Geographical, socioeconomic, and ecological determinants of exotic plant naturalization in the United States: insights and updates from improved data

Guo, Qinfeng; Rejmánek, Marcel; Wen, Jun

doi:10.3897/neobiota.12.2419

Cited by 24 publications

(29 citation statements)

References 30 publications

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“…Therefore, the neighborhood for our analyses was defined as a given hexagon and its six bordering hexagons. This pattern of localized spatial autocorrelation agrees with the finding that the spatial autoregressive processes contributing to macroscale invasion patterns occur at more localized scales (Guo et al , Iannone et al ).…”

Section: Methodssupporting

confidence: 90%

Biological invasion hotspots: a trait‐based perspective reveals new sub‐continental patterns

et al. 2015

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Invader traits (including plant growth form) may play an important, and perhaps overlooked, role in determining macroscale patterns of biological invasions and therefore warrant greater consideration in future investigations aimed at understanding these patterns. To assess this need, we used empirical data from a national‐level survey of forest in the contiguous 48 states of the USA to identify geographic hotspots of forest plant invasion for three distinct invasion characteristics: invasive species richness, trait richness (defined as the number of the five following plant growth forms represented by the invasive plants present at a given location: forbs, grasses, shrubs, trees, and vines), and species richness within each growth form. Three key findings emerged. 1) The hotspots identified encompassed from 9 to 23% of the total area of our study region, thereby revealing many forests to be not only invaded, but highly invaded. 2) Substantial spatial disagreement among hotspots of invasive species richness, invasive trait richness, and species richness of invasive plants within each growth form revealed many locations to be hotspots for invader traits, or for particular growth forms of invasive plants, rather than for invasive plants in general. 3) Despite eastern forests exhibiting higher levels of plant invasion than western forests, species richness for invasive forbs and grasses in the west were respectively greater than and equivalent to levels found in the east. Contrasting patterns between eastern and western forests in the number of invasive species detected for each growth form combined with the spatial disagreement found among hotspot types suggests trait‐based variability in invasion drivers. Our findings reveal invader traits to be an important contributor to macroscale invasion patterns.

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Section: Methodssupporting

confidence: 90%

Biological invasion hotspots: a trait‐based perspective reveals new sub‐continental patterns

et al. 2015

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“…Models were run both at the ecological division level (n = 5 random effects) and at the ecological section level (n = 91 random effects). Assuming independence among ecological sections/divisions was reasonable, as plots within a given section/division are more similar to one another with regards to a wide range of abiotic and biotic conditions than to plots within other sections/divisions (Cleland et al 1997), and because spatial autocorrelative processes contributing to macroscale invasion patterns likely occur at distances smaller than the sizes of ecological sections and divisions (Guo et al 2012;Iannone et al 2015). Calculating slopes estimates separately for each ecological section also controlled for variability among ecological sections with regards to the timing of invasive plant data collection.…”

Section: Resultsmentioning

confidence: 99%

“…Identifying the factors that contribute to the spatial heterogeneity in invadernative association magnitude and direction is clearly needed. Again, investigating those factors already known to affect macroscale invasion patterns such as propagule pressure, disturbance, or socioeconomic factors (Lockwood et al 2005;Gavier-Pizarro et al 2010;Pyšek et al 2010;Guo et al 2012;Liebhold et al 2013) may be of great utility. Future studies may benefit by incorporating smaller units of heterogeneity, as doing so may help to detect more fine-scale patterns and the threshold of heterogeneity at which understanding is maximized.…”

Section: Future Directionsmentioning

confidence: 98%

“…What these factors are is unclear. Determining the contributions of factors already known to affect macroscale invasion patterns such as propagule pressure, disturbance, and socioeconomic factors (Lockwood et al 2005;Gavier-Pizarro et al 2010;Pyšek et al 2010;Guo et al 2012;Liebhold et al 2013;Iannone et al 2015) will likely be beneficial. Furthermore, the potential for multiple factors to contribute to these patterns simultaneously must be considered.…”

Section: Key Findingsmentioning

confidence: 98%

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Evidence of biotic resistance to invasions in forests of the Eastern USA

et al. 2015

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Context Detecting biotic resistance to biological invasions across large geographic areas may require acknowledging multiple metrics of niche usage and potential spatial heterogeneity in associations between invasive and native species diversity and dominance.Objectives Determine (1) if native communities are resistant to biological invasions at macroscales; (2) the metrics that best quantify biotic resistance at these scales; and (3) the degree to which the direction and magnitude of invader-native associations vary with scale and/or location. Methods Using a mixed-effects modeling framework to account for potential sub-regional and crossscale variability in invader-native associations, we modeled the species richness and cover of invasive plants in 42,626 plots located throughout Eastern USA forests in relationship to plot-level estimates of native tree biomass, species richness, and evolutionary diversity.Results We found (1) native tree biomass and evolutionary diversity, but not species richness, to be negatively associated with invader establishment and dominance, and thus indicative of biotic resistance; (2) evidence that evolutionary diversity limits invader dominance more than it does invader establishment; Special issue: Macrosystems ecology: Novel methods and new understanding of multi-scale patterns and processes.(3) evidence of greater invasion resistance in parts of the agriculturally-dominated Midwest and in and around the more-contiguous forests of the Appalachian Mountains; and (4) the magnitude to which native tree biomass and evolutionary diversity limit invasion varies across the ranges of these metrics. Conclusions These findings illustrate the improved understanding of biotic resistance to invasions that is gained by accounting for sub-regional variability in ecological processes, and underscores the need to determine the factors leading to spatial heterogeneity in biotic resistance.

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“…Third, we found the need to account for spatial autocorrelation. Our preliminary analyses, however, by revealing the most appropriate neighbourhood distance to be 1 degree, suggest the majority of spatial autocorrelation contributing to macroscale invasion patterns occurs at relatively small scales, that is within a few‐county radius, a hypothesis supported by a recent study into patterns of exotic plant invasions having states as the sample unit (Guo et al ., ). Of course closer inspection of individual variables is needed to determine those to which this pattern applies.…”

Section: Discussionmentioning

confidence: 97%

Region-specific patterns and drivers of macroscale forest plant invasions

et al. 2015

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Aim Stronger inferences about biological invasions may be obtained when accounting for multiple invasion measures and the spatial heterogeneity occurring across large geographic areas. We pursued this enquiry by utilizing a multimeasure, multiregional framework to investigate forest plant invasions at a subcontinental scale. Location United States of America (USA). Methods Using empirical data from a national survey of USA forests, we compiled and mapped invasion richness (number of invasive species) and invasion prevalence (percentage of plots invaded) for 2524 counties. We then modelled each of these invasion measures as functions of 22 factors reflective of propagule pressure and/or habitat invasibility for eastern and western forests separately using simultaneous autoregressive spatial error models. Results Eastern forests had higher mean invasion richness (6.1) and prevalence (48%) than western forests (3.2 and 10%, respectively). Spatial patterns of invasion richness and prevalence differed, especially in the West. Propagule pressure factors were always positively associated with both invasion measures. Factors associated with human legacy were nearly six times more strongly associated with western than eastern invasions. Unlike propagule pressure factors, habitat invasibility factors shared inconsistent associations with invasion measures. Main conclusions The weaker associations between human legacy and invasions in the heavily invaded East, compared to the less‐invaded West, suggest a declining effect of propagule pressure over time with increasing invasion intensity. The importance of propagule pressure in less‐invaded western forests suggests that spatial variability in propagule inputs, coupled with lags between establishment and commonness, drives the spatial differences between invasion richness and prevalence during early invasion stages. Meanwhile, declining spatial disagreement between invasion measures and the relative unimportance of propagule pressure, in heavily invaded eastern forests, suggest that species‐specific variation in response to habitat invasibility drives spatial differences between invasion measures during later invasion stages. These insights further illustrate the importance of spatial heterogeneity in invasive plant management and policy at macroscales.

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Geographical, socioeconomic, and ecological determinants of exotic plant naturalization in the United States: insights and updates from improved data

Cited by 24 publications

References 30 publications

Biological invasion hotspots: a trait‐based perspective reveals new sub‐continental patterns

Biological invasion hotspots: a trait‐based perspective reveals new sub‐continental patterns

Evidence of biotic resistance to invasions in forests of the Eastern USA

Region-specific patterns and drivers of macroscale forest plant invasions

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