ROUGHNESS OF SOIL PORE SURFACE AND ITS EFFECT ON AVAILABLE HABITAT SPACE OF MICROARTHROPODS

Like the majority of natural objects, soil pores can be described by means of fractal geometry. Since the area of a fractal surface depends on the scale of measurement, the amount of available pore area for different size classes of non-burrowing soil animals should depend on the fractal dimension of the soil pore surface following the relationship A(delta) almost-equal-to delta2-Ds, were A is the area measured on scale delta, and D(s) is the fractal dimension of the surface. We estimated D(s) by photographing and digitizing thin sections of various Austrian soils. Images were analyzed using the area-perimeter method following the relationship P approximately A(Dp/2), where P is the perimeter of an intersected soil pore measured at any convenient scale, A is its sectional area, and D(p) is the fractal dimension of the boundary tine. D(p/2) can be recovered by a linear regression in a plot of In P against In A. Under the assumption of isotropy adding 1 to D(p) yields the estimate of the fractal dimension of soil pore surface. Our estimates of D(s) almost-equal-to 2.3 suggest that a decrease in an order-of-magnitude of body length will increase available habitat-space approximately 4 times. We discuss the usefulness of the measurement of pore-wall roughness for predicting a size-class abundance/body size relationship in soil micro-arthropod communities.