Only in a few swales with moist, shallow soils and standing water was vegetation diverse or structurally complex. Results indicated that 50 years or more were required for the accumulation of well-developed flora. Structural changes are expected to be even slower, correlating with slow soil development. Few relationships were found between soil characteristics and plant communities, probably as a result of immature soils exhibiting parent material characteristics. Relating vegetation succession to age of river structure was found to be a precise method of developing a time-scale of vegetation development, which could be valuable in managing riparian habitats along these structures.
New stems appear to be suppressed by existing stems.
Survival of new stems also is affected by water table fluctuations. Examples of more extensive case studies, well documented in the literature, are discussed in the Case Studies section.