Space as a Resource

Abstract

In this assay, we aim at defending the hypothesis that physically spoken sheer "empty" space in itself without any other commodities has the function of resource for plant life. Definitions of space, niche, and resource are examined. We consider competition for resources and space occupation and exploitation above ground, where light is often a decisive limiting factor. Steady-state and dynamic situations are assessed with respect to cost-benefit relations and using the examples of epiphytic niches and gaps of tropical rain forests. In a similar vein, belowground relations are evaluated with the morphological and physiological responses of roots, the role of different types of mycorrhiza characterized by fungal occupation of soil host rhizospheres, and the dynamic recognition of self and foreign by roots in the soil. Sharing of space is exemplified by describing vegetation islands on sand plains and epiphyte nests in tree canopies, where facilitation is distinguished from competition. Another example for natural facilitation is hydraulic redistribution. Applied facilitation with anthropogenic manipulation is illustrated by nurse effects in tree plantations. The new concept of "empty" space that can become a limiting resource, i.e., the central hypothesis of the essay, is supported by considering the four dimensions of space, namely the three dimensions of extension in length plus the dimension of time. However, in the simplest case of the one dimension of space provided for atmospheric bromeliads by a telephone-line wire devoid of any other commodities, we may recognize the most straightforward compelling argument for the conclusion we want to promote in this assay, namely, that sheer space in itself has the function of resource.