ABSTRACT
This chapter describes methods that can be used for extrapolating between levels of biological organization, examines their assumptions, indicate their strengths and weaknesses, and looks at forward to new directions for research. It explores the biochemical level and move upwards toward the ecosystem and landscape levels. The complexity of ecosystems makes it difficult to develop quantitative cause–effect relationships across levels of biological organization. Empirical studies that quantitatively link the responses to stressors at the biochemical level with those at the population, community, and ecosystem levels of biological organization are few. Semifield tests, sensu stricto, are experimental ecosystems that run under fieldlike outdoor conditions. A number of studies have been conducted to characterize the community structure and function of model ecosystems. Ecosystems are inherently complex, and a fundamental source of biological complexity is the interactions that occur between organisms within and between different trophic levels.
