The Experts below are selected from a list of 21747 Experts worldwide ranked by ideXlab platform
Petr Pysek - One of the best experts on this subject based on the ideXlab platform.
-
Naturalization of ornamental plant species in public green spaces and private gardens
Biological Invasions, 2017Co-Authors: Katharina Mayer, Patrick Weigelt, Holger Kreft, Franz Essl, Jan Pergl, Marten Winter, Wayne Dawson, Petr Pysek, Emily Haeuser, Bernd LenznerAbstract:Ornamental horticulture is the most important pathway for alien plant introductions worldwide, and consequently, invasive spread of introduced plants often begins in urban areas. Although most introduced ornamental garden-plant species are locally not naturalized yet, many of them have shown invasion potential elsewhere in the world, and might naturalize when climate changes. We inventoried the planted flora of 50 public and 61 private gardens in Radolfzell, a small city in southern Germany, to investigate whether local Naturalization success of garden plants is associated with their current planting frequency, climatic suitability (as assessed with climatic niche modelling) and known Naturalization status somewhere in the world. We identified 954 introduced garden-plant species, of which 48 are already naturalized in Radolfzell and 120 in other parts of Germany. All currently naturalized garden plants in Radolfzell have a climatic suitability probability of ≥ 0.75 and are naturalized in ≥ 13 out of 843 regions globally. These values are significantly higher than those of garden plants that have not become locally naturalized yet. Current planting frequencies, however, were not related to current Naturalization success. Using the identified local Naturalization thresholds of climatic suitability and global Naturalization frequency, and climate projections for the years 2050 and 2070, we identified 45 garden-plant species that are currently not naturalized in Radolfzell but are likely to become so in the future. Although our approach cannot replace a full risk assessment, it is well-suited and applicable as one element of a screening or horizon scanning-type approach.
-
introduction bias affects relationships between the characteristics of ornamental alien plants and their Naturalization success
Global Ecology and Biogeography, 2016Co-Authors: Noëlie Maurel, Petr Pysek, Jan Hanspach, Ingolf Kuhn, Mark Van KleunenAbstract:Aim Alien plants with certain characteristics may have been introduced earlier and more frequently than others. Such introduction bias may cause spurious associations between plant characteristics and Naturalization (the establishment of self-sustaining populations in the wild). We aimed to disentangle direct and indirect (i.e. mediated by introduction history) effects of species characteristics on the Naturalization success of alien plants introduced for horticulture. Location Germany (non-native range); rest of the world (native range). Methods We compiled a dataset of 435 alien plant species introduced in cultivation in Germany, including data on their year of introduction, the number of botanical gardens where they are planted, native range, biological traits and Naturalization success. We used path analysis to estimate the direct effects of geographical origin and biological traits on Naturalization, and their indirect effects mediated by year and/or frequency of introduction. Results We found significant direct positive effects of native range size and winter hardiness on Naturalization. Alien species native to other parts of Europe and species with a large native range were brought to the country earlier than other species. In addition, woody species, winter-hardy species and tall species were planted more frequently than others. Because the number of botanical gardens where a species is planted increased Naturalization success directly, and residence time did so indirectly through a significant positive association with the number of botanical gardens, most of the species characteristics had indirect effects on Naturalization. Main conclusions Our approach allowed us to show that apparent effects of species characteristics on Naturalization success can be at least partly indirect, due to introduction biases. This indicates that failure to recognize such introduction biases could impair our ability to explain the success of alien plant species.
-
plants capable of selfing are more likely to become naturalized
Nature Communications, 2016Co-Authors: Mialy Harindra Razanajatovo, Patrick Weigelt, Holger Kreft, Franz Essl, Jan Pergl, Wayne Dawson, Petr Pysek, Noëlie Maurel, Marten WinterAbstract:Many plant species have established self-sustaining populations outside their natural range because of human activities. Plants with selfing ability should be more likely to establish outside their historical range because they can reproduce from a single individual when mates or pollinators are not available. Here, we compile a global breeding-system database of 1,752 angiosperm species and use phylogenetic generalized linear models and path analyses to test relationships between selfing ability, life history, native range size and global Naturalization status. Selfing ability is associated with annual or biennial life history and a large native range, which both positively correlate with the probability of Naturalization. Path analysis suggests that a high selfing ability directly increases the number of regions where a species is naturalized. Our results provide robust evidence across flowering plants at the global scale that high selfing ability fosters alien plant Naturalization both directly and indirectly.
-
planting intensity residence time and species traits determine invasion success of alien woody species
Ecology, 2009Co-Authors: Petr Pysek, Martin Křivanek, Vojtěch JarosikAbstract:We studied the relative importance of residence time, propagule pressure, and species traits in three stages of invasion of alien woody plants cultivated for about 150 years in the Czech Republic, Central Europe. The probability of escape from cultivation, Naturalization, and invasion was assessed using classification trees. We compared 109 escaped–not-escaped congeneric pairs, 44 naturalized–not-naturalized, and 17 invasive–not-invasive congeneric pairs. We used the following predictors of the above probabilities: date of introduction to the target region as a measure of residence time; intensity of planting in the target area as a proxy for propagule pressure; the area of origin; and 21 species-specific biological and ecological traits. The misclassification rates of the Naturalization and invasion model were low, at 19.3% and 11.8%, respectively, indicating that the variables used included the major determinants of these processes. The probability of escape increased with residence time in the Czech Re...
-
correlates of Naturalization and occupancy of introduced ornamentals in germany
Perspectives in Plant Ecology Evolution and Systematics, 2008Co-Authors: Jan Hanspach, Petr Pysek, Ingolf Kuhn, Evelin Boos, Stefan KlotzAbstract:Abstract Invasions are multistage processes and the performance of a species at different stages depends on socio-economic, biogeographical, ecological and evolutionary factors. Most studies addressing the factors that determine invasion success focus on one particular stage, usually by examining data on introduced species that have successfully naturalized, whereas species that fail to naturalize are often not considered. In this study, we examined Naturalization success (whether a species escaped from cultivation and became naturalized in the wild) and occupancy (the number of grid cells of 6′ longitude×10′ latitude in which it is recorded) of up to 8018 ornamental plant species introduced into botanical gardens in Germany. Data on these introductions were extracted from the SYSTAX database (Information System of German Botanical Gardens), information on successful Naturalization in Germany from the BiolFlor database and data on species traits from SYSTAX and the European Garden Flora. The effect of propagule pressure, biogeography, winter hardiness, life strategy, morphology and genetic variability on the probability of Naturalization and the number of grid cells occupied was tested using regression models. The influence of phylogenetic dependence was considered within simple single variable models as a nested random effect. All traits that appeared significant in these simple models were combined in a multivariable model. The simplified multivariable model revealed an increasing probability of Naturalization for species with a higher winter hardiness, a wider native range and a higher planting frequency in botanical gardens (Nagelkerke- R 2 of 0.196). Moreover, interactions between plant height and planting frequency and between growth form and winter hardiness also affected the probability of Naturalization. The number of grid cells occupied was best explained by the winter hardiness (pseudo- R 2 of 0.61). The stratified pre-selection of ornamental plants by gardeners may hold the key to their successful escape from cultivation and subsequent Naturalization.
Giuseppe Pietrantuono - One of the best experts on this subject based on the ideXlab platform.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
American Political Science Review, 2017Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the nonrandom selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are larger for more marginalized immigrant groups and when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
-
Naturalization fosters the long term political integration of immigrants
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Jens Hainmueller, Giuseppe Pietrantuono, Dominik HangartnerAbstract:Does Naturalization cause better political integration of immigrants into the host society? Despite heated debates about citizenship policy, there exists almost no evidence that isolates the independent effect of Naturalization from the nonrandom selection into Naturalization. We provide new evidence from a natural experiment in Switzerland, where some municipalities used referendums as the mechanism to decide Naturalization requests. Balance checks suggest that for close Naturalization referendums, which are decided by just a few votes, the Naturalization decision is as good as random, so that narrowly rejected and narrowly approved immigrant applicants are similar on all confounding characteristics. This allows us to remove selection effects and obtain unbiased estimates of the long-term impacts of citizenship. Our study shows that for the immigrants who faced close referendums, Naturalization considerably improved their political integration, including increases in formal political participation, political knowledge, and political efficacy.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
Social Science Research Network, 2015Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the non-random selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or narrowly lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are much larger for more marginalized immigrant groups and somewhat larger when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
Vojtěch Jarosik - One of the best experts on this subject based on the ideXlab platform.
-
planting intensity residence time and species traits determine invasion success of alien woody species
Ecology, 2009Co-Authors: Petr Pysek, Martin Křivanek, Vojtěch JarosikAbstract:We studied the relative importance of residence time, propagule pressure, and species traits in three stages of invasion of alien woody plants cultivated for about 150 years in the Czech Republic, Central Europe. The probability of escape from cultivation, Naturalization, and invasion was assessed using classification trees. We compared 109 escaped–not-escaped congeneric pairs, 44 naturalized–not-naturalized, and 17 invasive–not-invasive congeneric pairs. We used the following predictors of the above probabilities: date of introduction to the target region as a measure of residence time; intensity of planting in the target area as a proxy for propagule pressure; the area of origin; and 21 species-specific biological and ecological traits. The misclassification rates of the Naturalization and invasion model were low, at 19.3% and 11.8%, respectively, indicating that the variables used included the major determinants of these processes. The probability of escape increased with residence time in the Czech Re...
-
planting history and propagule pressure as predictors of invasion by woody species in a temperate region
Conservation Biology, 2006Co-Authors: Martin Křivanek, Petr Pysek, Vojtěch JarosikAbstract:: We studied 28 alien tree species currently planted for forestry purposes in the Czech Republic to determine the probability of their escape from cultivation and Naturalization. Indicators of propagule pressure (number of administrative units in which a species is planted and total planting area) and time of introduction into cultivation were used as explanatory variables in multiple regression models. Fourteen species escaped from cultivation, and 39% of the variance was explained by the number of planting units and the time of introduction, the latter being more important. Species introduced early had a higher probability of escape than those introduced later, with more than 95% probability of escape for those introduced before 1801 and <5% for those introduced after 1892. Probability of Naturalization was more difficult to predict, and eight species were misclassified. A model omitting two species with the largest influence on the model yielded similar predictors of Naturalization as did the probability of escape. Both phases of invasion therefore appear to be driven by planting and introduction history in a similar way. Our results demonstrate the importance of forestry for recruitment of invasive trees. Six alien forestry trees, classified as invasive in the Czech Republic, are currently reported in nature reserves. In addition, forestry authorities want to increase the diversity of alien species and planting area in the country. Resumen: Estudiamos 28 especies de arboles no nativos que actualmente estan sembrados con fines forestales en la Republica Checa para determinar la probabilidad de su escape del cultivo y naturalizacion. Utilizamos indicadores de la presion de propagulos (numero de unidades administrativas en que una especie esta sembrada y area total de siembra) y del tiempo de introduccion al cultivo como variables explicativas en modelos de regresion multiple. Catorce especies escaparon del cultivo, y 39% de la varianza fue explicada por el numero de unidades de siembra y del tiempo de introduccion, con mayor importancia del ultimo. Las especies introducidas temprano tuvieron una mayor probabilidad de de escapar que las introducidas posteriormente, con mas de 95% de probabilidad de escapar las introducidas antes de 1801 y < 5% las introducidas despues de 1892. La probabilidad de naturalizacion fue mas dificil de pronosticar, y 8 especies fueron clasificadas erroneamente. Un modelo sin las 2 especies de mayor influencia sobre el modelo produjo predictores similares de la naturalizacion y de la probabilidad de escapar. Por lo tanto, ambas fases de la invasion parecen ser dirigidas de manera similar. por la historia de siembra y de introduccion. Nuestros resultados demuestran la importancia de la silvicultura en el reclutamiento de arboles invasores. Actualmente, seis arboles forestales no nativos, clasificados como invasores en la Republica Checa, son reportados en reservas naturales. Adicionalmente, las autoridades forestales desean incrementar la diversidad de especies no nativas y el area de siembra en el pais.
-
planting history and propagule pressure as predictors of invasion by woody species in a temperate region
Conservation Biology, 2006Co-Authors: Martin Křivanek, Petr Pysek, Vojtěch JarosikAbstract:We studied 28 alien tree species currently planted for forestry purposes in the Czech Republic to determine the probability of their escape from cultivation and Naturalization. Indicators of propagule pressure (number of administrative units in which a species is planted and total planting area) and time of introduction into cultivation were used as explanatory variables in multiple regression models. Fourteen species escaped from cultivation, and 39% of the variance was explained by the number of planting units and the time of introduction, the latter being more important. Species introduced early had a higher probability of escape than those introduced later, with more than 95% probability of escape for those introduced before 1801 and <5% for those introduced after 1892. Probability of Naturalization was more difficult to predict, and eight species were misclassified. A model omitting two species with the largest influence on the model yielded similar predictors of Naturalization as did the probability of escape. Both phases of invasion therefore appear to be driven by planting and introduction history in a similar way. Our results demonstrate the importance of forestry for recruitment of invasive trees. Six alien forestry trees, classified as invasive in the Czech Republic, are currently reported in nature reserves. In addition, forestry authorities want to increase the diversity of alien species and planting area in the country.
Jens Hainmueller - One of the best experts on this subject based on the ideXlab platform.
-
a randomized controlled design reveals barriers to citizenship for low income immigrants
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Jens Hainmueller, Duncan Lawrence, Justin Gest, Michael Hotard, Rey Koslowski, David D LaitinAbstract:Citizenship endows legal protections and is associated with economic and social gains for immigrants and their communities. In the United States, however, Naturalization rates are relatively low. Yet we lack reliable knowledge as to what constrains immigrants from applying. Drawing on data from a public/private Naturalization program in New York, this research provides a randomized controlled study of policy interventions that address these constraints. The study tested two programmatic interventions among low-income immigrants who are eligible for citizenship. The first randomly assigned a voucher that covers the Naturalization application fee among immigrants who otherwise would have to pay the full cost of the fee. The second randomly assigned a set of behavioral nudges, similar to outreach efforts used by service providers, among immigrants whose incomes were low enough to qualify them for a federal waiver that eliminates the application fee. Offering the fee voucher increased Naturalization application rates by about 41%, suggesting that application fees act as a barrier for low-income immigrants who want to become US citizens. The nudges to encourage the very poor to apply had no discernible effect, indicating the presence of nonfinancial barriers to Naturalization.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
American Political Science Review, 2017Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the nonrandom selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are larger for more marginalized immigrant groups and when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
-
Naturalization fosters the long term political integration of immigrants
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Jens Hainmueller, Giuseppe Pietrantuono, Dominik HangartnerAbstract:Does Naturalization cause better political integration of immigrants into the host society? Despite heated debates about citizenship policy, there exists almost no evidence that isolates the independent effect of Naturalization from the nonrandom selection into Naturalization. We provide new evidence from a natural experiment in Switzerland, where some municipalities used referendums as the mechanism to decide Naturalization requests. Balance checks suggest that for close Naturalization referendums, which are decided by just a few votes, the Naturalization decision is as good as random, so that narrowly rejected and narrowly approved immigrant applicants are similar on all confounding characteristics. This allows us to remove selection effects and obtain unbiased estimates of the long-term impacts of citizenship. Our study shows that for the immigrants who faced close referendums, Naturalization considerably improved their political integration, including increases in formal political participation, political knowledge, and political efficacy.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
Social Science Research Network, 2015Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the non-random selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or narrowly lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are much larger for more marginalized immigrant groups and somewhat larger when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
Dominik Hangartner - One of the best experts on this subject based on the ideXlab platform.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
American Political Science Review, 2017Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the nonrandom selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are larger for more marginalized immigrant groups and when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
-
Naturalization fosters the long term political integration of immigrants
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Jens Hainmueller, Giuseppe Pietrantuono, Dominik HangartnerAbstract:Does Naturalization cause better political integration of immigrants into the host society? Despite heated debates about citizenship policy, there exists almost no evidence that isolates the independent effect of Naturalization from the nonrandom selection into Naturalization. We provide new evidence from a natural experiment in Switzerland, where some municipalities used referendums as the mechanism to decide Naturalization requests. Balance checks suggest that for close Naturalization referendums, which are decided by just a few votes, the Naturalization decision is as good as random, so that narrowly rejected and narrowly approved immigrant applicants are similar on all confounding characteristics. This allows us to remove selection effects and obtain unbiased estimates of the long-term impacts of citizenship. Our study shows that for the immigrants who faced close referendums, Naturalization considerably improved their political integration, including increases in formal political participation, political knowledge, and political efficacy.
-
catalyst or crown does Naturalization promote the long term social integration of immigrants
Social Science Research Network, 2015Co-Authors: Jens Hainmueller, Dominik Hangartner, Giuseppe PietrantuonoAbstract:We study the impact of Naturalization on the long-term social integration of immigrants into the host country society. Despite ongoing debates about citizenship policy, we lack reliable evidence that isolates the causal effect of Naturalization from the non-random selection into Naturalization. We exploit the quasi-random assignment of citizenship in Swiss municipalities that used referendums to decide on Naturalization applications of immigrants. Comparing otherwise similar immigrants who narrowly won or narrowly lost their Naturalization referendums, we find that receiving Swiss citizenship strongly improved long-term social integration. We also find that the integration returns to Naturalization are much larger for more marginalized immigrant groups and somewhat larger when Naturalization occurs earlier, rather than later in the residency period. Overall, our findings support the policy paradigm arguing that Naturalization is a catalyst for improving the social integration of immigrants rather than merely the crown on the completed integration process.
