Biological invasions in the Cape Floristic Region: history, current patterns, impacts, and management challenges

Wilson, John R.; Gaertner, Mirijam; Griffiths, C.L.; Kotze, Inge; Maitre, David C Le; Marr, SM; Picker,; Spear, Dian; Stafford, Louise; Richardson, D.M.; Wilgen, B.W. van; Wannenburg, A.

doi:10.1093/acprof:oso/9780199679584.003.0012

Cited by 17 publications

(19 citation statements)

References 64 publications

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“…The different species are morphologically similar, but can be reliably distinguished by their advertisement calls (Turner et al 2004;Turner & Channing 2008). Their limited distributions in montane fynbos habitat make them susceptible to invasions from alien plants (mostly pines and Australian acacias) that are prominent in this area (Wilson et al 2014) and have resulted in high threat levels for many of the species (Measey 2011). Fynbos is a fire-dependent ecosystem, and woody invasive species increase fire temperatures and shorten fire return intervals (Kraaij & van Wilgen 2014) threatening moss frogs and other endemic species.…”

Section: S T U D Y S P E C I E Smentioning

confidence: 99%

Counting chirps: acoustic monitoring of cryptic frogs

Measey

Stevenson

Scott

et al. 2016

Journal of Applied Ecology

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Summary1. Global amphibian declines have resulted in a vital need for monitoring programmes that follow population trends. Monitoring using advertisement calls is ideal as choruses are undisturbed during data collection. However, methods currently employed by managers frequently rely on trained observers and/or do not provide density data on which to base trends. 2. This study explores the utility of monitoring using acoustic spatially explicit capturerecapture (aSCR) with time of arrival (ToA) and signal strength (SS) as a quantitative monitoring technique to measure call density of a threatened but visually cryptic anuran, the Cape peninsula moss frog Arthroleptella lightfooti. 3. The relationships between temporal and climatic variables (date, rainfall, temperature) and A. lightfooti call density at three study sites on the Cape peninsula, South Africa, were examined. Acoustic data, collected from an array of six microphones over 4 months during the winter breeding season, provided a time series of call density estimates. 4. Model selection indicated that call density was primarily associated with seasonality fitted as a quadratic function. Call density peaked mid-breeding season. At the main study site, the lowest recorded mean call density (0Á160 calls m À2 min À1 ) occurred in May and reached its peak mid-July (1Á259 calls m À2 min À1 ). The sites differed in call density, but also the effective sampling area. 5. Synthesis and applications. The monitoring technique, acoustic spatially explicit capturerecapture (aSCR), quantitatively estimates call density of calling animals without disturbing them or their environment. In addition, time of arrival (ToA) and signal strength (SS) data significantly add to the accuracy of call localization, which in turn increases precision of call density estimates without the need for specialist field staff. This technique appears ideally suited to aid the monitoring of visually cryptic, acoustically active species.

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Section: S T U D Y S P E C I E Smentioning

confidence: 99%

Counting chirps: acoustic monitoring of cryptic frogs

Measey

Stevenson

Scott

et al. 2016

Journal of Applied Ecology

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“…South Africa has been a prominent contributor to global invasion science since the 1980s (Macdonald et al 1986;Richardson et al 1997;Wilson et al 2014), and the management of invasions has been a strong component of this research (van Wilgen 2018). Given the importance of catchment areas for providing water and conserving the country's rich biodiversity, coupled with the escalating threat posed by alien plant invasions in these areas, it is not surprising that ecological restoration has developed here as a complementary research stream to invasion biology (van Wilgen et al 2016).…”

Section: Biological Invasions and Restoration Ecology In South Africamentioning

confidence: 99%

Biological Invasions and Ecological Restoration in South Africa

Holmes

Esler

Gaertner

et al. 2020

Biological Invasions in South Africa

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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

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“…The spread of alien (non-native) plant species, like climate change, is a significant but insidious global threat to natural ecosystems that has resulted from trade networks and deliberate or accidental species introductions (Wilson et al, 2009(Wilson et al, , 2014. Invasion success depends on characteristics of the introduced species, such as those linked to propagule pressure, as well as those of the invaded community, including abiotic and biotic conditions and species interactions (Richardson & Pyšek, 2006;Catford et al, 2009;Le Roux et al, 2020).…”

Section: Ecosystem Degradation Alien Plant Invasion and Restorationmentioning

confidence: 99%

Ecological restoration of ecosystems degraded by invasive alien plants in South African Fynbos: Is spontaneous succession a viable strategy?

Holmes

Esler

Wilgen

et al. 2020

Transactions of the Royal Society of South Africa

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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 widespread and their control continues to be a major undertaking. As funding is limited, active restoration interventions are rarely implemented and the focus is on invader removalthe assumption being that ecosystems will self-repair. This paper reviews research findings from the past three decades to assess in which situations spontaneous succession is a viable strategy for restoring alien-invaded ecosystems. We found that ecosystems can self-repair, provided that key biotic and/or abiotic thresholds have not yet been crossed. Self-repair has been observed in many cases where dense invader stands with short residence times have been cleared and where diverse native plant growth forms survive, either in the aboveground vegetation or in soil seed banks. However, several factors influence this generalisation, including the identity of the invader, the ecosystem type, and the efficacy of alien control. Thresholds are crossed sooner with invasions of alien Acacia and Eucalyptus species than those of Hakea and Pinus species, resulting in lower potential for spontaneous recovery. Lowland fynbos ecosystems are less resilient to invasion, and have a lower capacity for self-repair, than mountain fynbos ecosystems. Poorly implemented alien plant control measures can result in a resurgence of the invader to the detriment of native species recovery. We outline some management principles for optimising spontaneous succession potential and integrating alien control and restoration interventions.

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Biological invasions in the Cape Floristic Region: history, current patterns, impacts, and management challenges

Cited by 17 publications

References 64 publications

Counting chirps: acoustic monitoring of cryptic frogs

Counting chirps: acoustic monitoring of cryptic frogs

Biological Invasions and Ecological Restoration in South Africa

Ecological restoration of ecosystems degraded by invasive alien plants in South African Fynbos: Is spontaneous succession a viable strategy?

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