12 km inland. From the floristically rich coastal turf and scrub that occupies the most recent terrace there is a distinct sequence of vegetation. Tall mixed silver beech-podocarp-broadleaved forest on the lower altitude terraces (Terraces 2,to 4, < 150 m elevation) grades via mixed mountain beech-podocarp-manuka woodland through shrubland to open bog on the five terraces above 250 m.A postulated long-term, uninterrupted soil-vegetation chronosequence has not been confirmed. Soil development has been strongly affected by devegetation and surface deflation under periglacial conditions, and differential accumulation of loess during Pleistocene glacial periods. It is concluded that the vegetation pattern is related to a range of soil factors, particularly gradients in profile wetness that are associated with the increasing elevation between terraces and minor differences in topography within terraces.The sequence provides an extensive, essentially unmodified and valuable soilvegetation complex representative of marine terrace ecosystems formerly of widespread distribution nationally, which justifies formal reservation.

Conventional soil mapping is limited in its capabilities in that it presents a summary of the soil surveyor's conceptual view of soil variation. As such, the method conveys little regarding what is known about the variation of individual soil properties, or the quantitative nature of their variation. We developed a new method for soil mapping, based on the concepts employed in the PROSPECTOR mineral exploration system, which builds on existing soil surveyor knowledge to construct quantitative statements about individual soil properties via the development of a network of rules. These rules operate within a system of Bayesian inference to assign the varying probability of occurrence of a soil property of interest within an area, given evidence that relates to it in a known way. Permissible evidence includes the range of attributes normally used by a soil surveyor, such as landform, vegetation, land use, or parent material, and can also include remotely sensed digital data. Evidence is weighted according to the uncertainty associated with it, and combined to produce a single estimate of probability of a given attribute. The relationship between the evidence and prediction is stated explicitly at each stage of the procedure and is thus repeatable in a consistent manner. The system has the advantage that while it does not discard the evidence and knowledge used in conventional soil survey, it produces quantitative estimates of the distribution of soil properties, which can be used for a wide range of applications. The data produced is amenable to storage in geographic information systems and related data bases. As such, it can be updated or enhanced as new information or knowledge becomes available.

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A diverse range of acid sulphate soils occur in Negara Brunei Darussalam on the inland flat areas that are important agricultural lands. Prior to this study, there was no information on their occurrence. Information about these soils is critical because they present significant management challenges for both agriculture and protection of the environment. Field surveys and laboratory analysis conducted in eight areas of the Brunei‐Muara district and four areas of the Belait district identified, characterized and classified using Soil Taxonomy, a wide range of 10 acid sulphate soil types in four soil orders: Histosols, Vertisols, Inceptisols and Entisols. A user‐friendly soil identification key using easily observed soil characteristics was developed to assist users with the recognition of the range of acid sulphate soils. Conceptual soil hydro‐toposequence models in the form of cross‐sections were constructed to explain the spatial heterogeneity of (i) acid sulphate soil properties comprising a range of features (e.g. organic‐rich materials/peats, clays, sands, cracks and jarosite‐rich mottles), sulphidic material and sulphuric horizons, (ii) pyrite shale outcrops and (iii) soil types using both the soil identification key and Soil Taxonomy. The soil hydro‐toposequence models together with the soil identification key helped to easily visualize and illustrate the complexities and importance of understanding specific sites to assess the detailed behaviour and implications of various soil, regolith and topographic features.