Plant-frugivore interactions in a heterogeneous forest landscape of South Africa

Seed dispersal by animals is a very important ecological process, especially in tropical and sub-tropical forest landscapes where up to 90% of fleshy fruiting plant species depend on this process for the transportation of their propagules to suitable habitats. Frugivorous birds are among the most important vertebrates consuming fruits, thereby contributing to natural forest regeneration. However, changes in quality of forest habitats and structure of the surrounding matrix have been shown to disrupt the structure of single-pair seed dispersal interactions. Changes in forest habitats can also alter the functional diversity of dispersers within these seed dispersal communities and can have far reaching implications for natural regeneration processes of plants. To assess the overall effects of forest patch quality and matrix habitat on ecological processes and functioning, I compared (i) the structure of plant-frugivore interaction networks and (ii) functional diversity of frugivore communities within the studied networks among forest patches surrounded by dissimilar matrix habitats in and around Vernon Crookes Nature Reserve in South Africa. In addition, I experimentally tested the impact of seed ingestion and treatment in the digestive tracts of avian frugivores on germination to assess their legitimacy as seed dispersers. During the plant-frugivore networks study, I compared the network structure in a large scarp forest surrounded by a natural forest matrix with those of two small natural forest types, one surrounded by natural grassland and the other by sugarcane agriculture in relation to both forest patch quality and matrix habitat. Overall, I recorded a total of 54 avian frugivorous species involved in fruit removal activities on 31 fleshy fruiting plant species. Network structures across forest patches did not vary with matrix habitat. Instead, they were similarly robust and strongly influenced by forest patch quality. These findings suggest that the structure and stability of plant-frugivore interaction networks is rather determined by local forest patch quality than by surrounding matrix habitat. During the functional diversity study, I compiled data on three functional traits related to seed dispersal, namely body mass, gape width and degree of frugivory for the frugivore species observed in the seed dispersal networks. I then tested the effect of forest patch quality and matrix habitat on three measures of functional diversity as well as on species richness of frugivore communities. Results suggest that all forest types sustained a comparably high functional diversity among the seed disperser communities. Overall, functional diversity and shifts in functional composition were rather determined by forest patch quality than by matrix habitat. During the seed ingestion experiment, I collected fruits from sixteen woody plant species and I fed them to four avian frugivore species. Defecated seeds were planted and their seedling emergence and germination probabilities were compared with those of ripe manually depulped seeds and whole fruits. Results show no difference in seedling emergence and germination probability among the birds and remained similar across all treatments. The results suggest that the effect of frugivorous birds on natural forest regeneration is more on seed transportation, than enhancing germination of dispersed seeds per se. Overall, findings from the first two studies suggests that forest patch quality is an important driver of both network stability and functional diversity among frugivore communities. Therefore, given high habitat quality, forest patches surrounded by variable matrices can be of conservation importance in highly heterogeneous forest landscapes. Thus, as the seed ingestion experiment has shown that frugivorous birds are legitimate dispersers, the sustenance of seed dispersal processes will largely depend on maintenance of forest patches of high quality and with less restrictive matrix habitats

Application of Conservation and Veterinary Tools in the Management of Stray Wildlife in Zambia

In recent years, Zambia has seen an increase in the incidences of conflicts involving stray wild animals with humans. Notable among these animals include the African elephants, buffalo and lion. Consequently, this triggers a response from law enforcement units of both government and the department of national parks to control the animals. Regrettably, most of their responses have involved the shooting down of these animals, rather than taking advantage of conservation and veterinary tools to relocate the animals back into protected areas, and this raises concerns about the welfare of these animals. Therefore, this chapter will bring to light some of the locally available tools that could be used to control stray wildlife in order to contribute towards both conservation and reducing human-wildlife conflicts in Zambia

Contextualizing the Factors Affecting Species Diversity and Composition in the African Savanna

Recently, sustainable forest management has been the top priority for many international forest conservation organizations, governing authorities, and interest groups. Forest conversion to farmland for fuel wood removal, charcoal production, and woodland grazing is the principal mechanism of forest degradation, habitat change, and loss of biodiversity. Despite the increasing acknowledgment of conservation values of savanna, our understanding of the factors affecting species diversity and composition for the African savanna remains limited. This chapter provides a systematic review of the factors affecting species diversity and composition in an African savanna. However, in order to reduce this inadequacy, a careful examination of the existing literature was conducted. After a thorough review, it was revealed that species diversity and composition in savanna are significantly shaped by grazing, fire, and resource availability, that is, rainfall and soil nutrients, as well as anthropogenic activities. Understanding the diversity and composition of tree species is vital since they provide resources and habitats for several other species. Botanical assessments, such as floristic composition, species diversity, and structural analysis studies, are significant for providing accurate information on species richness, which is valuable for sustainable forest management and helps to understand forest ecology and ecosystem functions

Patch - Occupancy Survey of Elephant (Loxodonta africana) Surrounding Livingstone, Zambia

Wild elephants represent the biggest human–wildlife conflict issue in Livingstone, Zambia. However, little is known about their movements. This survey investigated elephants’ habitat use outside a core protected and fenced zone that forms part of Mosi-oa-Tunya National Park, Zambia. Using ‘patch-occupancy’ methodology, indications of elephant presence (feeding behaviour, dung and tracks) were surveyed. The survey aimed to assist proposed future monitoring exercises by defining the geographical extent that should be considered to improve accuracy in species abundance estimates. Results were supplemented using collected indications of elephant presence from prior monitoring exercises, and during this survey. Elephant presence was confirmed up to 8 km from the boundary of the protected core habitat, focussed in: (1) an unfenced zone of the national park, (2) along a road leading from the national park to the Dambwa Forest to the north and (3) along two rivers located to the west (Sinde River) and east (Maramba River) of the core area. Detection probability of elephant presence was high using these methods, and we recommend regular sampling to determine changes in habitat use by elephants, as humans continue to modify land-use patterns. Conservation implications: Identification of elephant ranging behaviour up to 8 km outside of the Mosi-oa-Tunya National Park in southern Zambia will assist in managing human– elephant conflict in the area, as well as in assessing this seasonal population’s abundance

Mean ± SE specialisation of frugivores and plants within plant-fugivore networks. (n = 9).

<p>Mean ± SE specialisation of frugivores and plants within plant-fugivore networks. (n = 9).</p

Habitat Characteristics of Forest Fragments Determine Specialisation of Plant-Frugivore Networks in a Mosaic Forest Landscape

<div><p>Plant-frugivore networks play a key role in the regeneration of sub-tropical forest ecosystems. However, information about the impact of habitat characteristics on plant-frugivore networks in fragmented forests is scarce. We investigated the importance of fruit abundance, fruiting plant species richness and canopy cover within habitat fragments for the structure and robustness of plant-frugivore networks in a mosaic forest landscape of South Africa. In total, 53 avian species were involved in fruit removal of 31 fleshy-fruiting plant species. Species specialisation was always higher for plants than for frugivores. Both species and network-level specialisation increased with increasing fruit abundance and decreased with increasing fruiting plant species richness and canopy cover within fragments. Interaction diversity was unaffected by fruit abundance and canopy cover, but increased slightly with increasing fruiting plant species richness. These findings suggest that especially the availability of resources is an important determinant of the structure of plant-frugivore networks in a fragmented forest landscape.</p> </div

Economic Impact and Challenges of Jatropha curcas L. Projects in North-Western Province, Zambia: A Case of Solwezi District

Forest products, wood and non-wood, remain vital among smallholder households in Zambia with charcoal being the most sought after product. This has led to increased exploitation of forest trees to meet the needs for fuel wood, among others. However, Jatropha curcas plant has been identified as a potential fuel source. In the early 2000s, profit-making organizations encouraged smallholder households to grow Jatropha for use as an alternative fuel source. This paper reports on a study conducted in Solwezi between 2011 and 2014 to evaluate the impact of Jatropha cultivation for biofuel production. A sample of 100 small-scale farmers involved in Jatropha cultivation and key informants were interviewed to evaluate the impact of growing Jatropha at the small-scale level. Results show that farmers lost out on time; income from sale of edible non-wood forest products; and experienced reduction in maize (Zea mays) and bean (Phaseolus vulgaris) production, worsening household economic conditions. Farmers attributed this loss to unclear policy alignment on biofuel production by government. We therefore recommend that project implementation should involve interactions of all legislative bodies and any other concerned stakeholders. There is also a need to promote the value chain, from production to marketing, which focuses on minimizing detrimental effects on the livelihood of small-scale farmers

Effects of habitat characteristics and trophic level on the structure of plant-frugivore networks.

<p>Species specialisation (<i>d'</i>), network specialisation (<i>H₂'</i>), interaction diversity and robustness of plant-frugivore networks (n = 9) in relation to fruit abundance, fruiting plant species richness, canopy cover (%) and trophic level (plant <i>vs.</i> frugivore). To investigate effects on species specialization, trophic level was nested within plot in a linear mixed effect model; effects on all other dependent variables were analysed using linear models. Given are <i>R²</i>, <i>t</i> and <i>P</i> values, if applicable. Note: all significant or marginally significant <i>P values</i> are highlighted in bold.</p

The generality of cryptic dietary niche differences in diverse large-herbivore assemblages

Ecological niche differences are necessary for stable species coexistence but are often difficult to discern. Models of dietary niche differentiation in large mammalian herbivores invoke the quality, quantity, and spatiotemporal distribution of plant tissues and growth forms but are agnostic toward food plant species identity. Empirical support for these models is variable, suggesting that additional mechanisms of resource partitioning may be important in sustaining large-herbivore diversity in African savannas. We used DNA metabarcoding to conduct a taxonomically explicit analysis of large-herbivore diets across southeastern Africa, analyzing ?4,000 fecal samples of 30 species from 10 sites in seven countries over 6 y. We detected 893 food plant taxa from 124 families, but just two families?grasses and legumes?accounted for the majority of herbivore diets. Nonetheless, herbivore species almost invariably partitioned food plant taxa; diet composition differed significantly in 97% of pairwise comparisons between sympatric species, and dissimilarity was pronounced even between the strictest grazers (grass eaters), strictest browsers (nongrass eaters), and closest relatives at each site. Niche differentiation was weakest in an ecosystem recovering from catastrophic defaunation, indicating that food plant partitioning is driven by species interactions, and was stronger at low rainfall, as expected if interspecific competition is a predominant driver. Diets differed more between browsers than grazers, which predictably shaped community organization: Grazer-dominated trophic networks had higher nestedness and lower modularity. That dietary differentiation is structured along taxonomic lines complements prior work on how herbivores partition plant parts and patches and suggests that common mechanisms govern herbivore coexistence and community assembly in savannas