The bar charts below illustrate the
distribution of individual plant species along the North/South Belt Transect. The red bars
represent the % cover of the plant species in each 1m quadrat along the line. This shows
where each species occurred on the line, as well as how much of it there was at each
point. The vertical scale is the same for each bar chart. The blue bars in the charts
represent the water depth, with maximum depth being 65cm.
These bar charts can be directly related to the plant zonation diagrams produced as part of the line transect
results. The species colours are co-ordinated between the diagrams and these charts.
Comparison of the two illustrates the difference in the type of results obtained using
line and belt transect methods.
Most species will have an optimum zone within their
range where the environmental conditions are best suited to their growth. In the diagrams
below, this zone will be indicated by the area where the species reaches its maximum %
cover. The percentage cover will often tail off gradually to either side of the optimum
zone. Common Duckweed (below) shows this pattern very clearly where it occurs in the
shallow water of the swamp area.
It is difficult to pick out any similar pattern for the
remaining species. This is due to the fact that environmental conditions in the wetland
are extremely variable locally, as are the water depths. The water depths marked were
correct at the time of the survey but they will of course vary with the amount of water
entering the wetland from rainfall and run-off. This means that there may be many optimum
places for a species in a particular zone.
Yellow Iris and Branched Bur-reed both grow in the same
general area. It is evident from matching the charts, that of the two, Yellow Iris
dominates, except where the water depth begins to increase substantially. Here, the
Bur-reed obviously has an advantage over the Yellow Iris and out competes it.