Forested landscapes frequently have a higher degree of heterogeneity than agricultural landscapes at the site and hillslope scales. The terrain may have a high proportion of rock outcrop, standing trees, fallen logs, and various forms of biotic disturbance. Aspects of the soil and land surface are not well characterised in current description systems even though they influence landscape processes, productivity and management. Explicit methods for locating observations and describing components of the soil and land have been developed and tested in a forested granitic landscape in southeast NSW, Australia. Potential sampling patches were generated by computer prior to fieldwork using terrain analysis methods in a Geographic Information System. Areal density and height of rock outcrop was measured along two 10m transects using a line intercept method. Estimation of area occupied by sub-surface boulders was made using a soil probe to a depth of 0.5m at every metre along the transects. All of the rock fragments with an axis >0.05m were excavated from the soil pit and three axes measured with a ruler. The dimensions of the soil pit were also recorded, allowing calculation of volumetric rock content in various size classes. Rock fragments 0.005–0.05m were sieved and weighed from disturbed horizon samples to estimate mass percentage of different grades of rock fragment. The volume of dead wood per ha was estimated using a line intercept method, while the volume of live wood was estimated using basal area wedges. Surface cover and disturbance were estimated as percentages and types at metre intervals along the transects. Litter was collected, dried and weighed, and expressed on a mass per ha basis. The methods were developed and used in conjunction with conventional soil description methods (McDonald, R.C., Isbell, R.F., Speight, J.G., Walker, J., Hopkins, M.S., 1990. Australian Soil and Land Field Handbook, 2nd Edition. Inkata Press, Melbourne, 197 pp.), an expanded set of morphological descriptions (McKenzie, N.J., Jacquier, D.W., 1997. Aust. J. Soil Res. 35, 803–826), and laboratory measurements to provide quantitative estimates of soil and hydraulic properties across forested landscapes. Statistical models were developed to predict the distribution of individual attributes across the catchments with specified levels of confidence. Some properties (such as rock outcrop, percent clay in the B horizon) could be predicted with some reliability across the catchments, while others (such as litter loads, surface cover) could not. Many of the predictable attributes are directly useful to forest managers and also enable estimation of more complex properties (e.g. plant-exploitable soil volume or hydraulic properties). Selected results clearly demonstrate the utility of the additional site and soil descriptors presented in this paper.

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   |wiki=    Wicri/Agronomie
   |area=    SisAgriV1
   |flux=    Istex
   |étape=   Curation
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   |clé=     ISTEX:51D3509A5BD7D798C8525A3AEFFE63FC0801A742
   |texte=   Quantitative site and soil descriptors to improve the utility of forest soil surveys
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