Abundance and diversity of soil invertebrate macro-fauna in different land uses at Shenkolla watershed, South Central Ethiopia

Abstract

BackgroundLand use can exert a strong influence on the abundance, diversity, and community composition of soil macro-fauna. This study was conducted to evaluate the effects of four land use types on the abundance and diversity of soil invertebrate macro-fauna communities. These land uses include forest land, grazing land, crop cultivated outfields, and homestead garden fields present at Shenkolla watershed, south central Ethiopia. Monolith sampling of soil macro-fauna was done according to the standard of Tropical Soils Biology and Fertility Institute (TSBF) procedure. Five sampling points were chosen in each land use type and small monolith (25 × 25 × 30 cm) was dug out at 5-m interval along a transect with randomly positioned starting point, but perpendiculars to the slope. A total of 20 monoliths (4 treatments × 5 replications) were taken across all the land use types. Sampling of SIMF was carried out in April 2019 where soil macro-faunas are known to be more active. To evaluate the SIMF community eight parameters were measured: Shannon-Wiener index, Simpson diversity index, Pielou’s measure of evenness, Margalef’s diversity index, the Number of Occurrence Index, Relative abundance, Density (individuals per square meter) of each taxon and density of all SIMF and Bray-Curtis similarity index. The data were further analyzed using ANOVA and a general linear model to determine the variation and the influence of land use type, respectively.ResultsIn general, 332 individuals, 10 orders, 12 families, and 15 species were identified, from the collected samples. There were significant differences (p < 0.05) among the four land use types for SIMF except wireworm, spiders, and millipedes. Overall abundance and diversity were lowest in the crop cultivated outfields and highest in homestead garden fields and forest land. Bray-Curtis’ similarity was highest between the sampled sites s16 and s19 with in the forest land, and lowest (2%) between sites s1 (crop cultivated out fields) and s14 (homestead garden fields).ConclusionThe results revealed that the diversity of SIMF was positively influenced by forest land and homestead garden fields and negatively influenced in grazing land and cultivated outfields. Therefore, maintenance of a continuous litter cover at the surface and application of a wide range of organic fertilizers (farmyard manure, household refuse, and compost) is very much critical to prevent the decrease in diversity of SIMF.