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I explored the importance of decaying wood to survival and growth of trees in south coastal British Columbia, and the effect of decaying wood on the intensity of podzolization on mesic sites. A field pot study was carried out in both high light and low light conditions using woody and non-woody forest floor materials. After two growing seasons, Pseudotsuga menziesii, Tsuga heterophylla, and Abies amabilis seedlings growing in clearcuts had greater survival and growth in the non-woody substrate; however, in the understory, the effect was much less. The proliferation of western hemlock roots was used as an indicator of the value of decaying wood to trees. In both greenhouse trials (using seed sown on a series of planting pots with each half filled with either a woody substrate or a non-woody substrate), and in field sampling of woody and non-woody substrates in mature stands, the non-woody substrate had a larger density of fine and very fine roots compared to the woody substrates or mineral soil. Ten litres of concentrated solutions of non-woody humus substrate and woody substrates were leached through soil columns. Both the non-woody and woody solutions had similar mean pH but significantly different chemical properties. The non-woody solution leachate had greater net average output of dissolved organic C, Fe, and Mn. The mineral soil treated with the nonwoody solution had significantly greater concentrations of total N and pyrophosphate-extractable Fe. In the field, forest floor and soil samples were compared between pedons having large accumulation of decaying wood and pedons with non-woody humus forms. Despite large and significant differences in chemical properties between the two substrates, there were generally no significant differences between the chemical properties of the soils directly under these substrates. In most cases, the results of (3-analyses showed that the means were not pedologically different. Additionally, 18 pairs of zero tension plate lysimeters were installed under the two substrates. The lysimeter solutions showed no significant differences. I concluded that coarse woody debris appears not to have either a positive effect of increased productivity of trees or a negative effect of increased intensity of podzolization.

In landscape ecology, it is widely acknowledged that landscape is as much a social and cultural entity as it is biophysical, and that people and place must be jointly considered to fully understand the evolution of spatial pattern. This thesis explores the overlapping biophysical and human dimensions of landscape in the context of an (i) ecological and (ii) ethnoecological classification on the local landscape of the Tayal Mrqwang indigenous people in north central Taiwan. The goal of the ecological classification was to identify ecosystem types for a ~3000 acre landscape by relating vegetation patterns to gradients of physiography, soil, humidity, light, pixel brightness, and human modification across 76 transect sample plots. Using multivariate analyses, seven ecosystem types were identified, ranging from xeric through submesic pine, bamboo, alder, and laurel forests to mesic evergreen broadleaved and mixed coniferous forests. At the broad scale, ecosystems were distributed along gradients of elevation, soil, humidity and human modification, while factors related to local variability in physiography and soil development were more important at the fine scale (i.e., within elevational ecoregions). Within lower elevation sites in particular, patterns of forest variation and soil development were resonant of ancestral practices, including shifting cultivation, terrace farming, arboriculture, and selective extraction. The objective of the ethnoecological classification was to explore whether the Mrqwang people categorize landscape variation according to systematic or multidimensional knowledge structures. Results of interviews and free-listing exercises revealed an unsystematized classification that recognizes a continuum of forest variation through the intersection of three overlapping categories: history of disturbance, topography and substrate, vegetation. These categories are modified through land tenure and toponyms. The classification appears accommodating of personal experience, and it is theorized that this flexibility results in dynamic knowledge that evolves with time, generating variable characterizations of forest variation rather than formalized categories. The thesis concludes that despite the lack of formalization, the Tayal are nonetheless highly cognizant of how current forest variation coincides with the environment and the activities of their ancestors. This knowledge represents immense local expertise and must not be excluded from conservation and co-management projects in the local area. / NSERC CGS-D

Dominant understorey species, such as herbs, ferns, palms and shrubs may influence forest tree species diversity and dynamics. Their influence may be through shading the forest floor, thereby affecting regeneration of shade-intolerant species and reducing species diversity, or it may be through competition with seedlings for space and belowground resources, thus modifying or changing the structure of the forest. These effects may be compounded if the life cycle of the understorey species consists of synchronized reproductive and mortality events. This study examines the influence of a dominant understorey species, Isoglossa woodii (Acanthaceae), on regeneration of trees in Indian Ocean subtropical coastal dune forest in southern Africa. The species is a semiwoody herb and has population-wide synchronous reproduction at 4-7 year cycles after which it dies and regenerates from seed. In this thesis I examine three aspects of the ecology of this suppressive herb: (i) the ecological and environmental correlates of the distribution of I. woodii; (ii) the evolutionary advantages of synchronous monocarpy; and (iii) the ecological effects of the extensive cover and putative recruitment window caused by I. woodii on forest tree seedling dynamics and diversity. Isoglossa woodii covered 65–95 % of the understorey, while gaps in this understorey cover occupied the remaining 5–35 % of the area. The spatial distribution of I. woodii was strongly related to tree canopy structure, with the species excluded from sites with dense canopy cover. Woody seedling establishment was inhibited by low light availability ( / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

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.

In this study I investigated patterns of invertebrate diversity in Limpopo Province indigenous forests, in order to highlight forests and taxa of special conservation significance. Invertebrates from seven target taxa were sampled in 11 patches of indigenous forest in Limpopo Province from February 2001 to January 2002, including six forests in the Soutpansberg and five forests in the northern Drakensberg. Selected forests comprise three distinct vegetation subtypes and the target taxa selected were millipedes, centipedes, earthworms, terrestrial molluscs, spiders, scorpions and amphipods. Invertebrates were sampled by active searching of quadrats and line transects and pitfall traps. A total of 11 969 indigenous target group individuals were sampled, comprising 14 orders, 50 families, 86 genera and 142 species (including at least nine new). There was a significant difference in the total invertebrate species richness and diversity of forest patches but results varied considerably when different target group figures were analyzed. With the exception of spiders, the factors influencing total and individual target group richness in forests could not be determined. Introduced invertebrates comprised a large proportion of the species and individuals sampled, but were not shown to affect indigenous fauna. Invertebrate species assemblages were most similar between forests sharing the same vegetation subtype and between forests in the same mountain region. However, each forest patch had unique species and some even had unique families. Limpopo Province forests support high numbers of endemic invertebrates. A total of 47 endemic invertebrate species were sampled, including six site endemics, eight local endemics, nine regional endemics and 24 national endemics. The numbers and scales of endemism varied by target group. Invertebrate species’ distributions in Limpopo Province forests generally support the biogeographic theories of Pleistocene forest refugia and the Limpopo River valley as a radiation barrier, although some important contradictions were found. Local endemism in Limpopo Province forests is likely the product of historical processes. Although some significant relationships were found between surrogate and true measures, single taxon biodiversity indicators, the higher taxon method, morphospecies and land classes could not accurately predict patterns of target invertebrate species richness in Limpopo Province forests. Results show that formal species identification should be used if accurate richness estimates are desired; the use of surrogates is not supported by this study. Conservation of Limpopo Province forests is vital for the preservation of valuable invertebrate communities. No forest sampled in this study can be considered unimportant. Effective forest conservation and management is dependent upon the protection of forests of varying patch size, careful evaluation and control of utilization and the establishment and maintenance of corridors linking isolated forest patches. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

African elephants (Loxodonta africana) are ecosystem engineers in that they substantially alter the environment through their unique foraging and feeding habits. At high densities, elephants potentially have negative impacts on the environment, specifically to large trees. Because of this, recent increases of elephants in the Associated Private Nature Reserves (APNR) on the Western Boundary of Kruger National Park, South Africa have caused concern regarding the health of several species of tree. My objective was to assess the effectiveness of wrapping protective wire netting around the trunk of the tree in preventing and reducing bark stripping by elephants. 2,668 trees, 1352 marula (Sclerocarya birrea), 857 knobthorn (Acacia Nigrescens), and 459 false marula (Lannea schweinfurti), were assessed for elephant impact in the APNR, 1387 (52%) of which had previously been wrapped in protective wire netting (789, 548, and 50 respectively). For knobthorn and marula, wire netting significantly decreased the number of the trees that were bark stripped. For all trees, wire netting decreased the level of bark stripping especially for the highest impact levels. No trees wrapped with wire were ringbarked, compared to 23 unwired trees. In addition, wire netting had an effect on the distribution of damage for the highest impact class incurred regardless of type. A higher relative frequency of wired trees were found in lower impact categories compared to unwired trees. Wire netting is a low maintenance and ecologically valuable technique that alleviates bark stripping for some species. The judicial use of wire netting on trees could serve to maintain elephant and trees populations in areas of heavy confinement with locally high densities of elephants.

Studies were carried out in a lowland evergreen rain forest (LERF), on an ultisol, in the 'Reserva da Campina', 45 km north of Manaus, and in two facies of the highly distinct formation called heath forest, on spodosols. The spodosols had a layer of mor humus of thickness varying from nil in some parts in the smaller facies of heath forest (SHF) to 35 cm in the taller facies (THF). The overall aim was to investigate the forest soil biota and its role in nutrient turnover by comparing the SHF, THF and LERF. Microbial biomass, soil respiration and nitrogen transformation rates were measured in the three forest types in both wet and dry seasons. Field and laboratory fertilization experiments were made to investigate potential limiting nutrients for microorganisms and plants. The role of fine roots in decomposition and litter animal colonization was assessed in litter bag studies. SHF soils have a small microbial population with no net nitrification in any season. THF soils showed a variable microbial population adapted to high acidity, which immobilises nitrogen during the wet season, but which allows a net release during the dry season. LERF showed the most diverse population which causes mineralization and nitrification in both seasons. A bioassay with nutrient addition showed that the low pH, and nitrogen and sulphur supply were likely to be limiting nitrogen dynamics in all forest types, but especially in THF and LERF. The ingrowth bags showed that despite the lower values of fine root growth in the SHF (particularly when the white sand of the spodosol was used as the substrate), the roots showed in all plots an increased production with added calcium as carbonate or sulphate. In the decomposition bioassay to evaluate the role of roots in the nutrient turnover it was shown that in all forest types there was no effect of roots on the mass loss of Clitoria leaves but there was a significant effect on concentrations of some nutrients. In general, roots contributed to the accumulation of aluminium and iron and to a faster release and uptake of calcium, magnesium and zinc. A survey of the mycorrhizal associations in all forest types showed that both VAM and ECM fungi with some unknown VAM fungal species are common. VAM and ECM adaptation to low pH and high phenolic compounds in the soils may be important in the maintenance of these ecosystems.