396 Island Biogeography mathematical model However, the model is easily understood from Figure For example, a large archipelago, such as the Fijian Islands, situated nearer to continental source areas for the dispersion of biota, would have richer species equilibria than a large archipelago, such as the Hawaiian Islands, which is much farther removed from any biotic source area The reality of species equilibria is highly questionable, yet the theory has been and continues to be very inspirational If applied not simply to species per se, but instead to different life forms, such as indigenous trees, ferns, or shrubs, the results may show differing values of species richness and endemism in relation to size of island areas and degrees of Figure The MacArthur and Wilson (1963, 1967) models of dynamic species equilibria as controlled by distance of islands from biotic source areas (from near to far) and by size of islands (from small to large) Reproduced from MacArthur RH and Wilson EO (1963) An equilibrium theory of insular zoogeography Evolution 17: 373–387 and MacArthur RH and Wilson EO (1967) The Theory of Island Biogeography Princeton, N.J.: Princeton University Press Table isolation Moreover, these in turn may lead, with additional ecological studies, to a better understanding of the function of biodiversity in different island ecosystems At this point, another limitation of this theory should be mentioned This relates to the fact that size of island area is only a most general predictor of species richness At least elevational range and substrate type should be added to make the theory more predictable This brings us to the next theory The Biome Theory This theory predicts that there are broad life zones that are indicated by groups of biota of key plant life forms, which are controlled by certain broad-area climatic and edaphic (soil) parameters For example, the biome theory predicts that in mountainous environments there are altitudinal life zones (Holdridge, 1967) or vegetation zones (Mueller-Dombois and Ellenberg, 1974) that can be distinguished by tree species and other life forms into lowland, upland, and high-altitude zones Also, such familiar terms as desert, grassland, deciduous forest, coniferous forest, and tundra depict different latitudinal biome types, which in turn can be defined by climatic parameters as ‘‘zonobiomes’’ (Walter et al., 1975) It is assumed that conditions for life within a biome are more homogenous than life conditions across different biomes (such as grassland versus desert) Applied to island biogeography, the biome theory lends itself to a more appropriate refinement in the analysis of biodiversity than is offered by the two ecosystem parametersFsize and isolationFin the above described theory of island biogeography For example, comparative biodiversity research within a Pacific-wide biome type, such as the montane rain forest on volcanic high islands of basaltic origin, is scientifically more satisfying than biodiversity research based simply on size of island area The size approach groups different types of islands into the same category, which thus can be a very Areas of specialization within the field of Geobotany, their synonyms, and Anglo-American equivalents Area of specialization (and synonyms, European terms) Subject matter Anglo-American equivalents (and synonyms) Floristic geobotany Study of geographic distribution of plant taxa and their evolutionary relationships Study of composition, development, geographic distribution, and environmental relationships of plant communities Plant geography (phytogeography) Sociological geobotany (vegetation science, plant sociology, phytosociology, phytocoenology) Ecological geobotany (plant ecology) Autecology (ecophysiology) Demecology (population ecology) Synecology (habitat science; ecosystem research) Historical geobotany Study of physiological functions of individual organisms in the field environments and communities; life-history studies of species or ecotypes Study of structure and function of populations Study of genetic variation in populations Study of habitat factors and the physiological response of species and species groups to these factors; study of community functioning, and niche functions of plant populations in an ecosystem context Study of historical origins and development of populations and communities Synecology (community ecology, plant ecology in part) Autecology (physiological ecology, population ecology in part) Population ecology Genecology Ecosystem ecology (community process ecology, functional ecology, systems ecology) Paleobotany (paleoecology) Source: Reproduced from Mueller-Dombois D and Ellenberg H (1974) Aims and Methods of Vegetation Ecology New York: John Wiley & Sons