Using the Landscape Ecosystem Approach to Assess Species and Ecosystem Diversity

Diversity was determined for ground-cover species within and among landscape ecosystem groups of the University of Michigan Biological Station, nortbern lower Michigan, USA. The concept of ecosystem diversity, number, kinds, and patterns of landscape ecosystems and their processes, was introduced and illustrated. The 4000-ha area has been highly disturbed by logging and repeated post-logging fires. Early successional species now dominate the overstory of upland ecosystems. Twenty-one upland landscape ecosystem groups were identified, classified, described, and mapped on the basis of interrelationships among climate, physiography, soil, and vegetation. Six landscape ecosystem groups, representative of extremes along moisture, nutrient, and microclimate gradients, were selected for the analysis of alpha and beta diversity of ground-cover vegetation. Alpha diversity indices calculated were species richness, Shannon-Wiener diversity, Shannon-Wiener evenness, and Simpson's index. Beta diversity was measured by percentage similarity and Jaccard's coefficient. The most moist and nutrient-rich ecosystem group had the highest alpha diversity. The general pattern of decreasing alpha diversity was moist and nutrient-rich, moderately moist and moderately nutrient-rich, moist and nutrient-poor and climatically extreme, dry and nutrient-poor and climatically extreme, and dry and nutrient-poor. Beta diversity analysis revealed significant between-ecosystem diversity, despite the fact that the landscape appears relatively flat and strongly dominated by big-tooth (Populus grandidentata Michx.) and trembling (P. tremuloides Michx.) aspens. The richness of landscape ecosystems among four regional landscapes in Michigan, including the Biological Station was contrasted and described. Greater ecosystem richness of the Biological Station reflects greater geologic-physiographic complexity of the area due to its glacial history. Distinguishing and mapping landscape ecosystems proves an excellent framework for assessing alpha and beta diversity of plant species and for similar analyses of whole landscape ecosystems and their processes. Utilización del enfoque ecosistémico a nivel de paisaje para evaluar la diversidad de especies y ecosistemas.