Articles by Author: B H Walker

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  1. The systems approach to ecological research

    The systems approach to ecological research

    The systems approach to ecology developed from a recognition that studying the separate parts of an ecosystem was not enough. Accepting that there should always be room for individualistic research, the greatest need at present is for multi‐disciplinary systems studies...
  2. 1. An assessment of the ecological basis of game ranching in Southern African savannas

    1. An assessment of the ecological basis of game ranching in Southern African savannas

    Game and cattle ranching are compared at the three successive levels of primary production, efficiency of vegetation use and secondary production, It appears that the increase in grass growth following bush clearing more than offsets the loss in edible browse,...
  3. Feeding niches of four large herbivores in the hluhluwe game reserve, natal<sup>1</sup>

    Feeding niches of four large herbivores in the hluhluwe game reserve, natal<sup>1</sup>

    The differences and similarities between buffalo, zebra, wildebeest and white rhino, with respect to the variables characterizing their feeding localities, were determined using a discriminant function analysis. The dimensions of the community niche are described using the Latent Roots and...
  4. Stable production versus resilience: A grazing management conflict?

    Stable production versus resilience: A grazing management conflict?

    The dynamics of grazed semi‐arid savannas are analysed in terms of four main variables, viz. grass, woody vegetation, soil moisture and herbivore stocking rate. It is contended that under conditions of good veld management the composition and structure of the...
  5. Growth patterns and annual growth cycle of <em>Acacia karroo</em> Hayne in relation to water stress I. Leaf and shoot growth

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    A field study was conducted to describe the growth patterns of A. karroo at different levels of water stress in different edaphic situations.
  6. The role of competition in the spacing of savanna trees <em>die rol wat kompetisie in die spasieering van savanne bome speel</em>

    The role of competition in the spacing of savanna trees <em>die rol wat kompetisie in die spasieering van savanne bome speel</em>

    Past and present research on savanna rangeland has emphasized the role of tree — grass interactions as the limiting factor in the woody — grass balance. The present study examines tree — tree interactions in savannas through the use of...
  7. The response of the herbaceous layer in a dystrophic Burkea Africana savanna to increased levels of nitrogen, phosphate and potassium

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    Plots of herbaceous vegetation in a natural savanna were treated with various levels and combinations of N P K fertilizer, over a period of four years. Variation between replicate plots was high, both within and between years. This can be...
  8. A gradient analysis of grassed mountain catchments in the natal Drakensberg

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    An indirect gradient analysis was carried out on vegetation and environmental data from the Mdedelelo Wilderness Area of Cathedral Peak State Forest in Highland Sourveld. Vegetation ordination axes were correlated with environmental variables deduced to have influenced species‐composition. Altitude proved...
  9. Effect of intensity of defoliation by goats at different phenophases on leaf and shoot growth of <em>acacia karroo</em> hayne

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    Defoliation by goats (leaves plus shoots) during the growing phenophases resulted in a considerable stimulation of leaf and shoot growth relative to non‐defoliated plants. The response differed considerably depending on the intensity and phenophase of defoliation. Plants were most susceptible...
  10. Simulating browse production and response of <em>Acacia karroo</em> to defoliation I. Model description and sensitivity analyses

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    The model is aimed at synthesizing existing data to enhance the understanding of this data and explore the consequences of possible browse management strategies. It gives a good reproduction of the shoot and leaf growth responses used to develop it...