Showing papers on "Biodiversity published in 1983"

Studies on the arboreal marsupial fauna of eucalypt forests being harvested for woodpulp at Eden, N.S.W. II. Relationship between the fauna density, richness and diversity, and measured variables of the habitat

Abstract: The relationships were examined between measurements of forest habitat (10 explanatory variables: X) and densities of three species of arboreal marsupials (greater glider, feathertail glider and sugar glider); the sum of these three and an additional five species that occurred; species richness and diversity of all eight species present in the area (six response variables: Y). The habitat variables were: landform profile; elapsed time since a severe fire; degree of forest maturity (total basal area of wood); an index of den tree density; ratio of number of regeneration size trees to den trees; floristic diversity; basal area of peppermints; basal area of gums; basal area of eucalypts with a low level of nutrients in their foliage; and an index of potassium concentration in the foliage. The principal component transformation of the X set of variables (PCA) was used as an aid to interpret the individual response of Y to joint intercorrelated explanatory variables X. The regressions of Y on PCA-transformed X explained 76.2% of variation in density for the greater glider, 50.4% for the feathertail glider, 21.1% for the sugar glider, 68.3% for all arboreal marsupials, 49.7% for species richness and 30.1% for species diversity. The weak regressions obtained for densities for the sugar glider were attributed to probable non-measurement of important understorey habitat variables for this species, and those for species richness and diversity, to the presence of a curvilinear rather than linear relationship to foliage nutrients. The gradient in foliage nutrient concentration appears to be the major determinant of the density and species richness and diversity of arboreal marsupials in the Eden forests. Exceptions to the trend seem to occur where the forests include certain xeromorphic eucalypt species that are high in foliage nutrients yet poor in fauna, and, for the feathertail and sugar glider, in those sections of the Eden forests exhibiting fire successional stages and that are usually composed of eucalypts with low nutrient levels in their foliage.

Plant species richness at the 0.1 hectare scale in Australian vegetation compared to other continents

Abstract: New data are reported, and literature data compiled, for species richness in 0.1 ha plots in Australian vegetation. We conclude that on present evidence the same vegetation types are rich, and the same types poor, at a 0.1 ha scale, in Australia as elsewhere. Tropical rainforest averages 140 species per 0.1 ha in permanently humid types. Temperate sclerophyll shrub-dominated types on low-nutrient soils are generally in the range 50–100 species, with open woodlands somewhat richer than scrublands. Warm semi-desert shrublands can have 50–80 species, counting ephemerals both of summer and of winter. Temperate closed forests generally have fewer than 50 species per 0.1 ha. For none of these types is there clear evidence that they are richer or poorer in species at a 0.1 ha scale than types in similar environments with similar growth-form mixes on other continents. We give data for grassy woodlands and sclerophyll scrublands in the monsoonal tropics; the fragments of data on such types available from other continents suggest there may be a wide range of species richness in sub-types of this very broad grouping. Generally, available data do not support the idea that floristic evolutionary history is a strong influence on the species richness of vegetation at the 0.1 ha scale, relative to the influence of the present-day climatic and soil environment.

Diversity relations in Cape shrublands and other vegetation in the southeastern Cape, South Africa

Abstract: This paper investigates, and seeks explanations for, the diversity relations of Cape shrublands (fynbos and renosterveld), subtropical thicket and Afromontane forest, in the biogeographically complex SE Cape. Global comparisons of richness at the 0.1 hectare scale, of communities in the study area and elsewhere in South Africa with analogous vegetation on other continents, were largely inconclusive. Reasons for this are the unexplained variability of richness within vegetation types, problems associated with the scale of diversity used, and difficulties in defining analogous vegetation types. Diversity comparisons within the Cape Region and within the study area communities showed that alpha diversity of fynbos was not consistently higher than other vegetation types. In the study area highest richness was recorded in renosterveld and highest equitability in subtropical thicket; the most species-poor communities were Mountain Fynbos and Afromontane forest. The results of a correlation analysis showed that an index of phytochorological diversity was the factor most strongly correlated with richness in all vegetation types. Soil nutrients did not emerge as significant correlates of diversity except in fynbos where low levels of available nutrients were associated with low values of phytochorological diversity and low species richness. The diversity of fire-prone and grazed communities could be partly explained by non-equilibrium models of species diversity. Ecological and historical hypotheses were presented as explanations for the richness of communities having island-like distributions in the study area. It was generally concluded that historical and ecological factors should be given equal weight in descriptive studies which seek regional and global explanations of the evolution and maintenance of species diversity.

Alien trees, shrubs and creepers invading indigenous vegetation in the Hluhluwe-Umfolozi Game Reserve Complex in Natal

Abstract: The results of a survey and monitoring programme conducted in the Hluhluwe-Umfolozi Game Reserve Complex in Natal are presented. The area consists of 900 km2 of savanna and forest vegetation. Twenty alien tree, shrub and creeper species currently invading indigenous vegetation within the Complex are listed. Herbaceous aliens were not surveyed. An analysis of the habitats being invaded by these alien plants is presented and it is concluded that riverine and forest-edge habitats are those most seriously threatened by alien plant infestations. The distribution, nature and history of the infestations of each species are summarized. Distribution maps given for the eight species which are currently most important in the Complex. The potential threat posed by each species is estimated and the species are ranked in order of priority for control action. The South American composite, Chromolaena ( Eupatorium ) odorata, is identified as being the alien species currently posing the greatest threat to natural vegetation in the Complex. The Asian tree, Melia azedarach, is considered the second most important alien species invading the area. It is concluded that both these species should be declared noxious weeds throughout the Republic and that research into their biological control is urgently required.

Evaluation of economic forest ecosystem services in China

Abstract: This paper quantitatively evaluated the economic forest ecosystem services in the provinces of China in 2003, based on the long-term and continuous observations of economic forest ecosystems in this country, the sixth China national forest resources inventory data, and the price parameter data from the authorities in the world, and by applying the law of market value, the method of substitution of the expenses, and the law of the shadow project. The results showed that in 2003, the total value of economic forest ecosystem services in China was 11763.39 x 10(8) yuan, and the total value of the products from economic forests occupied 19.3% of the total ecosystem services value, which indicated that the economic forests not only provided society direct products, but also exhibited enormous eco-economic value. The service value of the functions of economic forests was in the order of water storage > C fixation and O2 release > biodiversity conservation > erosion control > air quality purification > nutrient cycle. The spatial pattern of economic forest ecosystem services in the provinces of China had the same trend with the spatial distribution of water and heat resources and biodiversity. To understand the differences of economic forest ecosystem services in the provinces of China was of significance in alternating the irrational arrangement of our present forestry production, diminishing the abuses of forest management, and establishing high grade, high efficient, and modernized economic forests.

Species number, area and habitat diversity in the Galapagos Islands

Abstract: The Galapagos vascular plant species are divided into two groups, showing preferences for dry and wet habitats This division is based on the results of a phytosociological study and is not influenced by such factors as island area, elevation, climate or soil types The different distribution patterns of the dry and wet species are discussed and it is concluded that habitat diversity offers a better explanation for species numbers and distribution patterns than do island size and isolation Claims that a dynamic MacArthur-Wilson type equilibrium has been reached for vascular plants in the Galapagos archipelago seem premature

Comparative Ecology of Pardalotes, including the Forty-Spotted Pardalote, Pardalotus quadragintus (Aves : Pardalotidae) in SOuth-Eastern TAsmania

Abstract: Three species of pardalote co-occur only in eastern Tasmania. We examined habitat selection and foraging ecology of the three species, Pardalotus punctatus, P. quadragintus and P. striatus, in that area. Overlap and similarity between all three species was high in both foraging activity and habitat choice. All three species are specialized leaf-gleaners and favoured Eucalyptus virninalis forests. The distributions of the species were related to Eucalyptus species diversity, species of Eucal.vptus dominant, disturbance, and number of hollows and overmature trees at sites. It is suggested that there is substantial interaction between P. quadragintus and P. striatus and that this may affect the distribution and abundance of the restricted and declining P. quadragintus.

Weed flora of South Africa 2: power shifts in the veld

Abstract: This paper, the second in a series analysing data from the National Weed List, concentrates on weedy changes that affect the indigenous flora. The incidence of weediness and of threatened species is used as an indication of success or failure of families under prevailing conditions of disturbance. The resulting power shifts between indigenous families and the impact of exotic weeds on the situation are reviewed. Many power shifts are taking place between indigenous species in the veld. Superficially it seems as though a relatively few invasive species are displacing a larger number of threatened species, but evidence from Natal points to more species increasing than decreasing under conditions of over-utilization. Amongst small families power shifts are almost as prevalent and important as at species level. Seventeen small families have over 20% indigenous weed species. Thirty small families have over 20% threatened species, and 21 small families have had their species numbers bolstered by more than 20% by exotic weeds. A very few large and medium-sized families contain over 50% of our weeds and our threatened species. It is mostly temperate (Cape) families that are under pressure relative to more tropical families. This trend is echoed at sub-family level within the Fabaceae.

Threatened plants at the south-western corner of Africa

Abstract: An account is given of the extent of floristic and habitat destruction in the area currently and formerly covered by the Cape Floristic Kingdom. An evaluation is given of the proportions of habitat threats and other factors affecting a sample of critically rare species. It is shown that invasive plants introduced from other countries pose a major threat to critically rare species in the areas where natural vegetation has not been fully replaced by suppressive land-uses. The value of the Cape Flora as a genetic resource for purposes such as an expanding cut-flower export-industry is demonstrated and research needs in this field are outlined.

Weed flora of South Africa 3: more power shifts in the veld

Abstract: This paper deals with shifts towards plants with particular life cycles, growth forms, or from particular geographic areas. Exotics probably have their greatest impact in the aquatic habitat where they almost equal in number of species (the ratio is 3:5) and out-perform the indigenous aquatic flora. In the streambank habitat exotic weed species, mostly trees, outnumber indigenous weed species by more than 3 to 1. They are completely replacing indigenous streambank communities in many places. An investigation of their effect on stream flow and water loss is urgently required. The problems of the winter rainfall area are highlighted by the fact that it has 300% more indigenous species and 109% more weed species per unit area than the summer and all year rainfall areas. In the veld as a whole there is a significant and so far unremarked invasion by exotic annuals. The major invasive weed groupings are herbs from Europe and Asia and trees from Australia but South America probably has the greatest potential to provide us with new and dangerous weeds. A comparison of the weed floras of the southern continents could contribute much to an understanding of our own weed flora.