The concept of the ecological niche has already been mentioned as one means by which greater biodiversity is achieved, with species co-existing as close neighbours but not directly conflicting because they exploit different aspects of the environment. This can be viewed in terms of the relative
Different degrees of massing shown by plant species in the wild (from Hansen and Stahl (1993))
Six possible patterns for two-species populations: (a) and (b) not
segregated; (c) fully segregated; and (d), (e) and (f) partly segregated (adapted from Pielou (1961))
Phenological change in a woodland ground flora community in Totley Wood, Sheffield. (a) Photographs of the same area over the period 10 th April-13th June 2001; (b)
Diagramatic representation of the area occupied by each species; (c)
The relative heights of different species over the time period; (d)
Flowering times for each species; (e) Characteristics of each species; (f)
Plan showing the locations of clumps or individuals of each species in the studied area. Figure drawn from unpublished data by Cruz Garcia Albarado
abundance of different species, with dominant species (usually small in number in any
plant community) grabbing most of the resources, and a larger number of sub-dominant
species fitting in around the dominants. Figure 4.6 illustrates change in a woodland floor plant community over a period of three months or so in the spring.
One of the most important points from this detailed study is that a diversity of species gives a long period of display within a small unit of space. This is very different from the sort of display obtained from more standard horticultural block planting, where continuity of display might occur over larger distances. In Figure 4.6, the dominant species, Myrrhis odorata, which occupies the majority of the space at the end of the sequence, comes into growth relatively late and effectively hides the dying back remains of the earlier flowering species. The phenology of a species, i. e. its growth pattern through the growing season, can therefore be a crucial factor in creating compatible mixtures of species that have a long season of display.