As a general rule, the larger an area under consideration, the more likely the vegetation will be heterogeneous across it. Two main factors are at work. First, the temporal dynamics of disturbance and succession are increasingly unlikely to be in synchrony across any area as the size of that area increases. That is, different areas will be at different developmental stages due to different local histories, particularly their times since last major disturbance. This fact interacts with inherent environmental variability (. in soils, climate, topography, etc.), which is also a function of area. Environmental variability constrains the suite of species that can occupy a given area, and the two factors together interact to create a mosaic of vegetation conditions across the landscape. Only in agricultural or horticultural systems does vegetation ever approach perfect uniformity. In natural systems, there is always heterogeneity, although its scale and intensity will vary widely. A natural grassland may be homogeneous when compared to the same area of partially burned forest.
Eric Karlstrom began teaching at California State University, Stanislaus in 1990, after five years as an Assistant Professor at Northern Arizona University, one year as a Visiting Professor at The University of Kansas, and one year as an Adjunct Professor at the University of Wyoming. At CSUS, in addition, to teaching physical and environmental geography courses (Geomorphology, Climatology, Introduction to Physical Geography, Human Ecology), he has also taught courses cross-listed with the Geology department (Geology/Geography of Soils, Physical and Environmental Geology), and an honors course (State of the World: The Environmental Perspective).