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January 1992 - April 2002
Publications
Publications (54)
Parthenium hysterophorus L. (Parthenium), an annual to biennial herbaceous plant, is well established in parts of the Kruger National Park (KNP). Over the past two decades Parthenium has become widespread in the southern region of KNP, demonstrating an ability to spread rapidly. While large programmes and substantial financial resources have been d...
Identifying pathways of introduction remains a major priority to prevent future
plant invasions into natural areas. In this study, we assessed whether forestry plantations favor alien plant dissemination into the National Park of Reunion. Results showed significant decrease in the percentage of alien plant biomass from the forestry plantations to t...
We visited the island with the intention of helping initiate a system of rapid survey transects to assess the alien plant invasions occurring on the island of Mauritius. The transects employed the same standardized data collection protocols that had been developed by the authors on the island of Réunion and recently applied in a short survey on Rod...
We visited the island with the intention of establishing some rapid survey transects to assess the alien plant invasions occurring on the island of Rodrigues. The transects employed the same standardized data collection protocols that had been developed by the first author on the island of Réunion. We worked with local conservation and forestry sta...
This paper reviews the 40 verbal presentations and 14 poster papers from the inaugural research symposium of the Working for Water programme, held at Kirstenbosch, Cape Town, in August 2003. Papers and posters were presented under six themes hydrology [8 papers and posters], ecology (including the ecology of wetlands) [19], biological control [5],...
The Cape Peninsula, a 470 km2 area of rugged scenery and varied climate, is located at the southwestern tip of the Cape Floristic Region, South Africa. The Peninsula is home to 2285 plant species and is a globally important hot-spot of biodiversity for higher plants and invertebrates. This paper provides a broad overview of the physiography, biolog...
The SCOPE Programme on the Ecosystem Function of Biodiversity is aimed at ascertaining whether it is necessary to prevent the predicted man-induced extinction of much of the Earth’s current biodiversity (Ricklefs et al. 1990) on the grounds of securing the adequate functioning of global life-support systems. Given this background, it would appear i...
In semi-arid and arid magisterial (administrative) districts (n = 45) in the Cape Province, South Africa, there has been a mean 44·4 ± 14·6% (S.D.) reduction in the stocking rates of domestic livestock over the period 1911-81. In five savanna districts there has been a mean 36·8 ± 8·5% increase in stocking rate. For all districts during the period...
The results of a replicated field-scale trial of a range of control treatments for Acacia saligna were used to create a probabilistic model of the effects of repeated treatment applications. Using estimates of costs per plant treated for each treatment and for each of four size classes of plants, it was possible to compute the costs for every treat...
Two categories of historical change in vertebrate populations are analysed: decreases leading to species being included in local Red Data Books and changes in distribution and abundance of what are often more common species, as revealed by regional surveys. The former category of change tends to reflect radical anthropogenic influences (e.g. habita...
The seed dispersal of two introduced Acacia species by the black korhaan Eupodotis afra, a 700-g ground- feeding bird (Otididae), was studied in the southwestern Cape region of South Africa. The seeds of Acacia cyclops A. Cunn ex G. Don. possess conspicuous scarlet pseudarils derived from the funicle and were consumed in preference to those of A. s...
Although most of the lowland endemic forests of the mountainous Indian Ocean island of La Réunion have been converted by Man to other land-uses, relatively intact ecosystems still survive at higher elevations. Given the particular conservational value of these remnants of primary forest, detailed knowledge of the threats faced by these native ecosy...
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 made of published and unpublished data on plant species richness in fynbos with different levels of invasion and d...
Concern about the invasion of this reserve by alien trees and shrubs, principally Acacia cyclops, A. saligna, A. longifolia, Eucalyptus lehmannii and Pinus pinaster, was first expressed in 1941, 2years after its proclamation. Control operations were started by 1943 and were almost totally ineffective for at least the first 35years; no systematic co...
Vernon, C.J., Macdonald, I.A.W. & Dean, W.R.J. 1989. Birds of an isolated tropical lowland rainforest in eastern Zimbabwe. Ostrich suppl. 14:111-122.There are 72 species of birds in the forest at the Haroni-Lusitu river junction, perhaps the richest forest avifauna in southern Africa. Some species are represented by isolated populations and are not...
The costs of the initial clearing of mixed stands of the alien Acacia cyclops and A. saligna invading fynbos vegetation were compared in a replicated trial on the Pella Fynbos Research Site. Costs were estimated using a regression-based model of the individual cost components. Felling was the cheapest clearing method, with felling plus the strippin...
There is no summary to this chapter - only a two-page section entitled 'Summary and Conclusions' which is too long to reproduce here.
The following five papers collectively form a report of the Working Group on Nature Reserves, associated with the SCOPE programme on the ‘Ecology of Biological Invasions’. This introduction (i) defines the aims of the SCOPE programme, (ii) describes the approach of the Working Group, (iii) provides definitions so that these do not have to be given...
The invasions of introduced species into three nature reserves in California, two in Australia, one in Chile and one in South Africa are described. In most reserves the major invasion has been by herbs, primarily annual grasses from Europe and the Mediterranean Basin. It appears likely that fire regimes have been altered and the density of some nat...
The invasions of introduced species into five reserves in tropical savannas and dry woodlands are described. Vascular plants are the group having the most introduced species; invasions are least important in dry, regularly burned savannas, more important in moist, derived savannas (where scrambling shrubs are invading) and most important in wetland...
The alien vascular plant flora of the Kruger National Park is listed. Annotations cover the invasive status, modes of introduction and dispersal, dates of first recording, ecological impacts and control status of each species. The list comprises 156 species of which 113 are considered invasive within the park. Most of the species have been accident...
The alien tree species Cinchona succirubra , the Red Quinine-tree (Rubiaceae), was introduced to the Galápagos Islands, Ecuador, in 1946, for purposes of cultivation, but causes much concern as, by 1987, it was found to cover about 4,000 hectares in the highlands of Santa Cruz Island, changing the original, largely endemic, vegetation. Some limited...
The environment and history of this 19 485 km tropical and subtropical savanna national park are described. The growth in awareness of the problems posed by alien organisms is documented: protected since 1898 and proclaimed as a national park in 1926, the first major policy decisions and control programmes for introduced species were initiated in t...
This volume presents the proceedings of a conference held to review the state of knowledge on long-term data series from southern African ecosystems. Three chapters relate to marine environments: those of the West Coast shelf, the South-East Coast shelf and the intertidal zone. Two chapters cover inland waters, estuaries and the hydrological cycle....
(1) Populations of buried viable seeds of Acacia cyclops and A. saligna, invasive aliens of fynbos, were estimated to assess the effects on them of different shrub-clearing treatments. (2) Seed populations of both species declined significantly after 1 year with burning, but in general, not thereafter. (3) Seed banks of A. cyclops, but not of A. sa...
An annotated species list of the alien vascular plant flora of the Cape of Good Hope Nature Reserve is presented. The flora comprises five gymnosperm and 68 angiosperm species that are definitely alien to the reserve and four angiosperm species that are possibly alien. The life-form distribution of the alien flora is shown to be significantly diffe...
Macdonald, I. A. W. 1986. Range expansion in the Pied Barbet and the spread of alien tree species in southern Africa. Ostrich 57: 75–94Apparent range expansions of the Pied Barbet Lybius leucomelas into fynbos, karoo, grassland and mesic savanna areas have occurred this century. The number of loci from which the barbet was recorded in each biome pr...
The southern African range of the habeda ibis Bostrychia hagedash has expanded from 530 900 km 2 in 1910 to 1 323 300 km 2 in 1985. Major range expansions have occurred in the fynbos biome of the south-western Cape, the Karoo, the grasslands of the eastern Cape, the Orange Free State and the Transvaal highveld. Smaller expansions are documented for...
The status and distribution of the six large mammalian carnivore species known to occur in the Cape Province are presented. This is compared with their past distribution and status. Current threats to the various species are detailed. The hunting dog Lycaon pictus is extinct as a breeding species and three species are only represented by small popu...
The composition of a coastal dune forest in the Mlalazi Nature Reserve was studied 3 yr after a fire and compared with adjacent unburnt forest. The communities had similar plant densities but there was a marked decrease in biomass and diversity in the burnt community. Measured as density, basal area or canopy volume, Trema orientalis contributed >7...
The population changes of the 5 major invasive species between 1966 and 1976-1980 are described, with observations on 3 additional invaders of less importance. -from Authors
This report consists of two types of chapters. Most of the chapters are short syntheses of particular aspects of the alien plant problem in Natal, written by groups of participants during the workshop meeting. They are brief accounts of the state of knowledge on the various topics and rely heavily on tabulations. They cover the following topics: th...
This chapter describes characteristics of voluntary "hack groups" that have arisen to help manage invasive alien plant invasions in the Fynbos Biome of the Cape Floral Kingdom. It contrasts these characteristics with those of professional (paid) organizations involved in this work and proposes how best these volunteer efforts can be integrated with...
The avifauna of the Mountain Zebra National Park (MZNP) has been recorded over a period of some two decades (Skead 1965, Koedoe 8: 1-40; Penzhorn & Bronkhorst 1976, Koedoe 19: 171-174; Penzhorn 1977, Koedoe 20: 205-207; Grobler & Bronkhorst 1981, Koedoe 24: 199-203). Collett (1982 Southern Birds 9: 1-65) has summarised all the available information...
Floristic analyses do not support the hypothesis that the fynbos biome is more susceptible to alien plant invasions than are other South African biomes. Current levels of infestation indicate that the fynbos is more severely invaded than the other biomes. Hypotheses that have been proposed to explain the invasion of the fynbos by alien plants are l...
The structural changes that have occurred in the vegetation of the Hluhluwe-Umfolozi Game Reserve Complex have been quantified using 1937, 1960 and 1975 aerial photographs, and related to the management history. A progressive increase in both tree and shrub cover has occurred. In the short term, both intensive woody plant removal operations and con...
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 a...
Dean, W. R. J. & MacDonald, I. A. W. 1981. A review of African birds feeding in association with mammals. Ostrich 52:135–155.Feeding associations between African birds and mammals are defined. 96 species of birds show, or possibly show, some form of feeding associations with mammals. Five major categories of feeding association are identified, whic...
The greatest threat of invasion of alien species of plants and animals is posed by species which originate from similar arid habitats in other parts of the world. In general the smaller the number of individuals of an alien species introduced into the country, the smaller are its chances of becoming established as an invasive problem species. For t...