Agriculture plays an important role in Botswana, providing food, income, employment and investment opportunities for the majority of the rural population. However, over the last two decades, the contribution of agriculture to the economy and rural development has declined leading to a progressive increase in food imports. Low growth in the agricultural sector has been attributed to low productivity, which could be attributed to the recurring drought conditions that prevail in many parts of the country, and partly by the small scale of farms. Remarkably, this decline in agricultural performance in Botswana has coincided with a period of major policy reform, the objective of which is to improve agricultural performance. This study measures the performance of the agricultural sector and investigates the reasons for continuing decline in spite of considerable public expenditure. Using panel data from 1979 to 2012, the study calculates various indicators to assess the different drivers of the performance of the sector across different agricultural districts, agro-ecological regions, production systems and sub-sectors. A nonparametric approach is employed to examine trends in agricultural productivity in six regions of Botswana. Measures of total factor productivity (TFP) are obtained and decomposed into various sources including efficiency change (technical, scale and mix efficiency) and technical change. The results show that TFP declined due to a fall in overall efficiency at 3.1 per cent per annum. Moreover, a parametric stochastic distance frontier approach is used to examine sources of efficiency, productivity and output growth and the possible reasons for the decline in productivity. It was found that the main driver of productivity is improvement in technical efficiency. The results show that various programs introduced during the study period did not lead to any improvement in productive efficiency. Results from both parametric and nonparametric approaches indicate that overall efficiency varies from region to region, which suggest that there is a scope for improving productivity by taking a differential regional approach to efforts aimed at increasing efficiency.

Plant species diversity on the North-West Slopes of New South Wales is threatened by pastoral management activities, both past and present. Native vegetation has been extensively cleared for livestock grazing, which has created a landscape in which only remnants of original vegetation are retained. However, large areas of derived native pasture have been retained on private grazing land, providing habitat for many native flora and fauna. This thesis investigates the patterns of plant species distribution across the region to determine the contribution of each of the major land uses to regional plant diversity. A particular focus was on the impact of land management at broad (landscape and regional) spatial scales.

Scattered paddock trees are keystone features in temperate grazing landscapes in Australia. These scattered trees provide a range of ecological functions, and the impact of these trees on the environment is large relative to the small area they individually occupy. However, our understanding of the influence of these trees on their immediate environment is limited. In this thesis, the effects of scattered mature Eucalyptus trees on both native and sown pasture systems are examined in the temperate landscapes of the Northern Tablelands of New South Wales, Australia. Specifically, the influence of scattered trees on soil fertility, litter distribution, the nutrient pools in litter, pasture production and nutrient status, as well as the root distribution of a mature tree and the influence of shade on pasture biomass, are observed. The coarse tree roots (≥10 mm) of a scattered tree decreased with increasing depth in the soil and distance from the tree, forming a broad inverted conical structure. Most roots were largely restricted to within 2 canopy radii of the tree, and 80% of coarse roots were found below 20 cm in the soil profile. This suggests that coarse tree roots and pasture roots are unlikely to compete for the same soil resources because they occur largely at separate depths in the soil profile.