The Distribution of Insects along Elevational Gradients

The distribution of insects along elevational gradients is controversial. Recent long- term sampling studies have concluded that mid-elevational peaks in species richness identified previously may have come from the short-term sampling regimes employed, and from disturbance at lower elevations. Long-term sampling seems likely to reveal peaks at lower elevations. Analysis of 20 studies taken from the literature add the possibility that the latitude at which a study is undertaken influences the elevation of peak species richness. A study of 12 open sites in the southeastern U.S., ranging in elevation from 100 m to 1700 m, reveals that both principal reasons advanced previously for mid-elevational peaks may be valid, if short-term sampling is employed. Taken together, all of the evidence indicates that a complex interplay of local ecological interactions, latitude, disturbance, and sampling regime determines the elevation of maximum insect species richness. The temporal and spatial scale employed strongly influences the evaluation of this ecological pattern