Multivariate Analysis Desert Snail Distribution by Dillon (1 results)

Multiple discriminant analysis and principal component analysis were found useful in interpreting distributions of two land snails in a desert canyon in Arizona. Snail presence and abundance in small, arbitrarily chosen sites can be accurately predicted from 5 environmental variables: elevation, slope angle, slope aspect, percent vegetational cover and substrate type. Though correlation among the environmental variables was high, vegetational cover was found to account for most of the variance in snail presence. Independent of vegetation, slope aspect, slope angle, and elevation were not demonstrated to affect the presence of snails. The 2 snail species commonly found living in the canyon, Discus cronkhitei and Sonorella baboquivariensis cossi, differ significantly in their preference of slope angle and substrate. Apparently Sonorella was found more commonly on steep rocky slopes because it requires rocks for shelter. Discus, a much smaller snail, can find adequate shelter in loosely packed humus and thus inhabits shallower slopes where humus accumulates. 7 pp., 2 figs, gr. 8. …