Vertical and horizontal distribution of soil properties influenced by individual trees in grazing landscapes of NSW Australia

Scattered paddock trees play an important role in the Australian environment and influence their immediate environment both above- and below-ground. These trees are rapidly being lost from the landscape and there is a need to understand their functions more fully in order to optimise landscape management. This investigation aimed to quantify how single trees influence the soil resource with depth and to investigate the spatial extent of their influence. Three isolated trees were comprehensively examined for their influence on soil chemistry to a depth of 75 cm and to a radial distance of more than 3.5 canopy radii. Modification of soil condition was strongly dependent on the soil property examined, although typically values were higher under the tree at the surface and diminished with distance. We conclude that single trees significantly improve soil condition and that a distance of 2.5 canopy radii is sufficient to explain the spatial influence of scattered trees.