| dc.description.abstract | Wetlands are one of the most valuable ecosystems but are fast getting degraded. Increasing
threats of environmental degradation to wetlands has driven adoption of ecological
rehabilitation as one of the tools for conservation. Rehabilitation has further been emphasized
to compensate for the biodiversity values lost in carrying out development projects in fragile
ecosystems. For a mined wetland at Lwera, an attempt was made to: (i) study the spatial
patterns of wetland fragmentation using landscape metrics computed from satellite-based
land cover classification, and (ii) test differences in establishment of the dominant wetland
vegetation in the area (Cyperus Typha angustifolia and Phragmiles). To assess the mining
footprint, the active mining wetland area was mapped and constrained around some area for
landscape analysis using sensor data. To test a rehabilitation strategy, a northerly transect was
selected with random intervals at pits where experimental pits were set. In each of the pits,
six replicate plots were set up, that is, for each species two arrays of four platforms, one
arranged parallel and the other conterminous at the edges. The platforms were each lined with
perforated sisal bags anchored on supports at the platform corners. Rhizomes of the plants
were then planted on the platforms where wetland soil material had been placed. The results
of landscape analysis showed fragmentation of the wetland, mostly by mining activities. For
instance, using a representative metric, namely vegetation patch number, it was shown that
the number of patches under vegetation increasesd from 400 in 2016 to 620 in 2017 and then
to 7 10 in 2018, depicting a discontinuous and patchy landscape and with this was a change in
landscape structure. Further, the results on testing establishment of the native wetland species
showed that the species rapidly established, but Papyrus was particularly more successful
growing up to a shoot length of 94cm as compared to Typha (80. I 4cm) and Phragmites
(64cm). It was also shown that the distance from the lake had a significant effect on
establishment of the three species tested (P S 0.05). The results were beneficial in reporting
the effects of mining on the wetland and demonstrated the possibility of using remote sensing
to quantify spatial changes in the wetland. It was however clear that expansion dynamics of
the planted species cannot be studied in a short period of time which calls for a long term
study. | |
