Ecology Letters (2010) 13: 528-541 We review studies that address economically optimal control of established invasive species. We describe three important components for determining optimal invasion ...management: invasion dynamics, costs of control efforts and a monetary measure of invasion damages. We find that a management objective that explicitly considers both costs and damages is most appropriate for determining economically optimal strategies, but also leads to large challenges due to uncertainty in components of the management problem. To address uncertainty, some studies have included stochasticity in their models; others have quantified the value of information or focused on decision-making with limited information. Our synthesis shows how invasion characteristics, such as costs, damages, pattern of spread and invasion and landscape size, affect optimal control strategies and goals in systematic ways. We find that even for simple questions, such as whether control should be applied at the centre of an invasion or to satellite patches, the answer depends on the details of a particular invasion. Future work should seek to better quantify key components of this problem, determine best management in the face of limited information, improve understanding of spatial aspects of invasion control and design approaches to improve the feasibility of achieving regional control goals.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In a world of increasing interconnections in global trade as well as rapid change in climate and land cover, the accelerating introduction and spread of invasive species is a critical concern due to ...associated negative social and ecological impacts, both real and perceived. Much of the societal response to invasive species to date has been associated with negative economic consequences of invasions. This response has shaped a war-like approach to addressing invasions, one with an agenda of eradications and intense ecological restoration efforts towards prior or more desirable ecological regimes. This trajectory often ignores the concept of ecological resilience and associated approaches of resilience-based governance. We argue that the relationship between ecological resilience and invasive species has been understudied to the detriment of attempts to govern invasions, and that most management actions fail, primarily because they do not incorporate adaptive, learning-based approaches. Invasive species can decrease resilience by reducing the biodiversity that underpins ecological functions and processes, making ecosystems more prone to regime shifts. However, invasions do not always result in a shift to an alternative regime; invasions can also increase resilience by introducing novelty, replacing lost ecological functions or adding redundancy that strengthens already existing structures and processes in an ecosystem. This paper examines the potential impacts of species invasions on the resilience of ecosystems and suggests that resilience-based approaches can inform policy by linking the governance of biological invasions to the negotiation of tradeoffs between ecosystem services.
•The relationship between biological invasions and ecological resilience is complex.•Invasions can build or erode resilience, which can be positive or negative.•Invasions have great capacity to affect global environmental change.•Biological invasions affect ecological resilience and ecosystem services.•Adaptive governance approaches biological invasions as suites of ecosystem services.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Species introductions of anthropogenic origins are a major aspect of rapid ecological change globally. Research on biological invasions has generated a large literature on many different aspects of ...this phenomenon. Here, we describe and categorize some aspects of this literature, to better understand what has been studied and what we know, mapping well‐studied areas and important gaps. To do so, we employ the techniques of systematic reviewing widely adopted in other scientific disciplines, to further the use of approaches in reviewing the literature that are as scientific, repeatable, and transparent as those employed in a primary study. We identified 2398 relevant studies in a field synopsis of the biological invasions literature. A majority of these studies (58%) were concerned with hypotheses for causes of biological invasions, while studies on impacts of invasions were the next most common (32% of the publications). We examined 1537 papers in greater detail in a systematic review. Superior competitive abilities of invaders, environmental disturbance, and invaded community species richness were the most common hypotheses examined. Most studies examined only a single hypothesis. Almost half of the papers were field observational studies. Studies of terrestrial invasions dominate the literature, with most of these concerning plant invasions. The focus of the literature overall is uneven, with important gaps in areas of theoretical and practical importance.
We employ the techniques of systematic reviewing and field synopses, widely adopted in other scientific disciplines, to describe and categorize a substantial portion of the literature on biological invasions, to better understand what has been studied and what we know, mapping well‐studied areas and important gaps. Among other findings, we report that studies of terrestrial plant invasions dominate the literature, and we identify important gaps in areas of theoretical and practical importance.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Invasive alien species are among the most concerning threats to native biodiversity world‐wide, and the level of landscape heterogeneity is considered to affect spatial patterns of their occurrence ...and spread. However, as previous studies on these associations report contrasting results, the role of landscape heterogeneity on its susceptibility to invasions remains poorly understood. Landscape heterogeneity is usually described by two measures: configuration and composition. Both measures may differently affect invasive species and these impacts may be additionally scale dependent. Nevertheless, their relative contribution to invasion patterns is poorly known.
We investigated the effect of two landscape heterogeneity components: configuration (edge density) and composition (number and evenness of land cover types) measured at different spatial scales (from within 0.25 to 5 km of the studied locations) on the local abundance of one of the most invasive alien plant species in Europe, the North American goldenrods (Solidago canadensis and S. gigantea). Using publicly available geospatial environmental data and a novel method based on remote analysis of Google Street View images, we collected and analysed large dataset on goldenrod occurrence along 1,347 roadside transects in agricultural landscapes of Poland.
Both the compositional and configurational heterogeneity were positively associated with the local abundance of goldenrods, however, the effect size of these relationships was dependent on spatial scale. While abundance–heterogeneity associations were most pronounced at the largest spatial scale for compositional heterogeneity, the pattern was the opposite for configurational heterogeneity.
Synthesis and applications. Landscape heterogeneity is a clear correlate of plant invasion potential, with occurrences of invasive plants generally higher in more heterogeneous landscapes. However, scale dependence of this association means that researchers and practitioners may miss the association if only concentrating on a single spatial scale. While increasing heterogeneity of rural landscapes is widely introduced as a way to promote farmland biodiversity, we show that it may also support invasive plants, and thus conflict with original goals of biodiversity‐oriented strategies. Therefore, we suggest implementing regular management and eradication schemes in most heterogeneous landscapes. Finally, we demonstrate how remote analysis of plant invasions using existing imagery can advance our understanding of invasion biology.
Landscape heterogeneity is a clear correlate of plant invasion potential, with occurrences of invasive plants generally higher in more heterogeneous landscapes. However, scale dependence of this association means that researchers and practitioners may miss the association if only concentrating on a single spatial scale. While increasing heterogeneity of rural landscapes is widely introduced as a way to promote farmland biodiversity, we show that it may also support invasive plants, and thus conflict with original goals of biodiversity‐oriented strategies. Therefore, we suggest implementing regular management and eradication schemes in most heterogeneous landscapes. Finally, we demonstrate how remote analysis of plant invasions using existing imagery can advance our understanding of invasion biology.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Intraspecific trait variation is ubiquitous and is likely to influence species coexistence. Despite theoretical progress, empirical work on the effects of intraspecific variation on the dynamics of ...competing species is rare. This is because of the formidable empirical requirements necessary to link intraspecific variation in species' functional traits with intraspecific variation in the demographic and competitive rates that mediate coexistence. Here we partially overcome these challenges to determine how intraspecific variation in reproductive phenology in a native Californian annual plant species Lasthenia californica affects its ability to coexist with two non‐native species Bromus madritensis and Lactuca serriola that display contrasting phenological patterns. Using data from a field experiment, we empirically parameterize a model of competitive population dynamics, accounting for the effects of intraspecific phenological trait variation on the native species' response to both intra‐ and interspecific competition. We find that intraspecific variation in phenology drives differences in the native species' response to competition. Moreover, simulations of the parameterized model show that this variation improves the competitive performance of the native species. This occurs because of the effects of nonlinear averaging mediated by a nonlinear, concave‐up competition function that is a general feature of competition across a wide range of taxa. While intraspecific variation improves competitive performance, we also find that the magnitude of the benefit is predicted to be insufficient to prevent competitive exclusion against the non‐native species with early phenogy Bromus. Against the second non‐native species with later phenology Lactuca, intraspecific variation is predicted to result in coexistence where competitive exclusion would otherwise occur, but we could not rule out alternative qualitative outcomes for this interaction.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
High-resource environments typically favor quick-growing, poorly defended plants, while resource-poor environments typically favor slow-growing, well-defended plants. The prevailing hypothesis ...explaining this pattern states that, as resource availability increases, well-defended, slow-growing species are replaced by poorly defended, fast-growing species. A second hypothesis states that greater resource availability increases allocation to growth at the expense of defense, within species. Regardless of mechanism, if exotic species are released from enemies relative to natives, shifts in allocation to growth and defense both within and among species could differ by geographic provenance. To test whether resource availability alters growth or defense, within and among species, and whether any such effects differ between natives and exotics, we manipulated soil nutrient supply and access of aboveground insect herbivores and fungal pathogens under field conditions to individuals of six native and six exotic grass species that co-occurred in a North Carolina old field. The prevailing hypothesis’ prediction—that species-level enemy impact increases with species’ nutrient responsiveness—was confirmed. Moreover, this relationship did not differ between native and exotic species. The second hypothesis’ prediction—that individual-level enemy impact increases with nutrient supply, after accounting for species-level variation in performance—was not supported. Together, these results support the idea, across native and exotic species, that plant species turnover is the primary mechanism underlying effects of nutrient enrichment on allocation to growth and defense in plant communities.
Aim
Darwin posited that invaders similar to native species are less likely to be successful due to competitive exclusion. A key axis across which such competition occurs across angiosperms is the ...timing of flowering, or reproductive phenology. It has been hypothesized that temporal isolation facilitates the establishment of introduced species. However, our knowledge of how the timing of flowering may influence invasion success is lacking at broader geographic and larger taxonomic scales. To address this impasse, we investigated: (i) how flowering phenology differs between native and non‐native species; (ii) whether the flowering phenology of successful invaders is distinct from native taxa; and (iii) whether invasive species tend to be more closely related to natives than other less successful, non‐invasive introduced species are.
Location
California, USA.
Time Period
Present.
Major Taxa Studied
Angiosperms.
Methods
We compiled phenological data for over 6000 angiosperm species across California, a highly invaded biodiversity hotspot, from published flora. Using these data, we assessed the degree of phenological and phylogenetic similarity among native, non‐invasive introduced, and invasive species. We also examined how this similarity varies with climate.
Results
Both non‐invasive introduced and invasive species were more phenologically and phylogenetically distant from natives than natives were from each other. However, invasive plants tend to be more similar to native species in terms of flowering phenology and phylogenetic relationships than non‐invasive introduced species. Further, the degree of similarity between native and non‐native species was mediated by climate, where phenological and phylogenetic similarities were greater in cooler regions.
Main Conclusions
Together, our results demonstrate that both similarity and distinctiveness can facilitate plant invasions and that invaders just similar enough to the native flora are more likely to be successful.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Regular variation is a powerful tool for analyzing fat-tailed invasions.•Tail indices control rates of acceleration of fat-tailed invasions.•Our analyses apply to populations with either no or weak ...Allee effects.•Initial conditions also affect fat-tailed invasion rates.•Measuring accelerating invasions requires new tools and methods.
Display omitted
Integrodifference equations (IDEs) are used in ecology to model the growth and spatial spread of populations. With IDEs, dispersal is specified with a probability density function, called the dispersal kernel, and the shape of the kernel influences how rapidly invasions progress. In this paper, we apply tail additivity, a property of regularly varying probability densities, to model invasions with fat-tailed (power-law decay) dispersal in one dimension. We show that fat-tailed invasions progress geometrically fast, with the rate of spread depending on the degree of fatness of the tails. Our analyses apply to populations with no Allee effect as well as weak Allee effects, and we conduct simulations to show that fat-tailed invasions with weak Allee effects produce accelerating invasions. We analyze point-release and front-release invasions, corresponding to newly-established and well-established populations, and we find that front-release invasions gain a permanent speed-up over point-release invasions, invading at a faster geometric rate that persists for all time. Since accelerating invasions are qualitatively different than constant-speed invasions, we also discuss how measures of invasion must be modified and reconsidered when invasions accelerate.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
•Secondary invader germination is not influenced by available soil nitrogen.•Elevated available soil nitrogen favours secondary invader growth.•Secondary invader species respond differently to ...available soil nitrogen.•Secondary invasion can be managed through a reduction in soil nitrogen levels.
Invasive alien nitrogen-fixing species, such as Australian acacias, often leave a legacy of elevated available soil nitrogen after their removal. This legacy effect can facilitate secondary invasion by other alien species, thereby preventing natural restoration of areas being managed. To restore viable native plant communities in ecosystems where secondary invasion is a barrier to restoration, it is important to understand the soil legacy effects of invasions. Using Acacia saligna (Labill.) H. L. Wendl. (Fabaceae) invasions in the South African fynbos as case study, we determined (1) the extent to which levels of available soil nitrogen influence the germination and growth of secondary invaders; and (2) how this differs between secondary invader species. We chose five of the most common species that have been identified as secondary invaders after clearing invasive A. saligna in the Cape Flats Sand Fynbos: (i) Avena fatua (L.) (Poaceae), (ii) Briza maxima (L.) (Poaceae), (iii) Bromus diandrus (Roth.) (Poaceae), (iv) Hypochaeris radicata (L.) (Asteraceae), and (v) Raphanus raphanistrum (L.) (Brassicaceae). Using proportional fertigation, we created soil nitrate levels similar to those found in non-invaded areas (1mg/kg), and the lowest (3 mg/kg), median (7.5 mg/kg) and highest (12 mg/kg) levels typically found in areas previously invaded by A. saligna up to ten years after clearing. For each soil nitrate level, we germinated secondary invader seeds (five seeds per petri dish) in an incubator (five species × four soil nitrate levels × five replicates = 100 petri dishes). Furthermore, for each soil nitrate level, we grew secondary invaders (one plant per pot) in a greenhouse tunnel for five months (five species × four soil nitrate levels × five replicates = 100 pots). There was no significant relationship between germination success and soil nitrate level for any species. However, root and shoot dry mass were significantly positively correlated to soil nitrate level for all species. The relationship was nonetheless only linear for Bromus diandrus, Hypochaeris radicata, and Raphanus raphanistrum. These results indicate that the legacy of elevated available soil nitrogen does not have an effect on the germination of secondary invaders, but favours their growth. Therefore, secondary invasion can be managed through a reduction in soil nitrogen levels. However, secondary invader growth does not decrease at the same rate for all species in response to a decrease in available soil nitrogen. Thus, the use of soil nitrogen reduction as a tool for the management of secondary invasions should take into account the species being managed. However, given that multiple secondary invader species often dominate a restoration site, restoration efforts should reduce soil nitrogen to non-invaded levels to account for the different response rates to available soil nitrogen, and simply management efforts.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
You have reached the maximum number of search results that are displayed.
For better performance, the search offers a maximum of 1,000 results per query (or 50 pages if the option 10/page is selected).
Consider using result filters or changing the sort order to explore your results further.
PDF
