Abundance and biodiversity of soil mesofauna in different layers of conifers forest soils

In order to investigate the diversity and population fluctuations of soil mesofauna (Acari and Collembola) of conifers (cypress and pine trees) at Ilam province, Iran, soil samples monthly (0–5 and 5–10 cm) were collected during September 2018 to September 2019. The soil mesofauna were extracted using a Berlese funnel and they were counted and identified. The number of arthropods was compared in different soil layers and in different seasons of the year. The analysis of variance of data showed that soil layers and seasons had significant effect on the population densities of soil mesofauna in both cypress and pine trees (P≤0.01), but their interaction did not vary significantly. Based on the means comparisons, the highest and the lowest values of population density of soil mesofauna were ​​belonged to cypress trees with values of 26.5±8.22 (at autumn) and 0.74±0.15 (at summer). In addition, based on the mean comparison, the highest and the lowest amount of population density of soil mesofauna in pine trees were 4.31±1.26 (at autumn) and 0.63±0.14 (at spring). Diversity of arthropods was calculated by using biodiversity indices. The results showed that the most diversity of species based on Shannon-Wiener and Simpson indices observed in seasons and sampling area (cypress and pine trees) with values of 3.77 and 0.97 for pine and summer time and the least diversity detected with 2.44 and 0.83 for cypress and spring time, respectively. Also, the highest amount of species richness of Margalef (11.68) related to the soil of pine trees in autumn season and lowest amount (7.89) related to the soil of cypress trees in spring season. The highest values ​​of Pielou evenness index (0.97) related to soil of pine trees in summer time and lowest value (0.64) related to the soil of cypress trees in spring time. Generally, the calculated biodiversity indices in the soil of pine trees were higher than in the soil of cypress trees, which could be more widely used in the forestry system