Using two-dimensional foraging arenas, laboratory tests were conducted to investigate the effect of soil type, soil moisture level and ambient temperature on the exploratory tunneling by Coptotermes formosanus Shiraki. In choice arenas consisting of two substrate types having two moisture levels each, and conducted at a constant temperature of 22 °C, a significantly greater proportion of termit...

Habitat-specialist species may be restricted to a narrower range of microhabitats than habitat-generalist species. We addressed this hypothesis by comparing microhabitats of two pairs of congeners that differ in habitat specificity and co-occur in one distinct habitat type, Florida rosemary scrub. We characterized microhabitats of rosemary scrub specialists, Polygonella basiramia and Lechea cer...

This study applies artificial neural networks (ANN) to simulate the soil stress-strain relationship observed in test data from triaxial shear testing of saturated sand. A genetic algorithm is used to obtain an optimal framework for the ANN. The results show that the proposed genetic adaptive neural network (GANN) can effectively model undrained monotonic and cyclic triaxial behaviour of saturat...

Population increase of Pratylenchus hexincisus on corn was tested over 3 months at 15, 20, 25, and 30 C in Marshall silt loam, Clarion silt loam, Buckner coarse sand, and Haig silty clay loam soils. The optimum temperature for increase was 30 C in all soils. The nematode population was significantly larger in Buckner coarse sand than in other soil types at 50 C. The recovered P. hexincisus popu...

Most of the Tylenchulus semipenetrans larvae applied on the surface of four soils in pots 14.5-cm deep moved no further downward than 6.5 crn, and remained in the upper half of the pot. The percentage of second-stage larvae that developed into adult females on 'Homosassa' sweet orange in the soils were: sandy loam, 6.8% in the same soil with inoculation holes, 8.6%; loamy sand, 5.4%; coarse san...

In the current paper results of a well instrumented experimental procedure for studying the arching effect in loose and dense sand are presented. The apparatus comprises concentric circular trapdoors with different diameters that can yield downward while stresses and deformations are recorded simultaneously. As the trapdoor starts to yield, the whole soil mass deforms elastically. However, afte...

This study determined the susceptibility of cultured soil microorganisms to the effects of Ekodiesel Ultra fuel (DO), to the enzymatic activity of soil and to soil contamination with PAHs. Studies into the effects of any type of oil products on reactions taking place in soil are necessary as particular fuels not only differ in the chemical composition of oil products but also in the composition...

In the current paper the results of a numerical simulation that were verified by a well instrumented experimental procedure for studying the arching effect over a trapdoor in sand is presented. To simulate this phenomenon with continuum mechanics, the experimental procedure is modeled in ABAQUS code using stress dependent hardening in elastic state and plastic strain dependent frictional harden...

Soil thermal conductivity is significantly influenced by saturation and dry density. In this paper, a family of empirical correlations are presented which relate soil thermal conductivity to saturation for five soil types, namely, gravel, sand, silt, clay and peat, in both the frozen and unfrozen states. These correlations were developed from a soil thermal conductivity database which was const...

In many cases of heavy earthquakes, liquefaction has resulted in serious damages. Existing anisotropy in soil layers results  in some difficulties to realize the reason for these phenomena. Loose sand lenses buried in fine soils are one of the cases which may result in these problems and as a weak point during the earthquake can cause this phenomenon. In this paper, using FLAC 2D software, doub...