Showing papers on "Biodiversity published in 1987"
TL;DR: In this paper, the authors describe a tallgrass prairie from Konza Prairie, Kansas, USA with respect to plant species compositional changes over a five-year period in response to fire and topography.
Abstract: Native unploughed tallgrass prairie from Konza Prairie, Kansas, USA is described with respect to plant species compositional changes over a five year period in response to fire and topography. The principal gradient of variation in the vegetation is related to time since burning. Species show an individualistic response in terms of relative abundance to this gradient. Both the percentage of and cover of C4 species and all grasses decrease as the prairie remains unburnt. Forb and woody plant species numbers and abundance increase along this gradient. A secondary gradient of variation reflects topography (i.e. upland versus lowland soils). Upland soils support a higher species richness and diversity. Upland and lowland plant assemblages are distinct except on annually burnt prairie. The interaction between burning regime, topography and year-to-year climatic variation affects the relative abundance of the plant species differentially. The most dominant species overall, Andropogon gerardii, was affected only by year-to-year variation (i.e. climate). Its position at the top of the species abundance hierarchy was unaffected by burning regime or soil type. The other dominant species showed a suite of varying responses to these factors.
294 citations
240 citations
TL;DR: Although the mean number of species per 0.1 ha plot was higher in coppice samples, species richness and index of diversity were lower than in old-growth samples, which indicate lower species diversity in regenerating miombo.
Abstract: Miombo woodland in Zambia is divided into wetter and drier types by the 1100 mm mean rainfall isohyet. In the present study two wetter (Northern, Northwestern) and three drier (Central, Eastern, Western) miombo subtypes were recognized.A survey of the woody flora of 94 old-growth and 58 coppice stands in the five miombo subtypes revealed some significant differences in species diversity among them. The floristic differentiantion of miombo subtypes was best achieved by the use of the Shannon species diversity index (H′) and species density (number of species 0.1 ha−1 or 0.4 ha−1). H′ in miombo decreased from 2.247 in Northwestern to 2.136 in Northern, 2.052 in Eastern, 1.918 in Central and 1.824 in Western subtypes. Although species density was not significantly different between wetter miombo subtypes, this decreased in a similar fashion from 18.78 0.1 ha−1 in Northwestern to 18.30 in Northern, 16.65 in Eastern, 14.79 in Central and 12.29 in Western subtypes. The low species diversity in Western drier miombo was attributed to the combined effects of low soil fertility and rainfall.Although the mean number of species per 0.1 ha plot was higher in coppice samples, species richness (d) and index of diversity (H′) were lower than in old-growth samples. These results indicate lower species diversity in regenerating miombo. The dynamic aspects of species structure should therefore be considered in the future conservation of biological diversity in miombo woodland.
73 citations
TL;DR: There was a positive correlation between density of koalas and the density of E. viminalis, and Koalas used this species in preference to other tree species, and there were seasonal differences in the use of both vegetation associations and tree species.
Abstract: The use of specific vegetation associations and tree species by koalas in a forest containing six Eucalyptus spp. is described. There was a positive correlation between density of koalas and the density of E. viminalis, and koalas used this species in preference to other tree species. There were seasonal differences in the use of both vegetation associations and tree species. Associations dominated by E. viminalis were preferred in most seasons. E. viminalis was the most preferred species in all seasons except summer, when E. ovata was preferred. This was not reflected in a change in preference for vegetation associations. Male koalas showed a preference for E. macrorhyncha, and to a lesser extent E. viminalis and E, ovata. Females showed a consistent preference for E. ovata and E. viminalis. Koalas showed a strong preference for large trees in all seasons, and for specific trees within species.
56 citations
TL;DR: Differential preferences for and utilisation of regrowth pasture, and interference interactions between cattle and macropodids, are suggested as possible reasons for the differing responses.
Abstract: Utilisation of pasture in relation to time since burning occurred was assessed on a monthly basis for 16 months, for three species of macropodids and cattle. Utilisation by the eastern grey kangaroo, red-necked wallaby and cattle increased after burning, but the magnitude and particularly the timing of the responses differed between species. Burning did not affect utilisation by the whiptail wallaby. Differential preferences for and utilisation of regrowth pasture, and interference interactions between cattle and macropods, are suggested as possible reasons for the differing responses.
27 citations
TL;DR: In this paper, the authors studied the habitat preferences of nine grass species on a nature reserve which forms part of the southern African moist savanna biome and found that the abundance of the species in the study area is determined by changes along gradients of pH levels in soils and rockiness.
Abstract: Habitat preferences of nine grass species were studied on a nature reserve which forms part of the southern African moist savanna biome. Multiple regression and correspondence analysis related the distribution of the species to habitat parameters that included edaphic factors, geomorphological structure and vegetation density. Results of the two analyses generally matched and complemented one another, indicating that the abundance of the species in the study area is determined by changes along gradients of pH levels in soils and rockiness. Slope, vegetation density and mineral content contribute to the variation within these gradients. The combination of qualitative and quantitative information gave an overview of the distribution pattern of grass species, emphasizing some of the underlying factors operating in the system.
14 citations
TL;DR: Evidence for changes in the herbaceous layer is less conclusive but it is likely that there has been a reduction in density of desirable perennial grasses and an increase in less palatable species.
Abstract: This article combines data from historical records, recently published maps and a field survey to document changes in the vegetation of a pastoral area in south-western Queensland. Examples are given where wildfire, ringbarking,clearing and grazing by both rabbits anddomestic stock have had major influences on the vegetation. The greatest change to the trees and inedible shrubs has been one of density. Evidence for changes in the herbaceous layer is less conclusive but it is likely that there has been a reduction in density of desirable perennial grasses and an increase in less palatable species.
14 citations
TL;DR: Biodiversity in temperate forests is high, and the threats faced are many, but this great diversity resides not so much in high species numbers, but in the genetic variation that exists within species.
Abstract: Tremendous species diversity, together with accelerating deforestation and land development, has been a formula for rampant extinction and community collapse in tropical forests Conservationists have brought the crisis of tropical forests to the attention of the international community, showing that continued efforts are needed to conserve the biotic riches of these regions The forests of temperate latitudes, although less in worldwide focus, also have urgent conservation needs, but of a somewhat different nature As in tropical forests, biodiversity in temperate forests is high, and the threats faced are many This great diversity resides not so much in high species numbers, but in the genetic variation that exists within species
3 citations