Are Industrial Wetlands Changing Over Time?

Abstract

Species richness and diversity of native plant taxa are not correlated significantly with wetland age; there are no trends in these indicators over time in process-affected and OSREF wetlands. In the marsh and meadow and emergent classes of industrial wetlands, wetland age is not significantly correlated with weed species richness or total weed cover in the industrial wetlands. Given that industrial wetlands have higher weed species richness and total weed cover than natural wetlands, the lack of correlation between wetland age and weediness indicates that the weediness of the industrial wetlands is a persistent feature. No patterns are evident that suggest time leads to detectable changes in the frequency of the vegetation types in industrial wetlands. Ordination reveals that wetland age is not correlated significantly with vegetation composition. Because there is no clear successional trajectory over time, there is no evidence that vegetation development over time will result in convergence towards natural vegetation assemblages. Industrial wetland plant assemblages appear to be synecologically stable with respect to time. The impaired condition of the industrial wetland vegetation will therefore persist. In contradiction to these results, deterministic and erroneous beliefs about wetland vegetation succession have become Alberta government policy.

For time will teach thee soon the truth, there are no birds in last year’s nest.

Henry Wadsworth Longfellow, It Is Not Always May, 1845