Plant Succession on Tundra Mudflows: Preliminary Observations

Tundra mudflows are one of the characteristic features of arctic slopes with unstable soils. They generally occur during the early part of the thaw period, but may occur after a heavy rainfall. Only two relatively short-lived vegetation elements were evident and both are characteristic of disturbed sites. Islands of vegetation and soil of the type that dominate the slope before the mudflow are left scattered within the flow lines. Once a turf of grasses, sedges and herbs has formed the island, vegetation is able to colonize the turf mat. Areas where previous mudflows have occurred are clearly recognizable both by a long depression parallel to the direction of the slope and terminal fan of debris. Detailed studies on such naturally occurring phenomena would be of great value in view of increased use of heavy vehicular equipment by the oil and mining companies in the Canadian North

Resistance in maize to Sitophilus zeamais

Rev. versio

Traditional farmers' knowledge of Sorghum (Sorghum bicolor [Poaceae]) landrace storability in Ethiopia

Traditional knowledge of grain storage was studied on small farms in Ethiopia. Sixteen of sixty landraces of sorghum collected from small farms in Shewa and Welo regions of Ethiopia were identified by the farmers as being stored sorghum landraces. Farmers were interviewed and asked to rate the storability of these stored-sorghum landraces with respect to the major insect pest of the area, the rice weevil. A farmers' index of storability was then calculated for each landrace. The landraces were then assessed for rice weevil, Sitophilus oryzae (L.), susceptibility in standardized tests at 70% relative humidity and 27°C. The mean farmers' index for the 16 landraces was found to be inversely related with the susceptibility parameters of F1 emergence (r2=0.80), oviposition (r2 =0.76), weight loss (r2=0.88), and Dobie Index (r2=0.95). It was much less strongl