Sampling Design and Sampling Techniques
The diversity and threats of medium and large mammals in Arjo Diga
Forest and its environs were studied using systematic wildlife survey
techniques (Norton-Griffiths, 1978). Mammalian diversity was measured
using stratified sample approaches in a variety of habitats, including
dense forest, shrubs, grassland, and cropland based on the vegetation
structure and topography of the landscapes ( Girma et al ., 2012;
Mamo et al ., 2012). In the case of stratified habitat types,
transect lines were inserted at random and proportional to the habitat
type’s area (Varman & Sukumar, 1995). Transect line method was used to
estimate the abundance and density. The adjacent transects were at least
1 to 2km apart and all transect lines were roughly parallel to each
other and their ends were not less than 1km far from the habitat edge
(Regassa & Yirga, 2013) and the transect length was measured and
located in the study area with the help of GPS location. The sample
transect was covered 25% (15.84 km2) of the study
area (63.35 km2). A total of 32 line transects were
established across the four major habitat types. The number of transects
varied among habitats depending on the area cover of each habitat: 12 in
the dense forest, 15 in shrubs, 3 in crop land, and 2 in grassland
habitat. The size of every transect line was once 5 km and a constant
sighting distance of 100 m on each aspect of transect was used in the
habitat. In addition to direct observation of stray animals, oblique
proof was used to the habits survey; it is one of the excellent methods
for estimating the abundance of exceedingly massive and conspicuous
mammals (Krebs, 2006). Therefore, combining the diurnal lines‐transect
with oblique surveys (including sparkling tracks, feces, hair, horns,
burrows, and digging) can beautify the detectability for many mammal
species, contributing to maximize the species lists( Larsen, 2016).
Additionally, to collect data on the current threatening variables,
semi-structured open and closed-ended questionnaires, interviews, and
direct and indirect observations were used. The Arjo Diga forest was
fractured in eight of the Diga district’s 24 Kebeles. A total of 80
people (10 people per sample site) participated in an interview
questionnaire survey and a group discussion to identify present problems
and conservation concerns, as well as possible future solutions.