Kwamgumi Forest Reserve - Frontier-publications.co.uk

12 Kwamgumi Forest Reserve
available nutrients. As recorded in the AFIMP survey, the nutrient holding capacity of these
soils is directly related to the organic matter content (Hamilton, 1989b).
The soils of Kwamgumi were found to be predominantly sandy by both surveys, although
the increasing clay content recorded in sub-soils by the AFIMP survey was only observed
on the mid-slope site during this study. The soil catena examined during this survey was
located at a lower altitude than that of the AFIMP study, and was typical of the overbank
floodplain of the Muzi River. This may account for the coarser sediments which
characterised the Kwamgumi soils sampled during this survey.
The pH of soils was found to be relatively acidic in both surveys, though soils were recorded
as having slightly lower pH during this survey. This may be due to testing errors. The
acidity of the soil shows the importance of the gneiss parent material, a rock type with a high
quartz component which results in relatively acid soils. On the Kwamgumi transect, a
correlation between slope angle and soil depth was observed: as the slope angle increased,
the depth of the soil decreased and stoniness increased. Therefore, the parent material is
probably more influential on slopes than on gentle terrain, which were characterised by
sandier soils.
As is typical of many tropical soils, the soils of Kwaumgumi have a small A horizon due to
the rapid rate of organic matter breakdown and nutrient cycling (Holmes, 1995). Given that
nutrient retention is directly related to organic matter content, the loss of the A horizon
would result in rapid soil impoverishment. Such a scenario could occur if the natural forest
were cleared (Hamilton, 1989b).
East Usambara Conservation Area Management Programme Technical Paper 40