Landscape Ecology vol. 3 nos. 229-243 (1989) SPB Academic Publishing bv, The Hague

this paper are to (1) identify concepts related to pattern and process in transition zones where steep gradients are likely to occur, (2) develop sample hypotheses of ecosystem dynamics associated with change in transition zones, and (3) provide examples of techniques and tools that allow measurement and extrapolation to scales appropriate for broad-scale transition zone studies. 2. Transition zones as sensitive indicators There is a growing literature on the role of ecotones in influencing ecological flows (i.e., energy, resources, information) and biodiversity and in detecting change in the global environment (Hansen et al. 1988). Ecotones can be defined as transition zones or tension zones and can be sensitive indicators of change. Although ecotones often are as- sociated with relatively fine-scale phenomena (e.g., forest edge, lake edge, patch edge), the concepts can be applied to broader-scale characteristics such as a biome boundary where ecological change may be distributed over many kilometers. The structural features of fine-scale ecotones (hundreds of meters) are likely determined by site-specific characteristics such as soil discontinuities, lake edge, and even fire. Climate appears as a constant across such small dis- tances. Broad-scale transition zones between mes (i.e., many kilometers) are more likely to be a result of large-scale climatic features working on a 231 Biomass Nutrient One-Dimensional Environmental Gradient (distance) STRUCTURAL CHARACTERISTICS Biomass Two-Dimensional Environmental Gradient (distance) Fig. I. Structural features that define the transition zone as an association of life-forms from adjoining biomes. A: Structural characteristics expected where biome transition is controlled by a single environmental factor, such ..

A comparative analysis of potential nitrification and nitrate mobility in forest ecosystems

Mobilization in a wide range of forest ecosystems were investigated through a combination of field and laboratory experiments.Trenched plot experiments were performed in 17 forests, and laboratory incubation studies of potential ammonium and nitrate production were made on soils from 14ofthese sites