scholarly journals Impacts of alien plant invasions on species richness in Mediterranean-type ecosystems: a meta-analysis

2009 ◽  
Vol 33 (3) ◽  
pp. 319-338 ◽  
Author(s):  
Mirijam Gaertner ◽  
Alana Den Breeyen ◽  
Cang Hui ◽  
David M. Richardson
Keyword(s):  
South Africa ◽  
Species Richness ◽  
Alien Species ◽  
Plant Species ◽  
Native Species ◽  
Meta Analysis ◽  
Growth Forms ◽  
Alien Plant ◽  
Native Species Richness ◽  
Mediterranean Type Ecosystems

Besides a general consensus regarding the negative impact of invasive alien species in the literature, only recently has the decline of native species attributable to biological invasions begun to be quantified in many parts of the world. The cause-effect relationship between the establishment and proliferation of alien species and the extinction of native species is, however, seldom demonstrated. We conducted a meta-analysis of studies in Mediterranean-type ecosystems (MTEs) to examine: (1) whether invasion of alien plant species indeed causes a reduction in the number of native plant species at different spatial and temporal scales; (2) which growth forms, habitat types and areas are most affected by invasions; and (3) which taxa are most responsible for native species richness declines. Our results confirm a significant decline in native species richness attributable to alien invasions. Studies conducted at small scales or sampled over long periods reveal stronger impacts of alien invasion than those at large spatial scales and over short periods. Alien species from regions with similar climates have much stronger impacts, with the native species richness in South Africa and Australia declining significantly more post-invasion than for European sites. Australian Acacia species in South Africa accounted for the most significant declines in native species richness. Among the different growth forms of alien plants, annual herbs, trees and creepers had the greatest impact, whereas graminoids generally caused insignificant changes to the native community. Native species richness of shrublands, old fields and dune vegetation showed significant declines, in contrast to insignificant declines for forest habitats.

Native plant species richness on Eastern Polynesia’s remote atolls

2015 ◽  
Vol 40 (1) ◽  
pp. 112-134 ◽  
Author(s):  
Sébastien Larrue ◽  
Jean-François Butaud ◽  
Pascal Dumas ◽  
Stéphane Ballet
Keyword(s):  
Species Richness ◽  
Sea Level ◽  
Plant Species ◽  
Native Species ◽  
Abiotic Factors ◽  
Plant Species Richness ◽  
Native Plant ◽  
Volcanic Island ◽  
Native Plant Species ◽  
Native Species Richness

Which abiotic factors influence the number of native plant species on remote atolls is an important question to understand better the spatial pattern of the species observed on these low and vulnerable coral islands. However, this issue is still very poorly documented, often due to human degradation, partial botanical surveys or the difficult geographic access of remote atolls for researchers. The remote atolls of Eastern Polynesia, which are among the most isolated in the world, are of great interest for studies of native species’ distribution due to their isolation, low human density and urbanisation. In this study, we selected 49 remote atolls of Eastern Polynesia with complete botanical surveys to test the relative influence of eight abiotic factors on native plant species richness (i.e. indigenous and endemic species). Abiotic factors used as potential predictors included atoll area (km2), shoreline length (km), atoll elevation (m) and index of isolation (UNEP), but also the coastal index of the atoll ( Ic), the distance to the nearest similar atoll (km), the distance to the nearest large volcanic island ≥ 1000 km2 (here, Tahiti as a potential stepping-stone island) and the distance to the nearest raised atoll ≥ 15 m a.s.l. (here, Makatea or Henderson as a potential refugium during sea-level highstands). Spearman’s rank correlation, linear regression analysis and frequency diagrams were used to assess the relative influence of these factors on native species richness. No relationship was found between the species richness and the index of isolation or the distance to the nearest similar atoll. Atoll area and distance to the nearest raised atoll of Makatea explained 47.1% and 40%, respectively, of the native species richness variation observed on the remote atolls. The distance to the volcanic island of Tahiti and the coastal index explained 36.9% and 27.3% of the variation, while elevation and shoreline length explained 23.3% and 18.4% of the variation, respectively. Native species richness on the atolls surveyed increased with the increasing atoll area, elevation and shoreline length, but decreased with the increasing distance to the nearest raised atoll of Makatea and the large volcanic island of Tahiti. This supports the view that the spatial pattern of native species richness observed on the remote atolls was strongly influenced by (i) atoll area but also by (ii) the distance to the raised atoll of Makatea, and (iii) the distance to the volcanic island of Tahiti. This finding suggests that the raised atoll may be viewed as a refugium during sea-level highstands while the large volcanic island played the role of stepping-stone island, both islands influencing the dispersal of native species on remote atolls and attenuating the isolation effect in the study area.

scholarly journals Urbanization and Human Population Favor Species Richness of Alien Birds

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 72
Author(s):  
Maria Lazarina ◽  
Mariana A. Tsianou ◽  
Georgios Boutsis ◽  
Aristi Andrikou-Charitidou ◽  
Elpida Karadimou ◽  
...  
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Human Activities ◽  
Native Species ◽  
Human Population ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Land Uses ◽  
Time Periods ◽  
Native Species Richness

Human activities like urbanization and agriculture affect spatial biodiversity patterns. The presence and activities of humans richly benefit alien species, but native species usually decline in human-impacted areas. Considering that the richness of alien and native species are inter-related, we explored the effect of human population density, human-related land uses (agricultural and urban), and natural land area on avian (alien and native) species richness of Massachusetts for two time periods using Generalized Additive Models. Avian alien species richness increased with native species richness in both time periods. Despite the predominant role of native species richness as a major driver of alien species richness, human activities play an important additional role in shaping species richness patterns of established aliens. Human-related land uses (urban and agricultural) and human population favored alien species richness in both time periods. Counter to expectations, human activities were also positively associated to native avian species richness. Possible explanations of these patterns may include habitat heterogeneity, increased availability of resources, and reduced predation risk.

Maireana brevifolia (Chenopodiaceae: Camphorosmeae), a new naturalized alien plant species in South Africa

Bothalia ◽  
2011 ◽  
Vol 41 (2) ◽  
pp. 235-238 ◽  
Author(s):  
L. Mucina ◽  
D. A. Snijman
Keyword(s):  
South Africa ◽  
Alien Species ◽  
South African ◽  
Plant Species ◽  
Western Cape ◽  
Alien Plant Species ◽  
The South ◽  
Alien Plant ◽  
African Flora

We describe and discuss the distribution of a new, naturalized alien species, Maireana brevifolia (R.Br.) Paul G.Wilson (Chenopodiaceae), a native of Australia, in the western regions of South Africa. First discovered near Worcester, Western Cape in 1976, the species is now established in disturbed karoo shrubby rangelands, along dirt roads and on saline alluvia, from northern Namaqualand to the western Little Karoo. In the South African flora, M. brevifolia is most easily confused with the indigenous Bassia salsoloides (Fenzl) A.J.Scott, from which it is distinguished by the flat to cup-shaped and almost glabrous perianth with woolly-ciliate lobes, and the hardened and winged fruiting perianth.

Alien species Impatiens parviflora invasion into forest communities of Lithuania

2012 ◽  
Vol 18 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Rasa Dobravolskaitė
Keyword(s):  
Alien Species ◽  
Plant Species ◽  
Native Species ◽  
Plant Invasions ◽  
Forest Communities ◽  
Alien Plant Species ◽  
Alien Plant ◽  
Native Communities ◽  
Impatiens Parviflora ◽  
Number Of Individuals

Abstract Dobravolskaitė R., 2012: Alien species Impatiens parviflora invasion into forest communities of Lithuania [Svetimžemės rūšies Impatiens parviflora invazija į Lietuvos miškų bendrijas]. - Bot. Lith., 18(1): 3-12. Alien plants threaten native communities by altering their species composition and reducing native biodiversity. Forests are considered to be relatively stable ecosystems and resistant to plant invasions. Impatiens parviflora DC. is one of the most intensively spreading alien plant species in the forests of Lithuania. Phenotypic variations among I. parviflora populations in three different habitat types (with different species of dominant tree and the coverage of the first tree layer) in the environs of Vilnius (South East Lithuania) were analysed. The results of the investigation enabled to evaluate alien plant species I. parviflora invasion into different forest communities and estimate relationships between plants of forest communities and I. parviflora. The study has shown that this invasive species is spreading not only in disturbed areas, but also in places where other species do not grow due to the lack of the light. However, the number of individuals is increasing in proportion while the coverage of trees and shrubs is decreasing. The rise of the level of illumination increases not only the number of individuals in the populations, but also the above-ground biomass of I. parviflora: plants are larger, produce more side shoots. The correlation between the coverage of I. parviflora and native species statistically is significantly negative (r = -0.78) in the disturbed places.

scholarly journals Non-native species in the vascular flora of highlands and mountains of Iceland

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1559 ◽  
Author(s):  
Pawel Wasowicz
Keyword(s):  
Alien Species ◽  
Plant Species ◽  
Hot Spots ◽  
Native Species ◽  
Vascular Plant ◽  
Temporal Trends ◽  
Plant Colonization ◽  
Native Plant ◽  
Alien Plant ◽  
Vascular Plant Species

The highlands and mountains of Iceland are one of the largest remaining wilderness areas in Europe. This study aimed to provide comprehensive and up-to-date data on non-native plant species in these areas and to answer the following questions: (1) How many non-native vascular plant species inhabit highland and mountainous environments in Iceland? (2) Do temporal trends in the immigration of alien species to Iceland differ between highland and lowland areas? (3) Does the incidence of alien species in the disturbed and undisturbed areas within Icelandic highlands differ? (4) Does the spread of non-native species in Iceland proceed from lowlands to highlands? and (5) Can we detect hot-spots in the distribution of non-native taxa within the highlands? Overall, 16 non-native vascular plant species were detected, including 11 casuals and 5 naturalized taxa (1 invasive). Results showed that temporal trends in alien species immigration to highland and lowland areas are similar, but it is clear that the process of colonization of highland areas is still in its initial phase. Non-native plants tended to occur close to man-made infrastructure and buildings including huts, shelters, roads etc. Analysis of spatio-temporal patterns showed that the spread within highland areas is a second step in non-native plant colonization in Iceland. Several statically significant hot spots of alien plant occurrences were identified using the Getis-Ord Gi* statistic and these were linked to human disturbance. This research suggests that human-mediated dispersal is the main driving force increasing the risk of invasion in Iceland’s highlands and mountain areas.

scholarly journals Flowering phenology of invasive alien plant species compared with native species in three Mediterranean-type ecosystems

2008 ◽  
Vol 103 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Oscar Godoy ◽  
David M. Richardson ◽  
Fernando Valladares ◽  
Pilar Castro-Díez
Keyword(s):  
Plant Species ◽  
Native Species ◽  
Flowering Phenology ◽  
Alien Plant Species ◽  
Alien Plant ◽  
Invasive Alien Plant ◽  
Mediterranean Type Ecosystems

Biogeography of island floras in the Great Lakes. II. Plant dispersal

1989 ◽  
Vol 67 (6) ◽  
pp. 1803-1820 ◽  
Author(s):  
J. K. Morton ◽  
E. H. Hogg
Keyword(s):  
Great Lakes ◽  
Alien Species ◽  
Plant Species ◽  
Native Species ◽  
Vascular Plant ◽  
Species Dispersal ◽  
Alien Plant ◽  
Plant Dispersal ◽  
Alien Flora ◽  
Nesting Sites

Experimental and observational data were used to determine the adaptations for dispersal in each of the 335 vascular plant species in the flora of Barrier Island, a typical limestone island in the Great Lakes. Most have adaptations for more than one mode of dispersal. Adaptations for dispersal by water were found in 211 species (63% of the flora), and by birds in 205 species (61% of the flora); only 22 species (6.5% of the flora) do not appear to have effective adaptations for dispersal by either of these means. The other three modes of dispersal to these islands are by wind (14% of plant species), dispersal across snow and ice (10%), and by man (6%). Alien species (23% of the flora) show greater dependence on birds (85% of the alien species) and man (12% of the alien species) for dispersal than do native species (54 and 5%, respectively). Sea gulls, particularly the Herring Gull (Larus delawarensis Ord.), are the major factor in the introduction of the alien flora. The heavily disturbed habitats created in the nesting sites of both Herring and Ring-billed (Larus argentatus Pontoppidan) gulls favour the persistence of many alien plant species on these islands.

Effects of size, shape, and edge on vegetation in remnants of the upland boreal mixed-wood forest in agro-environments of Alberta, Canada

2007 ◽  
Vol 85 (3) ◽  
pp. 273-284 ◽  
Author(s):  
L. Dennis Gignac ◽  
Mark R.T. Dale
Keyword(s):  
Species Richness ◽  
Alien Species ◽  
Plant Species ◽  
Fragment Size ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
Percent Cover ◽  
Shrub Species ◽  
Alien Plant ◽  
Species Richness And Abundance

Forty-one remnants of the aspen-dominated upland forest in three subregions of the dry boreal mixed-wood in Alberta were studied to determine effects of fragment size and shape on native and alien plant species richness and abundance in agro-environments. The percent cover of all vascular plant species was visually estimated in 5 m diameter circular plots along transects that covered the length and the width of each fragment. A subset of 12 of the largest fragments (>900 m2) that had distinct interiors (portions of the fragment >15 m from any edge) was used to measure edge effects on the vegetation. Regression analyses revealed significant positive relationships between species richness and area regardless of the subregion. Species richness stabilized in fragments that were larger than 11 ha. Edges did not affect shrub species richness and only affected herbaceous species richness on west- and south-facing aspects. Shrub abundance decreased and herb abundance increased up to 20 m from the edges regardless of orientation. Edges did not support a different suite of species than interiors, although several species occurred more frequently in the interior than along the edges. Alien species richness and abundance reached their highest values between 5 and 15 m from the edge, and some of those species could be found up to 40 m from the edge. Although larger fragments generally supported more alien species than smaller fragments, the smallest fragments had the greatest number of species per metre squared. Results from this study indicated that it would be preferable to conserve larger woodlots rather then several smaller woodlots on the landscape.

scholarly journals Trait–environment relationships of plant species at different stages of the introduction process

NeoBiota ◽  
2020 ◽  
Vol 58 ◽  
pp. 55-74
Author(s):  
Marija Milanović ◽  
Sonja Knapp ◽  
Petr Pyšek ◽  
Ingolf Kühn
Keyword(s):  
Land Cover ◽  
Alien Species ◽  
Plant Species ◽  
Functional Traits ◽  
Environmental Conditions ◽  
Native Species ◽  
Alien Plant Species ◽  
Alien Plant ◽  
Non Invasive ◽  
The Relationship

The success of alien plant species can be attributed to differences in functional traits compared to less successful aliens as well as to native species, and thus their adaptation to environmental conditions. Studies have shown that alien (especially invasive) plant species differ from native species in traits such as specific leaf area (SLA), height, seed size or flowering period, where invasive species showed significantly higher values for these traits. Different environmental conditions, though, may promote the success of native or alien species, leading to competitive exclusion due to dissimilarity in traits between the groups. However, native and alien species can also be similar, with environmental conditions selecting for the same set of traits across species. So far, the effect of traits on invasion success has been studied without considering environmental conditions. To understand this interaction we examined the trait–environment relationship within natives, and two groups of alien plant species differing in times of introduction (archaeophytes vs. neophytes). Further, we investigated the difference between non-invasive and invasive neophytes. We analyzed the relationship between functional traits of 1,300 plant species occurring in 1000 randomly selected grid-cells across Germany and across different climatic conditions and land-cover types. Our results show that temperature, precipitation, the proportion of natural habitats, as well as the number of land-cover patches and geological patches affect archaeophytes and neophytes differently, regarding their level of urbanity (in neophytes negative for all non-urban land covers) and self-pollination (mainly positive for archaeophytes). Similar patterns were observed between non-invasive and invasive neophytes, where additionally, SLA, storage organs and the beginning of flowering were strongly related to several environmental factors. Native species did not express any strong relationship between traits and environment, possibly due to a high internal heterogeneity within this group of species. The relationship between trait and environment was more pronounced in neophytes compared to archaeophytes, and most pronounced in invasive plants. The alien species at different stages of the invasion process showed both similarities and differences in terms of the relationship between traits and the environment, showing that the success of introduced species is context-dependent.

scholarly journals Floristics and Diversity of Invasive Alien Plant Species in Humbo District, South Ethiopia

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Markos Kuma ◽  
Zewde Achiso ◽  
Alefu Chinasho ◽  
Dalga Yaya ◽  
Samuel Tessema
Keyword(s):  
Species Diversity ◽  
Alien Species ◽  
Plant Species ◽  
Native Species ◽  
Invasive Alien Species ◽  
Fallow Land ◽  
Alien Plant Species ◽  
Grazing Land ◽  
Alien Plant ◽  
Invasive Alien Plant

Deliberate and unintentional introduction of invasive alien plant species on native biodiversity by aid agencies and other bodies directly or indirectly are being a series of problems on the economy, ecology, politics, and health of life on earth. Identifying and compiling floristics and the status of invasive alien species and identifying which have viable populations are necessary to manage the ecosystems. The present study is therefore intended to provide information for concerned bodies on the area which needs management priority computing the composition, structure, and diversity of invasive alien plants. A field assessment was conducted to determine the distribution and heterogeneity of invasive alien plant species, and then, six kebeles were chosen and transact lines were laid using a purposeful sampling technique. The vegetation and environment data were collected from farmland, grazing land, fallow land, and road sides using 95 subquadrats (5 m × 5 m) set in the center and corner of 19 main quadrats (20 m × 20 m). The voucher specimens collected were taken to the Herbarium of Ethiopia (ETH) for taxonomic identification and future reference. The frequency and density of floristics data were analyzed using MS Excel version 2010, and species diversity was calculated using Shannon (H′), Simpson (D), and evenness (E) indices. Among 35 alien plant species invading natural vegetation in Ethiopia, 25 alien plant species were found in the Humbo district of the Wolaita zone. The densest invasive alien plant species in the area were Parthenium hysterophorus consisting of 15197 individuals/ha, followed by Richardia scabra consisting of 11908 individuals/ha, Xanthium strumarium consisting of 7292 individuals/ha, and Ocimum forskolei consisting of 6280 individuals/ha. The highest species diversity was computed in fallow land (H′ = 2.369), which is followed by farmland (H′ = 1.627) and grazing land (H′ = 1.419). The higher the density of the invasive alien species, the higher the ability to change the structure and diversity of native species of the area results in a decrease in the function and services of the ecosystem. Therefore, management methods must prioritize land types that had the highest diversity of invasive alien species.

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