Abstract

Microarthropods have been found to be of immense advantage to soil fertility and plant life. Their abundance and diversity therefore are largely dependent on the presence of organic matters. Hence, the influence of floristic composition on abundance and species diversity of microarthropods were surveyed in soils under Secondary Forest, Gmelina arborea, Tectona grandis and Leuceana leucocephala plantations in Federal University of Agriculture, Abeokuta. Soil samples from the four land use types were collected randomly for the study. A total of 13,811 individuals of microarthropods (distributed among 74 taxonomic groups) were recorded in the studied habitats. A total of 46 mite groups were identified in four orders (Oribatida (18), Gamasida (8), Actinedida (7) and Collembola (13)). Twenty-eight other groups of microarthropods were also identified. Soil microarthropods abundance was highest (29.78%) in the Secondary forest while Gmelina, Leuceana and Tectona plantations had 28.40%, 20.96% and 20.85% respectively. Among the microarthropods identified, 46.02% belongs to oribatids family, 15.28% (Collembola), 5.78% (Gamasids), 3.01% (Actinedids) while the remaining 29.90% was classified under other microarthropods. Highest number (30.77%) of oribatid mites occurred in Gmelina plantation while the least (18.88%) in Leuceana. Collembola was found to be highest in Leuceana (32.51%) and lowest in Tectona (17.91%). Gamasid had the highest number in the Secondary forest (38.47%) and the least in Tectona plantation (11.15%). In Actinedid, highest number was found in Tectona (35.10%) while the least was in Gmelina (14.90%). Other arthropods that were classified occurred most in Gmelina (29.93%) while the least in Leuceana (17.49%). Dominance and diversity index for microarthropod count was highest in the secondary forest (19, 0.075) while the Leuceana (17) and Tectona (0.088) plantations recorded the least dominance and diversity respectively. Although chemical analysis showed that soil in the secondary forest were richer, physico-chemical parameters of the soil indicated that influence of soil properties on the distribution of microarthropods in the secondary forest and also, in the plantations were not significantly. Soil moisture content and microarthropods were significantly correlated at p 0.05. The relationship between pH and microarthropod abundance and diversity showed that they are significantly (p 0.05) correlated. The soil temperature of the study sites (27.26 to 28.15⁰C) was moderate for arthropods to thrive. This study confirmed that land use types influence diversity of soil mites. Hence adoption of land use types that conserve soil mites by the foresters will help promote ecosystem productivity.

Key Words: Diversity, Microarthropods, Abundance, Mesofauna, Vegetation, Composition