Study area
This study was undertaken in Kween District located at 01 25N, 34 31E found in the Mount Elgon agro-pastoral landscape. This highland district is located on the Northern slopes of Mount Elgon, at an average altitude of about 1,900 meters (6,200 Feet, above sea level). The slopes of Mt. Elgon are characterized by high and well-distributed rainfall (averaging 1,200 mm/year), high altitude with deep valleys (ranging from 700 to 2,800 meters above sea level), cool temperatures (averaging 17˚C), and predominantly volcanic soils.
The major economic activity is subsistence farming and the major crops grown are; maize, beans, bananas, wheat, barley, and cowpeas. Whereas the soils of the area are perceived to be fertile, the area experiences a lot of inorganic fertilizer application. Farmers apply fertilizers due to the loose nature of the soils and the problem is aggravated by heavy rains. The study sites -Kaptum and Cheminy sub-counties- were selected because they have approximately three-quarters of the five main land uses considered for this study, which include grassland, maize mono-crop, natural forest, maize-beans, and coffee-banana land uses.
Study design
Within each land use, three plots were established and replicated 50 m apart. In each replicate, a sampling point for surface and below ground biota assessment was randomly selected. For surface and below biota assessment, a pitfall trap and monolith were installed respectively. The pitfall trap method was used to trap the surface crawling macro fauna, both diurnal and nocturnal ones. The pitfall method involved laying a 3liter bucket into the ground; the top leveling off with the surface. The surrounding area of the bucket was restored to its natural state. In the bucket, 50 ml of 70% ethanol was added in order to demobilize and preserve the trapped organisms. The trapped organisms were removed every after 24 hours for 3 days and packed in well-labelled plastic bottles containing 70% ethanol. On the other hand, the monolith measuring 30 × 30 × 30 cm was used to collect below-ground macro-organisms. The monolith was built into the soil but 8 m from the pitfall trap in each land use. All the soil within the monolith was put in clean and marked plastic bags. All the organisms collected using the pitfall trap and monolith were taken to Makerere University College of Agricultural and Sciences Soil Laboratory for analysis and macro fauna identification.
Data analysis
Data was analyzed using Real Statistica Statistical Software Package. Descriptive statistics were used to obtain frequencies and consequently species richness and abundance. Simpson’s diversity index was used to compute the species diversity. Differences in diversity between subsurface and belowground macro fauna was tested using Wilcoxon’s rank sum test whereas the Kruskal-Wallis H test was used to test differences in diversity between the different land uses [18].