because of their relative shortness they cannot normally compete with the Raffia palms for light, they are more tolerant of salinity.)
6.4 SUB-ECOZONES OF THE FAM ECOZONE
There are seven sub-ecozones in the Freshwater ecozone.
6.4.1 THE LEVEE TROPICAL RAINFOREST SUB-ECOZONE
#This is similar to the LEM rainforest described but with three characteristic variations:
- it tends to be long and narrow in shape, so that there is less 'deep forest' and a greater proportion is forest margins;
- on these forest margins, palm trees are more apparent than in the LEM because of their predominance in the adjacent sub-ecozones; and
- species requiring soils deeper than 1 metre, such as the Silk Cotton tree, are less common.
#Eleven trees typical of the levee tropical rainforest after okafor
| Brachystegia eurycoma | |
| Cola laurifolia | |
| Cleitopholis patens | |
| Cynometra vogelli | |
| Irvingia grandifolia | ('Bitter Bush Mango') |
| Irvingia smithii | ('Sweet Bush Mango') |
| Myrianthus grandifolia | |
| Khaya grandiflora | ('Mahogany') |
| Pterocarpus santaniloides | |
| Trichilia heudelotica | |
| Uapaca spp. |
6.4.2 THE SWAMP SUB-ECOZONE
Fresh-water swamp ecosystems may be permanent or seasonal, but both may be subject to tidal influences. Very little is known about either because access is so difficult.
The soils form illuvial Catenas that are entirely hydromorphic; that is, water is the prime factor in their formation. They are basically all Inceptisol Aquept Gley soils (see 4.5.5), but vary between seasonal and permanent swamp areas.
Obviously, reduction is greater in the permanent swamps, although seasonal rising and falling of water levels still allows some oxidation. The soils are likely to be peaty, organic matter building up in these reduced conditions.
Peat: a soil rich in organic material because the break-down of dead plant and animal material is slow as a result of low oxygen levels caused by water-logging.
