Dates for the middle stone age of East Africa

Three potassium-argon age determinations on sanidine from crystalrich pantellerite and volcanic ash in the Main Rift Valley of central Ethiopia indicate that the Middle Stone Age of East Africa began prior to 180,000 years ago. This suggests that the technological developments which characterize the Middle Stone Age have a far greater antiquity than previously estimated.     

Butterfly distribution in fragmented landscapes containing agroforestry practices in Southeastern Brazil

Agroforestry practices, such as Shaded Coffee and Homegardens, may provide habitat for forest butterflies and contribute to their conservation in fragmented agricultural landscapes. To determine the influence of agroforestry practices in an agricultural mosaic, the distribution of fruit-feeding butterflies was studied using a systematic approach that compared butterfly species richness in six land-use practices (Eucalyptus [Eucalyptus spp.], Shaded Coffee, Homegardens, Secondary Growth, Pastures, and monocultures of Cassava [Manihot esculenta] and Sugarcane [Saccharum officinarum]), and in natural habitat (secondary Forest Edge and Interior) in two study areas (agricultural landscapes). In each study area, Van Someren-Rydon butterfly traps were placed as a grid every 150 m, creating quadrants of 2.2 and 2.4 km² that encompassed the different land-use practices. Land-use, plot area, number of traps and distance to the forest were set as covariates to compare species richness values. Butterfly species composition was compared using linear discriminant analysis (LDA). With the exception of Pastures, Cassava and Sugarcane, significant differences were not identified between the rest of the agricultural land-use practices and the forest habitats (edge and interior). The species composition in the agricultural practices was however, different to that found in forest habitats. Overall, Shaded Coffee practices that represent long-term mixed tree and crop stands have a better potential of conserving forest butterfly species compared to monoculture practices.     

Preliminary studies on the salt tolerance and sodium relations of common ornamental plants

The salinity tolerance of local varieties of five ornamental species Begonia, Chlorophytum, Coleus, Geranium, and Mesembryanthemum was assessed in a medium term pot experiment. The pot grown plants were watered for 50 days with water salinised at 5 dS/m and 15 dS/m and a tap water control. Based on growth parameters and on survival, Begonia was classified as salt sensitive, Coleus, Geranium, and Chlorophtytum as moderately tolerant, and Mesembry‐ anthemum as salt tolerant. Shoot sodium (Na) content was measured at the end of the experiment. It appears that the restriction of Na entry to the shoot is linked to salinity tolerance. Mesembryanthemum seems to be able to control Na entry to the shoot at water salinities above 5 ds/m.