Seasonality and Structure of the Arthropod Community in a Forested Valley in the Uluguru Mountains, Eastern Tanzania

The structure of an arthropod community in the forest floor vegetation was studied in a low altitude (about 700 m a.s.l.) forest valley in the Uluguru Mountains near Morogoro, Tanzania, by monthly sweep net sampling during one year (December 1996–November 1997). The community structure of arthropods changed relatively little during the study period. Eight groups (Araneae, Hymenoptera, Heteroptera, Homoptera, Diptera, Coleoptera, Orthoptera and Lepidoptera) made up over 95% of all the arthropod individuals caught. There were seasonal peaks in the abundances. The highest numbers of arthropods per sample were found during the late rainy season and early dry season (May–August). Arthropod groups generally follow the rainfall pattern; in particular the abundance of Diptera, Hymenoptera and Hemiptera increases with rains.