This study investigates the effects of forest fragmentation and matrix type on the diversity and distribution of epigaeic invertebrates in selected Afromontane forests of the KwaZulu-Natal midlands. The consequences of area reduction and matrix transformation, due to commercial forestry, for epigaeic invertebrate diversity, and the role of small forest fragments in their conservation, are particularly examined. Data are used to provide guidelines for the management and conservation of Afromontane forest and adjacent land use. Epigaeic invertebrates were sampled using pitfall-trapping quadrats set along gradsect lines in eleven Afromontane mistbelt mixed Podocarpus forests, five of which were surrounded by commercial pine, and five surrounded by the natural grassland matrix. The two sets of five forests were approximately matched in pairs by area (0.5ha to 215ha) and compared for differences in the epigaeic invertebrate communities to determine potential effects of fragmentation and landscape transformation on these communities. A large tract of forest (Leopards Bush Private Nature Reserve, 705ha, hereafter Leopards Bush) situated within the continuous Karkloof forest, served as the control. Trapping intensity increased with forest area. Invertebrates were identified to morphospecies, and where possible, further identification was carried out by specialists. A total of 61 282 epigaeic invertebrates, representing 168 morphospecies, were collected. There was a significant positive species-area effect evident in the Balgowan complex (grassland matrix), but not in the Gilboa complex (pine matrix). There was thus a confounding influence of the pine matrix in the Gilboa, since the matrix represented the single most important difference between the two forest complexes. In afforested landscapes it is thus crucial to conserve the largest intact forest fragments to preserve overall epigaeic invertebrate species richness. Density compensation was evident in the Balgowan complex but not in the Gilboa complex. Recolonisation dynamics may play a small role in the regional persistence of a species within forest in a pine matrix, and persistence would be ensured by the preservation of a small number of large forest fragments containing large, extinction-resistant populations. The establishment of ecologically functional grassland corridors (i.e. wide enough to maintain "natural" ecological processes) between mistbelt mixed Podocarpus forest fragments would facilitate dispersal of epigaeic invertebrates between forest fragments. The results of this study indicated that edge effects were experienced deeper in the forests than the expected 32m suggested by Kotze and Samways (1999) and thus any changes to the epigaeic invertebrate communities induced by edge effects had already taken place inthese forests. Cluster analyses revealed that twenty-two percent (n = 37) of invertebrate species recorded were common to all forests and these shared species were generalist feeders. The effect of matrix type on diversity of epigaeic invertebrate communities was most notable for large forests (i.e. over 30 ha). Large fragments with core areas unaffected by edge-induced disturbance would support more forest dependent species than small fragments due to a lower susceptibility to invasions. Although not significantly nested, epigaeic invertebrate communities in both forest complexes tended toward nestedness. Isolation of forest fragments appeared to play a lesser role than patch area in determining the invertebrate community composition. Assuming that communities are extinction-dominated, community convergence in small fragments has probably already occurred, with invasions from the matrix confounding patterns of deterministic extinction of forest-dependent epigaeic invertebrate species. A habitat disturbance gradient was evident from the relatively undisturbed control (Karkloof quadrats) to the more disturbed pine dominated Gilboa quadrats, with intermediate disturbance values for the Balgowan (natural grassland matrix) fragments. The undisturbed Karkloof forest was characterised by a deep, abundant leaf litter layer, dense sub-canopy, and an abundance of seedlings indicating high rates of natural regeneration. Leaf litter depth was the most important variable in explaining the variation of epigaeic invertebrate species. A "shopping basket" of eight selected ecological indicators are mostly unrelated species. In general, this study supports the wealth of evidence advocating the use of epigaeic invertebrates, especially Carabid and Staphylinid beetles, as ecological indicators. In this study, eight species were identified by canonical correspondence analysis as ecological indicators that were sensitive to forest disturbance. This suite of species in the mistbelt mixed Podocarpus forests of the KwaZulu-Natal midlands will provide an accurate indication of forest condition in summer when abundance data is used. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Considered key landscape elements, ecotones play an important role in landscape ecology. In heavily fragmented, or heterogeneous landscapes, ecotones become a major, even dominant, feature. Yet, there are relatively few studies investigating communities of invertebrates associated with ecotones, especially across natural boundaries. Furthermore, most analyses of habitat loss do not consider the characteristics of the areas surrounding remaining habitat, the matrix. This thesis attempts to partially fill the gap. Afromontane forest-grassland ecotones are characteristically sharp (usually a few metres), are mainly fire-maintained, and have been in existence for, perhaps, millions of years. Therefore they provide a good opportunity to study ecotone, forest patch and grassland matrix characteristics together, and the associated species assemblages. In short, I investigated the diversity and distribution patterns of epigaeic invertebrates across ecotones between the natural and isolated patches of Afromontane forests and the surrounding natural grassland matrix, in the province of KwaZulu-Natal, South Africa. In particular, the following primary hypothesis was evaluated; do edge effects, in terms of elevated abundance and species richness, and in terms of abrupt, significant changes in environmental conditions, occur across near-natural ecotones. These edge effects quite often occur across anthropogenically-created habitat junctions, but it is not clear whether they do across natural ones. To test this hypothesis, the following secondary hypotheses were evaluated. Firstly, often a single invertebrate taxon is used for assessing changing landscape patterns. However, recent work has suggested that patterns and responses vary widely between taxa, and that management programmes based on the knowledge of a single taxon would not necessarily predict or safeguard that of others. Therefore, in chapter I, the hypothesis whether a single taxon could be used in biodiversity studies, or alternatively, whether it is better to select an array of taxa, was tested. Several invertebrate taxa were selected to investigate this. These included terrestrial amphipods, spiders, carabids, staphylinids and ants. Indeed, results showed that species diversities and assemblage-compositions of epigaeic spiders, carabids, staphylinids and ants were significantly different in different-sized Afromontane forest patches. Only carabids and staphylinids correlated positively with each other in terms of numbers of species. The other taxa showed only weak positive, or negative, correlations in their species richness. Results supported the multi-taxa approach in conservation studies, even among groups sharing a common habitat stratum. Secondly, organismal diversity usually increases at disturbed habitat edges. This phenomenon is commonly referred to as the biological edge effect. This pattern, however, is not universal and a number of authors have shown evidence contradicting this hypothesis. In chapter II amphipods, ground beetles and ants were collected to test the biological edge effect hypothesis. In addition, a number of abiotic factors were measured across these forest-grassland boundaries in an attempt to relate the biotic with the abiotic. Little evidence was found to support the classical edge-effect hypothesis (elevated species richness at the ecotone). In fact, carabid abundance and species richness was high in forests, decreasing gradually through the ecotone to a low in grasslands. In contrast, ant species richness increased significantly from a low in forests, increasing gradually through the ecotone, to a high in grasslands. Certain species did, however, show a significant increase in abundance at the ecotone, such as Talistroides africana, a terrestrial amphipod, and Tetramorium avium, a seed-predatory ant. Afromontane forest-grassland ecotones are natural and are not the result of anthropogenic clear-cut fragmentation. They also lacked any great changes in micro-environmental conditions. I hypothesise that edge effects are of less importance at more naturally maintained habitat boundaries even if these boundaries are sharp. Thirdly, climatic variation has a major impact on invertebrate communities. The Afromontane landscape experiences hot and wet summers, and cool and dry winters. I hypothesised that invertebrate distribution patterns across an ecotone change from one season to the next (chapter III). For example, it is expected that certain winter-active species might disperse from one location along the gradient to another, perhaps to escape predators, or find winter-refugia. This would, in turn, change the pattern of distribution of the selected taxa across these ecotones. Surprisingly, the general pattern of distribution across these ecotones changed little. However, there were significant differences between summer, spring, winter and autumn catch, and species identities changed from one season to the next. For example, carabid abundance and species richness was higher in the forest, compared to in the grassland, while ants were species richer in the grassland, compared to in the forest. These patterns were consistent from one season to the next. Again, as was found in chapter II, T. africana was significantly more abundant at the ecotone, compared to either forest or grassland interiors, in all seasons throughout the year. To summarise, amphipods favoured the ecotone environment, carabids the forests and ants the grasslands, throughout the year. Finally, scientists have recently become aware of the importance of the matrix surrounding habitat patches, in the survival and occurrence of organisms in the habitat patch. I tested whether the quality of the matrix, as a function of human disturbance, has an influence on invertebrate occurrence and distribution patterns across Afromontane forest-grassland boundaries. Redgrass (Themeda triandra Forssk.) dominated Afromontane grasslands are, and have been experiencing varying degrees of anthropogenic disturbance. Consequently, ecotones vary from being very abrupt (heavy disturbance in the matrix) to gradual (little disturbance in the matrix), although still sharp compared to most ecotones elsewhere. Level of grassland disturbance influenced amphipod, carabid and ant assemblage-structure across Afromontane ecotones (chapter IV). Results support the hypothesis that the dynamics of remnant areas are influenced by factors arising in the surrounding landscape. In particular, carabid assemblage-composition changed highly significantly from undisturbed to disturbed sites (this taxon was mainly captured from forests). Furthermore, only a single carabid individual was captured from 8 to 128 m into the grassland and only 14 T. africana individuals were captured from 2 m inside the forest to 128 m into the grassland of the most disturbed site. Clearly, matrix quality influenced not only the patterns of occurrence of organisms in the grassland matrix, but also at the ecotones and in the forest patches. In conclusion, it is imperative to investigate a number of taxonomic groups in conservation ecology to give more reliable results, and thus conservation recommendations. Of course, not all taxa can be considered, and the selection of appropriate taxa still poses a problem, but a set of taxa that are considerably different biologically is a good start. Native Afromontane forest-grassland mosaics are in urgent need of conservation, as much of this habitat is subject to heavy anthropogenic disturbance such as human settlement, forestry, cattle grazing, agriculture, and frequent, out of season, fires. Unfortunately only 2% of this biome is protected in South Africa. Furthermore, matrix quality is important because it determines the survival rate of propagules moving between remnant patches of habitat, and therefore the success rate of such movements. Private land-owners own most of this grassland area in the Afromontane region, but no guidelines are available to them on how to protect this habitat. Throughout this thesis I emphasised the importance of protecting both native forest and the surrounding native grassland. A first initiative is simply to protect a zone of grassland around the forest patches, both in terms of less frequent burning regimes, and less, or no cattle grazing here. By doing so, a rich grassland ant fauna will be conserved, the grassland matrix quality will improve, and a rich carabid fauna, favouring predominantly Afromontane forest remnants, will be conserved. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.

Monospecific stands of Acacia karroo establish naturally on disturbed coastal dunes in KwaZulu-Natal, South Africa. While the A. karroo successional pathway is successful in rehabilitating mined dunes at the Richards Bay Minerals mining company (RBM), the same pathway has become arrested in the coastal dune forest at Cape Vidal in the Greater St. Lucia Wetland Park. This study examines the efficacy of the A. karroo successional pathway for restoring disturbed coastal dune forests. Dispersal of seeds and successful recruitment of seedlings are essential for habitat restoration. Seed and seedling banks were compared between previously disturbed A. karroo stands and adjacent forest at Cape Vidal. Different seed bank composition and higher seed bank richness in the forest suggest that seed dispersal into A. karroo stands is limited. Protected seed banks in A. karroo stands had increased seedling richness, indicating that dispersal limitation does not fully explain the lack of seedling establishment. At RBM, the seed bank richness of A. karroo stands increased with age since mining. While cumulative species richness of the seed bank of the oldest A. karroo stand at RBM was marginally lower than that at Cape Vidal, successful rehabilitation at RBM is associated with low seedling mortality. Consequently, forest tree species richness is high at RBM in the A. karroo stands and is converging on natural forest richness and composition. Although seed dispersal is reduced, it does not totally limit establishment of forest tree species in A. karroo stands at Cape Vidal, which implicates a post-establishment factor. Soil fertility potentially reduces seed germination and seedling growth. Soil nutrients in A. karroo stands at Cape Vidal were similar to those in the adjacent forest, and total nitrogen levels in A. karroo stands at Cape Vidal were higher than at RBM. Thus, soil conditions were unlikely to be limiting tree regeneration in A. karroo stands. Total nitrogen accumulated in the oldest stand at RBM at a rate of 10.0 g.m2.y(1 and a similarly rapid rate occurred at Cape Vidal. Therefore the A. karroo stands were not nitrogen limited. Nitrogen supplementation experiments at Cape Vidal demonstrated that a range of forest tree species establish in A. karroo stands regardless of nitrogen level, but there is low survival of seedlings. Thus, nitrogen availability is not arresting succession at Cape Vidal. Herbivory can also inhibit seedling recruitment. Selective feeding may enhance the persistence of species with defences against herbivory, such as A. karroo, ultimately altering the tree community composition. Browsing and trampling by large mammalian herbivores in A. karroo stands at Cape Vidal decreased survival and growth of forest tree seedlings. Large herbivores such as kudu, waterbuck, bushbuck and red duiker preferentially used the A. karroo stands as they offer abundant food and their topography allowed easy movement. This topdown pressure reduced recruitment, growth, and survival of seedlings of undefended species. Few wild herbivores occur at RBM, which allowed succession to proceed unhindered, ultimately restoring coastal dune forest at this site. Despite successful rehabilitation of coastal dune forest on mined dunes at RBM, limited seed dispersal and high levels of herb ivory have arrested succession at Cape Vidal. Thus, the A. karroo successional pathway must be implemented only after careful consideration of site-specific factors such as distance to a source of propagules and the intensity of herbivory in the system. In areas where herbivore densities are high, management interventions focusing on reducing herb ivory and encouraging visitation by seed dispersers are necessary for the successful use of this successional pathway. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Coastal forests are a significant component of the remaining natural vegetation in the greater Durban area. Being closely associated with an historical and rapidly developing urban environment, these forests are invariably small, isolated and variously disturbed. The nature of disturbance as an ecological phenomenon, coupled with unknowable disturbance histories and ongoing disturbance events poses particular challenges to traditional and tradition-bound attempts to understand and manage such forests. The intention of this study was to discuss as deeply as possible the nature of such challenges, while at the same time considering the broader relevance of practising ecology in the urban environment. At a practical level the forests were sampled in an attempt to describe forest communities, to assess the effects of disturbance on them, and to gain insight into the effects of different disturbance histories and regimes on forest physiognomy and floristics with a view to proposing management guidelines. Various descriptive approaches, as well as a multivariate analysis using Detrended Correspondence Analysis were used in an attempt to interpret the data collected. The unsatisfying nature of the data led the thesis to propose a review of the paradigm in which its methods were rooted. Both the data, and the broader issues on which the thesis touched were discussed in terms of biology's rootedness in philosophical assumptions. This led the thesis to a methodological position aligning it both epistemologically and ontologically with a philosophical method of investigation called phenomenology. While other philosophical contentions were touched upon, the main conclusion of the thesis was that phenomenological thinking, while challenging to apply, was relevant to philosophically mature and methodologically appropriate attempts to conserve the forests with which the thesis was concerned. / Thesis (M.Sc.)-University of Natal, Durban, 1993.

Resprouting is an important means of plant regeneration especially under conditions that do not favour regeneration through seeding such as frequent disturbances, low productivity, unfavourable soil conditions, extreme cold and limited understorey light availability. Sprouts may be advantageous over seedlings because they have higher survival and growth rates than seedlings, since they use resources from parent plants unlike seedlings that have to acquire their own resources. Resprouting is well documented for ecosystems that experience severe disturbances that damage aboveground biomass. For example, resprouting is important for plant persistence against fire in fire-prone savannas and Mediterranean shrub-lands, and hurricanes and cyclones in tropical forests. In these ecosystems, resprouting often results in multi-stemming, because this dilutes the risk of damage among many stems, improving the chances of individual survival. This study was conducted at coastal dune forest at Cape Vidal in north-eastern South Africa, where there is a high incidence of multi-stemmed trees due to resprouting in response to chronic disturbances of low severity. This study examines (1) the importance of resprouting to tree survival and dynamics in an environment where disturbance severity is low but pervasive, and (2) how this resprouting strategy differs from the more familiar sprouting response to severe disturbances such as fire and hurricanes. Analysis of the relationship between multi-stemming and a number of disturbances potentially causing multi-stemming revealed that stem leaning and substrate erosion were the most important disturbances associated with multi-stemming. There were fewer multistemmed trees on dune slacks that had a stable substrate and were protected from sea winds than on dune crests and slopes that had unstable substrate and were exposed to sea winds. Trees resprouted and became multi-stemmed from an early stage to increase their chances of survival against leaning caused by strong sea winds and erosion, and occasional slumping of the unstable dune sand substrate. These low severity disturbances are persistent and are referred to as chronic disturbances in this thesis. As a result of these chronic disturbances, both single and multi-stemmed trees had short stature because taller individuals that emerged above the tree canopy would be exposed to wind damage. Under chronic disturbances plants may manifest a phylogenetically determined sprouting response. However, in this study resprouting and multi-stemming were the results of the tree-disturbance interaction and not a property of a plant or species and were not phylogenetically constrained. Because the disturbances are predominantly of low severity, leaning trees were able to regain the vertical orientation of the growing section by turning upward (a process referred to as ‘turning up’ in this study) and hence survive without resprouting. Species that were prone to turning upward had a low incidence and degree of leaning of their individuals, low frequency of loss of primary stems and high abundance of individuals. Although turning up is less costly to the individual than resprouting, it could only be used by leaning trees that had small angles of inclination and were not eroded. High intensities of the latter require that individuals resprout to survive. The form and function of resprouting varied between seedlings and juvenile and mature trees. Resprouting in seedlings resulted in a single replacement shoot, unlike sprouting in juvenile and mature trees that resulted in multi-stemmed trees. Like sprouting in juvenile and mature trees, sprouting in seedlings was not phylogenetically constrained. Resprouting in seedlings increased seedling persistence; hence species with more sprout seedlings had larger individual seedlings and seedling banks. Resprouting in seedlings increased the chances of seedling recruitment, whereas resprouting in juvenile and mature trees increased the chances of an established plant maintaining its position in the habitat. After disturbances of high severity, which destroy the photosynthesizing parts, plants resprout using carbohydrates stored below- or above ground. In this study, good resprouters stored more carbohydrates both below- and above ground than poor resprouters. The carbohydrates were mobilized for resprouting after disturbance. More carbohydrates were stored in stems than in roots because the prevailing disturbances were mostly of low severity and hence above ground resources were readily available. Similar to storage by plants in severely disturbed habitats, carbohydrates were stored by reserve formation, which competes for carbohydrates with growth and maintenance and forms permanent storage, rather than accumulation, which temporarily stores carbohydrates in excess of demands for growth and maintenance. Stored carbohydrates are not necessary for resprouting of plants after disturbances of low severity because they can resprout using resources remobilized directly from the disturbed photosynthesizing parts. However, in this study, stored carbohydrates served as a bet-hedge against occasional severe disturbances that occurred in addition to chronic disturbances. Allocation of carbohydrates to permanent storage diverts them from growth and reproduction and hence good resprouters had lower growth rates, seed output, seed size and seedling recruitment than poor resprouters. However, the costs of these traits that resulted in low recruitment from seed by good resprouters, were compensated for by high persistence of established individuals of good resprouters through recruitment of sprout stems. This study demonstrates that resprouting is not only advantageous in severely disturbed environments, but also in environments where disturbances are of low severity but nevertheless confer an advantage on individuals that persist. Thus in forest environments where aboveground biomass is seldom destroyed and individuals are relatively long-lived, resprouting can confer significant fitness and selective advantage on individuals. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.