Managing roads, rivers and power line servitudes as biodiversity corridors through the landscape

National and Provincial road verges are managed to promote road safety and conserve biodiversity. In most cases the management is carried out by contractors and funded by the Extended Public Works Programme. In some cases, over zealous management or poor training appears to be damaging roadside vegetation and promoting weeds without necessarily improving road safety. Similarly, the clearing of vegetation below power lines can cause damage to vegetation or soil or result in introduction and establishment of invasive alien plant species. A related issue is the clearing of invasive alien plants from river corridors to conserve indigenous vegetation and improve river flow and water yield. However, depending on the density and nature of the alien vegetation and the clearing method, such management sometimes results in erosion that defeats the clearing objectives. The roads and rivers workshop in June 2006 brought together road safety managers, conservation managers and other interested parties to develop "best practice" guidelines acceptable to all parties.C.I.

Biocultural diversity: A Mongolian case study

Although conceptual frameworks describing biodiversity and cultural keystone species have been widely accepted over the past 15 years, there remains a need for an overarching framework that covers the various components of biocultural diversity. We present a conceptual framework to enable the better understanding, monitoring, and maintenance of biocultural diversity across a range of spatial scales, from the landscape and ecosystem level to the species and gene/meme level. This is done by combining the concepts of biological diversity and cultural diversity, including cultural values and symbols, ethnoscientific approaches, as well as power relations and institutions, to form a biocultural diversity framework. To illustrate the framework, we use a systems diagram and practical examples from a case study on the ethnoveterinary knowledge and practices of Mongolian pastoralists. Ethnoveterinary knowledge is an example of traditional ecological knowledge and therefore offers valuable insight into biocultural diversity. Using the conceptual framework as a tool, our investigation of biocultural diversity in the Mongolian pastoralist context strongly suggests that an understanding of the historical, political, and cultural contexts, as well as the interrelatedness of cultural processes and ecological systems, is essential for maintaining biocultural diversity. More specifically, our results indicate that retaining a mobile herding way of life as well as the associated balance and communication with nature, is vital for both the continued transmission of ethnoveterinary knowledge and the sustainable use of ecological resources that Mongolian pastoralists rely on. There is a need for national policies that acknowledge, support, and maintain the important and complex processes underlying the Mongolian landscape and the associated worldviews, knowledge, and practices. The development of a coherent framework for biocultural diversity therefore allows for a clearer understanding of the various components and the selection of appropriate indicators for monitoring biocultural diversity

Drought induced xylem embolism in four riparian trees from the Western Cape Province: Insights and implications for planning and evaluation of restoration

AbstractIn Mediterranean climates, rainfall is restricted to periods of low evaporative demand, leaving plants to survive the summer drought. The purpose of this study was to determine the contribution of drought tolerance to the distribution of riparian species. These physiological insights will assist in developing target species lists for restoration of riparian ecosystems in the Western Cape, currently heavily degraded due to land clearing and invasive aliens. We estimated P50 and P100 from vulnerability curves and Ψx in four species across a range of summer water availability estimated by streamflow. As expected, decreasing streamflow resulted in lower predawn and mid-day xylem water potential, and species identified in previous studies as having broad distributions, such as Brabejum stellatifolium and Metrosideros angustifolia, sustained greater decreases in mid-day xylem water potential and were less vulnerable to cavitation than Rapanea melanophloeos or Brachyleana neriifolia, species with more restricted distributions. These results provide preliminary evidence that a consideration of drought tolerance might be useful in refining lists of target species for active restoration and evaluation of restoration success across projects in streams and rivers with different fluvial regimes

Assessing restoration potential of a critically endangered vegetation type following alien acacia removal

The Fynbos vegetation of the Cape Lowlands is ecologically distinct from mountain Fynbos within the Cape Region of South Africa, but has been highly impacted by agriculture and urban development, while alien plants have invaded most of the remaining natural habitats. Cape Flats Sand Fynbos is a critically endangered lowland vegetation type containing many endemic and threatened species. 100 ha of this vegetation type which was invaded by alien Acacia saligna was cleared in 2012. The standard clearing methods utilised in Lowland Fynbos have resulted in poor native vegetation recovery. Therefore this study aimed to test novel passive (burning) and active (seed sowing) treatments on recovery of native vegetation. After two years all treatments resulted in different recovery trajectories, and modelling treatment responses showed these trajectories to be maintained in the long-term. The passive clearing without burning treatment resulted in herbaceous vegetation dominating, while the active treatment resulted in higher cover, species richness and density of non-sprouting shrubs. A follow-up sowing treatment involving seed pre-treated with smoke and heat improved shrub species richness and seedling density of certain species, especially Thamnochortus punctatus, a dominant structural component species. Therefore an active treatment involving sowing pre-treated seeds after clearing and burning results in best Fynbos recovery compared to either of the passive treatments tested. These restoration methods should be adaptable to other lowland vegetation types within the Fynbos region as well as other Mediterranean climate regions

Allelopathic effects of invasive Eucalyptus camaldulensis on germination and early growth of four native species in the Western Cape, South Africa

Eucalyptus camaldulensis Dehnh. (red river gum; Myrtaceae) is an invasive tree in riparian habitats of the Western Cape, South Africa, where it replaces indigenous vegetation and affects ecosystem functioning. These invasions lead to changes in river geomorphology and reduction in stream flow. The mechanisms that drive these effects are poorly understood. The potential for allelopathic effects of aqueous extracts of E. camaldulensis tissues and of soil and litter collected beneath E. camaldulensis trees on the germination and seedling growth of four selected native plant species was investigated in a greenhouse experiment. Soils collected beneath E. camaldulensis trees were used in three treatments: untreated soils, sterilised soils and sterilised soils overlaid with a eucalypt litter layer. In addition, soils collected from underneath native species were used in two treatments: untreated soils and soils overlaid with a eucalypt litter layer. All soil treatments were watered with three E. camaldulensis leaf, bark and root aqueous treatments. Compounds present in the aqueous extracts and fresh samples were identified using gas chromatography. Soil and aqueous treatments showed varying effects on germination and seedling growth of the four native species. Germination and seedling growth of Olea europaea subsp. africana and Dimorphotheca pluvialis were significantly reduced by E. camaldulensis root and bark aqueous extracts as well as by the soils treatments. The addition of eucalypt litter to native and sterilised soils reduced shoot and root growth of all four native species. Compounds such as -phellandrene, eucalyptol, p-menth-1-en-8-ol and a-pinene, which have the potential to inhibit germination and plant growth, were identified in E. camaldulensis aqueous extracts and fresh samples. Although the methods applied in this study had limitations (e.g. lack of control treatment to litter addition), the results provide an additional motivation to prioritise removal of invasive E. camaldulensis stands from riparian ecosystems. Restoration initiatives should target native species that are not negatively affected by allelopathy

Active seed sowing can overcome constraints to passive restoration of a critically endangered vegetation type

Invasive alien plants negatively impact ecosystems, but recovery of native vegetation may fail following standard methods of alien species removal alone. Alternative management actions may thus be required. Cape Flats Sand Fynbos is a critically endangered vegetation type in the Cape Floristic Region of South Africa which is threatened by Acacia saligna invasion, but standard clearing methods have failed to restore native vegetation structure. A restoration study was performed comparing passive treatments i.e. clearing without burning (stack-block) versus clearing and burning (burn-block), as well as active intervention by sowing seeds of native species, either initially after burning or a year later, in which seeds were either not pre-treated or pre-treated with smoke and heat exposure before sowing. After two years all treatments resulted in different recovery trajectories, although none resembled the reference condition. Clearing without burning facilitated recovery in less degraded areas with higher initial native shrub cover, but otherwise resulted in limited vegetation recovery. Limited recovery facilitated secondary invasion by herbaceous weeds. Active seed sowing resulted in the highest recovery of native shrub cover and diversity. These findings suggest that passive restoration is constrained by seed limitation, due to the lack of recovery of vegetation components under passive clearing treatment. Active sowing was able to partially overcome this constraint through improved recovery of total shrub cover. However, non-sprouting shrub cover was higher while resprouting shrubs and species of Restionaceae were lower compared to the reference condition. Pre-treatment of seeds before sowing improved establishment of some species. Active treatment involving sowing pre-treated seeds after clearing and burning therefore resulted in best fynbos recovery compared to either of the passive treatments tested. A decision tree has been developed based on these findings in order to guide best protocol for managers

Assessment of post-burn removal methods for Acacia saligna in Cape Flats Sand Fynbos, with consideration of indigenous plant recovery

The Greater Cape Floristic Region (GCFR) of South Africa is a biodiversity hotspot threatened by the impacts of habitat transformation and invasive alien species. Cape Flats Sand Fynbos (CFSF) is a critically endangered vegetation type occurring within the GCFR, and its largest remaining fragment is the focus of a large-scale invasive plant control and biodiversity restoration project. Acacia saligna is a highly problematic invasive in CFSF and the main target of the control. To mitigate damage caused by this species, stands are removed and burned, which stimulates both the large invasive seed-bank and the indigenous seed-bank in the soil. Although there are no clear methods on how to manage the re-invasion at this stage without damaging indigenous plant recovery, three post-burn removal methods have the potential to be effective: (1) cutting the Acacia saplings below the coppicing point, (2) cutting the saplings and applying herbicide to the stumps, and (3) foliar herbicide spray. The aims of this studywere to (i) find the most effective post-burn A. saligna control treatment, (ii) find the treatment that causes the least harm to indigenous plant recovery, (iii) determine the most cost-effective treatment, and (iv) establish which treatment is the most suitable for large-scale use. Cutting below the coppicing point of the A. saligna provided the most effective removal and was also the least damaging to indigenous vegetation recovery. The foliar spray treatment, however, saved the most time and costs. The best method is therefore dependent on the project goals, scale, and density of the A. saligna invasion. These results may be applicable to other types of fynbos and to other fire-stimulated invasive Acacia species

Exploring the dynamics of research collaborations by mapping social networks in invasion science.

Moving towards more integrative approaches within the invasion sciences has been recognized as a means of improving linkages between science, policy, and practice. Yet despite the recognition that biological invasions pose complex social-ecological challenges, the invasion literature poorly covers social-ecological or distinctly integrative research. Various initiatives and investments have been made towards building research capacity and conducting more integrative research aimed at improving the management of biological invasions. Using a combination of social network and thematic analysis approaches, and the South African Working for Water (WfW) program as a case study for the management of invasive species, we identify and explore the roles of core authors in shaping collaboration networks and research outputs, based on bibliographic records. We found that research produced under the auspices of WfW is authored by a handful of core authors, conducting primarily ecologically-focused research, with social research significantly underrepresented. Core authors identified in this study play an essential role in mediating relationships between researchers, in addition to potentially controlling access to those seeking to form collaborations, maintaining network cohesion and connectivity across institutional and disciplinary boundaries. Research projects should be designed to span disciplines and institutions if they are to adequately address complex challenges