Latest Articles from NeoBiota Latest 11 Articles from NeoBiota https://neobiota.pensoft.net/ Fri, 29 Mar 2024 09:24:30 +0200 Pensoft FeedCreator https://neobiota.pensoft.net/i/logo.jpg Latest Articles from NeoBiota https://neobiota.pensoft.net/ Effects of invasive Rosa rugosa on Baltic coastal dune communities depend on dune age https://neobiota.pensoft.net/article/97275/ NeoBiota 82: 163-187

DOI: 10.3897/neobiota.82.97275

Authors: Marcin W. Woch, Paweł Kapusta, Małgorzata Stanek, Katarzyna Możdżeń, Irena M. Grześ, Elżbieta Rożej-Pabijan, Anna M. Stefanowicz

Abstract: Rosa rugosa Thunb. (Japanese Rose) is one of the most invasive species in Europe. It spreads spontaneously in coastal areas of western, central and northern Europe, posing a threat to dune habitats, including those indicated in the EU Habitats Directive as particularly valuable. R. rugosa has already been reported to displace native plants and alter soil properties. However, little is known about how these effects are mediated by the habitat context or the invader condition (health, ontogenetic stage). This study addressed that gap by examining vegetation and soil in 22 R. rugosa-invaded sites, half of which were in yellow dunes and the other half in grey dunes, i.e. two habitats representing the earlier and later stages of dune succession. The study was conducted on the Hel Peninsula (Poland’s Baltic coast). R. rugosa had a significant impact on dune vegetation, but the impact was strongly dependent on the habitat type. In the yellow dune sites, R. rugosa outcompeted most resident plant species, which translated into a strong decline in their total cover and richness. The invasion was almost not accompanied by changes in soil properties, suggesting that it affected the resident vegetation directly (through space takeover and shading). In the grey dunes, R. rugosa caused a shift in species composition, from that characteristic of open communities to that typical of forests. In this habitat, a significant increase in the soil organic layer thickness under R. rugosa was also observed, which means that both direct and indirect effects of the invasion on the vegetation should be assumed. Finally, a negative relationship was found between the total chlorophyll content in R. rugosa leaves and the parameters of resident plant communities, showing that the invasion effects can vary not only across habitats, but also with the condition of the invader. The results may have practical implications for managing R. rugosa invasions in coastal sand dune systems. Since R. rugosa accelerates grey dune succession, protecting this habitat may be more urgent and, at the same time, more complicated than protecting dunes at the earlier stages of development.

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Research Article Thu, 2 Mar 2023 18:30:19 +0200
Germination of the invasive legume Lupinus polyphyllus depends on cutting date and seed morphology https://neobiota.pensoft.net/article/56117/ NeoBiota 60: 79-95

DOI: 10.3897/neobiota.60.56117

Authors: Yves P. Klinger, Rolf Lutz Eckstein, David Horlemann, Annette Otte, Kristin Ludewig

Abstract: In semi-natural grasslands, mowing leads to the dispersal of species that have viable seeds at the right time. For invasive plant species in grasslands, dispersal by mowing should be avoided, and information on the effect of cutting date on the germination of invasive species is needed. We investigated the germination of seeds of the invasive legume Lupinus polyphyllus Lindl. depending on the cutting date. We measured seed traits associated with successful germination that can be assessed by managers for an improved timing of control measures. To this end, we sampled seeds of L. polyphyllus on six cutting dates and analyzed the germination of these seeds in climate chambers and under ambient weather conditions. We collected information on seed morphology (color/size/hardseededness) for each cutting date to identify seed traits associated with successful germination. Observed germination patterns were highly asynchronous and differed between seeds cut at different dates. Seeds cut early, being green and soft, tended to germinate in autumn. Seeds cut late, being dark and hard, were more prone to germinate the following spring, after winter stratification. This allows the species to utilize germination niches throughout the year, thus indicating a bet-hedging strategy. Seed color and the percentage of hard seeds were good predictors of germination percentage, but not of mean germination time and synchrony. Managers should prevent the species producing black and hard seeds, while cutting plants carrying green and soft seeds is less problematic. Furthermore, germination patterns differed between climate chambers and the common garden, mainly because germination of dormant seeds was lower in climate chambers. More germination experiments under ambient weather conditions should be carried out, as they can give information on the germination dynamics of invasive species.

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Research Article Tue, 25 Aug 2020 15:00:17 +0300
Emerging invasion threat of the liana Celastrus orbiculatus (Celastraceae) in Europe https://neobiota.pensoft.net/article/34261/ NeoBiota 56: 1-25

DOI: 10.3897/neobiota.56.34261

Authors: Zigmantas Gudžinskas, Lukas Petrulaitis, Egidijus Žalneravičius

Abstract: The woody vine Celastrus orbiculatus (Celastraceae), Oriental bittersweet, is an alien species that recently has been found to be spreading in Europe. Many aspects of its biology and ecology are still obscure. This study evaluates the distribution and habitats, as well as size and age of stands of C. orbiculatus in Lithuania. We investigated whether meteorological factors affect radial stem increments and determined seedling recruitment in order to judge the plant’s potential for further spread in Europe. We studied the flower gender of C. orbiculatus in four populations in Lithuania and found that all sampled individuals were monoecious, although with dominant either functionally female or male flowers. Dendrochronological methods enabled us to reveal the approximate time of the first establishment of populations of C. orbiculatus in Lithuania. The youngest recorded individual with fruits was determined to be 10 years old. Analysis of radial increments revealed no reliable correlations with meteorological conditions. Therefore, we conclude that climatic conditions in the region are favourable for the growth, reproduction, and invasion of this species. C. orbiculatus produces viable seeds, successfully reproduces and spreads within and around the established stands. The presence of seedlings and two- to four-year-old saplings in the population confirms constant generative recruitment. Available information on the distribution of C. orbiculatus in Europe revealed its existence in 13 countries. In total, 58 occurrences of this species have been recorded in Europe so far. We consider that the lag period lasted until 2005 and that the exponential population growth phase has now set in. In Lithuania, the invaded area is quite small (0.51 ha); however, the total estimated invaded area in Europe could be about 250 ha. At the current stage of invasion and distribution in Europe, measures for control, management, and eradication of C. orbiculatus have a chance of being effective and economically feasible.

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Research Article Fri, 10 Apr 2020 13:54:18 +0300
Light and propagule pressure affect invasion intensity of Prunus serotina in a 14-tree species forest common garden experiment https://neobiota.pensoft.net/article/30413/ NeoBiota 46: 1-21

DOI: 10.3897/neobiota.46.30413

Authors: Andrzej M. Jagodziński, Marcin K. Dyderski, Paweł Horodecki, Kathleen S. Knight, Katarzyna Rawlik, Janusz Szmyt

Abstract: Experiments testing multiple factors that affect the rate of invasions in forests are scarce. We aimed to assess how the biomass of invasive Prunus serotina changed over eight years and how this change was affected by light availability, tree stand growth, and propagule pressure. The study was conducted in Siemianice Experimental Forest (W Poland), a common garden forest experiment with 14 tree species. We investigated aboveground biomass and density of P. serotina within 53 experimental plots with initial measurements in 2005 and repeated in 2013. We also measured light availability and distance from seed sources. We used generalized additive models to assess the impact of particular predictors on P. serotina biomass in 2013 and its relative change over eight years. The relative biomass increments of P. serotina ranged from 0 to 22,000-fold. The success of P. serotina, expressed as aboveground biomass and biomass increment, varied among different tree species stands, but was greater under conifers. Total biomass of P. serotina depended on light and propagule availability while biomass increment depended on the change in tree stand biomass, a metric corresponding to tree stand maturation. Our study quantified the range of invasion intensity, expressed as biomass increment, in a forest common garden experiment with 14 tree species. Canopy cover was the most important variable to reduce susceptibility to invasion by P. serotina. Even a modest decrease of overstory biomass, e.g. caused by dieback of coniferous species, may be risky in areas with high propagule pressure from invasive tree species. Thus, P. serotina control may include maintaining high canopy closure and supporting natural regeneration of tree species with high leaf area index, which shade the understory.

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Research Article Fri, 10 May 2019 09:25:33 +0300
Even well-studied groups of alien species might be poorly inventoried: Australian Acacia species in South Africa as a case study https://neobiota.pensoft.net/article/23135/ NeoBiota 39: 1-29

DOI: 10.3897/neobiota.39.23135

Authors: Nkoliso Magona, David M. Richardson, Johannes J. Le Roux, Suzaan Kritzinger-Klopper, John R. U. Wilson

Abstract: Understanding the status and extent of spread of alien plants is crucial for effective management. We explore this issue using Australian Acacia species (wattles) in South Africa (a global hotspot for wattle introductions and tree invasions). The last detailed inventory of wattles in South Africa was based on data collated forty years ago. This paper aimed to determine: 1) how many Australian Acacia species have been introduced to South Africa; 2) which species are still present; and 3) the status of naturalised taxa that might be viable targets for eradication. All herbaria in South Africa with specimens of introduced Australian Acacia species were visited and locality records were compared with records from literature sources, various databases, and expert knowledge. For taxa not already known to be widespread invaders, field surveys were conducted to determine whether plants are still present, and detailed surveys were undertaken of all naturalised populations. To confirm the putative identities of the naturalised taxa, we also sequenced one nuclear and one chloroplast gene. We found evidence that 141 Australian Acacia species have been introduced to South Africa (approximately double the estimate from previous work), but we could only confirm the current presence of 33 species. Fifteen wattle species are invasive (13 are in category E and two in category D2 in the Unified Framework for Biological Invasions); five have naturalised (C3); and 13 are present but there was no evidence that they had produced reproductive offspring (B2 or C1). DNA barcoding provided strong support for only 23 taxa (including two species not previously recorded from South Africa), the current name ascribed was not supported for three species and, for a further three species, there was no voucher specimen on GenBank against which their identity could be checked. Given the omissions and errors found during this systematic re-evaluation of historical records, it is clear that analyses of the type conducted here are crucial if the status of even well-studied groups of alien taxa is to be accurately determined.

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Research Article Tue, 26 Jun 2018 09:06:06 +0300
Biotic constraints on the establishment and performance of native, naturalized, and invasive plants in Pacific Northwest (USA) steppe and forest https://neobiota.pensoft.net/article/10820/ NeoBiota 34: 21-40

DOI: 10.3897/neobiota.34.10820

Authors: Brian M. Connolly, Jennifer Powers, Richard N. Mack

Abstract: Factors that cause differential establishment among naturalized, invasive, and native species are inadequately documented, much less often quantified among different communities. We evaluated the effects of seed addition and disturbance (i.e., understory canopy removal) on the establishment and seedling biomass among two naturalized, two invasive, and two native species (1 forb, 1 grass in each group) within steppe and low elevation forest communities in eastern Washington, USA. Establishment within each plant immigrant class was enhanced by seed addition: naturalized species showed the greatest difference in establishment between seed addition and no seed addition plots, native and invasive species establishment also increased following seed addition but not to the same magnitude as naturalized species. Within seed addition plots, understory canopy disturbance resulted in significant increases in plant establishment (regardless of plant immigration class) relative to undisturbed plots and the magnitude of this effect was comparable between steppe and adjacent forest. However, regardless of disturbance treatment fewer invasive plants established in the forest than in the steppe, whereas native and naturalized plant establishment did not differ between the habitats. Individual biomass of naturalized species were consistently greater in disturbed (canopy removed) versus undisturbed control plots and naturalized species were also larger in the steppe than in the forest at the time of harvest. Similar trends in plant size were observed for the native and invasive species, but the differences in biomass for these two immigration classes between disturbance treatments and between habitats were not significant. We found that strong limitations of non-native species is correlated with intact canopy cover within the forest understory, likely driven by the direct or indirect consequences of low light transmittance through the arboreal and understory canopy. Considered collectively, our results demonstrate how seed limitation and intact plant ground cover can limit the abundance and performance of naturalized species in Pacific Northwest steppe and low elevation forest, suggesting that local disturbance in both habitats creates microsites for these species to establish and survive. Future studies evaluating interactions between multiple barriers to establishment using more representatives from each immigration class will further reveal how biotic interactions ultimately influence the demography and distribution of non-native plants within these communities.

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Research Article Thu, 23 Feb 2017 10:55:53 +0200
Aliens in Transylvania: risk maps of invasive alien plant species in Central Romania https://neobiota.pensoft.net/article/4527/ NeoBiota 24: 55-65

DOI: 10.3897/neobiota.24.7772

Authors: Heike Zimmermann, Jacqueline Loos, Henrik von Wehrden, Joern Fischer

Abstract: Using the MAXENT algorithm, we developed risk maps for eight invasive plant species in southern Transylvania, Romania, a region undergoing drastic land-use changes. Our findings show that invasion risk increased with landscape heterogeneity. Roads and agricultural areas were most prone to invasion, whereas forests were least at risk.

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Short Communication Fri, 16 Jan 2015 00:00:00 +0200
Forestry trial data can be used to evaluate climate-based species distribution models in predicting tree invasions https://neobiota.pensoft.net/article/1266/ NeoBiota 20: 31-48

DOI: 10.3897/neobiota.20.5778

Authors: Rethabile Motloung, Mark Robertson, Mathieu Rouget, John Wilson

Abstract: Climate is frequently used to predict the outcome of species introductions based on the results from species distribution models (SDMs). However, despite the widespread use of SDMs for pre- and post-border risk assessments, data that can be used to validate predictions is often not available until after an invasion has occurred. Here we explore the potential for using historical forestry trials to assess the performance of climate-based SDMs. SDMs were parameterized based on the native range distribution of 36 Australian acacias, and predictions were compared against both the results of 150 years of government forestry trials, and current invasive distribution in southern Africa using true skill statistic, sensitivity and specificity. Classification tree analysis was used to evaluate why some Australian acacias failed in trials while others were successful. Predicted suitability was significantly related to the invaded range (sensitivity = 0.87) and success in forestry trials (sensitivity = 0.80), but forestry trial failures were under-predicted (specificity = 0.35). Notably, for forestry trials, the success in trials was greater for species invasive somewhere in the world. SDM predictions also indicate a considerable invasion potential of eight species that are currently naturalized but not yet widespread. Forestry trial data clearly provides a useful additional source of data to validate and refine SDMs in the context of risk assessment. Our study identified the climatic factors required for successful invasion of acacias, and accentuates the importance of integration of status elsewhere for risk assessment.

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Research Article Fri, 24 Jan 2014 00:00:00 +0200
Do species differ in their ability to coexist with the dominant alien Lupinus polyphyllus? A comparison between two distinct invaded ranges and a native range https://neobiota.pensoft.net/article/1243/ NeoBiota 17: 39-55

DOI: 10.3897/neobiota.17.4317

Authors: Martin Hejda

Abstract: The community-level impacts of invasive plants are likely to vary depending on the character of native species of the target communities and their ability to thrive within the stands of the dominant alien invader. Therefore, I examined the response of native species richness to the cover of the dominant alien Lupinus polyphyllus in two distinct invaded ranges: Czech Republic (Central Europe) and New Zealand. I compared the relation between native species richness and the cover of the dominant alien L. polyphyllus with that in its native range, Pacific Northwest, USA.In the native range, I found no response of native species richness to the cover of L. polyphyllus. In the Czech Republic (central Europe), the richness of native species related to it negativelly, but the relation was only marginally significant. Contrary to that, the richness of species native to New Zealand related to the cover of L. polyphyllus strongly negatively and the negative relation was significantly stronger than that of species native to Europe.Of the two invaded ranges, species native to New Zealand have been documented to be much more vulnerable to the conditions associated with the invasion and dominance of L. polyphyllus, compared to species native to central Europe. This principle has been shown both across these two invaded ranges and in New Zealand, where the aliens of european origin successfully coexist with the dominant invasive alien L. polyphyllus. Similarly, species in the native range of L. polyphyllus showed no relation to its cover, indicating their ability to thrive even in dense stands of this dominant species.

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Research Article Fri, 28 Jun 2013 00:00:00 +0300
Germination performance of native and non-native Ulmus pumila populations https://neobiota.pensoft.net/article/1234/ NeoBiota 15: 53-68

DOI: 10.3897/neobiota.15.4057

Authors: Heidi Hirsch, Catherina Wypior, Henrik von Wehrden, Karsten Wesche, Daniel Renison, Isabell Hensen

Abstract: Germination is a crucial step for invasive plants to extend their distribution under different environmental conditions in a new range. Therefore, information on germination characteristics of invasive plant species provides invaluable knowledge about the factors which might contribute to the invasion success. Moreover, intra-specific comparisons under controlled conditions will show if different responses between non-native and native populations are caused by evolutionary changes or by phenotypic plasticity towards different environmental influences.This paper focuses on the germination of native and non-native Ulmus pumila populations. We expected that non-native populations would be characterized by their higher final germination percentage and enhanced germination rate, which might indicate an influence due to corresponding climatic conditions.Germination experiments with a moderate and a warm temperature treatment did not reveal significant differences in final germination percentage. However, seeds from the North American non-native range germinated significantly faster than native seeds (p < 0.001). Additionally, mean time to germination in both ranges was significantly negatively correlated with annual precipitation (p = 0.022). At the same time, this relationship is stronger in the native range whereas mean time to germination in non-native populations seems to be less influenced by climatic conditions.Different germination responses of the North American populations could be caused by a fast evolutionary change mediating a higher tolerance to current climatic conditions in the non-native range. However, our findings could also be caused by artificial selection during the introduction process and extensive planting of U. pumila in its non-native range. Nevertheless, we assume that the faster germination rate of non-native populations is one potential explanation for the invasion success of U. pumila in its new range since it might provide a competitive advantage during colonization of new sites.

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Research Article Fri, 14 Dec 2012 00:00:00 +0200
Secondary wind dispersal enhances long-distance dispersal of an invasive species in urban road corridors https://neobiota.pensoft.net/article/1206/ NeoBiota 9: 49-70

DOI: 10.3897/neobiota.9.1469

Authors: Ingo Kowarik, Moritz von der Lippe

Abstract: Roads contribute to habitat fragmentation and function as dispersal barriers for many organisms. At the same time many nonnative plant species are associated with road systems, a relationship that has been explained by the availability of disturbed habitats along roadsides and traffic-mediated dispersal of species. By studying secondary wind dispersal (SWD) over paved ground in an urban road corridor, we add the perspective of corridor-specific, but traffic-independent dispersal processes to the complex dispersal systems along roads. We analyzed (1) the seed shadow of an invasive tree Ailanthus altissima along a sidewalk subsequent to a strong wind and (2) the movements of painted samaras of this species released at ground level at the same site to identify the functioning of SWD. For the first experiment, we searched for samaras in the vicinity of an isolated tree three days after a strong wind. For the second experiment, we tracked the movement of the released samaras repeatedly over a period of 9–11 days, approximated probability-distance functions to the frequency distribution of samaras along the transect for different times after release, and related nearby measured wind data to changes in dispersal kernels. Single samaras from an isolated tree formed a seed shadow that extended for a distance of 456m and fragments of fruit clusters traveled up to 130m. Forty-twopercent of the sampled samaras were moved >100 m. The second experiment revealed that painted samaras released on the ground were moved up to 150m over the pavement. Dispersal distances increased with time after seed release. A significant increase in the scale parameter b of the dispersal kernel with higher wind sums above 3.7 m/s illustrates a threshold for movement of samaras over the ground. Habitat shifts to safe sites for germination occurred during SWD, and different types of pavement influenced these processes. Smooth-surfaced pavement enhanced SWD, while cobbles with irregular surfaces slowed down or terminated SWD. During the observation period, 17% of released samaras accumulated in patches with a planted tree. Some were recaptured within the median strip and thus must have been lifted and moved over four lanes of heavy traffic. Our results suggest that impervious surfaces within road corridors can function as powerful avenues of wind-mediated long-distance dispersal and may counteract fragmentation of urban habitats. This also offers a functional explanation for the invasion success of Ailanthus at isolated urban sites.

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Research Article Thu, 11 Aug 2011 00:00:00 +0300