| dc.description.abstract | Based on quantitative comparative data collected In Kakamega forest and the
surrounding farmlands, analyses were done to ascertain to which extent different modes
of land use and seasonal changes affect guild structure, abundance and species diversity
of dung beetle assemblages. The human influences studied included extensive cattle
fanning and deforestation.
These studies were performed between October 2002 and August 2003 during the short
rainy, dry, start of long rainy and end of the long rainy seasons in the primary forest,
secondary forest, grazed, and ungrazed grasslands in Kakamega forest and the
surrounding farmlands. The experiments were done by depositing 10 standard samples
of 1 kg fresh cow dung on standard areas in the habitats in each season at night and
during the day to attract the beetles, which were recovered using the floating method.
The 80 samples made yielded a total of 21,604-.dung beetles representing the families
Scarabaeidae, Hydrophilidae, Staphylinidae and H.i•steridae. The family Scarabaeidae
contained category guild groups of tunnelers, dwellers, and rollers were the guilds
represented in the -farnily Scarabaeidae. For the effect of seasons on the dung beetles
structure individuals and guilds were compared from different seasons.
The studies indicate that the extensive cattle grazing and forest degradation influence
both the guild structure and abundance of dung beetles. There was high abundance in the
grazed grassland, followed by the ungrazed grassland. All the studied habitats had a
significant conditional effect on the families and the guild structure of the dung beetles
and that different guild of dung beetles have strong association with different habitats.
During the day the dwellers were significanty associated with the primary forest,
tunnelers with the secondary forest while rollers, Staphylinidae and Hydrophilidae were
associated with the ungrazed grassland.
It is also shown that the dung beetle assemblages were significantly affected by seasonal
changes and that the impact of the seasons on the dung beetle guilds is significantly
influenced by human activities. The dung beetles were more abundant during the rainy
seasons (start of long rainy and short rainy seasons) and fewer specimens were collected
during the dry season. The tunnelers were significantly associated with the start of the
long rainy and short rainy seasons at night while the rollers were strongly associated
with the dry season during the day. At night, however, the tunnelers and the dwellers
were significantly associated with the grazed grassland.
In the forest areas a total of 55 species of Scarab beetles were collected. As shown by
various diversity indices, and rarefaction plot, primary forest had higher species
diversity than the secondary forest. However dung beetles were more abundant in the
secondary forest.
These studies have shown that differences in the beetle guild structure, abundance, and
species diversity in Kakamega forest and the surrounding farmlands could be due to
human land use modes and seasonal changes. The changes in the dung beetle
assembleges were therefore significant predictors of susceptibility to habitat
degradation. | en |
