Articles by Keyword: Diversity Indices

Search results for Diversity Indices

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  1. OBSERVATIONS ON TEMPORAL TRENDS IN PHYTOPLANKTON DIVERSITY IN THE VAAL RIVER AT BALKFONTEIN, SOUTH AFRICA

    OBSERVATIONS ON TEMPORAL TRENDS IN PHYTOPLANKTON DIVERSITY IN THE VAAL RIVER AT BALKFONTEIN, SOUTH AFRICA

    Item type: Journal Article • Journal: Journal of the Limnological Society of Southern Africa
    Phytoplankton diversity in the Vaal River at Balkfontein from March to October 1984 was investigated by employing different diversity indices. Most diversity indices showed appreciable variation during the study period indicating specific temporal trends. Greatest diversity was demonstrated for warmer...
  2. Life form and species diversity on abandoned croplands, Roggeveld, South Africa

    Life form and species diversity on abandoned croplands, Roggeveld, South Africa

    Item type: Journal Article • Journal: African Journal of Range & Forage Science
    The Roggeveld consists of an island of Mountain Renosterveld (Fynbos biome) surrounded by Succulent Karoo biome vegetation. Since management of abandoned croplands depends on a better understanding of their succession sequences, vegetation recovery on abandoned croplands in the Roggeveld was...
  3. Benthic freshwater nematode community dynamics under conditions of Tilapia aquaculture in Egypt

    Benthic freshwater nematode community dynamics under conditions of Tilapia aquaculture in Egypt

    Item type: Journal Article • Journal: African Journal of Aquatic Science
    Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr...
  4. Reductions in Plant Species Richness under Stands of Alien Trees and Shrubs in the Fynbos Biome

    Item type: Journal Article • Journal: South African Forestry Journal
    The reduction of species richness of indigenous plants is one of the major problems associated with the presence of dense stands of invasive alien trees and shrubs in the Fynbos Biome of the Cape Province, South Africa. A synthesis was...
  5. Seasonal Fluctuations and Diversity of Bark and Wood-boring Beetles in Lowland Forest: Implications for management Practices

    Item type: Journal Article • Journal: South African Forestry Journal
    The phenology and diversity of wood-living beetles attacking Cedrela mexicana, Khaya nyasica and Milicia excelsa were observed for one year with weekly window-flight-trap collections. A total of 150 species (10 known to be common pests of timber) were collected, most...
  6. A mathematical model for assessing the influence of stocking rate on the incidence of droughts and for estimating the optimal stocking rates<sup>1</sup>

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    The Putu 11 simulation model was used to simulate veld production for each of 47 years, using weather input data and soil properties of a site at Glen. Grassland drought was defined as that condition encountered when 100 kg/ha or...
  7. A preliminary investigation of woody plant increase in the western Transvaal and implications for veld assessment

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    The relationships between tree density and indices of pasture and soil condition were examined in Western Transvaal grasslands where Acacia karroo had increased following disturbance. The correlation between tree density and pasture condition was not linear, indicating a threshold in...
  8. Vegetation response to wagon wheel camp layouts

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    Wagon wheel camp layouts have been favoured, in some quarters, for rotational grazing due to the economy and convenience of having the camps radially arranged around central facilities. A possible disadvantage of such layouts is the tendency for over‐grazing near...
  9. A comparison of several nitrogen- availability indices on four Natal maize-producing soils

    A comparison of several nitrogen- availability indices on four Natal maize-producing soils

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Four methods used in obtaining nitrogen-availability indices were compared using soil and plant samples taken from maize trials conducted on four widely differing Natal soils. NO3 − N was determined after extraction of the soil with NH4HCO3, Ca(OH)2 and KCl,...
  10. Diversity, abundance and behaviour of diurnal insects on flowering capitula of commercial sunflower in the Transvaal

    Diversity, abundance and behaviour of diurnal insects on flowering capitula of commercial sunflower in the Transvaal

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Sunflower, Helianthus annuus L., is an insect-pollinated crop and the different insect taxa visiting the flowering head play a role of greater or lesser importance in cross-pollination. Species diversity, abundance and behaviour of insects visiting commercial sunflower during flowering are...