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20 Pág. Departamento de Medio Ambiente y Agronomía​, Restoration of degraded drylands is urgently needed to mitigate climate change, reverse desertification and secure livelihoods for the two billion people who live in these areas. Bold global targets have been set for dryland restoration to restore millions of hectares of degraded land. These targets have been questioned as overly ambitious, but without a global evaluation of successes and failures it is impossible to gauge feasibility. Here we examine restoration seeding outcomes across 174 sites on six continents, encompassing 594,065 observations of 671 plant species. Our findings suggest reasons for optimism. Seeding had a positive impact on species presence: in almost a third of all treatments, 100% of species seeded were growing at first monitoring. However, dryland restoration is risky: 17% of projects failed, with no establishment of any seeded species, and consistent declines were found in seeded species as projects matured. Across projects, higher seeding rates and larger seed sizes resulted in a greater probability of recruitment, with further influences on species success including site aridity, taxonomic identity and species life form. Our findings suggest that investigations examining these predictive factors will yield more effective and informed restoration decision-making., We would like to thank the supporters of the Global Arid Zone Project. The intellectual and energetic input of the network participants made this work possible. We also acknowledge the many employers and funding agencies that supported projects and the authors’ time in preparing this work and contributing data to the GAZP database. Please note that any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the US Government

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.

Ecological restoration is a global imperative to reverse widespread habitat loss and degradation, including by invasive alien plants. In South Africa’s Core Cape Subregion, alien tree invasions are...

1 Pág. Correción errata., In the version of this Article originally published, the surname of author Tina Parkhurst was incorrectly written as Schroeder. This has now been corrected.

Pine plantations and pine invasions have numerous impacts on native ecosystems in the Fynbos biome of South Africa. The severity of these impacts greatly determines the extent of potential ecosystem recovery after the pines are felled. The recovery potential of fynbos after felling of pine plantations of varying longevity and the subsequent application of ecological burns was investigated in the Helderberg Nature Reserve, Western Cape Province, South Africa. Above-ground vegetation, soil seed bank and abiotic variables were sampled across three treatments (reference fynbos and sites that had been under pines for 30 and 50 years respectively) using 1 m2 quadrats placed along 50 m line transects. The soil seed bank samples were smoke treated and then monitored in a greenhouse to determine the soil seed bank species and growth form composition. Areas previously under 30 year old pine plantations had high native species and growth form density (number of species/growth forms per unit area) and similar plant density (number of individuals per unit area) to the reference fynbos areas. Conversely, areas previously under 50 year old pine plantations had significantly lower native species and growth form density and plant density than the reference fynbos and were dominated by alien species. In addition, areas previously under 50 year old pine plantations had lower species diversity than the reference fynbos areas and areas previously under 30 year old pine plantations which were found to be similar to one another. Felled pine plantations were shown to minimally impact on soil abiotic variables, with only soil temperature and pH showing significant differences. Therefore, areas previously under 30 year old pine plantations have higher recovery potential following pine removal than 50 year old plantations, owing to the depleted native soil seed bank in the latter. Consequently, active restoration may be needed to re-introduce the missing long-lived growth forms and to prevent soil erosion. Pine plantation and invasion management in the Fynbos biome should aim to fell pines before the native seed bank is depleted to maintain the recovery potential of fynbos and prevent the need for active restoration.

Invasive alien plant species can be a major cause of ecosystem degradation in South Africa, and ecosystem recovery may require restoration interventions beyond controlling the target alien species. Active restoration interventions are usually required if legacy effects result from the invasion. Legacy effects may induce regime shifts when thresholds to autogenic recovery are breached. In such cases, active restoration interventions will be required to manipulate the ecosystem along a trajectory to recovery. In some cases, alien control measures may be sufficient to restore a structurally and functionally representative ecosystem, provided that implementation occurs early in the invasion process and that the control methods do not hamper spontaneous regeneration. It is important that key stakeholders discuss and set realistic restoration goals at the project planning stage. Studies on the costs and benefits of ecological restoration indicate that when important services are improved, benefits outweigh the costs of alien clearing (assuming spontaneous regeneration of the native ecosystem). The costs of moderate, active restoration interventions are economically viable, whereas the costs of fully restoring ecosystem structure, functioning and composition in highly degraded ecosystems are rarely deemed economically justifiable. Valuations of specific biodiversity components, such as threatened ecosystems and species, remain problematic to assess, and these components could be under-valued in such studies. South African researchers have made significant contributions to the theory and practice of restoration ecology globally and have produced local guidelines for ecological restoration. However, there has been limited uptake in implementing active restoration projects at larger scales. This apparent knowing-doing gap may have three causes: firstly, insufficient co-production by all stakeholders in planning restoration projects, including prioritisation and goal setting; secondly, shifting beyond clearing invasive alien species to restoring ecosystems; and thirdly, insufficient resources to implement active restoration projects at the necessary scale. To achieve Convention on Biological Diversity and the UN Sustainable Development Goals, interventions must shift from controlling invasive alien species alone to restoring native ecosystem structure and functioning.

This study investigated the autogenic recovery potential of native vegetation after clearing of dense stands of invasive alien trees in two critically endangered vegetation types in South Africa's Cape Floristic Region: Cape Flats Lowland Fynbos and Swartland Alluvium Fynbos. Sampling was done in areas previously occupied by the invasive tree Acacia saligna and plantations of Pinus radiata and in a fynbos reference site. Treatments varied in terms of the length of invasion and management histories. Plots previously under pines recovered well in terms of indigenous perennial species richness, but indigenous species cover decreased with increasing number of planting rotations. Areas cleared of acacia recovered poorly in terms of indigenous species cover (after one cycle of invasion), and indigenous species richness exhibited a declining trend with increasing cycles of invasion. Proteoid overstorey was lost in all previously invaded/planted plots and this element will need to be re-introduced to areas after one cycle of invasion regardless of the invasive species. Acacias changed some abiotic variables after two cycles of invasion. Follow-up clearing generally promoted better vegetation recovery in terms of overall species richness and structure but care should be taken not to damage indigenous ericoid shrubs. Overall, acacia invasion caused a greater change in biodiversity and vegetation structure than pine plantations.

Invasive alien plants impact ecosystems, which often necessitates their removal. Where indigenous species recovery fails following removal alone, an active intervention involving reintroduction of seed of native species may be needed. This study investigated the potential for a combination of the fire cues of smoke and heat as a pre-treatment of seeds in breaking dormancy and facilitating increased germination. Species were selected to represent different functional types within Cape Flats Sand Fynbos; a fire-prone, critically endangered vegetation type in South Africa. Seeds were exposed to either a heat pulse (temperatures between 60 and 300°C for durations of between 30 s and 20 min) or dry after-ripening (1 or 2 months at milder temperatures of 45°C or less). Thereafter, seeds were soaked in smoke solution for 18 h and subsequently placed on agar at 10/20°C for germination. Most species fell into one of two main groups: Seed germination in the first group was greatest following a lower temperature (60°C) heat pulse, an extended period of mild temperature (20/40°C or 45°C) exposure, or no pre-treatment with heat. Seed germination in the second group was promoted after brief exposure to higher (100°C) temperatures. No germination occurred in any species following heat treatments of 150°C or higher. Species which responded better to higher temperatures were mainly those possessing physical dormancy, but seed morphology did not correlate with germination success. This study showed that heat stimulation of seeds is more widespread in fynbos plant families than previously known and will enable the development of better seed pre-treatment protocols before large-scale sowing as an active restoration treatment after alien plant clearing.

Invasive non-native species are often more prevalent in cities than in rural areas because of numerous environmental disturbances and higher propagule pressure. Attempts to manage invasive species in cities are often controversial because of the diversity of stakeholder views. Until now, however, environmental managers in cities have managed invasive species using approaches and paradigms developed for a rural context, despite the radically different socio-environmental conditions that prevail in cities. We examine the case of Cape Town, South Africa, a rapidly growing metropolitan centre within a global biodiversity hotspot and a developing country, to underline the considerable challenges and complexities of managing invasive species in cities. We argue that traditional management approaches need to be supplemented by consideration of stakeholder views and the social consequences of management actions. We present a framework for selecting appropriate goals for the management of invasive species, ranging from eradication to acceptance.

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 study were 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.

Peninsula Shale Renosterveld, a Critically Endangered ecosystem, requires ecological restoration intervention on transformed areas. Yet there is little guidance due to very few renosterveld studies and limited knowledge of the mechanisms driving ecological responses. This study set out to test the effects of 32 interventions, comprised of five crossed factors (seeding of 31 species, fire, tillage, herbicide application and rodent exclusion), on vegetation recruitment on a site dominated by alien, annual grasses. Actual experimental responses were compared with predicted responses presented in an a priori ecological-response model. Responses to the interventions were highly variable. Sowing on its own was almost ineffectual, but restoration of species was enhanced when seeding was implemented with one or more of the other factors. In combination with other treatments, seeding made significant contributions to overall seedling density, species richness and canopy cover and is imperative if this ecosystem is to recover from extensive alien grass invasion. Several three- to five-factor interventions resulted in a full set of desired responses. Half of the responses predicted in an ecological-response model were confirmed. Study outcomes have the potential to guide future research and implementation of larger scale renosterveld restoration.

The considerable risk factors associated with ecological restoration make the reintroduction of appropriate species critical to restoration success. In seed-based restoration efforts, using high quality seed is central to good in-field yields; consequently, determining the physiological status of seed prior to large-scale collection and use is important. To gain insight into the suitability of species for use in large-scale seed-based restoration efforts, this study set out to determine the seed viability and seedling emergence of 31 little-studied renosterveld species through laboratory and glasshouse trials, respectively. The outcomes of these seed quality tests were assessed in conjunction with several additional criteria, suggested throughout the literature as relevant to species selection and seed collection, towards determining an overall score, a restoration species index, as a measure of how suitable each species is likely to be in future seed-based restoration efforts. Among the 31 selected species, seedling emergence and to a lesser extent seed viability were variable yet moderate to high for the majority of species. The restoration species index presented here, drawing several considerations into a single, novel approach to species selection, proved useful in this study where the vast majority of species exhibited moderate to high potential.

Resources for biodiversity conservation and invasive plant management are limited, and restoring invaded vegetation is labour-intensive and expensive. Managers must prioritize their actions to achieve their goals efficiently and effectively. They must distinguish between areas that require only the removal of invasive alien plants (“passive restoration”) from those that require additional restoration measures (“active restoration”). This study used a multi-criterion approach (Analytical Hierarchical Process) to develop a framework for identifying areas that require active restoration, and then to prioritize these areas for active restoration. The South African city of Cape Town is used as a test case to illustrate the utility of the framework. Framework criteria selected in determining the need for active restoration included: dominant alien species invading the area, density of invasion, duration of invasion, indigenous vegetation cover, adjacent land use, level of disturbance, size of the area, aspect, soil texture, soil depth and erodibility, slope and vegetation type. In deciding which areas to prioritize for active restoration, factors such as vegetation conservation status, selection in a regional conservation plan and connectivity function were assessed. Importance in ecosystem functioning (by providing a diversity of habitats and soil conservation) and the delivery of ecosystem service benefits were also considered. The resulting framework provides an objective tool for prioritizing sites for active restoration.

Background : Predicting which alien species may become invasive is important in prioritising scarce resources for management. Objectives : Sixteen naturalised ornamentals in Cape Town were assessed for invasion potential in relation to a mechanistic framework. The recently spreading species, Centranthus ruber (L.) DC., was studied in detail following management actions and vegetation fires. Method : The mechanistic framework was developed using nine features most likely to promote invasiveness. Species were assessed from their known characteristics, local usage and distribution records, including citizen science surveys. Surveys were conducted for C. ruber to assess its ability to survive and spread post-fire. Control efficacy for Centranthus ruber was assessed in plots at two sites. Results : Nine species with more than 25 naturalisation records had a median of seven features that promote invasion compared to five features in the less recorded group of seven species. Centranthus ruber was widespread in modified urban habitats and persisted in natural habitats following vegetation fires and is a high priority for control. Post-fire mechanical and chemical control of C. ruber significantly reduced its density and cover, but did not eliminate it. Conclusion : Naturalised ornamentals can move rapidly from latent to invasive phases; therefore, monitoring should start during the latent phase to detect sudden change. In firedriven ecosystems it is essential to have good pre-fire baseline data. More residents should be encouraged to become spotters through citizen science programmes and to report new naturalised ornamentals. It is important to act early in the invasion process and to allocate sufficient resources, if a newly invasive species is to be contained.

Aim The biophysical impacts of invasive Australian acacias and their effects on ecosystem services are explored and used to develop a framework for improved restoration practices. Location South Africa, Portugal and Chile. Methods A conceptual model of ecosystem responses to the increasing severity (density and duration) of invasions was developed from the literature and our knowledge of how these impacts affect options for restoration. Case studies are used to identify similarities and differences between three regions severely affected by invasions of Australian acacias: Acacia dealbata in Chile, Acacia longifolia in Portugal and Acacia saligna in South Africa. Results Australian acacias have a wide range of impacts on ecosystems that increase with time and disturbance, transform ecosystems and alter and reduce ecosystem service delivery. A shared trait is the accumulation of massive seed banks, which enables them to become dominant after disturbances. Ecosystem trajectories and recovery potential suggest that there are important thresholds in ecosystem state and resilience. When these are crossed, options for restoration are radically altered; in many cases, autogenic (self-driven and self-sustaining) recovery to a pre-invasion condition is inhibited, necessitating active intervention to restore composition and function. Main conclusions The conceptual model demonstrates the degree, nature and reversibility of ecosystem degradation and identifies key actions needed to restore ecosystems to desired states. Control and restoration operations, particularly active restoration, require substantial short- to medium-term investments, which can reduce losses of biodiversity and ecosystem services, and the costs to society in the long term. Increasing restoration effectiveness will require further research into linkages between impacts and restoration. This research should involve scientists, practitioners and managers engaged in invasive plant control and restoration programmes, together with society as both the investors in, and beneficiaries of, more effective restoration.

The City of Cape Town (City) covers 2460 km2 in the southwestern corner of the Cape Floristic Region biodiversity hotspot. Established in 1654, by 1700 there were no animals larger than 50 kg within 200 km of the City. However, apart from an appreciation that timber and firewood were becoming scarce, it was only in the 1930s that the first farm near Cape Point was set aside for conservation. Table Mountain was declared a National Monument in 1958, while it was largely covered by pine and gum plantations. Conservation of the montane areas thereafter expanded, whereas the lowlands were largely ignored, except for a few bird sanctuaries. Only in 1982 was the plight of the lowlands highlighted. Although ad hoc conservation planning was undertaken subsequently, 1997 saw the first priority categorization and conservation plan. The current situation is perilous: a huge effort will be required to meet basic conservation targets for the lowland vegetation types and threatened species. Local and international partners and funders will be key to achieving this. In eight of the City's 19 national vegetation types the minimum conservation targets are not achievable. Of the 3250 plant species estimated to occur in the City, 13 are extinct and 319 are threatened according to the IUCN Red List: this is 18% of the threatened Red List species in South Africa. Now for the first time, implementation is being attempted holistically across the metropole with discussion between internal City and external stakeholders to implement the conservation plan. However, the interim plans towards achieving this — that 60% of the unproclaimed target is secured by 2014, requires that over 40 km2 be conserved per annum. This leaves 340 km2 that should be secured by 2020 when projections from City spatial growth indicate that the last critical remnants will be urbanized.

CITATION: Esler, K.J. et al. 2008. Riparian vegetation management in landscapes invaded by alien plants: Insights from South Africa. South African Journal of Botany, 74(3):397-400. doi:10.1016/j.sajb.2008.01.168

Riparian zones are complex disturbance-mediated systems that are highly susceptible to invasion by alien plants. They are prioritized in most alien-plant management initiatives in South Africa. The current practice for the restoration of cleared riparian areas relies largely on the unaided recovery of native species from residual individuals and regeneration from soil-stored seed banks. Little is known about the factors that determine the effectiveness of this approach. We need to know how seed banks of native species in riparian ecosystems are affected by invasion, and the potential for cleared riparian areas to recover unaided after clearing operations. Study sites were selected on four river systems in the Western Cape: the Berg, Eerste, Molenaars and Wit Rivers. Plots were selected in both invaded (>75% Invasive Alien Plant (IAP) canopy cover) and un-invaded (also termed reference, with

Rivers are conduits for materials and energy; this, the frequent and intense disturbances that these systems experience, and their narrow, linear nature, create problems for conservation of biodiversity and ecosystem functioning in the face of increasing human influence. In most parts of the world, riparian zones are highly modified. Changes caused by alien plants — or environmental changes that facilitate shifts in dominance creating novel ecosystems — are often important agents of perturbation in these systems. Many restoration projects are underway. Objective frameworks based on an understanding of biogeographical processes at different spatial scales (reach, segment, catchment), the specific relationships between invasive plants and resilience and ecosystem functioning, and realistic endpoints are needed to guide sustainable restoration initiatives. This paper examines the biogeography and the determinants of composition and structure of riparian vegetation in temperate and subtropical regions and conceptualizes the components of resilience in these systems. We consider changes to structure and functioning caused by, or associated with, alien plant invasions, in particular those that lead to breached abiotic- or biotic thresholds. These pose challenges when formulating restoration programmes. Pervasive and escalating human-mediated changes to multiple factors and at a range of scales in riparian environments demand innovative and pragmatic approaches to restoration. The application of a new framework accommodating such complexity is demonstrated with reference to a hypothetical riparian ecosystem under three scenarios: (1) system unaffected by invasive plants; (2) system initially uninvaded, but with flood-generated incursion of alien plants and escalating invasion-driven alteration; and (3) system affected by both invasions and engineering interventions. The scheme has been used to derive a decision-making framework for restoring riparian zones in South Africa and could guide similar initiatives in other parts of the world.

The potential of Cephalophyllum inaequale was investigated for use in initiating ecosystem restoration in degraded landscapes of Namaqualand, South Africa. Cephalophyllum inaequale, a perennial shrub, is a member of the succulent Mesembryanthemaceae family, typical of the Succulent Karoo Biome and in particular of the Namaqualand area. A bioclimatic envelope was modeled to establish the area in which this species might feasibly be used. The regional bioclimatic potential for C. inaequale proved to be extensive, covering approximately 17,500 km2. An examination of the functional role of C. inaequale showed it to facilitate early seedling survival in this community. A nearest-neighbor study found no evidence of interspecific competition between C. inaequale and its dominant co-occurring species, possibly due to vertical stratification of rooting structures. Cephalophyllum inaequale significantly reduced wind speed and soil erosion. Experiments to test the feasibility of propagating, reintroducing, and establishing this species showed that it easily germinates from seed, and transplanted cuttings have a high survival rate. This study demonstrates that C. inaequale has potential for use in initiating the restoration of degraded lands in South Africa.

In fire-prone communities such as fynbos, many species rely on regeneration from seed banks in the soil. Persistent seed banks are particularly important for species with life spans shorter than the average fire cycle, in order to counter local extinction. Persistent seed banks also give potential for restoring ecosystems following disturbances such as alien plant invasion. This study investigated the seed persistence patterns of 25 perennial species, representing several growth forms and life histories, during a three-year burial. Long-term persistence (i.e., seed bank half-life exceeding two years) was found in the hard-seeded Fabaceae and Pelargonium, and the nut-fruited Proteaceae. In this group, germinability was low and dormancy increased further following burial, resulting in a highly viable, dormant seed bank after three-year's burial. A second group with potentially long-term persistent seeds includes four taxa (Pseudopentameris, Passerina, Elegia and Restio) that either have low germinability or develop secondary dormancy following burial. Dormancy in the latter group was partially countered by exposure to smoke-seed primer. Of the small-seeded species, only two Erica species with high initial dormancy had long-term persistent seed banks. The other species mostly displayed high initial germinability and short-term persistent seed banks (i.e., seed bank half-life less than two years). This group included taxa with short to medium life-spans (Syncarpha, Roella) that were expected to have long-term persistent seeds in order to buffer against local extinction following average to long fire-return intervals. We hypothesize that light may play a role in overcoming secondary dormancy in those species, and could have resulted in an underestimate for seed persistence in this study. Alternatively, those short to medium life-span species persist via inter-fire recruitment in gaps or long-distance dispersal (of the smallest seed). No correlations were found between seed persistence and seed mass or variance in seed dimensions. Nor was a correlation found between seed persistence and phenol concentration. In fynbos, seed burial of larger seeds by ants and rodents are major processes that operate in conjunction with passive burial of small seeds. Selection for persistence can be expected to operate across all seed sizes and shapes in fire-prone communities.

South African fynbos vegetation is threatened on a large scale by invasive woody plants. A major task facing nature conservation managers is to restore invaded areas. The aim of this study was to determine the restoration potential of fynbos following dense invasion by the Australian tree Acacia saligna. The impacts of dense invasion on seed-bank composition and depth distribution were investigated to determine which fynbos guilds and species have the most persistent seed-banks. Soil samples were excavated at three different depths for invaded and uninvaded vegetation at two sand plain and mountain fynbos sites. Seed-banks were determined using the seedling emergence approach. Invasion caused a significant reduction in seed-bank density and richness at all sites. There was a significant, but smaller, reduction in seed-bank density and richness with soil depth at three sites. Seed-bank composition and guild structure changed following invasion. Low persistence of long-lived obligate seeders in sand plain fynbos seed-banks indicates that this vegetation type will be difficult to restore from the seed-bank alone following alien clearance. The dominance of short-lived species, especially graminoids, forbs and ephemeral geophytes, suggests that regenerating vegetation will develop into a herbland rather than a shrubland. It is recommended that seed collecting and sowing form part of the restoration plan for densely invaded sand plain sites. As seed density remained higher towards the soil surface following invasion, there is no general advantage in applying a mechanical soil disturbance treatment. However, if the shallow soil seed-bank becomes depleted, for example following a hot fire through dense alien slash, a soil disturbance treatment should be given to exhume the deeper viable seed-bank and promote recruitment.

The control of invasive alien plants is one of the major tasks facing conservation managers of South African fynbos vegetation. Extensive clearance work currently is underway, but the ultimate success of these operations depends upon good indigenous vegetation recovery. Fynbos species potentially may recruit from persistent seed banks in the soil, but surface seed banks may become depleted under dense aliens and deeper seed banks may fail to germinate. In this study, the effect on fynbos recovery of disturbing the soil mechanically, to a depth of 100–150mm, following alien clearance, was investigated. It was hypothesised that soil disturbance would promote germination from persistent, soil-stored seed banks. It was further hypothesised that soil disturbance would have a greater effect following high compared to low fire intensities. Soil disturbance had no effect on total plant recruitment. There was a significant negative relationship between fire intensity and plant density two years post-fire. Recruitment levels at the study site were low compared to those at sites invaded for two to three decades. This indicates that fynbos seed persistence may decline rapidly after four decades of burial. Soil disturbance resulted in higher indigenous species richness and projected canopy cover at the final census, two years post-fire. Changes to guild structure following soil disturbance included an increase in the cover of shrubs relative to graminoids and forbs, and small-seeded species relative to larger-seeded myrmecochorous species. Soil disturbance caused similar changes to guild structure in both high and low fire intensity plots. Soil disturbance is not recommended as a universal treatment following the clearance of dense stands of aliens. Used in conjunction with indigenous sowing, it may improve restoration at long-invaded, deep-soil sites, following fires of unnaturally high intensity. Post-fire soil disturbance should promote species richness in seedling recruits, plant growth conditions and the development of vegetation cover, while sowing would increase plant density and re-introduce guilds not present in relict soil seed banks.

Invasion by woody alien plants, construction, and mining operations are among the major disturbances degrading vegetation in the Cape Floristic Kingdom, South Africa. The aim of this study was to assess whether native fynbos shrubland vegetation could be restored following dense alien invasion and disturbance by mining. An area supporting dense alien trees was cleared and topsoil was stripped and stockpiled to simulate mining disturbance. A field trial investigated the effects of topsoil depth, seed mix application, and fertilizer on native species recruitment and vegetation development over a three-year period. Soil-stored seed banks contributed 60% of the species recruited, indicating that areas invaded for three decades have good restoration potential. The addition of a fynbos seed mix, which included serotinous overstory species, improved both the richness and structural composition of the vegetation. Most species sown in untopsoiled plots established, but survival and growth was low compared to topsoil plots. Poor growth in combination with a lack of soil seed bank species, indicate that restoring a diverse and functional cover of indigenous vegetation on subsoil is not possible in the short-term. Soil amelioration is required to improve rooting conditions and initiate ecosystem processes. Shallow and deep topsoil treatments yielded high plant density, richness, and projected canopy cover, but canopy cover was higher in deep topsoil plots throughout the trial. Fertilizer addition increased canopy cover in untopsoiled and shallow topsoil plots via an increase in alien annual species. Fertilizer addition ultimately may lead to increased native vegetation cover in untopsoiled areas, but as it increased proteoid mortality on deep topsoil plots, it is not recommended for sites where topsoil is available. A species-rich and structurally representative fynbos community may be restored on topsoiled areas provided that the native disturbance regime is simulated and seeds of major structural guilds not present in the soil seed bank are included in the seed mix.

The recovery of fynbos vegetation after invasion by dense stands of alien trees, and clearing by either 'burn standing', 'fell and burn', or 'fell, remove and burn' treatments, was investigated in two watersheds in the Western Cape Province, South Africa. Native plant density, cover, functional and biological guilds and species richness were compared with matched control sites that were not invaded, but were burnt in the same fires. Species richness was lower for invaded sites compared to controls, at all scales measured (up to 2000 m 2 ). Species area curves for invaded sites did not converge with those of controls, indicating that lower richness at smaller scales was not compensated by increased species survival at a larger scale. Indigenous plant density and cover were lower for invaded sites compared to controls. Overall, treatment differences were non-significant, but the 'burn standing' treatment caused the least change to vegetation variables, and the 'fell, remove and burn' and 'fell and burn' treat- ments caused greater, similar changes. Changes to the guild structure of the recovering fynbos stands differed among treatments, and indicated that the 'fell and burn' treatment had the greatest negative effect on guild survival. In the 'fell and burn' treatment, which resulted in an exceptionally intense fire, only non-mycorrhizal graminoids (predominantly myrmecochores) persisted relatively well. Because of practical problems associated with the 'burn standing' and 'fell, remove and burn' treatments, managers often have little option but to apply the 'fell and burn' treatment. Our results illustrate the dangers of this, and highlight the need for intervention before areas become densely invaded. They also highlight the need for effective biological control agents to reduce rates of spread of aggressively invasive species.

South African fynbos ecosystems are under threat from alien plant invasions and transformations to alternative land uses. If large-scale habitat loss and species extinction are to be halted, restoration actions are urgently required. We postulate that by adopting an approach in which an understanding of community and ecosystem dynamics is applied to restoration practices, protocols can be developed which will lead to more efficient restoration. This understanding is based on a review of the relevant ecological literature, focusing on recruitment dynamics, community structure, and ecosystem function, which are particularly relevant to restoration. We develop a conceptual framework for restoration and apply our protocols to a case study area on the Cape Peninsula. Before ecological restoration can begin, the cause of transformation must first be removed or ameliorated. The next step is to ensure that the important ecological processes are functioning. We contend that a fully functioning community requires a good balance of the major growth-form, regeneration, and nutrient acquisition guilds. Fire is the natural disturbance event initiating recruitment in fynbos. It is, therefore, essential to either burn a site or provide fire-related germination cues in order to stimulate recruitment. Where guilds are under-represented, corrective reintroductions will further improve the long-term resilience of the restored community. Many taxa have persistent soil-stored seed banks, so it is important to conserve topsoil and optimize use of this local species pool. Seed dispersal distances are generally very short, and in highly transformed sites it will be necessary to reintroduce seed of the major guilds in order to restore community structure and functioning. Post-fire succession in fynbos begins with the full complement of species; species gradually die out from the vegetation according to their respective life spans. In order to stimulate germination and promote successful establishment, it is important to sow seed after fire or site clearing in late summer or autumn. Introducing seed or plants at a later stage in the succession is very likely to fail. Because of the localized distributions of many taxa, extreme care must be taken when selecting species for reintroduction if local gene pools are to be conserved.

We investigated vegetation-seed bank relationships at three fynbos sites on the Cape Peninsula, South Africa, and the impacts to these sites of invasion by the alien tree Acacia saligna. Soil-stored seed banks in uninvaded fynbos were of a similar density to those previously measured in fynbos (ca. 1100–1500 seeds m-2) and were dominated by mostly short-lived species. Lack of similarity between mature vegetation and seed banks, suggests that seed banks are poor predictors of mature vegetation composition and structure in fynbos. This lack of correspondence was attributed to the ephemerals (present only in the soil seed bank) and the dominance of serotinous (aerial seed bank) and sprouting (soil seed bank low to absent) species, in mature vegetation. Long-lived seeders were among the 10 most abundant species in the seed banks at all sites and at two sites shrub species contributed more to seed bank richness than any other growth form. Soil-stored seed banks, therefore, boost species richness and diversity both in early post-fire and later seral stages.

"Regional and global scale ecosystem service assessments have demonstrated the socioeconomic value of protecting biodiversity and have been integrated into associated policy. Local government decision makers are still unsure of the applicability, return on investment, and usefulness of these assessments in aiding their decision making. Cape Town, a developing city in a globally recognized biodiversity hotspot, has numerous competing land uses. City managers, with a tightly constrained budget, requested an exploratory study on the links between ecosystem services and biodiversity conservation within this municipal area. We set out to develop and test a simple and rapid ecosystem service assessment method aimed at determining the contribution natural vegetation remnants make to ecosystem service provision. We took selected services, identified in conjunction with city managers, and assessed these in two ways. First we used an area weighted approach to attribute services to vegetation types and assessed how these had changed through time and into the future given development needs. Second, we did a regulatory and cultural service remnant distance analysis to better understand proximity effects and linkages. Provisioning services were found to have been most severely affected through vegetation transformation. Regulatory services have been similarly affected, and these losses are more significant because regulatory services can only function in situ and cannot be outsourced in the way provisioning services can. The most significant losses were in coastal zone protection and flood mitigation services, both of which will be placed under even greater pressure given the predicted changes in climatic regimes. The role of remnant vegetation in regulating and cultural services was shown to be a significant additional consideration in making the case for conservation in the city. Our rapid assessment approach does not allow for nuanced and individual understanding of the trade-offs presented by individual remnant patches, but is particularly strong in quickly identifying issues, key focus areas, and opportunities provided by this research direction, and thereby serving to facilitate and drive constructive engagement between ecosystem service experts and city planners."

We investigated the plasticity of seedlings to shade in six shrub species common in subtopical thicket, in order to assess their microhabitat preferences for regeneration. Cassine peragua and Sideroxylon inerme , which also occur in adjacent forests, were the most shade tolerant and would be unlikely to require canopy gaps for recruitment: their relative reduction in growth in dense shade was slight, as was their increase in leaf weight ratio (LWR); leaf inclination was adjusted to near horizontal in dense shade and maximum net photosynthetic rate ( A max ) remained fairly low in sun-acclimated plants. Rhus glauca , which also occurs on forest margins, demonstrated the highest growth rates, especially in the open, and together with its high potential A max is well-equipped as a pioneer, and would benefit from canopy gaps for establishment. Cassine aethiopica , which is also common in coastal forests, was slower growing than Rhus , but less shade tolerant than C. peragua and Sideroxylon and would probably benefit from canopy gaps for establishment. Pappea capensis and Schotia afra , which also occur in open savanna vegetation, demonstrated a growth and morphological pattern indicative of species adapted to periodic drought, in having a high ratio of woody conductive tissue to leaf tissue with accompanying slow growth. Their relatively poor performance in deep shade suggests that canopy gaps would benefit their recruitment. We concluded that canopy gaps may be essential for recruitment of the full species complement in sub-tropical thickets.

Taxonomic, edaphic and biological aspects of endemism were studied in a phanerogamous flora from the Agulhas Plain, a coastal lowland area of the Cape Floristic Region. Of the 1751 species in the flora, 23.6% were regional endemics and 5.7% were local endemics. Families which were over-represented in terms of endemics included the Ericaceae, Rutaceae, Proteaceae and Polygalaceae. Under-represented families included the Poaceae, Cyperaceae, Scrophulariaceae and Orchidaceae. Highest levels of local endemism were recorded on limestone and colluvial acid sand. Sixty-nine percent of regional endemics and 85% of local endemics were confined to a single substratum. An analysis of the frequency of biological traits associated with species with different categories of endemism enabled the establishment of a biological profile of a local endemic: a dwarf to low, non-sprouting shrub with soil stored seeds which are ant-dispersed and/or form a symbiotic relationship with microbes. It is argued that lineages with these characteristics are vulnerable to severe population reduction or even local extinction. An effect of this would be the promotion of rapid, edaphic speciation as a result of catastrophic selection. Thus, certain traits (e.g. non-sprouting) prevail or even predominate in the flora not because of any adaptive advantage but because high speciation rates of lineages which possess them, overwhelm low survival rates.

Acacia saligna and A. cyclops are invasive alien shrubs in lowland ecosystems of the fynbos biome, South Africa. Both species typically form dense thickets and accumulate large soil-stored seed banks. Seed removal rates, relative to seed availability in the litter layer of Acacia-infested vegetation, were studied to determine the importance of indigenous ants and vertebrates as dispersors and predators, respectively. There was a relative loss to the annual seed-fall of 50% and 80–95% in dense A. saligna and A. cyclops stands, respectively. Ants and rodents removed significant quantities of seeds, but a large proportion may have rotted. In a dense A. saligna stand, ants usually removed all seeds presented to them after 7 days presentation, compared to only 36% of seeds in a dense A. cyclops stand. In dense stands of both species, rodents were relatively slow to take seeds, removing 31% within 7 days. Removal from trays was least during and following seed-fall (January-March) and greatest prior to seed-fall (September-November) and decreased as A. cyclops canopy cover increased. In a low-density A. cyclops stand, ants and rodents competed for seeds. The results indicate that indigenous ants have played a critical role in maintaining and accumulating Acacia seed banks and thus may have facilitated the development of dense Acacia stands.

Percentage viability of A. saligna and A. cyclops seed banks was determined for stands cleared of mature plants for different time intervals. Seedling emergence following recent clearing was monitored for a year at one site of each species. Percentage viability of A. saligna seed banks was uniformly high and was not affected by age since clearing. Percentage dormancy in A. saligna was high since few seedlings emerged in the field (1% of viable seed bank), but after fire, 70% of the remaining viable seed bank germinated. Percentage viability of A. cyclops seed banks differed significantly among sites, with the proportion of viable seeds in the soil increasing significantly with age since clearing at one site. Percentage germination and viability of fresh A. cyclops seeds also differed significantly among sites. Although seedling emergence in A. cyclops (9% of viable seed bank) exceeded that in A. saligna, pre-emergence mortality was implicated as the more important process in A. cyclops seed bank decline. In order to markedly reduce seed banks, it is recommended that A. saligna stands should be burnt and A. cyclops stands cleared in any way which removes the vegetation cover.

The effect of dry heat on the percentage germination, germination rate and lethal temperatures of selected legume species was investigated by exposing seeds to different intensities and durations of heat. Two alien invasive legumes (Acacia saligna and A. cyclops) and two indigenous legume species: Podalyria calyptrata, which is a fynbos species, and Virgilia oroboides, a forest precursor, were tested. Results were compared to predictions based on published accounts of the species’ ecology. Acacia saligna and P. calyptrata fitted predictions: high percentage germination, fast germination rates and a tolerance to high temperatures; with A. saligna outperforming P. calyptrata in the latter two responses. Both A. cyclops and V. oroboides did not conform to predictions: dry heat had little positive effect on germination, and in A. cyclops it had a negative effect.

Acacia cyclops is an invasive shrub of natural vegetation in the fynbos biome of South Africa. Its large soil-stored seed banks make eradication difficult. In this study, a dense, mature stand of A. cyclops was cleared using four commonly applied treatments. Few seeds above 30-mm depth in the soil profile survived burning treatments, and percentage viability was reduced at depths up to 40 mm. Seed germinability was not enhanced by fire. Seedling emergence and mortality, monitored over 13 months post-clearing, were much higher following non-burning and ‘fell and burn’ treatments than ‘burn standing’ and ‘fell, pile and burn’ treatments. Nevertheless, the pattern of seedling emergence and survival was similar in all treatments, with survival low until October, 9 months post-clearing. Although all treatments resulted in significant reductions in seed density 1 year post-clearing, burning treatments were more effective than the non-burning treatment. The ‘burn standing’ treatment killed more seeds than the ‘fell and burn’ treatment, and may be recommended where labour costs are prohibitive. Since all treatments induced a rapid seed-bank decline in A. cyclops , it is recommended that the choice of treatment be dictated by other factors, such as possible effects on the recovery of indigenous plant species.

The effects of commercial exploitation on the mortality and seed production of a serotinous, obligate reseeder, Brunia albiflora, were investigated in fynbos vegetation, South Africa. Plant size, fruit production and plucking intensity were assessed in three exploited and two unexploited populations. Mortality in commercially exploited populations of B. albiflora varied between 8 and 33%, compared with a natural mortality of 1 to 3%. Mortality was much greater (14–33%) in exploited populations on hired land than in a population plucked by the owner, despite a higher intensity of utilization in the latter. Mortality and plucking intensity varied considerably within populations in the Kleinmond Nature Reserve, probably reflecting both population structure and plucking preferences. Fruit production in exploited populations was reduced to one-third that of unexploited populations. Larger plants were selected by pluckers, thus reducing seed production in the population's most productive plants. Plucking increased the proportion of plants which produced epicormic buds at the trunk of the plant. A method for assessing the impacts of exploitation of vegetation is required to ensure that populations of B. albiflora are not exploited beyond their capacity to regenerate. Until data on such impacts become available, it is recommende that all plucking in nature reserves and conservation areas in fynbos should be terminated.

This paper reviews the results of recent research on riparian vegetation recovery following the clearance of invasive alien plants. In Fynbos, Grassland and Savanna Biomes, riparian ecosystems were found to have relatively-high ecological resilience to invasion by alien plants, except in some situations of closed alien stands (75–100% aerial cover). Where alien invasion is the primary disturbance at a site, and invasion intensity is low (

In 1998, a restoration field trial was initiated in a catchment near Wellington (Western Cape, South Africa) to determine whether fynbos riparian scrub vegetation cleared of woody invasive alien trees require post-clearance restoration actions to accelerate indigenous vegetation recovery. The aim was to assess the relative effectiveness of three sowing treatments for restoring indigenous vegetation cover after the widely used “Fell & Burn” method of clearing invasive alien trees. Sowing treatments included non-invasive alien grasses to determine whether they have a negative effect on recovering native vegetation. A summer fire, eight years after trial initiation, provided an opportunity to determine how resilient restoration treatments are to alien re-invasion and fire. Restoring the site after alien clearing by sowing indigenous seeds increased both diversity, by improving species presence and abundance. However, a census done 8 years later (in 2006) revealed that seedlings of woody invasive alien plants dominated all plots, and had also survived the burn by resprouting, indicating the importance of follow-up control to justify initial clearing and restoration costs. Indigenous grass density was significantly reduced in plots where alien grasses were sown, while in the control and fynbos sowing treatment, indigenous grass density increased. By 2006, alien grass density was negligible in all treatments, indicating that the two grass species sown are not persistent or invasive. Active restoration of riparian areas after alien plant clearing has potential to facilitate vegetation recovery, but must be coupled with a long-term plan for adequate follow-up removal of post-clearance and post-fire alien recruits.

Riparian vegetation, which normally differs structurally and compositionally from surrounding vegetation, has been degraded in many parts of the fynbos biome by several species of invasive Australian Acacia . Systematic clearing of dense stands of these alien trees was initiated in 1995, and information is urgently needed to guide the restoration of riparian habitats. A problem is that degradation of these communities is so advanced and widespread that in many cases managers do not know what species to use in restoration, or what kinds of target communities to aim for. This study's aim was to provide baseline information on riparian plant community structure and composition from non-transformed habitats. Species and environmental data were recorded from 76 sites located along the headwater systems of six rivers in the southwestern part of the Western Cape province. Analysis of the data, applying multivariate classification (TWINSPAN) and ordination (Detrended Correspondence Analysis) techniques, identified four prospective plant communities: 1) a Nivenia corymbosa - Brachylaena neriifolia Community; 2) a Leucadendron salicifolium - Berzelia lanuginosa Community; 3) a Cliffortia ruscifolia - Metrosideros angustifolia Community; and 4) a Kiggelaria africana - Brabejum stellatifolium Community. These formed a continuum with only the Leucadendron and Kiggelaria communities separating in ordination space. Soil pH differed between the latter two communities, reflecting different geology. It was found that many riparian specialist species are relatively widespread. For the study area, it is concluded that where information on the historical composition of riparian communities is lacking, target communities for restoration can be defined from pristine communities with similar geology, and secondly, altitude. In all cases the target community will comprise a large proportion of widespread, predominantly resprouting, riparian species.

The Working for Water programme is tasked with the important role of controlling invasive alien plants with an assumption that indigenous vegetation will recover naturally. This study assessed vegetation composition and structure following alien clearance in closed-stand invasion of riparian areas and a minimum of two years' passive recovery. Three initial clearing treatments — Fell Only, Fell & Remove and Fell & Burn — were compared to uninvaded Reference conditions. The aim was to ascertain the nature of vegetation recovery, as well as to determine which clearing treatment was most successful in promoting recovery. A Detrended Correspondence Analysis revealed that the Fell & Remove treatment most closely approached the Reference condition while Fell Only and Fell & Burn plots had altered composition and structure. All clearing treatments had significantly lower vegetation cover than the Reference and species composition was altered by invasion and clearance. Important growth forms, such as small (3–10 m) trees were suppressed by felled slash and burning. Although burning was the best method to reduce woody alien species, secondary invasion by alien herbaceous species occurred where natural riparian vegetation did not re-establish. The Fell & Remove treatment is recommended as the best to use in promoting indigenous vegetation recovery, and together with continued alien follow-up control, is able to minimize alien re-invasion of riparian ecosystems. Managers are advised to consider active restoration measures in areas where recovery is likely to be protracted.

Decay rates in seed populations of Acacia cyclops and A. saligna of known viability and dormancy were determined after one and two years of burial at different densities. Decay rates differed significantly between the two species, but there was no clear effect of density. Decay rates were high, despite an initially high level of dormancy: an average of 97% and 45% of A. cyclops and A. saligna seeds, respectively, were lost in the first year. Decay rates were significantly lower in the second than in the first year and it is predicted that decay rates would continue to decline in seeds surviving more than two years. Acacia seed populations in the soil do not have a continuous and constant death risk and consequently do not fit the log-linear (i.e. Deevey Type II) survivorship curve reported in the literature for soil-stored seeds. As a small proportion of the Acacia seed population may have great longevity, clearing operations should incorporate a programme of periodic follow-up control.