Soil Fauna of Ranibari Community Forest, Kathmandu, Nepal

Ranibari Community Forest (RCF) is the important forest patch present within the highly urbanized Kathmandu Valley with information gaps on soil fauna. This study aimed to explore the soil meso and macrofauna of the forest. Fourteen random quadrats (1 × 1 m²) were laid within seven blocks. Leaf litter samples and soil cores were collected, screened, sieved, and searched under a white sheet, once a fortnight from May to November 2019. The results showed that the diversity, abundance, and richness of soil fauna were the highest in the summer season (H´ = 2.897, abundance = 1,973, S = 84) dominated by Collembola. The Soil Biological Quality Index (QBS-ar) value was also found to be the highest in summer (QBS-ar = 417) and successively decreased in succeeding seasons. Soil fauna was diverse and evenly distributed in soil layers throughout the seasons, but the abundance was greater in leaf litters, particularly in summer. Fauna like Chilopoda, Diplopoda, Haplotaxida, and Isopoda were seen to be affected negatively by soil temperature in summer and autumn seasons. Soil moisture content was found to be positively correlated with immature insects, earthworms, and millipedes in the rainy and autumn seasons. Besides, the pH of the soil was seen to affect Diplura only in the autumn season. The relation of fauna with the physicochemical parameters (temperature, moisture, and pH) and also with other taxa showed their ecological roles and adaptation to a specific microclimate.