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Development of a new piosphere in arid chenopod shruhland grazed by sheep. 1. Changes to the soil surface
Author(s) -
ANDREW MARTIN H.,
LANGE ROBERT T.
Publication year - 1986
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1986.tb01409.x
Subject(s) - shrubland , arid , stocking , environmental science , rangeland , soil compaction , deposition (geology) , grazing , soil crust , grazing pressure , hydrology (agriculture) , ecology , geology , geography , soil water , soil science , biology , agroforestry , forestry , ecosystem , geomorphology , sediment , geotechnical engineering
Piospheres, that is, zones of attenuating stocking impact extending out from watering places, are a feature of arid pastoral regions. The present authors studied, for the first time, the initial development of a piosphere in respect of a number of variables of the soil surface. The site was near‐pristine chenopod shrubland, part of a paddock of 1340 ha near Whyalla, South Australia, stocked with ca. 200 sheep on a new watering point. Soil features monitored over the first 2.5 years were dung deposition, sheep track development and surface erosion, the soil lichen crust, compaction of the soil surface and dustfall, using fenced plots of at least 550 m 2 as controls. Piosphere patterns (i.e. patterns reflecting the concentricity of stocking pressure around water) were manifest within the first 3 months for sheep dung deposition, sheep track development, and lichen cover. Soil compaction, which was confined to sheep tracks and then largely to the surface 5 cm, displayed a piosphere pattern when it was first recorded 6 months after stocking. Bulk density of this layer was elevated by up to 20%. There was only a weak piosphere pattern in dustfall. The piosphere patterns in sheep track development and destruction of the lichen crust became more pronounced in time. Track direction was near radial. After 2 years the limit of the piosphere pattern ranged from ca. 10 m from the trough for infiltration into dry soil after an abrupt rainstorm, to greater than 800 m for sheep track intensity. These changes occurred at stocking levels amongst the lowest in Australian arid zone pastoral situations. After the first 9 months of sheep stocking there was no discernible effect of grazing on the density of the short‐lived grasses or on the pattern of kangaroo arid rabbit activity as judged by the pattern of their dung deposition. No discernible erosion of the soil surface other than in sheep tracks occurred during the first 2 years.