Spatial Distribution of Plants and Plant Communities

Abstract

In this chapter we describe the spatial patterns of plant species and communities that developed over time. Together with Chap. 17, it underlines the significance of dynamics in space and time for a thorough understanding of biotic interactions within ecosystems. In the first section, we describe the different types of propagule dispersal and explain the importance of safe sites and seed banks for successful plant establishment. Depending on the effectiveness of dispersal vectors and on habitat requirements, plant species may be widespread (cosmopolites) or—owing to slow dispersal and specific demands—live only within small regions (endemics). The following section discusses general aspects of vegetation geography. Species with similar characteristics and habitat requirements may coexist in areas with comparable environmental conditions and belong to one area type (floristic element, geoelement). In the next section, we deal with species–area relationships and present the classical equilibrium theory of island biogeography. On the basis of this theory, many models were developed to better understand how plants become established on islands. Some of these models regard islands not only as terrestrial areas surrounded by the sea but also as, for example, forest “islands” within an otherwise tree-free matrix. Finally, we discuss two kinds of general vegetation models: (1) stochastic models, which possess some inherent randomness, and (2) deterministic models, which are fully determined by parameter values and initial conditions (i.e. intensity of competition, habitat diversity, degree of disturbances).