A Ecological Baseline Surveys Of: - Lake Bisina - Nature Uganda

4.3.4 Ecosystems challenges
This ecosystem has been modified through:- Over grazing; siltation and poor farming methods and
fishing. This is expected to change the ecosystem and the anticipated adverse impacts include:
wetland loss, siltation, floods, species loss, and soil fragility.
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4.3.5 Environmental and vegetation management
The massive collection of silt affect the seed bank in the soil and most annuals will die. To control
siltation along the plains, there is need to make contours along the slopes to reduce on the amount
of silt from the slopes that drain into the plains. Plant cover may have a priority in any effort to
improve on water management, infiltration, biomass production and soil conservation. Many herbs
tend to be annuals and this means that during the unfavourable or dry seasons, many species will
die leaving a lot of exposed patches which at the beginning of the dry season suffer a lot of erosion.
Also due to trampling by animals grazing and access to watering points, too much exposure to
the scorching sun of the dry season, the exposed soil may degrade in quality through too much
water loss and hardening. This could affect the soil seed bank, leaving these exposed patches
permanently bare or with scanty vegetation during the wet season.
4.3.6 Monitoring indicators and regimes
The monitoring indicators and regimes will be indirectly through, water quality changes, soil erosion
levels, plant species diversity change and any environmental changes must be observed and reacted
upon. The indicator species that should be used include; Cyperus papyrus, C. articulatus, Leersia
hexandra, Limnophytum angolense, Caldesia reniformis, Wisneria filifolia (these will die with less
water and silting). If the water levels increase, marsh or seasonally flooded species like Echinochloa
pyramidalis will die. The seed bank will be washed away into the lake and these will all die.
4.3.7 Discussion
Lake Bisina and Lake Opeta have rich diversity of species and with some localised rare plant
species like Ottellia fischeri and Suddia sagittifolia. The Suddia sagitifolia though not sighted during
the study is confirmed to be present at the site based on Herbarium material. The Suddia sagitifolia
was until recently believed to be limited to southern Sudan but it has now been established that this
plant also occurs in Uganda in the Lake Kyoga Basin.
The threats here include: over-fishing, poor farming methods like overgrazing, and low levels of
environmental awareness may all be contributing to the deterioration of the ecological system of
Lake Bisina-Opeta wetland system. Increased flood risk within the catchment due to erosion from
the mountains and siltation within the systems has reduced the ability to absorb flood waters.
This might be partly due to overpopulation, weak enforcement of existing regulations and lack of
enforceable policies and reasonable management measures.
4.3.8 Conclusions and recommendations
The different degradation treatments had significant effects on species composition, plant cover and
species diversity, and thus affect the ecological function of plant communities. Therefore, decisions
and strategies such as flood control, re-vegetation planning, species selection and seedling
management should be carefully considered. Replanting with native dominant plant species or
natural restoration is a reasonable choice for re-vegetation. Other interventions such as boundary
marking, wetlands restoration, wise use of resources and promotion of some income generating
activies (eco-tourism) should be considered for the whole landscape.
Ecological Baseline Surveys of Lake Bisina, Lake Opeta, Lake Mburo and Nakivali Wetlands Systems 71