The Nebulous Ecology of Native Invasions

Nackley, Lloyd L.; West, Adam G.; Skowno, Andrew; Bond, William J.

doi:10.1016/j.tree.2017.08.003

Cited by 119 publications

(111 citation statements)

References 58 publications

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“…84 of 1998) affords indigenous forests better protection than Fynbos ecosystems (Pooley, ). This is another alarming case of a ‘native invasion’, akin to the encroachment of savannas by woody plants throughout the globe (Nackley, West, Skowno, & Bond, ). Here too, reduced fire activity has been identified as a major driver, likely due to human activities that have altered the ignition catchments (Venter et al, ).…”

Section: Discussionmentioning

confidence: 99%

Altered ignition catchments threaten a hyperdiverse fire‐dependent ecosystem

Slingsby

Moncrieff

Rogers

et al. 2019

Global Change Biology

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Human activities affect fire in many ways, often unintentionally or with considerable time‐lags before they manifest themselves. Anticipating these changes is critical, so that insidious impacts on ecosystems, their biodiversity and associated goods and services can be avoided, mitigated or managed. Here we explore the impact of anthropogenic land cover change on fire and biodiversity in adjacent ecosystems on the hyperdiverse Cape Peninsula, South Africa. We develop a conceptual framework based on the notion of an ignition catchment, or the spatial extent and temporal range where an ignition is likely to result in a site burning. We apply this concept using fire models to estimate spatial changes in burn probability between historical and current land cover. This change layer was used to predict the observed record of fires and forest encroachment into fire‐dependent Fynbos ecosystems in Table Mountain National Park. Urban expansion has created anthropogenic fire shadows that are modifying fire return intervals, facilitating a state shift to low‐diversity, non‐flammable forest at the expense of hyperdiverse, flammable Fynbos ecosystems. Despite occurring in a conservation area, these ecosystems are undergoing a hidden collapse and desperately require management intervention. Anthropogenic fire shadows can be caused by many human activities and are likely to be a universal phenomenon, not only contributing to the observed global decline in fire activity but also causing extreme fires in ecosystems where there is no shift to a less flammable state and flammable fuels accumulate. The ignition catchment framework is highly flexible and allows detection or prediction of changes in the fire regime, the threat this poses for ecosystems or fire risk and areas where management interventions and/or monitoring are required. Identifying anthropogenic impacts on ignition catchments is key for both understanding global impacts of humans on fire and guiding management of human‐altered landscapes for desirable outcomes.

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Section: Discussionmentioning

confidence: 99%

Altered ignition catchments threaten a hyperdiverse fire‐dependent ecosystem

Slingsby

Moncrieff

Rogers

et al. 2019

Global Change Biology

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“…This assumption is not consistent with the patterns of woody encroachment observed in this study, and a body of research already exists to show woody encroachment has major trade‐offs in temperate grasslands (Twidwell et al., ). Native invaders have not been given the same attention as invasive alien species, even though their impacts are structurally and functionally similar (Nackley, West, Skowno, & Bond, ). Conflicting messages between the science and management of native invaders can lead to double‐think policies and the simultaneous promotion and control of species (Roberts et al., ).…”

Section: Discussionmentioning

confidence: 99%

Social–ecological landscape patterns predict woody encroachment from native tree plantings in a temperate grassland

Donovan

Burnett

Bielski

et al. 2018

Ecology and Evolution

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Afforestation is often viewed as the purposeful planting of trees in historically nonforested grasslands, but an unintended consequence is woody encroachment, which should be considered part of the afforestation process. In North America's temperate grassland biome, Eastern redcedar (Juniperus virginiana L.) is a native species used in tree plantings that aggressively invades in the absence of controlling processes. Cedar is a well‐studied woody encroacher, but little is known about the degree to which cedar windbreaks, which are advocated for in agroforestry programs, are contributing to woody encroachment, what factors are associated with cedar spread from windbreaks, nor where encroachment from windbreaks is occurring in contemporary social–ecological landscapes. We used remotely sensed imagery to identify the presence and pattern of woody encroachment from windbreaks in the Nebraska Sandhills. We used multimodel inference to compare three classes of models representing three hypotheses about factors that could influence cedar spread: (a) windbreak models based on windbreak structure and design elements; (b) abiotic models focused on local environmental conditions; and (c) landscape models characterizing coupled human‐natural features within the broader matrix. Woody encroachment was evident for 23% of sampled windbreaks in the Nebraska Sandhills. Of our candidate models, our inclusive landscape model carried 92% of the model weight. This model indicated that encroachment from windbreaks was more likely near roadways and less likely near farmsteads, other cedar plantings, and waterbodies, highlighting strong social ties to the distribution of woody encroachment from tree plantings across contemporary landscapes. Our model findings indicate where additional investments into cedar control can be prioritized to prevent cedar spread from windbreaks. This approach can serve as a model in other temperate regions to identify where woody encroachment resulting from temperate agroforestry programs is emerging.

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“…The use of the phrase “native invasions” in this context (Nackley et al. ) is unfortunate as it conflates biogeographic, demographic, and impact phenomena.…”

Section: First Component: Circumscription Of the Phenomenonmentioning

confidence: 99%

“…Such expansion mechanisms include tsunamis that transport anthropogenic debris carrying species, range shifts due to human‐mediated climate change, and range shifts due to human‐mediated modifications to biogeographic barriers, such as the Lessepsian migration following the opening of the Suez Canal (Hoffmann and Courchamp , Nackley et al. ). In response to this, protocols have been developed that explicitly incorporate estimates of uncertainty (Essl et al.…”

Section: First Component: Circumscription Of the Phenomenonmentioning

confidence: 99%

A four‐component classification of uncertainties in biological invasions: implications for management

et al. 2019

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Although uncertainty is an integral part of any science, it raises doubts in public perception about scientific evidence, is exploited by denialists, and therefore potentially hinders the implementation of management actions. As a relatively young field of study, invasion science contains many uncertainties. This may explain why, despite international policies aimed at mitigating biological invasions, the implementation of national‐ and regional‐scale measures to prevent or control alien species has done little to slow the increase in extent of invasions and the magnitude of impacts. Uncertainty is therefore a critical aspect of invasion science that should be addressed to enable the field to progress further. To improve how uncertainties in invasion science are captured and characterized, we propose a framework, which is also applicable to other applied research fields such as climate and conservation science, divided into four components: the need (1) to clearly circumscribe the phenomenon, (2) to measure and provide evidence for the phenomenon (i.e., confirmation), (3) to understand the mechanisms that cause the phenomenon, and (4) to understand the mechanisms through which the phenomenon results in consequences. We link these issues to three major types of uncertainty: linguistic, psychological, and epistemic. The application of this framework shows that the four components tend to be characterized by different types of uncertainty in invasion science. We explain how these uncertainties can be detrimental to the implementation of management measures and propose ways to reduce them. Since biological invasions are increasingly tightly embedded in complex socio‐ecological systems, many problems associated with these uncertainties have convoluted solutions. They demand the consensus of many stakeholders to define and frame the dimensions of the phenomenon, and to decide on appropriate actions. While many of the uncertainties cannot be eliminated completely, we believe that using this framework to explicitly identify and communicate them will help to improve collaboration between researchers and managers, increase scientific, political, and public support for invasion research, and provide a stronger foundation for sustainable management strategies.

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The Nebulous Ecology of Native Invasions

Cited by 119 publications

References 58 publications

Altered ignition catchments threaten a hyperdiverse fire‐dependent ecosystem

Altered ignition catchments threaten a hyperdiverse fire‐dependent ecosystem

Social–ecological landscape patterns predict woody encroachment from native tree plantings in a temperate grassland

A four‐component classification of uncertainties in biological invasions: implications for management

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