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Cecropia obtusifolia (A) and Falcataria moluccana (B) are examples of early plantings in the Manoa Valley that became invasive. Natural or semi-natural vegetation is visible in the background of both photos, less than 500 m from these plantings. Photos: E. Caum, 31 December 1922.
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The lag time of an invasion is the delay between arrival of an introduced species and its successful spread in a new area. To date, most estimates of lag times for plants have been indirect or anecdotal, and these estimates suggest that plant invasions are often characterized by lag times of 50 years or more. No general estimates are available of l...
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Over the last 15 years studies on invasion genetics have provided important insights to unravel cryptic diversity, track the origin of colonizers and reveal pathways of introductions. Despite all these advances, to date little is known about how evolutionary processes influence the observed genetic patterns in marine biological invasions. Here, fir...
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... Despite these conditions, non-indigenous plant species are not often invasive on more than one island group even though they may be resident on many (Kueffer et al. 2010). The reasons for this are not uniformly apparent but are likely context dependent with variation in abiotic or biotic conditions affecting lag times or whether or not the spread phase of an invasion would occur (Ramírez and Montero 1988;Sakai et al. 2001;Davis et al. 2000;Crooks 2005;Daehler 2009;Colautti et al. 2010;Falcón et al. 2017; Soifer and Ackerman 2019). For those species that are invasive on more than one island group, it is not clear whether conditions are similar among those invaded islands, or whether the invader has broad tolerances, either through phenotypic plasticity or genetic variability. ...
... Vol:. (1234567890) plant recorded was in 1982 (Ackerman 1995) and may have been established just a few years earlier as average lag time for herbaceous plants is around five years (Daehler 2009). Since then, sightings of naturalized plants have accelerated across the island from east to west in the direction of the tradewinds, which is the same trajectory as another invasive ruderal orchid, Spathoglottis plicata (Falcón et al. 2017). ...
Traits associated with successful biological invasions across environmental gradients or geographical distances may vary depending on processes such as founder effects, ecological sorting, or adaptation to local conditions. Consequently, drivers of success are not necessarily consistent throughout the invasive range. We evaluate how plant traits, reproductive success and climatic preferences vary in populations of a naturalized orchid on islands in the Atlantic, Pacific and Indian oceans. Populations of Arundina graminifolia (bamboo orchid) were located on Puerto Rico, Hawaiian Islands (Hawai’i, O’ahu, Kaua’i), and Mauritius. Vegetative and reproductive traits were measured, and male and female success were assessed. Populations were compared using multivariate approaches. Species distribution modeling was used to assess potential climatic preferences within and among islands. Floral morphology differed among islands but considerable overlap in trait distributions exists. Reproductive success significantly differed among islands and was linked to floral traits, local pollinator pools and perhaps variable levels of florivory. Hawaiian populations occupied the broadest climatic niche space and Mauritius the most restricted. The effectiveness of using present points from the native range to reveal climatic suitability on invaded islands varied among islands. Successful invasions across a broad geographical range can occur even when morphology, reproductive success and climatic conditions are variable. As expected, some aspects of this global invasion are similar, but others differ among islands underscoring the context dependency of biological invasions and the difficulty of overall predictions.
... These species could become a particular concern for the surveyed communities given the short delays between the arrival of introduced species and their successful spread in tropical regions [62]. Estimates of the propagation lag times in tropical regions average 14 years for woody plants and five years for herbaceous plants, which are much shorter times than the average lag time (> 50 years) in temperate regions [63]. The results from the variance analysis showed that the richness of non-native plants among the gardens was similar, but there was more compositional variation among the surveyed gardens (Fig. 3). ...
Human cultivation facilitates the naturalization and subsequent invasion of non-native plant species through, for example, protection from predators or reducing environmental stochasticity. With the development of tourism, non-native plant species have been increasingly introduced into rural home gardens for landscape greening and amenity planting. However, few studies have examined non-native flora in rural home gardens, and in particular the importance of tourism in determining changes of garden non-native flora has not been scrutinized. In this study, we investigated non-native plant species in 135 home gardens across five rural tourism villages in tropical China. Attributes related to garden or household characteristics were also collected through interviews and questionnaires. A distance-based redundancy analysis was then performed to reveal the relationships between the non-native species composition and garden attributes. A total of 338 non-native plant species were recorded in the surveyed gardens. Among them, the majority (63%) were ornamentals, whereas 19% were for nutritional uses and 12% were spontaneous weeds. Gardening preference and distance to tourist attractions governed the non-native compositions, with gardens preferring cultural (ornamental) cultivation or gardens close to tourist attractions having more non-native species. These results highlight an increasing role of tourism in promoting non-native cultivation in rural gardens. Recommendations for species risk assessment, trade and supply regulation, and proper garden management are provided to help harness plant invasion along tourism development in rural China and other regions around the world.
... The United States had the highest percentage of species with lags (40%), while the North Island of New Zealand had the lowest (24%). Our analysis shows that lag phases are not as frequent and common as stated anecdotally in the invasion literature 5,7,44,47,48 . The use of inappropriate statistical methods, such as fitting models to cumulative time series 47 , probably resulted in an overestimation of the frequency of this phenomenon in plant invasions 41 . ...
... To investigate whether the end of the lag phase is associated with climate, we compared the climate envelopes of lag and expansion phases. For this analysis, we excluded species with fewer than 15 records per invasion phase and removed those with a very short lag phase of <5 years (n = 105), which appeared ecologically irrelevant 48 . A total of 553 species met the above criteria. ...
Successful alien species may experience a period of quiescence, known as the lag phase, before becoming invasive and widespread. The existence of lags introduces severe uncertainty in risk analyses of aliens as the present state of species is a poor predictor of future distributions, invasion success and impact. Predicting a species’ ability to invade and pose negative impacts requires a quantitative understanding of the commonality and magnitude of lags, environmental factors and mechanisms likely to terminate lag. Using herbarium and climate data, we analysed over 5,700 time series (species × regions) in 3,505 naturalized plant species from nine regions in temperate and tropical climates to quantify lags and test whether there have been shifts in the species’ climatic space during the transition from the lag phase to the expansion phase. Lags were identified in 35% of the assessed invasion events. We detected phylogenetic signals for lag phases in temperate climate regions and that annual self-fertilizing species were less likely to experience lags. Where lags existed, they had an average length of 40 years and a maximum of 320 years. Lengthy lags (>100 years) were more likely to occur in perennial plants and less frequent in self-pollinating species. For 98% of the species with a lag phase, the climate spaces sampled during the lag period differed from those in the expansion phase based on the assessment of centroid shifts or degree of climate space overlap. Our results highlight the importance of functional traits for the onset of the expansion phase and suggest that climate discovery may play a role in terminating the lag phase. However, other possibilities, such as sampling issues and climate niche shifts, cannot be ruled out.
... Often, invasive populations undergo a lag time throughout the invasion process, from the introduction and establishment to the final population explosion. The duration of these time lags can significantly vary among different organisms and ecosystems in various invasion stages, ranging from several years to several hundred years [46,47]. In the case of the golden mussel invasion in Beijing, the rapid spread has manifested during the very early stages of the invasion, effectively compressing or, in some instances, even negating the typical lag time observed from the introduction to subsequent spread. ...
Simple Summary
The world’s largest water diversion, the South-to-North Water Transfer Project (SNWTP) in China, diverts water from the Danjiangkou Reservoir in the Yangtze River basin to major cities such as Beijing and Tianjin in North China. This water diversion has effectively created an “invasion highway”, facilitating the spread of non-native invasive species such as golden mussels (Limnoperna fortunei) to aquatic ecosystems in Beijing. Despite the significance of this development, the dynamics of the spread and colonization patterns of golden mussels in Beijing have remained largely unexplored. In this study, we used environmental DNA (eDNA)-based early detection to conduct comprehensive surveillance across all water bodies in five river basins from 2020 to 2023. Our results revealed a rapid spread of golden mussels in Beijing over the past four years. Starting with four infested sites identified through field surveys in 2019, the count of sites exhibiting positive eDNA signals experienced a gradual rise. Between 2020 and 2022, an additional 10–13 sites were confirmed, followed by a substantial increase to 28 additional sites in 2023. Conventional field surveys confirmed the presence of golden mussels at 16 sites between 2020–2023. To date, golden mussels have rapidly expanded their presence to four out of the five investigated river basins, with only the Daqing River remaining uninfested.
Abstract
The world’s largest water diversion, the South-to-North Water Transfer Project (SNWTP) in China, has created an “invasion highway” to introduce invasive golden mussels (Limnoperna fortunei) from the Yangtze River basin to Beijing. To examine the spread and colonization patterns of this newly introduced invasive species, we conducted comprehensive environmental DNA (eDNA)-based early detection and conventional field surveys across all water bodies in five river basins in Beijing from 2020 to 2023. Our results indicated a rapid spread over the past four years. Among the 130 tested sites, the number of sites with positive signals from eDNA analysis exhibited an annual increase: Commencing with four infested sites identified through field surveys in 2019, eDNA analysis detected an additional 13, 11, and 10 positive sites in 2020, 2021, and 2022, respectively, and a substantial rise comprising an additional 28 sites in 2023. Conventional field surveys detected mussels 1–3 years later than eDNA-based analysis at 16 sites. Across all 16 sites, we detected a low population density ranging from 1 to 30 individuals/m². These findings collectively indicate that the invasions by golden mussels in Beijing are still in their early stages. To date, golden mussels have successfully colonized four out of the five investigated river basins, including the Jiyun River (22.2% positive sites), North Canal River (59.6% positive sites), Chaobai River (40% positive sites), and Yongding River (63.6% positive sites), with the North Canal River and Yongding River being the most heavily infested. Currently, only the Daqing River basin remains uninfested. Given the significant number of infested sites and the ongoing transport of large new propagules via SNWTP, further rapid spread and colonization are anticipated across aquatic ecosystems in Beijing and beyond. Consequently, we call for the proper implementation of effective management strategies, encompassing early detection, risk assessment, and the use of appropriate control measures to mitigate the potential ecological and economic damages in invaded ecosystems.
... In these studies, the duration of TLDR was evaluated in a specific case with a single driver parameter, and the timings of abrupt changes were recorded. For example, TLDR durations have been reported to be several years for increases in groundwater temperature (Menberg et al., 2014), several decades for salt marsh collapse (Altieri et al., 2012), several years to decades for invasive tropical plants (Daehler, 2009), and several months to centuries in stream responses to ecological restoration (Hamilton, 2012). The duration of TLDR is likely to be reproducible for at least one of these cases (increases in groundwater temperature) because increases in groundwater temperature are closely tied to the physical process of thermal diffusivity. ...
A better understanding of abrupt ecosystem changes is needed to improve prediction of future ecosystem states under climate change. Chronological analysis based on long-term monitoring data is an effective way to estimate the frequency and magnitude of abrupt ecosystem changes. In this study, we used abrupt-change detection to differentiate changes of algal community composition in two Japanese lakes and to identify the causes of long-term ecological transitions. Additionally, we focused on finding statistically significant relationships between abrupt changes to aid with factor analysis. To estimate the strengths of driver-response relationships underlying abrupt algal transitions, the timing of the algal transitions was compared to that of abrupt changes in climate and basin characteristics to identify any synchronicities between them. The timing of abrupt algal changes in the two study lakes corresponded most closely to that of heavy runoff events during the past 30-40 years. This strongly suggests that changes in the frequency of extreme events (e.g., heavy rain, prolonged drought) have a greater effect on lake chemistry and community composition than do shifts in the means of climate and basin factors. Our analysis of synchronicity (with a focus on time lags) could provide an easy method to identify better adaptative strategies for future climate change.
... The fact that in many invasive species there often is a lag time between the first introduction and the development of a large population has been observed in many investigations. This lag is variable, ranging from less than a year to decades and probably depends on many intrinsic, species specific, and environmental variables (Kiritani & Yamamura, 2003;Simberloff & Gibbons, 2004;Daehler, 2009). In order to estimate this lag time, the date of the first introduction needs to be known. ...
We summarized existing knowledge on Dreissena polymorpha (the zebra mussel) and D. r. bugensis (the quagga mussel), including data on their taxonomy, systematics, evolution, life cycle, reproduction, feeding, growth and longevity, population dynamics, interspecific competition, habitat requirements, and distribution within and among waterbodies. We analyzed the history of spread of both species and the major pathways and vectors of their spread in Europe and North America. Special consideration was given to their ecological and economic impacts and their natural enemies, like waterfowl, fishes, and parasites, as well as the prevention of their introduction, early detection, control, and containment. We also outlined the most salient ecosystem services provided by zebra and quagga mussels, including water purification, nutrient recycling, culling the effects of eutrophication, biomonitoring, and their role as a food resource for fish and waterfowl. Finally, we identified major knowledge gaps and key studies needed to better understand the biology, ecology, and impacts of these aggressive freshwater invaders. Our review indicates that much crucial information on the quagga mussel is still missing, including key life history parameters, like spawning cues, fecundity, and longevity, particularly for the profundal zone of deep lakes.
... Crooks and Soule (1999) defined this delay as an 'inherent lag,' or the normal early period of exponential growth that occurs before the inflection point in the curve of population growth. Prolonged lag phases occur when a species persists in an environment in low numbers for an extended period (Daehler 2009;Rilov et al. 2004). There are two basic types of lags: lags in population growth and lags in population spread, although the two can appear synonymous (Crooks & Soule 1999). ...
Invasive species are a leading cause of biodiversity loss worldwide. Deer have been introduced to environments around the world, and many species have gone on to become invasive. Feral deer potentially compete with native species and livestock, pose risks to vehicles or by acting as vectors of disease, as well as contributing to economic and social losses. Presently there are six free-living deer species in Australia: chital (Axis axis), fallow (Dama dama), hog (Axis porcinus), red (Cervus elaphus), rusa (Rusa timorensis), and sambar (Rusa unicolor). Four chital deer were liberated on Maryvale Station in Northern Queensland in 1886 and since then, the number and range of chital deer has slowly increased. The factors that contributed to both the delayed growth as well as their sudden range and population increase are not known, such as how they select and use habitat as well as the cues that drive their reproduction. Considering the broad economic and environmental impact chital could have on this region, understanding their ecology is critical to developing more effective management and control strategies, as well as predicting where these feral species are likely to spread next.
... In these studies, the duration of TLDR was evaluated in a specific case with a single driver parameter, and the timings of abrupt changes were recorded. For example, TLDR durations have been reported to be several years for increases in groundwater temperature (Menberg et al., 2014), several decades for salt marsh collapse (Altieri et al., 2012), several years to decades for invasive tropical plants (Daehler, 2009), and several months to centuries in stream responses to ecological restoration (Hamilton, 2012). The duration of TLDR is likely to be reproducible for at least one of these cases (increases in groundwater temperature) because increases in groundwater temperature are closely tied to the physical process of thermal diffusivity. ...
... Allee effects and evolutionary consequences of small population sizes resulting initially in low genetic diversity, genetic drift and bottlenecks) (Mack et al. 2000;Sakai et al. 2001;Clemens and Ditommaso 2011), lack of mutualists (Parker 2004), long period between reproductive events (Wangen and Webster 2006), spatial heterogeneity (Hastings 1996) and variable habitat connectivity (Mack et al. 2000). The observed lag time range of 12-126 yrs and mean of 45.9 yrs, as well as the proportion of weeds classified as having a lag phase (59%), are similar to values reported in the literature (Daehler 2009;Larkin 2012;Crooks 2005;Aikio et al. 2010;Hyndman et al. 2015). However, it should be noted that longer lag times (up to 300 years) have also been reported for weeds of temperate, Mediterranean, and other colder (e.g., subantarctic) regions (Kowarik 1995;Weber 1998;Brandle and Brandl 2012). ...
... A positive relationship between lag time and residence time was detected. This suggests that new introductions are spreading faster and earlier than longer established invaders (Daehler 2009;Aikio et al. 2010). This finding supports the parsimonious assertion that Queensland regions, as in many landscapes around the globe, may have become more susceptible to invasion in recent time (Seebens et al. 2018). ...
Herbarium records provide comprehensive information on plant distribution, offering opportunities to construct invasion curves of introduced species, estimate their rates and patterns of expansions in novel ranges, as well as identifying lag times and hence “sleeper weeds”, if any. Lag times especially have rarely been determined for many introduced species, including weeds in the State of Queensland, Australia as the trait is thought to be unpredictable and cannot be screened for. Using herbarium records (1850–2010), we generated various invasiveness indices, and developed simple invasion and standardised proportion curves of changes in distribution with time for ~ 100 established and emerging weed species of Queensland. Four major periods (decades) of increased weed spread (spikes) were identified: 1850s, 1900–1920, 1950–1960 and 2000–2010, especially for grasses and trees/shrubs. Many weeds with spikes in spread periods did so only 1–2 decadal times, except for a few species with higher spike frequencies > 6; the majority of these spikes occurred recently (1950–1990). A significant proportion (~ 60%) of Queensland’s weeds exhibit non-linear increase in spread with time, and hence have lag phases (mean: 45.9 years; range: 12–126 years); of these lag-phase species, 39% are “sleeper” weeds with > 50 years of lag time (mainly trees/shrubs and grasses). Twelve traits of invasiveness, including lag time and species-specific/historical factors were screened, of which frequency of invasion waves, spread rates and residence time were the main drivers of weeds’ distribution. The low predictive power of lag time on weed distribution suggests that retrospective analyses offer little hope for a robust generalisation to identify weeds of tomorrow.
... There are two plausible causes for these threatened exotic species to be not naturalized yet in adjacent native forests. First, time needed for invasion processes (including naturalization) were different for every species and the length may vary from months to years (Daehler 2009). Second, the adjacent native forest may have adequate resistance capacities to inhibit the naturalization processes of botanical garden exotic collections. ...
A primary objective of botanical gardens is to conserve threatened plant species from different regions and countries. However, such ex-situ conservation practices for exotic plant species may pose a significant plant invasion risks. In this study, we predict the naturalization probability of exotic threatened plant species of Cibodas Botanical Garden (CBG) collections based on leaf trait (specific leaf area, SLA) or as a function of invasion risk assessment scoring system (Tropical Weed Risk Assessment Protocol, TWRAP). We found that SLA and TWRAP were positively correlated with naturalization probability. The TWRAP model produced higher predictive probabilities with larger uncertainty compared to SLA model. Parmentiera cereifera and Burretiodendron hsienmu are two species that have highest naturalization probability based on SLA model. Chamaedorea oblongata has the highest naturalization probability based on TWRAP model. From practical and management point of view, we recommend the simultaneous use of SLA-based and TWRAP-based invasive species risk assessment to estimate the naturalization risk of exotic threatened collections of botanical gardens to adjacent mountain forests. Finally, given the important conservation value of threatened exotic collection of botanical garden, we need to be aware with the invasion risks of these species. The threatened condition of a plant species is not only caused by its natural characteristics but also may be caused (in fact mostly confounding with) by external disturbance either natural catastrophic or human related activities. Thus, a threatened species may not necessarily a non-invasive species outside their natural distribution ranges.
