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Cost ranges for four species-Ardisia elliptica, Cirsium vulgare, Pinus nigra and Cirsium vulgare-with available data. Points represent mean cost values, while lines represent cost ranges where available for these species. If cost ranges overlap, that indicates uncertainty in ranks generated using cost and cost-effectiveness.
Source publication
Management of invasive populations is typically investigated case‐by‐case. Comparative approaches have been applied to single aspects of management, such as demography, with cost or efficacy rarely incorporated.
We present an analysis of the ranks of management actions for 14 species in five countries that extends beyond the use of demography alone...
Contexts in source publication
Context 1
... found cost range data for 30Á5% out of the 82 management actions across the 17 management units. Overall, we found that only a small subset of actions had overlapping cost ranges for three of the four species, the exception being Ardisia elliptica with only two manage- ment actions where there was no overlap (Fig. ...
Context 2
... 040 per ha). Since cost seems to be driving cost-effectiveness, ignoring uncertainty in these cost estimates can lead to misin- formed management according to both cost and cost- effectiveness metrics. For four species with cost ranges, cost uncertainty had low to moderate effects on the rank- ing of management actions within a management unit (Fig. 4); however, the strong alignment between cost and cost-effectiveness ranks means that variations in cost will lead to corresponding responses in cost-effectiveness. Incorporating uncertainty in cost is also unlikely to make alignment between cost-effectiveness, cost and managers' ranks stronger. Therefore, our findings of alignment ...
Citations
... Invasions by exotic plant species can not only severely affect species composition, structure, and function of invaded ecosystems, but also pose a serious threat to the social economy Kerr et al., 2016;Iqbal et al., 2020;Kumar Rai and Singh, 2020;Zhao et al., 2020). Many studies have focused on understanding how exotic plants successfully invade new environments, and how to predict and prevent exotic plant invasions (Catford et al., 2009;Lau and Schultheis, 2015;Enders et al., 2020;Huang et al., 2020;Liu et al., 2022). ...
Introduction
Preference and plasticity in nitrogen (N) form uptake are the main strategies with which plants absorb soil N. However, little effort has been made to explore effects of N form acquisition strategies, especially the plasticity, on invasiveness of exotic plants, although many studies have determined the effects of N levels (e.g. N deposition).
Methods
To address this problem, we studied the differences in N form acquisition strategies between the invasive plant Solidago canadensis and its co-occurring native plant Artemisia lavandulaefolia , effects of soil N environments, and the relationship between N form acquisition strategy of S. canadensis and its invasiveness using a ¹⁵ N-labeling technique in three habitats at four field sites.
Results
Total biomass, root biomass, and the uptakes of soil dissolved inorganic N (DIN) per quadrat were higher for the invasive relative to the native species in all three habitats. The invader always preferred dominant soil N forms: NH 4 ⁺ in habitats with NH 4 ⁺ as the dominant DIN and NO 3 ⁻ in habitats with NO 3 ⁻ as the dominant DIN, while A. lavandulaefolia consistently preferred NO 3 ⁻ in all habitats. Plasticity in N form uptake was higher in the invasive relative to the native species, especially in the farmland. Plant N form acquisition strategy was influenced by both DIN levels and the proportions of different N forms (NO 3 ⁻ /NH 4 ⁺ ) as judged by their negative effects on the proportional contributions of NH 4 ⁺ to plant N ( f NH4 ⁺ ) and the preference for NH 4 ⁺ ( β NH4 ⁺ ). In addition, total biomass was positively associated with f NH4 ⁺ or β NH4 ⁺ for S. canadensis , while negatively for A. lavandulaefolia . Interestingly, the species may prefer to absorb NH 4 ⁺ when soil DIN and/or NO 3 ⁻ /NH 4 ⁺ ratio were low, and root to shoot ratio may be affected by plant nutrient status per se, rather than by soil nutrient availability.
Discussion
Our results indicate that the superior N form acquisition strategy of the invader contributes to its higher N uptake, and therefore to its invasiveness in different habitats, improving our understanding of invasiveness of exotic plants in diverse habitats in terms of utilization of different N forms.
... This is especially important since some of the management approaches for invasive species control must be performed over long time periods and may require continuous input of manpower and resources or maintenance. Thus, prioritization of these limited resources towards the most effective management option is of paramount importance (e.g., [93]), and models can serve as a much-needed tool in such decision-making. ...
Invasive crayfish are among the major threats to freshwater ecosystems, with the signal crayfish, Pacifastacus leniusculus, being one of the most successful crayfish invaders in Europe. Approaches to invasive crayfish control range from manual and physical to biological and biocidal control methods. However, all of these approaches have their drawbacks and have limited efficacy. Among traditional approaches with minimal impacts on environment and non-target species, manual control via trapping is the most frequently applied. More innovative approaches comprise, among others, usage of sterile male release technique, whose efficacy in the field is yet to be fully tested, especially how it combines with more traditional approaches. A good alternative to costly and logistically challenging field comparisons of these approaches and their combinations is population modeling. Population models can integrate all relevant species-specific biological and ecological information and can be applied to identify management scenarios of highest impact on invasive crayfish abundances. In this study, we developed a conceptual population model of the invasive P. leniusculus following the Pop-GUIDE framework. In addition, we expanded on the framework to increase its applicability to other fields beyond environmental risk assessment. Finally, we discuss potential application of the model and its future use as a management tool.
... Only recently have demographic models been used to assess components of invasion and to guide management of invasive species [15,[21][22][23][24][25], which can even include prioritization based upon cost [26]. Population dynamics of IAS commonly have high population growth rates [15], and transient dynamics seem to play a part in invasion success [16,27,28]. ...
Until recently, little research has focused on determination of the population dynamics of invasive species and evaluating their genetic variation. Consequently, not much is known of what drives clonal invasive species and their demography. Here, we describe the population dynamics of Kalanchoe delagoensis (Crassulaceae), considered invasive to several countries. We quantified the demography of a population in central Mexico using integral projection models (IPM) in a population that reproduced asexually exclusively through plantlets. The effect of clonal recruitment on population growth rate (λ) was evaluated by changing plantlet survival and simulating management scenarios that used previous data of watering and seven experimental herbicide treatments. The finite rate of population increase indicated that this Kalanchoe delagoensis population is growing (above one) and with water availability, growth rates will only accelerate. The IPM showed that plantlet survival and recruitment were the most critical steps in the cycle for the population, and simulations of different management scenarios showed that reducing plantlet survival significantly decreased λ only in two out of the seven herbicides used.
... Differences in demography between multiple populations of the same species can change management prescriptions . When determining the level of threat to a species or population (Mace & Lande, 1991) or when deciding how to intervene to manage a population (Burgman & Possingham, 2000), knowing which population processes have the greatest influence on population performance and which are most easily, economically, and reliably manipulated are critical for effective management (Baxter et al., 2006;Yokomizo et al., 2009;Kerr et al., 2016). Quantifying the demographic mechanisms through which the environment and species interactions influence population performance (Pagel & Schurr, 2012;Pironon et al., 2018) enables the development and testing of appropriate management interventions for the persistence of desirable populations or the elimination of undesirable populations (Caplat et al., 2012a;Kerr et al., 2016). ...
... When determining the level of threat to a species or population (Mace & Lande, 1991) or when deciding how to intervene to manage a population (Burgman & Possingham, 2000), knowing which population processes have the greatest influence on population performance and which are most easily, economically, and reliably manipulated are critical for effective management (Baxter et al., 2006;Yokomizo et al., 2009;Kerr et al., 2016). Quantifying the demographic mechanisms through which the environment and species interactions influence population performance (Pagel & Schurr, 2012;Pironon et al., 2018) enables the development and testing of appropriate management interventions for the persistence of desirable populations or the elimination of undesirable populations (Caplat et al., 2012a;Kerr et al., 2016). ...
... While comparative demography can be useful in identifying broad management targets for different populations that differ in their population growth rate or life histories Ramula et al., 2008), other management concerns should be also considered. Kerr et al. (2016) surveyed 44 managers of 14 invasive plant species (across 17 management units) and found that they considered efficacy of the management action equally as important as demography of the target species for guiding management strategies. Managers were also very concerned about off-target effects of management, such as disturbance of vegetation and use of chemicals in the environment. ...
Population ecologists develop theoretical and pragmatic knowledge of how and why populations change or remain stable, how life histories evolve, and devise management strategies for populations of concern. However, forecasting the effects of global change or recommending management strategies is often urgent, requiring ecologists to work without detailed local evidence while using data and models from outside the focal location or species. Here we explore how the comparative ecology of populations, population macroecology, can be used to develop generalisations within and between species across different scales, using available demographic, environmental, life‐history, occurrence, and trait data. We outline the strengths and weaknesses of using broad climatic variables and suitability inferred from probability of occupancy models to represent environmental variation in comparative analyses. We evaluate the contributions of traits, environment, and their interaction as drivers of life history strategy. We propose that insights from life history theory, together with the adaptive capacity of populations and individuals, can inform on “persist in place” vs. “shift in space” responses to changing conditions. As demographic data accumulates at landscape and regional scales for single species, and throughout plant phylogenies, we will have new opportunities for testing macroecological generalities within and across species.
... For IAS, RM includes the assessment of the practical, resource, social, ethical, political and legal constraints under which management must occur. It places these in the context of the biological characteristics of the species [31], its stage in the invasion process, the scale of the problem, as well as the socio-economic and ecological costs and consequences of its management [22,30]. RM principles have been applied to governmentled invasive species programs in countries such as Australia and New Zealand since the early 2000s [32,33], while the same process has been applied in a number of discrete studies [30,31,34]. ...
... It places these in the context of the biological characteristics of the species [31], its stage in the invasion process, the scale of the problem, as well as the socio-economic and ecological costs and consequences of its management [22,30]. RM principles have been applied to governmentled invasive species programs in countries such as Australia and New Zealand since the early 2000s [32,33], while the same process has been applied in a number of discrete studies [30,31,34]. However, the use of this approach remains sporadic and specific to particular countries or regions. ...
International agreements commit nations to control or eradicate invasive alien species. The scale of this challenge exceeds available resources and so it is essential to prioritise the management of invasive alien species. Species prioritisation for management typically involves a hierarchy of processes that consider the likelihood and scale of impact (risk assessment) and the feasibility, costs and effectiveness of management (risk management). Risk assessment processes are widely used, risk management less so, but are a crucial component of resource decision making. To assess the cost-effectiveness of prioritisation, we considered 26 high-risk species considered for eradication from Great Britain (GB) with pre-existing risk assessment and risk management outputs. We extracted scores to reflect the overall risk to GB posed by the species, together with the estimated cost and the overall feasibility of eradication. We used these to consider the relative reduction in risk per unit cost when managing prioritised species based on different criteria. We showed that the cost-effectiveness of prioritisation within our sample using risk assessment scores alone, performed no better than a random ranking of the species. In contrast, prioritisation including management feasibility produced nearly two orders of magnitude improvement compared to random. We conclude that basing management actions on priorities based solely on risk assessment without considering management feasibility risks the inefficient use of limited resources. In this study, the cost-effectiveness of species prioritisation for action was greatly increased by the inclusion of risk management assessment.
... In calculating cost-effectiveness, the benefits of a given action are weighted by management feasibility, and the perceived ecological or social value or both of the benefit obtained (Carwardine et al., 2019;Joseph et al., 2009). This approach has guided threatened species management (e.g., Project Prioritization Protocol [Joseph et al., 2009]), management of sites or regions of conservation significance (e.g., Priority Threat Management [Carwardine et al., 2012;), and mitigation of weed incursions (Dodd et al., 2017;Kerr et al. 2016). Recent work, however, shows the approximate solution found through ranking cost-effectiveness sometimes performs poorly relative to an exact solution (Hanson et al., 2019). ...
Land managers decide how to allocate resources among multiple threats that can be addressed through multiple possible actions. Additionally, these actions vary in feasibility, effectiveness, and cost. We sought to provide a way to optimize resource allocation to address multiple threats when multiple management options are available, including mutually exclusive options. Formulating the decision as a combinatorial optimization problem, our framework takes as inputs the expected impact and cost of each threat for each action (including do nothing) and for each overall budget identifies the optimal action to take for each threat. We compared the optimal solution to an easy to calculate greedy algorithm approximation and a variety of plausible ranking schemes. We applied the framework to management of multiple introduced plant species in Australian alpine areas. We developed a model of invasion to predict the expected impact in 50 years for each species-action combination that accounted for each species' current invasion state (absent, localized, widespread); arrival probability; spread rate; impact, if present, of each species; and management effectiveness of each species-action combination. We found that the recommended action for a threat changed with budget; there was no single optimal management action for each species; and considering more than one candidate action can substantially increase the management plan's overall efficiency. The approximate solution (solution ranked by marginal cost-effectiveness) performed well when the budget matched the cost of the prioritized actions, indicating that this approach would be effective if the budget was set as part of the prioritization process. The ranking schemes varied in performance, and achieving a close to optimal solution was not guaranteed. Global sensitivity analysis revealed a threat's expected impact and, to a lesser extent, management effectiveness were the most influential parameters, emphasizing the need to focus research and monitoring efforts on their quantification.
... Therefore, a better understanding of using the scarcity of resources is essential in the decision-making process. The difficulty in measuring costs, its context-dependence (IUCN, 2018), associated with the complex nature of invasion dynamics (Epanchin-Niell, 2017) make it a challenging (Kerr et al., 2016;Reyns et al., 2018), but necessary task for improving long-term management of IAS. Here, we develop a SD model for the analysis of the effectiveness and costs of control efforts of Hakea sericea (silky hakea), one of the worst woody IAS in Portugal. ...
Invasive alien species (IAS) are a significant component of global changes, causing severe economic and biodiversity damage. In this regard, Hakea sericea is one of the most widespread IAS throughout the Mediterranean region, including Portugal. The difficulty surrounding its management is exacerbated by post-fire situations, signifying a challenging task for managers. To assist in this effort, we used a system dynamic approach to model the population dynamics of Hakea sericea regarding the combinations of wildfire risk and control scenarios, which differ in periodicity, type of interventions, and cohort age. The ultimate goal of this study was to assess the effectiveness and costs of control efforts at reducing the abundance of this IAS. A Natura 2000 site Alvão/Marão (code PTCON0003) in northern Portugal, severely invaded by Hakea sericea, served as the study site. The modeling results demonstrate that Hakea sericea is likely to continue spreading if left uncontrolled. Although it may not be possible to ensure eradication of Hakea sericea from the study, repeated control actions aimed at the entire IAS population could be very effective in reducing its area. From a practical standpoint, removing all plants 24 months after each fire event followed by subsequent monitoring appears to be the most cost-effective strategy for managing Hakea sericea. Considering the modeling results, the dynamic modeling framework developed is a versatile, instructive tool that can support decision-making aimed at effective management of Hakea sericea.
... Such models are useful to estimate population growth rates (k) as well as to identify which demographic parameters have more impact on them (Lediuk et al. 2016). These parameters, in turn, are used to define which individuals should be prioritized in management actions (Sakai et al. 2001;Kerr et al. 2016). Most studies have used matrix models to produce such predictions (DeWalt 2006;Iles et al. 2016). ...
Population models are helpful for understanding demographic trends in invasive plants and crucial in defining effective management actions. Here, we assessed the dynamics of three populations of the invasive palm Roystonea oleracea on an island in the Atlantic Forest, Brazil. We aimed to verify variations in the life cycle parameters (survival, growth, fecundity) of individuals; to evaluate population growth rates (λ); and to understand which vital rates most impact λ. In 2015, we established plots (40 × 40 m) in areas occupied by R. oleraceae and tagged (numbered aluminum tags) and measured the diameter at ground level (DGL) of all palms in the plots. We conducted an annual census in each population in 2016, 2017, and 2018 where all palms were relocated and measured again. We used Integral Projection Models to verify differences in life cycle parameters and to calculate λ, and prospective analyses of elasticity to verify the contribution of each vital rates on λ. Palms with smaller DGL (< 10 mm) had lower rates of survival or remained in stasis, while palms with larger DGL (> 10 mm) had higher survival rates, increased in size, or reproduced. The λ values were different between populations: Population 1 was decreasing, Population 2 was increasing, and Population 3 was stable. Survival and growth of palms with larger diameters were the vital rates that most impacted λ. Management strategies to eliminate palms with DGL > 400 mm are essential to reduce the λ of the species and to control their spread to new locations.
... 394 take into account a wide range of criteria that go beyond risk(Dana et al., 2014, Kerr et al., 2016, 395 Simberloff, 2003. While risk management is traditionally included along with risk assessment as 396 part of an overall approach to risk analysis in other disciplines, such as plant health, animal health 397 and food safety(EFSA, 2010, OiE, 2017, Ahl et al., 1993, FAO, 2013 it has rarely been applied 398 so systematically to IAS. ...
Prioritising the management of invasive alien species (IAS) is of global importance and within Europe integral to the EU IAS regulation. To prioritise management effectively the risks posed by IAS need to be assessed, but so too does the feasibility of their management. While the risk of IAS to the EU has been assessed, the feasibility of management has not.
We assessed the feasibility of eradicating 60 new (not yet established) and 35 emerging (established with limited distribution) species that pose a threat to the EU, as identified by horizon scanning. The assessment was carried out by 34 experts in invasion management from across Europe, applying the Non‐Native Risk Management scheme to defined invasion scenarios and eradication strategies for each species, assessing the feasibility of eradication using seven key risk management criteria. Management priorities were identified by combining scores for risk (derived from horizon scanning) and feasibility of eradication.
The results show eradication feasibility score and risk score were not correlated, indicating that risk management criteria evaluate different information than risk assessment. Seventeen new species were identified as particularly high priorities for eradication should they establish in the future, while fourteen emerging species were identified as priorities for eradication now. A number of species considered highest priority for eradication were terrestrial vertebrates, a group that has been the focus of a number of eradication attempts in Europe. However, eradication priorities also included a diverse range of other taxa (plants, invertebrates and fish) suggesting there is scope to broaden the taxonomic range of attempted eradication in Europe. We demonstrate that broad scale structured assessments of management feasibility can help prioritise IAS for management. Such frameworks are needed to support evidence based decision making.
... We show how combining contemporary expert opinion methods with mechanistic modeling of the interaction between invasive species and human pathways might be incorporated within a broader decision-making framework for invasive species management. Although several studies have used this method to forecast standard population processes, such as the rates of population increase (Murray et al. 2009, Wittmann et al. 2014a, 2014b, 2014c, Kerr et al. 2016, to our knowledge, few have done so for multiple taxonomic groups that would allow for both interand intraspecific comparisons (c.f. Zhang et al. 2016). ...
Abstract Predicting the spatial and temporal dynamics of invasive species is critical for successful management intervention, yet substantial uncertainty exists about how species will interact with human pathways when introduced to new ecosystems. We demonstrate a novel approach for quantifying uncertainty when predicting the uptake, movement, and establishment of invasive species by combining mechanistic modeling of the spread process with expert opinion of the demographic factors that govern species performance. We demonstrate the utility of this approach using a case study involving the transfer potential of nonindigenous species (NIS) in the Laurentian Great Lakes basin (GLB). A survey using structured expert judgment was completed by 24 North American taxonomic experts, covering 60 species of NIS established in the GLB. Experts estimated species‐specific demographic parameters describing population growth and establishment potential, which were incorporated into an existing mechanistic model of human‐mediated spread via ballast water with species‐specific spread rates (number of ports or lakes invaded/year) as outputs. Expert judgments within each group varied widely, indicating that generalizable rates of spread across taxa are unlikely and highlighting the value of cross‐taxon comparisons. Most species were predicted to establish throughout the GLB within 10 yr, assuming status quo management conditions. Sensitivity analysis for expert performance‐based weighting demonstrated that most model outputs were insensitive to weighting (
