Abundance and diversity of soil arthropods in disturbed and undisturbed ecosystem in Western Amhara, Ethiopia

Arthropods are indispensable because of their role in the food chain and in the recycling of ecosystem resources. The objective of the study was to assess the diversity and abundance of soil arthropods in selected habitats in northwestern Ethiopia. Soil arthropod taxa richness and abundance were estimated using transect sampling from January 2019 to May 2020. Data were analyzed using analysis of variance, diversity indices, detrended correspondence analysis, and cluster analysis. A total of 5512 arthropods were found, i.e., 2585 macro- and 2927 micro-arthropods. Fifty-seven percent (3054) were found in the forest, 29% (1670) in the grassland and 14% (788) in the cultivated area. According to the Shannon-Weaver index, species diversity of soil macro-arthropods was higher in the forest and grassland (H ' > 2) habitats than the cultivated ((H ' < 2); Pielou's evenness showed that micro-arthropods were found to be more evenly distributed (J > 0.9) than macro-arthropods (J < 0.9). Macro-arthropods showed more Menhinick species richness (range: 0.37 to 0.63) than micro-arthropods (range: 0.13 to 0.24); Margalef index showed similar pattern. Berger-Parker dominance was higher on micro- (> 0.37) than macroarthropods (< 0.33). Macro-arthropods had higher Chao 1 index (12 to 14) than micro-arthropods (5). Number of soil arthropods varied significantly between habitats and between sampling dates (macro-arthropods: F = 16.5, df = 153,224, P < .0001; micro-arthropods: F = 15.7, df = 54, 80, P < .0001). The detrended correspondence analysis showed relationships between habitats and soil arthropods (e.g., wasps were relatively more associated with the forest habitat), and the cluster analysis grouped the different soil arthropods based on their degree of similarity in abundance (e.g., ants and termites stood out clearly separated). Biomass and soil moisture content was relatively less in March. The present study confirmed that soil arthropods thrived generally more abundantly in undisturbed habitats (forests) than in cultivated and grasslands. This implies the need to step up conservation schemes in more representative sites in this ecosystem.