The effects of landscape attributes and plant community on soil physical properties in rangelands

This study addressed the effect of landscape attributes on the spatial distribution of soil physical properties in an alpine rangeland in a semi-arid area of Iran. Soil physical properties are recognized for their important role in supporting plant growth. To identify the effects of landscape attributes on soil physical properties the present study collected and analysed information from air photos, satellite images, field survey, and the laboratory using statistical analyses. Land stratification allowed the study area to be subdivided into Land Unit Tracts (LUT), according to specified criteria including landform attributes (slope, aspect, and altitude) and vegetation type. A factorial model on the basis of a completely randomised design was used to analyse the data collected from 234 LUT. The interrelationships between soil physical properties and landscape attributes were, investigated and interpreted based on statistical analysis and expert knowledge. Slope significantly (P<0.05) affected most properties of the 0-10 cm topsoil including grade of pedality and slake test. Also many soil properties that reflect parent material and likely to be related to soil moisture status including coarse fragment ratio, soil profile effective thickness, first layer effective thickness, water retention capacity, and depth to water table were significantly related to slope gradient. These soil properties noticeably affect range productivity. (C) 2004 Elsevier B.V. All rights reserved.