Scott M. Pearson

Landscape Heterogeneity and Ungulate Dynamics: What Spatial Scales are Important?

Ungulates make foraging choices at a variety of spatial scales, but the environmental parameters that are most important at various scales are not well known. Clearly, the spatial arrangement and density of vegetation influences the success of herbivores in finding food (Kareiva 1983 Risch et al. 1983 Stanton 1983 Cain 1985 Bell 1991). Theoretical studies suggest that organisms must operate at larger spatial scales (i.e., search a larger area) as resources become scarce and clumped across a landscape (O’Neill et al. 1988 Turner et al. 1993). In addition, the effectiveness of different foraging tactics may vary with the spatial distribution of resources (e.g.Cain 1985 Roese et al. 1991). However, understanding the responses of animals to spatial pattern at multiple scales is in its infancy (Kotliar and Wiens 1990 Kareiva 1990 Hyman et al. 1991 Ward and Saltz 1994) and remains a high priority for ecology (Lubchenco et al. 1991 Levin 1992). In this chapter, we synthesize results from three studies of winter foraging by ways that consumers create and respond to heterogeneity in the resources they use. Large, mobile herbivores discriminate among spatially variable food resources, thereby altering the structure of plant communities and the rates of ecosystem processes. Improving our knowledge of the responses of large herbivores to spatial heterogeneity can contribute to understanding the workings of many other ecological processes.

Landscape-level processes and wetland conservation in the Southern Appalachian Mountains

The function of wetland ecosystems is not independent of the landscapes in which they are embedded. They have strong physical and biotic linkages to the surrounding landscape. Therefore, incorporating a broad-scale perspective in our study of wetland ecology will promote our understanding of these habitats in the Southern Appalachians. Changes in the surrounding landscape will likely affect wetlands. Broad-scale changes that are likely to affect wetlands include: 1) climate change, 2) land use and land cover change, 3) water and air-borne pollution, 4) a shift in disturbance/recovery regimes, and 5) habitat loss and fragmentation. Changes in climate and land cover can affect the hydrology of the landscape and, therefore, the water balance of wetlands. Excessive nutrients and toxin transported by air and water to wetlands can disrupt natural patterns of nutrient cycling. Periodic disturbances, like flooding in riparian zones, is required to maintain some wetlands. A change in disturbance regimes, such as an increase in fire frequency, could alter species composition and nutrient cycles in certain wetlands. Many plant and animal species that found in small, isolated wetlands have populations that are dependent on complementary habitats found in the surrounding landscape. Loss or fragmentation of these complementary habitats could result in the collapse of wetland populations.

Effective Exercises in Teaching Landscape Ecology

The development of landscape ecology and its many applications to land management created a need for courses that address both the conceptual and practical sides of the discipline. Graduate seminars and full-fledged courses in landscape ecology are now featured at many colleges and universities; undergraduate ecology courses may include an introduction to principles of landscape ecology. Because landscape ecology involves the study of spatially explicit ecological patterns and processes along with much larger regions than ecologists have typically studied, landscape ecologists often employ a variety of new quantitative analysis techniques in their work. In particular, metrics are used to quantify spatial patterns, and the importance of spatial heterogeneity for ecological processes is evaluated. Modeling also plays an important role in landscape ecology because it is logistically impossible to conduct truly replicated experiments across entire landscapes. Students of landscape ecology, even at the undergraduate level, need some familiarity with the tools of the discipline to gain confidence in the practice of landscape ecology and to develop a critical understanding of the strengths and weaknesses of these techniques.