Discussion
During the current study period, a total of 10 species were identified.
This result is comparable to the report of Kabeta et al ., (2019)
from Wabe fragmented forest, Atnafu & Yihune (2018) from communal
forest of northern Ethiopia and Geleta & Bekele (2016) from Wacha
protected forest in the western Ethiopia. But, the mammalian species
diversity recorded in the current study area is very low compared to
other protection areas found across the country (Meseret and Solomon,
2014; Gonfa et al ., 2015; Negari et al ., 2015). The low
mammalian species diversity of the present study area might be
associated with a limited survey period, variation in the size of the
study areas, and severe habitat loss and fragmentation by various
anthropogenic pressures.
Vervet monkey (Chlorocebus aethiops ) and guereza (Colobus
guereza ) were the most abundant mammals identified in the current study
area. Similar result was also reported by several studies conducted in
different parts of Ethiopia (Gonfa et al ., 2015; Geleta and
Bekele, 2016). This high abundance of these primates may be also
associated with the wide distributional range of the species (Boboet al ., 2014) and their more adaptive nature to different
habitats (Gonfa et al ., 2015). In addition, this is may be due to
the high reproductive successes, diversified foraging behavior and high
tolerance level of primates to human disturbances (Bobo et al .,
2014).
The overall difference in abundance of medium and large mammal species
among three habitats was not statistically significant. But, natural
forest harbored more mammalian records (424), followed by Open grassland
(114) and the least was in Human plantation (15). The possible reason
for this distribution and diversity of medium and large-sized mammal
species might be due to the presence of food and water and stability of
the area from disturbances. Several mammalian studies, revealed that
there is a tendency of mammals to favor one habitat over the other
following the change in the abundance and quality of resources (Yimer
and Yirga, 2013; Atnafu and Yihune, 2015; Gonfa et al ., 2015;
Negeri et al ., 2015; Geleta and Bekele, 2016). Similar studies
conducted in different part of the world showed that mammalian
distribution and their habitat association correlated mainly with better
availability of water, foraging opportunity and protection (Mekonnenet al ., 2011; Yaba et al ., 2011). For instance, in the
current study, Vervet monkey (C. aethiopis ) was mostly seen at
the edge of the forest closer to the river forests and at the center of
the natural forest. Similar result is reported by Meseret & Solomon,
(2014). The presence of this species at the edge of the riverine forest
might be associated with a system of feeding on crops from shorter
distance and easier sheltering when back off. According to the finding
of Fetene et al ., (2011) and Geleta & Bekele, (2016) guereza (C.
guereza) largely selected riverine and large trees, but was totally
absent in the scrublands. Particularly, they dwelled the top canopy ofJuniperus, Podocarpus (the dominant tree) and Bamboo tree of
natural forest. This could be probably due to relatively surplus fruits
and leaves and better protection provided by those tall tree species.
According to Gonfa et al ., (2015), this is riverine habitats and
large trees are inaccessible to humans. In addition, since, the forest
habitat is relatively less disturbed, it might have also contributed a
refuge for the shy behavior of Guereza.
The low diversity and abundance of mammals in human plantation area
suggests that mammals prefer relatively less human disturbed areas. This
might be due to the small proportion of sampling, and the dominance of
homogenous plant species, Eucalyptus species that provide low foraging
and protection opportunity for large mammals (Gonfa et al ., 2015;
Negeri et al ., 2015; Geleta and Bekele, 2016). According to
Matias et al ., (2011), there is positive correlation between
habitat heterogeneity and animal species diversity. Furthermore, habitat
homogeneity was reported for lower diversity (Mekonnen et al .,
2011).
Though, Yotyet/Yewezera community forest is given to Atrifo Kidus
Giorgis church to be conserved, it is not free from the anthropogenic
activities pressure. Human activities such as illegal logging of trees
for fuel wood, extraction of construction materials, grazing by
livestock, human encroachment, were recorded during Field observations.
These human activities may alter this natural environment. Anthropogenic
activities affect the interactions, distribution and diversity of
species through habitat loss and modifications (Torres et al .,
2016). Deforestation and habitat loss threaten mammals by decreasing
area, connectivity, and fragment size, and increasing edge effects and
number of fragments of the natural landscapes (Bernardo and Melo, 2013).
Livestock were also seen in certain part of the habitats competing for
food with mammalian species particularly. Other studies (Gonfa et
al ., 2015; Kabeta et al ., 2019) also report the adverse effects
of livestock on wildlife. If these threats continue, there might be no
more chance to see the present floras and faunas of the study area.
Recently, numerous anthropogenic factors have promoted habitat loss and
fragmentation, and the decline and losses of global mammalian
biodiversity (Bernardo and Melo, 2013; Geleta and Bekele, 2016). Change
in vegetation community structure due to human activities could be
altering the availability and quality of food, shelter and water. This
might be lead to alter the diversity, abundance and distribution of
population of a particular habitats or it may lead to additional
problems such as risk of predation or cost of migration for searching
food (Mengesha et al ., 2011). Habitat disturbance has also a
negative impact for forest specialist species as they do not have any
alternative foraging or breeding sites (Asefa et al ., 2017).
According to Asefa et al ., (2015) allowing large and repetitive
livestock population in to unprotected area will also lead to los of
grassland specialist species.