Human Use of Forest Trees and its Impact on Tree Diversity and Abundance in Chemususu Forest, Baringo County, Kenya
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Date
2020
Authors
Kipkoech, Morogo Hosea
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Trees provide both direct and indirect benefits to humans, who depend on them for their
livelihoods. Forest ecosystems are vulnerable to over-utilization and exploitation due to
the sensitivity of its complex and highly diverse ecosystem. The aim of the study was to
determine the human impact on tree species diversity, abundance, plant population
structure and uses of forest trees by local communities adjacent to Chemususu forest
Reserve in Koibatek Sub-County, Baringo County. Questionnaires and interview
schedules were used to collect data on uses of trees; the target group were households
within 3km stretch from the forest edge. The data on trees species, diversity, abundance
and plant population structure was collected by systematic sampling using six parallel
belt transects each starting from the forest edge. Sampling was conducted in quadrats of
20m x 20m (for trees) located along the transects at 500m intervals. In each of the
quadrats, all the trees species were identified, counted and diameter at breast height
(DBH), measured at 1.36m outside the bark to the nearest cm. Indicators of human
disturbance were assessed to determine the extent of human impact. The Statistical
Package for Social Sciences (SPSS) was the main tool for quantitative data analysis from
both questionnaires and interview schedules. Analysis of Variance (ANOVA) was used
to test whether the mean number of cut stems and debarked trees varied with distance
from forest edge. ANOVA was also used to test for variation in the mean diversity
indices, tree species abundance and DBH with distance from forest edge. In both cases,
tukey test was used to separate the means. Shannon-Wiener Diversity index (Magurran,
1988) was computed. Pearson’s correlation was carried out to determine the relationship
between abundance of cut stems and debarked trees with distance from human settlement
in each study plot and to investigate the relationship between mean species abundance,
diversity, and DBH with distance from human settlement. Majority of the local residents
had stayed in the region for more than 15 years and perceive the forest as important for
various uses, 98.4% for spiritual and cultural purposes, timber (97.52%), tourism and
recreation (96.3%) and hunting (97.1%).Three trees species, Olea europaea, Dombeya
torrida and Olea capensis were used for firewood as well as charcoal and formed a large
proportion of used trees. Trees used for timber Juniperus procera, Podocarpus falcatus
and the exotic cupressus lusitanica had been heavily extracted. There was no significant
relationship between the number of charcoal kilns and distance from the forest edge (r = -
0.849; P=0.069). This also applied to the number of plots with evidence of pit sawings
with distance from the forest edge (r = 0.555; P =0.333) but the number of plots with split
stems decreased significantly with distance from the forest edge (r = -0.892; P =
0.043).There was no significant variation in the mean number of cut stems and mean
number of debarked trees with distance from human settlement (F(4, 25) =0.082; P= 0.546)
and (F (4, 25) =1.795; P=0.162), respectively. Tree diversity did not vary with distance
from human settlement (F (4, 25) = 1.67; P=0.189).There was a significant difference in the
mean number of trees in different DBH classes (F (4, 25) = 5.181; P =0.002). The number
of trees on the lower DBH classes was more than those on the higher classes at various
distance intervals, but this difference was not statistically significant. The study showed
that the community role in forest degradation was significant and they highly depended
on it for their livelihood. Thus, it was important to understand the relationship between
the community and the forest. Alternative sources of trees used for timber and charcoal
should be encouraged to reduce pressure on forest trees.
Description
A Thesis Submitted In Partial Fulfillment Of The
Requirement for the Award of the Degree of Master of
Science (Plant Ecology) in the School of Pure and Applied
Sciences of Kenyatta University
Keywords
Forest Trees, Tree Diversity, Chemususu Forest, Baringo County, Kenya, Forest ecosystems, Plant population structure