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.