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.