Faculty Mentor(s)

Dr. K. Greg Murray

Document Type


Event Date



Size distributions of trees often yield valuable clues about changing environmental conditions and the responses of populations to them. In a recent study, we measured the size distribution of Eastern Hemlocks in several forests near Lake Michigan to determine whether active recruitment into the population is taking place at a similar rate as in the past. The diameter at breast height of trees was measured for a large sample of hemlocks in selected stands. Analysis showed that the size distribution was strongly skewed toward the intermediate and larger size classes (p < 0.001), suggesting a failure of recent recruitment relative to that in the past. Potential reasons for this decline in recruitment include, but are not limited to, herbivory by deer and possibly climatic changes in the last few decades (increasing temperatures and decreasing precipitation rates). Other studies in the Lake Michigan region, both inland and coastal, have documented declines in hemlock populations based on sample data and paleoecological trends. If the observed trend continues into the future, Eastern Hemlock will most likely continue to decline in density in these forests over the long term.