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Regular evaluation of protected area operations can enable policy makers develop strategic responses to pervasive management problems.

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Spear grass (Imperata cylindrica, L.) is one of the most serious weed problems facing farmers in the derived savanna zone of Nigeria. The study was designed to evaluate various control methods that would effectively control this noxious weed and increase crop yield in an environmentally sustainable way. The treatments were laid out in a randomized complete block design and these included: Glyphosate only applied at 1.8kg per hectare eight weeks after planting cassava; Glyphosate applied at 1.0kg per hectare eight weeks after planting cassava followed by the planting of Mucuna pruriens; Hand weeding followed by the planting of Mucuna pruriens eight weeks after planting cassava; and Three hand weedings at four, eight and twelve weeks after planting cassava. Analysis of variance (ANOVA) was used to analyse the data. Glyphosate effectively eliminated Imperata shoot both at 1.8kg and 1.0kg active ingredient per hectare but not all the rhizomes were killed. Imperata rhizome dry weight were significantly (P < 0.05) lower in glyphosate plus M. pruriens cover crop (0.5kg/ha) seconded by hand weeding plus M. pruriens cover crop (4.0kg/ha) as against 8.6kg/ha and 25.7kg/kg obtained in glyphosate alone and hand weeding alone, respectively. Cassava tubers and stem yields were significantly (P < 0.05) high in glyphosate applied at 1.0kg/ha plus M. pruriens cover crop (34.9kg/ha and 76.8 bundles/ha respectively). The next significantly (P < 0.05) high yield of cassava tubers and stems (29.5kg/ha and 65.4 bundles/ha respectively) were obtained in glyphosate alone treatment. There was no significant (P > 0.05) difference between Hand weeding plus M. pruriens cover crop and Hand weeding alone in terms of cassava tuber and stem yields. Glyphosate (1.0kg/ha) plus M. pruriens cover crop was recommended as the best method of speargrass (Imperata cylindrica, L.) control.

Human Consumption of snail is as old as man himself. Interest in snail farming in Nigeria is on the increase. No work has been done on the stocking density of this species of snails in the Derived Savanna Zone of Nigeria. Optimal stocking densities of breeding and hatchling snails of Archachatina marginata ovum, (A. m. o. wainson) were determined through two experiments between January and August 1999. In the first experiment, reproductive performance of Archachatina marginata ovum (Swainson) stocked in cages at increasing density levels of 8, 20, 40, 60, and 80 snails/m 2 was determined using 208 adult snails in a randomized complete block design. Reproductive indices measured included: the number of clutches, the number of egg per clutch, mortality of adult snails, percentage hatchability of eggs, and mass (g) of day-old hatchlings. In the second experiment, growth indices of hatchling snails of Archachatina marginata ovum (Swainson) stocked in cages at increasing density levels of 25, 50, 75, 100 and 125 snails/m 2 were measured using 60 hatchlings with a mean mass of 13 + 2.5 g and mean shell length of 3.9 + 0.25mm in a randomized complete block design. The growth parameters measured included mass (g), shell length (mm) and feed intake (g). Analyses of variance (ANOVA) followed by Duncan's Multiple Range Test where necessary were used to analyse data. For the breeding snails, treatment with 8, 20 and 40 snails/m 2 had mean mortalities of 0.0%, 8.3% and 6.0, respectively. These were not significantly different from each other but were significantly different (P<0.05) from treatments with 60 and 80 snails/m 2 (15.9% and 19.4% respectively). Eight snails/m 2 was found to be uneconomical. Twenty to 40 snails/m was found to be the optimal stocking density of breeding snails of A.m.o. This range is recommended for use in snail farms. For the snail hatchlings, treatment with 50, 75 and 100 snails/m 2 had mean daily mass gains of 6.6g, 3.8g and 3.3g; mean feed conversion rations of 4.3, 8.7 and 12.4; and mean shell length gains of 3.0 mm, 2.5 mm and 1.6 mm respectively, which gave some significant differences (P<0.05) from each other. Fifth snail hatchlings/m 2 was found to be uneconomical. The optimal stocking density of snail hatchings of A.m.o. was found to be between 70-100 snails/m 2. This range is therefore recommended to be used in snails' farms. It is also recommended that the