Vegetation patterns and plant reproductive processes in the succulent Karoo

This thesis focuses on vegetation patterns and plant reproductive processes at the Tierberg Karoo Research Centre (33°1 0'S, 22°17'E) in the semi-arid southern Succulent Karoo, South Africa. It begins with an investigation into the roles of soil properties and competition in explaining variation in species distributions. The aim was to investigate changes in soil properties associated with species turnover (replacement series). Patterns of species abundances have been attributed to cyclic succession driven by disturbance and inter-specific competition. Areas where dominant species replaced each other over apparent edaphic discontinuities were investigated to test the roles of soil properties and competition in explaining variation in species distributions. Only soil pH differed significantly across the gradients studied. However, inter-and intra-specific· competitive interactions were also inferred. It was concluded that species distribution patterns resulted from the combined effects of edaphic factors and competition. The bulk of the thesis focuses on the reproductive biology of key species in the cyclic succession in order to understand the demographic processes underlying these patterns. The vegetation model proposes that heuweltjies (or mima-like mounds) are the source of disturbance which initiates the successional process. A study of reproductive attributes of dominant species occurring on and off heuweltjies indicated that species occurring on heuweltjies had opportunistic life-history traits; seeds did not germinate readily and canopy seed banks were maintained. Species off heuweltjies had higher overall germination and did not maintain seed banks in the plant canopies. The differences in reproductive attributes were related to competition and disturbance

Insights into invasion and restoration ecology : time to collaborate towards a holistic approach to tackle biological invasions

The aim of our study is to provide an integrated framework for the management of alien plant invasions, combining insights and experiences from the fields of invasion and restoration ecology to enable more effective management of invasive species. To determine linkages between the scientific outputs of the two disciplines we used an existing data base on restoration studies between 2000 and 2008 and did a bibliometric analysis. We identified the type of restoration applied, determined by the aim of the study, and conducted a content analysis on 208 selected studies with a link to biological invasions (invasion-restoration studies). We found a total of 1075 articles on ecosystem restoration, with only eight percent of the studies having the main objective to control alien invasions. The content analysis of 208 invasion-restoration studies showed that the majority of the studies focused on causes of degradation other than alien invasions. If invaders were referred to as the main driver of degradation, the prevalent cause for degradation was invaders outcompeting and replacing native species. Mechanical control of alien plant invasions was by far the most common control method used. Measures that went beyond the removal of alien plants were implemented in sixty-five percent of the studies. Although invasion control was not as common as other types of restoration, a closer look at the sub-group of invasion-restoration studies shows a clear link between restoration and invasion ecology. Concerns, as identified in the literature review, are firstly that restoration activities mostly focus on controlling the invader while other underlying causes for degradation are neglected, and secondly that the current approach of dealing with alien invasions lacks a combination of theoretical and practical aspects. We suggest that closer collaboration between invasion and restoration ecologists can help to improve the management of alien plant invasions. We conclude with a framework and a case study from Perth Western Australia integrating the two disciplines, with the aim of informing restoration practice

Road verges facilitate exotic species’ expansion into undisturbed natural montane grasslands

Questions How has exotic plant species richness and composition changed in and adjacent to a montane road verge over a 10-year period? Are montane road verges conduits of exotic species’ dispersal into adjacent, undisturbed hinterland? Location Montane grassland, Maloti-Drakensberg Transfrontier Conservation Area, South Africa. Methods We surveyed road verge and adjacent hinterland transects (25 × 2 m; N = 80) across an elevational gradient of 1,500–2,874 m a.s.l. in 2007 and 2017. In each transect, we estimated the cover of each exotic plant species and the total cover of indigenous species. Generalised Linear Models were fitted to test if exotic species’ richness and cover had changed over time. A Canonical Correspondence Analysis was used to determine if exotic species’ composition had changed over time. Results Ten years onwards, exotic species richness had increased significantly across the entire elevational gradient, predominantly in the low- to mid-elevational range. Road verge and adjacent hinterland transects differed in species composition in 2007, but no longer in 2017. Conclusion Exotic species richness and composition displayed a high spatiotemporal rate of change. Over time, exotic species increasingly moved into the hinterland from the verges as a result of human-mediated colonisation pressure. These results indicate that montane road verges are far better conduits for the dispersal of exotic species than previously assumed, and that further colonisation of the hinterland by exotics can be expected

Identifying and categorizing stakeholders for protected area expansion around a national park in Namibia

Protected areas and adjacent landscapes are increasingly being viewed as integrated. A more general awareness is emerging of the relevance of collectively managed landscapes for conservation and human well-being. In Namibia, areas dedicated to conservation are increasing because of the proliferation of conservancies and game reserves. Management toward integrated conservation in these landscapes involves land use practices variably dedicated to wildlife management and the inclusion of land owners and resource users in the decision-making process. We use stakeholder analysis to identify participants integral to an expanded protected area network around the Etosha National Park in Namibia. We identified and categorized important stakeholder groups, and quantitatively and qualitatively assessed their relative importance to the protected area decision-making process. Twelve stakeholder groups were identified, and categorized according to proximity to the national park, land tenure, and land use type. Primary stakeholders, those who both affect and are affected by decision making, comprised livestock farmers, communal conservancy members, resettlement farmers, and tourism/hunting enterprises. For each group the cumulative values of position (level of support for, or opposition to the concept), interest (perceived disadvantages and advantages thereof), and power (resources stakeholders can mobilize to express their position) were calculated. These attributes provide an indication of stakeholder salience, i.e., how likely stakeholders are to affect or be affected by an integrated conservation landscape. We find that livestock farmers, although interested in the concept, mostly oppose protected area expansion. The conflict in opinion is linked to the benefits derived from being part of the conservation landscape and the losses endured due to the porous park fence, including human-wildlife conflict and regulations involving a veterinary cordon fence. A consideration of stakeholder salience, taking into account the different perceptions surrounding the benefits of living adjacent to a protected area, can potentially lead to the better implementation of integrated conservation areas

Towards best practice in management of road reserves

CITATION: Esler, K. J. & Milton, S. J. 2007. Towards best practice in management of road reserves. Veld & Flora, 93(1):11-12.The original publication is available at https://journals.co.za/journal/veldAn inevitable consequence of population pressure and a growing economy is that landscapes increasingly become converted to those where production and transport are primary concerns. The biodiversity-rich southern African landscapes are no exception to this global trend with our linear transport corridors (roads, power lines, railways) causing fragmentation of habitats. However, they can also be seen as essential linking corridors between habitat fragments where adjacent agricultural or urban activity has eliminated biodiversity.C.I.Bhttps://journals.co.za/doi/abs/10.10520/EJC113033Publisher’s versio

The influence of biophysical and socio-economic factors on the effectiveness of private land conservation areas in preventing natural land cover loss across South Africa

There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability). Biophysical and legal contextual factors had low explanatory power in the best model for the nationwide analysis (n = 5121 PLCAs). For a subset of PLCAs (n = 72) we found that effectiveness depended on the strategy they adopted to generate an income, as opposed to the amount of income itself. PLCAs that attracted high volumes of visitors to small properties to view charismatic "Big 5" wildlife were less effective in conserving natural land cover than larger, more exclusive "Big 5" PLCAs and those focused on hunting. Overall, site-specific management factors were better at explaining the effectiveness of PLCAs than biophysical factors. Our findings indicate that conservation practitioners and policy makers need to recognise the diverse goals, motivations and management models of PLCAs when considering how to support them in conserving biodiversity. Future studies could explore whether these trends hold for other proxies of biodiversity conservation, beyond land cover change.Peer reviewe

Effectiveness of private land conservation areas in maintaining natural land cover and biodiversity intactness

CITATION: Shumba, T. et al. 2020. Effectiveness of private land conservation areas in maintaining natural land cover and biodiversity intactness. Global Ecology and Conservation, 22:e00935, doi:10.1016/j.gecco.2020.e00935.The original publication is available at https://www.journals.elsevier.com/global-ecology-and-conservationPrivate land conservation areas (PLCAs) are increasingly looked to for meeting the deficit left by state-owned protected areas in reaching global conservation targets. However, despite the increasing extent and recognition of PLCAs as a complementary conservation strategy, little research has been done to quantify their effectiveness; a critical consideration if they are to be counted towards international biodiversity conservation targets. The long history of PLCAs in South Africa provides an interesting case study to address this knowledge gap. Here, we quantified the effectiveness of South African PLCAs by comparing losses in natural land cover and biodiversity intactness within PLCAs with different levels of protection to that of unprotected control points. Points within PLCAs were matched with unprotected control points to test the prediction that if PLCAs offer effective protection, losses in natural land cover and biodiversity intactness would be significantly lower within their boundaries in comparison to unprotected controls exposed to similar conditions. Consequences of natural land cover loss on biodiversity intactness were thus assessed, thus advancing standard approaches for quantifying effectiveness. Between 1990 and 2013, PLCAs lost significantly less natural land cover (3%) and biodiversity intactness (2%) than matched unprotected areas (6% and 4%, respectively). Of the natural land cover lost within PLCAs, most was converted to cultivated land. Farms can support more species than other land uses (e.g. mines), a likely explanation for why losses in biodiversity intactness were less than losses in natural land cover. Contrary to the predicted pattern, effectiveness did not increase with level of protection; informal PLCAs with no legal protection had comparable natural land cover and biodiversity intactness retention to strictly protected PLCAs, with most losses recorded among PLCAs with moderate protection. This study provides the first national-scale evidence that PLCAs can be an effective mechanism for conserving natural land cover and biodiversity intactness, which is highly relevant given current discussions around their likely long-term biodiversity conservation capacity.Publisher's versio

Restoration of invaded Cape Floristic Region riparian systems leads to a recovery in foliage-active arthropod alpha- and beta-diversity

The Cape Floristic Region of South Africa is a global biodiversity hotspot threatened by invasive alien plants (IAPs). We assessed the effect of plant invasions, and their subsequent clearing, on riparian arthropod diversity. Foliage-active arthropod communities were collected from two native and one invasive alien tree species. Alpha- and beta- diversity of their associated arthropod communities were compared between near pristine, Acacia-invaded and restored sites. Arthropod alpha-diversity at near pristine sites was higher than at restored sites, and was lowest at invaded sites. This was true for most arthropod taxonomic groups associated with all native tree species and suggests a general trend towards recovery in arthropod alpha-diversity after IAP removal. Overall, arthropod species turnover among sites was significantly influenced by plant invasions with communities at near pristine sites having higher turnover than those at restored and invaded sites. This pattern was not evident at the level of individual tree species. Although arthropod community composition was significantly influenced by plant invasions, only a few significant differences in arthropod community composition could be detected between restored and near pristine sites for all tree species and arthropod taxonomic groups. Assemblage composition on each tree species generally differed between sites with similar degrees of plant invasion indicating a strong turnover of arthropod communities across the landscape. Results further suggest that both arthropod alpha- and beta- diversity can recover after IAP removal, given sufficient time, but catchment signatures must be acknowledged when monitoring restoration recovery.The DST/NRF Centre of Excellence in Tree Health Biotechnologyhttp://link.springer.com/journal/108412017-02-28hb2016Microbiology and Plant Patholog

Plant functional trait data and reflectance spectra for 22 palmiet wetland species

CITATION: Rebelo, A. J., et al. 2018. Plant functional trait data and reflectance spectra for 22 palmiet wetland species. Data in Brief, 20:1209-1219, doi:10.1016/j.dib.2018.08.113.The original publication is available at https://www.sciencedirect.comWe provide reflectance spectra for 22 South African palmiet wetland species collected in spring 2015 from three wetlands throughout the Cape Floristic Region. In addition, we provide summarized plant functional trait data, as well as supporting and meta-data. Reflectance spectra were collected with a portable ASD Fieldspec Pro using standard methods. The 14 plant functional traits were measured on 10 replicates of each species, following standard protocols. We provide tables detailing these standard methods, as well a table with hypotheses on how these 14 continuous traits, as well as an additional 9 categorical traits, may affect ecosystem service provision. In addition, tables are attached which detail which functional and spectral groups these species belong to, according to the data. Finally, we include a photographic plate of the species data are provide for. We make these data available in an effort to assist in research on the understanding of how traits affect ecosystem service provision in wetlands, and particularly of whether remote sensing can be used to map these traits in wetlands.https://www.sciencedirect.com/science/article/pii/S235234091830965XPublisher's versio

Unlocking and securing ecological infrastructure investments : the needs and willingness to invest and institutional support mechanisms used

CITATION: Mbopha, M.S. et al. 2021. Unlocking and securing ecological infrastructure investments: The needs and willingness to invest and institutional support mechanisms used. South African Journal of Science, 117(9/10)#8666:1-9. https://doi.org/10.17159/sajs.2021/8666.The original publication is available at https://www.sajs.co.za/Ecological infrastructure (EI) is a natural and near-natural functioning ecosystem that delivers a range of essential services to humankind. Examples include mountain catchments, wetlands, coastal dunes, and riparian corridors. In a world where EI is underinvested, rapid degradation and threats such as unsustainable veld-fire regimes, droughts, climate change, and invasive alien plants persist in dominating the ecological landscape. In South Africa, there are government programmes that encourage the restoration, rehabilitation and protection of EI. However, inadequate funding allocations constrain scalingup and thus necessitate the unlocking of public and private sector investments to augment resources for ecosystem-based management interventions. A systematic literature review was conducted at a global scale to (1) understand the drivers behind EI investments, (2) understand the willingness and desire of private landowners and land users to participate and contribute to EI investments and (3) identify institutional support mechanisms used to encourage investments. Results suggest that the need to invest is driven by growing degradation of EI and the urgency to meet environmental sustainability goals. The willingness to invest is stimulated by the use of economic-based policies and compensatory mechanisms. Public–private partnerships, public policy, and market-based conservation instruments are institutional arrangements executed to protect EI. These include processes and systems used by the institutions to legislate and manage interventions towards fulfilling the conservation objective. Our review contributes to the EI investment research agenda by recommending coordinated efforts to encourage EI investment from both public and private partners. These measures will help to secure financial resources and mobilise investments beyond monetary terms by coordinating planning and developing capacity and reform policies.https://sajs.co.za/article/view/8666Publishers versio