Soil-living nematodes of a savanna community in Botswana: A preliminary report

A quantitative study was made of the soil-living nematodes in a natural savanna community located on the University of Botswana campus. Preliminary identifications produced 38 species in 33 genera, 14 families and seven orders. Nematode densities were measured beneath the grasses Panicum maximum, Schmidtia pappophoroides and Eragrostis sp., and were respectively 6,360,125, 2,388,250 and 2,039,375 m−2 in the top 100 mm of soil. These relatively high densities compared with those recorded in similar studies elsewhere in Africa probably reflect the high productivity of these grasses. P. maximum, in particular, is a very productive perennial which favors shaded, relatively moist environments. Unlike most soil habitats, the soil at 50–100 mm depth had as many nematodes as at 0–50 mm depth. Measurement of soil moisture content showed a greater percentage of soil moisture at 50–100 mm which, combined with high soil surface temperatures, may explain the relatively high densities at the greater depth. A search of the literature for other records of soil-living nematodes from Botswana located 12 formal and informal records which, combined with the species identified in the present study, produced a list of 82 species reported from Botswana.

► Thirtyeight nematode species were found in a Botswana savanna.
► Nematode densities beneath three grass species ranged from 2,039,375 m−2 to 6,360,125 m−2
► These densities are high compared with nematode densities in other African ecosystems.
► Eighty two species of soil-living nematodes have been reported from Botswana.