Microclimate and surface pH in limestone pavement fissures were investigated, with special attention to their correlation with topography. The diurnal cycles of light intensity at 60 points in the fissures were measured and variations in them explained by the interaction of topography and the position of the sun in the sky. Continuous recording of temperature and humidity in the grikes over a 5-day period suggested the presence of two air layers: an air layer in the lower two-thirds of each grike, characterized by stable temperature and humidity, with humidity decreasing upward; and a second layer continuous with the air above the surface and subject to much greater variation. This phenomenon was most pronounced in the narrowest grikes. Means and variances of light intensity, temperature, and humidity were selected as parameters of microclimate. Analyses of their variance with respect to topographic effects were performed, and all six parameters were shown to be highly correlated with topography. The pH determinations are not so correlated. The suitability of these seven variables for use in projected mathematical models of the determination of the probability of occurrence of species at defined points was investigated.
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