Community concepts in plant ecology: from Humboldtian plant geography to the superorganism and beyond
The paper seeks to provide an introduction to, and review of, the history of concepts of the plant community. Eighteenth-century naturalists recognised that vegetation was distributed geographically and that different species of plants and animals were interconnected in what would later be called ecological relationships. It was not, however, until the early nineteenth century that the study of vegetation became a distinctive and autonomous form of scientific inquiry. Humboldt was the first to call communities of plants "associations". His programme for the empirical study of plant communities was extended by many European and North American botanists, throughout the nineteenth and into the twentieth century. There developed an almost complete consensus among ecologists that vegetation was made up of natural communities, discrete entities with real boundaries. However, there was little agreement about the nature of the putative unit or how it should be classified. Gleason advanced the alternative view that vegetation was an assemblage of individual plants, with each species being distributed according to its own physiological requirements and competitive interactions. This debate was never wholly resolved and the divergent opinions can be discerned within early ecosystem theory.