Drylands’ poly-extreme conditions limit edaphic microbial diversity and functionality. Furthermore, climate change exacerbates soil desiccation and salinity in most drylands. To better understand the potential effects of these changes on dryland microbial communities, we evaluated their taxonomic and functional diversities in two Southern African dryland soils with contrasting aridity and salinity. Fungal community structure was significantly influenced by aridity and salinity, while Bacteria and Archaea only by salinity. Deterministic homogeneous selection was significantly more important for bacterial and archaeal communities’ assembly in hyperarid and saline soils when compared to those from arid soils. This suggests that niche partitioning drives bacterial and archaeal communities' assembly under the most extreme conditions. Conversely, stochastic dispersal limitations drove the assembly of fungal communities. Hyperarid and saline soil communities exhibited similar potential functional capacities, demonstrating a disconnect between microbial structure and function. Structure variations could be functionally compensated by different taxa with similar functions, as implied by the high levels of functional redundancy. Consequently, while environmental selective pressures shape the dryland microbial community assembly and structures, they do not influence their potential functionality. This suggests that they are functionally stable and that they could be functional even under harsher conditions, such as those expected with climate change.
21 August 2013 in International Journal of Biodiversity
Monitoring is a vital component of keeping protected areas in desired states. Lack of robust designs, however, impedes efficient monitoring. We ask two questions—how does effort at a specific site as well as number of sites in a plant community influence richness, abundance, and diversity indicators. Large mammal herbivory biodiversity influences are a key concern for managers of Mokala National Park. We anticipated that changes in biodiversity indicators (vegetation, ants, and birds) associate with herbivore intensity of use of landscapes. We identified flat deep sandy plains and undulating shallow rocky hills as focal landscapes. Our focus was on finding optimized effort at survey sites as well as the number of sites. Monitoring to evaluate change in diversity and abundance needs far less effort than evaluating change in richness. Furthermore, given the variance at the landscape level, monitoring of species abundance and diversity allows easier detection with less effort and at shorter intervals between surveys than that required for richness. Even though a mechanisms-based approach directs monitoring, conservationists need to evaluate feasibility. In our case, measurement of richness is unlikely to detect herbivore effects. In general though, we have illustrated that focused monitoring designs can robustly evaluate conservation objectives.
Monitoring is an essential component of measuring the performance of protected areas. This requirement led to the development of a biodiversity monitoring system for South African National Parks (SANParks). The system comprises of ten major programmes, each focusing on a core area of conservation biodiversity monitoring, with resource use being one of the focal areas. With the growing appreciation of the importance of natural resources for the socio-economic well-being of communities and other stakeholders, sustainable resource use is an important component of the management of natural areas and national parks. To gauge sustainability, a sound monitoring and research programme that fits within the context of the SANParks’ adaptive management approach towards social-ecological system management is required. The purpose of this article was to define the context and scope in which consumptive resource use takes place within SANParks and to outline the criteria necessary for developing a sound monitoring programme to assess the sustainability of such use. The monitoring programme is structured in view of the fact that sustainable resource use is achievable only where all dimensions of sustainability (social, economic and ecological) are considered simultaneously. In terms of the social and economic dimensions of sustainability, the programme provides for assessing stakeholder needs, trends in resource use and the social and economic impacts of resource use. Monitoring that relates to the ecological dimension of sustainability of biological resource use deals with the rate of turnover and population dynamics of target species, as well as harvest impact. In terms of abiotic (non-renewable) resources, monitoring deals with sound management practices to minimise impact on the environment, and to optimise benefits through responsible use.Conservation implications: The resource use monitoring programme is intended to ensure that monitoring relating to the harvesting of natural resources from national parks is scientifically sound and conducted in a structured way, towards meeting the objective of sustainable use and compliance with national legislation. The article illustrates how SANParks meets its obligation to monitor biodiversity conservation while at the same time meeting the needs for the consumptive use of resources.
Encephalartos eugene-maraisii is an endangered, endemic plant in the Waterberg Mountain range of South Africa. This is the first report of herbivory by Zerenopsis lepida (Lepidoptera: Geometridae) on natural populations of E. eugene-maraisii. The impact of herbivory by folivorous arthropods on this cycad species has not been studied before. This study aimed to determine the incidence and intensity of Z. lepida herbivory on E. eugene-maraisii under field conditions. Local plant dynamics were studied by recording the plant location, sex, size and phenological stage for each plant. Damage surveys were carried out over two consecutive seasons (2020–2021 and 2021–2022). Leaf damage was assessed on 227 plants comprising 692 stems. Approximately 40% of the stems had signs of leaf herbivory by Z. lepida and 10% of the total leaf area was removed by Z. lepida larvae. Less herbivory was recorded in areas where plants synchronously produced new leaf flushes compared to areas with asynchronous leaf flushes. Greater apparency of plants led to a greater incidence of herbivory and level of damage. Repeated damage to plants may delay future leaf and cone flushing events and contribute to the threat against this cycad species.
28 January 2019 in Koedoe - African Protected Area Conservation and Science