Factors influencing the population density and distribution of udzungwa red colobus monkey (piliocolobus. gordonorum) in magombera forest reserve, Tanzania
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
Primates perform essential roles in forest ecosystems such as
enhancing seed dispersion which is important in the regeneration of
fragmented forests and improving soil quality through defecation.
Despite their important role in forest ecosystem, they are faced with
a greater risk of extinction as a result of massive forest loss and
degradation which are greatly influenced by anthropogenic activities
such as logging, bush fires, agriculture and settlement expansion.
Furthermore, forest loss may be attributed by natural changes such
as climate change, droughts and tree die back which may result to
changes in forest cover or tree species composition. As an outcome
of all these, their population and distribution has been directly
impacted, increasing their risk of becoming extinct. Kilombero cluster
is one of the biodiversity hotspot areas as it comprises of several
protected areas that harbors the vulnerable P. gordonorum such as
Udzungwa National Park and the fragmented Magombera Forest
Reserve (MFR). Therefore, this study was conducted within
Kilombero cluster to identify the population density of P. gordonorum
in MFR, identify factors influencing the population density of P.
gordonorum in MFR and assess the impact of climate change on the
current and future distribution of suitable habitats for P. gordonorum
in Kilombero cluster. Systematic distance sampling technique using
line transect was used to obtain data for estimating population
density. Where a total of 15 transects were established in three
habitat types. Along each transect information about primate
sightings, occurrence locations, human disturbances and vegetation
structure were collected. Furthermore, a combination of field surveys
and data downloaded from Global Biodiversity Information Facility
was used to identify the current and future distribution of P.
gordonorum under the influence of climate change. Shannon Weiner
index was used to compute tree species diversity, Allometric models
was used for above ground biomass estimation, Generalized Linear
Model with Gaussian error function was run to determine the
influence of predictor variables on the density of P. gordonorum and non-parametric Kruskal Wallis test was used to test for significant
differences in every predictor variable. The results from this study
showed that the average density of P. gordonorum in MFR was
(27.4±22.12) individuals per km2 and it varied among the three
habitat types namely semi-evergreen, semi-deciduous and wooded
grassland with a density estimate of (44±11.3) individuals per km2,
(5.5±7.4) individuals per km2 and (1±0.5) individuals per km2
respectively. Vegetation structure, availability of preferred food tree
species and human disturbances was seen to influence the density
of P. gordonorum. Furthermore, findings from this study revealed
that, currently, the distribution of suitable habitats for the Udzungwa
red colobus monkey covers an area of 1 142 400 ha for highly
suitable habitats and these areas will decline to 392 000 ha and to
96 000 ha in 2050 and 2070 respectively according to RCP 8.5.
From the findings, isotherm and precipitation of the wettest month
were seen to greatly influence the current and future potential
distribution of suitable habitats for P. gordonorum. This study has
provided sufficient information on the status of P. gordonorum
population in MFR. And the impact of climate change on the
distribution of P. gordonorum. Furthermore, the study has helped in
the identification of high priority areas for conservation of the
vulnerable P. gordonorum. Finally, the study recommends for strong
management and conservation initiatives for those areas that P.
gordonorum have been predicted to occur. Such initiatives should
involve improved management capacity in the existing nature forest
reserves and village owned forests, protection of the existing wildlife
corridors to ensure habitat connectivity, the balance between socio-
economic gains and conservation and national wise mitigation
strategies such as the reduction of greenhouse gas emission. Thus, this
study calls for further research on mapping the distribution of
P.gordonorum with an account of climatic variables, vegetation
variables such as Normalized Vegetation Index (NDVI), percentage tree
cover, topographic variables, and proximity to human disturbances.
Description
MSc Dissertation
Keywords
Anthropogenic activities, Climate change, Distribution, Population density, Vegetation structure