Distribution Of Exotic Species Research Articles

A review of exotic earthworm observations in the Canadian boreal forest and taiga zones

Over the past few decades there has been increasing concern that boreal forests could convert from a carbon sink to a carbon source, thus accentuating the effects of climate change. Although forest fires are generally regarded as mainly responsible for causing boreal forests to transition to a carbon source, other factors, such as the activity of exotic earthworm species, could also play an important role. Invasive and exotic species of earthworm can affect nutrient cycling, biodiversity, and forest dynamics. In this context, greater knowledge of the distribution of exotic species of earthworm could help researchers to understand the likely changes in the ecosystems that they have colonized. Herein, we report the results of an exhaustive literature review of the presence of exotic species of earthworm in the Canadian boreal forest and taiga zones. We identified 230 sectors containing 14 earthworm species (11 exotic, two native, and one putative native) in six provinces and three territories across Canada’s boreal forest and taiga zone. We also report 23 as-yet unpublished observations from the province of Quebec. We noted the presence of earthworms in environments (acid soils, harsh climate) that were historically considered inadequate for their survival. This suggests that the portion of Canada’s boreal forests suitable for the presence or colonization of exotic species of earthworm is larger than was previously believed. This study represents the first compilation of locations with exotic species of earthworm in this large northern area. Factors that could affect their distribution and potential effects on boreal ecosystems are also discussed. We also report that several earthworm species seem to be overcoming the previously assumed limitations of temperature and soil pH.

Historical legacies and ecological determinants of grass naturalizations worldwide

The global distribution of exotic species is the result of abiotic, biotic and dispersal filtering processes that shape the movement and success of species outside their native range. In this study we aim to understand how these filtering processes drive the fluxes of grass species among regions, the factors that influence which species establish outside of their native range, and where they do so.We used national and subnational checklists of native and introduced grass species to determine the extent to which each region was a source or recipient of exotic grass species. We asked how species traits may distinguish those grass species that have naturalized outside their native range from those that have not, and how environmental conditions are related to the distribution of exotic grass species.We found that exotic grass establishment is shaped by an array of factors including characteristics of regions, traits of species and their interactions. Regions with a longer history of human occupation and larger numbers of native grass species were generally the most important sources of exotic species. Global flows of species were mostly driven by a climate match between the native and exotic ranges, but were also highly asymmetric, with regions with recent human arrival being the major hosts of exotic grass species. Tall, annual and C4 grass species exhibited particularly high probabilities of establishment outside their native range.Despite the idiosyncrasy and stochasticity characteristic of exotic species establishment, this biogeographical analysis revealed important generalities across this large plant group. Our results suggest that grass species that have co‐occurred with humans for a longer time may be better adapted to living in anthropogenic landscapes, explaining the global asymmetry in species introductions.

Allelopathic interference of the exotic naturalized Paspalum dilatatum Poir. threatens diversity of native plants in urban gardens

Urban greening may enhance the distribution of exotic species that represent a threat for the native species in new urban systems. Paspalum dilatatum Poir. is one of the exotic naturalized species dominating in gardens of new urban ecosystems in Egypt. This study was conducted to evaluate the allelopathic interference of such species on the native plants in these habitats. The field study showed that the plots infested with Paspalum attained lower coverage, diversity and biomass of native plants than those free from it. Amaranthus viridis and Dactyloctenium aegyptium were completely absent from the sites involving P. dilatatum. Moreover, Paspalum-infested soils were of more water content, available nitrogen and extremely higher nitrogenase activity. In a greenhouse experiment, the rhizosphere soil under Paspalum reduced germination and growth of some native species, namely, Amaranthus viridis, Medicago lupulina, Melilotus indicus and Plantago amplexicaulis. Moreover, growth inhibition was inversely related to the seed size of these tested species. The spectrophotometric analysis revealed that higher contents of phenolics and flavonoids were detected in the Paspalum-infested soils in comparison with free ones. Besides, the high performance liquid chromatographic (HPLC) analysis indicated the presence of some free phenolics and flavonoids with higher concentrations in Paspalum-infested soils. The results indicate that the exotic naturalized P. dilatatum had negative effects on coverage, biomass and diversity of the native species in urban gardens. The obtained inhibition in these criteria was not attributed to soil characteristics. Furthermore, the significant reduction in germination and growth of the target species under greenhouse conditions could be attributed to the higher phenolic and flavonoid contents in the Paspalum-infested soils. These findings suggest that allelopathy had, at least, partial role in the negative impact caused by P. dilatatum. This species may also represent a threat for the native plant communities in new urban ecosystems.

Invasiones en montañas: ¿Cuánto hemos avanzado en los últimos 10 años y cuáles son los desafíos para los ecosistemas de los Andes?

During the last decade, there has been a great interest in understanding the process of invasion of exotic plants in the ecosystems of the Andes mountain range, because they have a high diversity endemic species and are an important source of ecosystem services. Therefore, this review aims to assess the current state of knowledge about the invasion of plants in the mountain ecosystems of the Andes mountain range. Through a systematic quantitative review that I integrate publications made in the periods 1997-2017. The aim was to identify scientific productivity during the last 10 years, the main research trends and understand how global change processes will affect the invasion process. We determined that publications per year increase linearly (R2 = 0.68), being more noticeable during the last 10 years (2008-2017). More than 50% of the publications were concentrated in studies carried out in Andean ecosystems in Chile and Argentina. The most developed themes were new reports of exotic species (18.48%) and the study of anthropic disturbances as agents promoting invasion (16.38%). Based on the research patterns, it was exemplified how the anthropic factors model the patterns of distribution of exotic species in the ecosystems of the Andes and how the patterns of global change will have implications for the redistribution patterns of the exotic species. Finally, we conclude that it is necessary to strengthen experimental studies on climate change, impact assessment and the generation of control and management protocols for exotic species.

서울시 한강의 어류군집과 외래종 분포 특성

서울시 한강의 어류군집과 외래종 분포 특성

Environment and anthropogenic impacts as main drivers of plant assemblages in forest mountain landscapes of Southern Patagonia

Management of natural areas generated multiple trade-offs, and changes in the plant assemblages was identified as one of the most critical ones. In this context, understanding the drivers of change of exotic plant diversity is critically important for biodiversity conservation and land planning. The aim of this work was to evaluate the relationships between environmental gradients in mountain landscapes and anthropogenic impacts related to human uses as drivers for plant assemblages (native and exotic species) in Southern Patagonian forests. The study was located in the Andorra Valley basin (12,934 ha) in the southern Tierra del Fuego Island (Argentina), where mountain landscape units (land-cover and land-use) were identified according to their vegetation types (forests and open-lands), elevational effects (<400 and >400 m.a.s.l.) and anthropogenic impacts derived from economic activities (harvesting and cattle grazing). Classification was based on Landsat 8 OLI images with fieldwork samplings, relevating a total of 101 landscape units. In each unit, forest structure and floristic surveys (dicots, monocots, pteridophytas and bryophytes) were conducted. Data were evaluated using ANOVAs and multivariate analyses (cluster, detrended and canonical correspondence analysis). A total of 104 plant species were surveyed (88% natives and 12% exotics), where managed deciduous forests (Nothofagus pumilio) had the highest values of exotic species occurrence frequency (20%). Multivariate analyses showed that environmental gradients and anthropogenic impacts highly affected the distribution of exotic species. Native species had higher cover values at upper elevations, while exotic plants had a higher cover at lower elevations, where the N-S aspects were strongly correlated with plant preferences for shaded/lighted aspects. The occurrence of exotic species can be specifically related to human activities (e.g., Agrostis stolonifera and Rumex acetosella with cattle grazing; and Poa nemoralis, Ranunculus repens and Stellaria media with harvesting), however one of them (P. trivialis) was related with unharvested forests. We conclude that environmental gradients and anthropogenic impacts define the plant assemblages at landscape level, and they also influence the occurrence of the exotic species, where the main driver was the harvesting. We propose that land-sharing conservation strategy in these mountain landscapes could be the better approach towards sustainability ensuring the preservation of the land-cover and the land-use at the low and upper elevations.

Invasion stages and potential distributions of seven exotic terrestrial isopods in Japan

Evaluating potential distribution areas and limiting factors for the distribution of exotic species in invasive regions are essential to identify risks and protect the native ecosystem. However, less research has been conducted on the underground ecosystem than for above-ground. Factors, limiting the distributions of exotic terrestrial isopods, have been identified and their invasive stages and potential distribution areas in Japan evaluated. A database of distribution data has been developed for 17,412 terrestrial isopod specimens in Japan and two ecological niche models constructed using 19 bioclimatic variables; the regional model was calculated using data from Japan (invasive region) only, whereas a combination of data from Japan and North America (invasive regions) and Europe (native region) was used to construct the global model. The global model predicted that annual mean temperature and mean diurnal-temperature range were the important limiting factors for most exotic isopods. It was found thatArmadillidiumnasatumBudde-Lund, 1833,A.vulgareLatreille, 1804,HaplophthalmusdanicusBudde-Lund, 1880,PorcelliolaevisLatreille, 1804,P.scaberLatreille, 1804 andPorcellionidespruinosus(Brandt, 1833) were composed of stabilising and colonising populations, which enabled prediction of the future spread of distribution areas for these species in Japan.PorcelliodilatatusBrandt, 1833 was introduced in unstable environments and thus was found in fewer locations.

Interactive effects of source and recipient habitats on plant invasions: distribution of exotic species in Chile

AbstractAimMost studies on invasibility consider the characteristics of the habitats colonized. However, the success of the establishment of exotic species can be conditioned by the characteristics of the donor communities. In this study, we analyse the extent to which the distribution of exotic herbaceous species in Chile is conditioned either by the climatic characteristics of the recipient area or by the environmental features of the source areas on the Iberian Peninsula.LocationChile and the Iberian Peninsula (Portugal and Spain).MethodsFor Chile, we characterized the exotic species according to their current Chilean distribution and their region of origin. For the Iberian Peninsula, we compiled the floristic composition of 11,702 relevés. We classified each relevé according to key habitat characteristics (bioclimate, soil nutrient status and type of community associated with human activities) and calculated the percentage of species in common with Chile in different climatic regions therein.ResultsOver half of Chile's exotic species exhibited a geographic distribution related to the climate of the recipient area. The main donor communities were those associated with ruderal and arable land habitats, although their importance depended upon the climate in the recipient area. Correspondence was observed between the climatic characteristics of the communities in the source area and those of the recipient areas.Main conclusionsThe results highlight the influence of the characteristics of habitats in the source area on the successful establishment of exotic species in Chile. The relationships between source and recipient area are scale dependent, climate constituting the main driver at broad scale. Within each climatic region, the communities associated with habitats presenting greater anthropic influence act as the main donors. Both features indicate the existence of filters that select species pre‐adapted to the climatic and habitat conditions in the recipient area.

Spatio-Temporal Analysis of Land Cover/Land Use Changes Using Geoinformatics (A Case Study of Margallah Hills National Park)

In order to make any strategy for management of National Park, it is necessary to understand the dynamics of land use/ land cover changes .Remote Sensing and GIS have significant magnitude for analysis of spatial extent and temporal changes of land cover/land use in urban and regional planning studies. The objective of the present research is to identify the nature, extent and spatial pattern of land cover changes during 1997-2008 in MHNP Islamabad through high resolution satellite imagery .The Normalized Difference Vegetation Index (NDVI) and Maximum Likelihood Classification (MLC) algorithms are used to determine the vegetation cover and spatial extent of different land use/ land cover classes of the study area respectively. The second objective of this research is to find the spatial distribution of exotic species based on different environmental factors through decision tree classification method. Results show that vegetation cover declines during 1997-2008 and vegetation health is affected by the presence of these exotic species, because these species are not suitable to local ecosystem. About 2.5% area of the NP is occupied by Paper Mulberry (Broussonetia papyrifera) and 9.4% by Punch Phali (Lantana camara).The results provides the effective analysis of land cover of National park which might be helpful in efforts towards the conservation of this ecological heritage site.

Un ejemplar de Cypraea pantherina en una tumba Altoimperial de Augusta Emerita

In this brief report, we present a specimen of the marine mollusk shell recovered as part of a Roman burial deposit of High-imperial period. The element comes from a tomb excavated in the city of Merida (Spain). The taxonomic analysis indicates it concerned to the species Cypraea pantherina. It is an exotic element of Indo-Pacific origin, including occasionally as funeral offerings in the Roman world from the first century BC. This species, in particular, is associated with female graves. The shell associates connotations of fertility, good childbirth and procreation. The case of Mérida (Augusta Emerita) is the only one that has been reported in the Iberian Peninsula. This allows to extend this way our knowledge on the distribution of exotic species proceeding from distant seas by means of the human activity.

Substitutable habitats? The biophysical and anthropogenic drivers of an exotic bird’s distribution

Abstract The spread and distribution of exotic species depends on a number of factors, both anthropogenic and biophysical. The importance of each factor may vary geographically, making it difficult to predict where a species will spread. In this paper, we examine the factors that influence the distribution of monk parakeets (Myiopsitta monachus), a parrot native to South America that has become established in the United States. We use monk parakeet observations gathered from citizen-science datasets to inform a series of random forest models that examine the relative importance of biophysical and anthropogenic variables in different regions of the United States. We find that while the distribution of monk parakeets in the southern US is best explained by biophysical variables such as January dew point temperature and forest cover, the distribution of monk parakeets in the northern US appears to be limited to urban environments. Our results suggest that monk parakeets are unlikely to spread outside of urban environments in the northern United States, as they are not adapted to the climatic conditions in that region. We extend the notion of “substitutable habitats,” previously applied to different habitats in the same landscape, to exotic species in novel landscapes (e.g., cities). These novel landscapes provide resources and environmental conditions that, although very different from the species’ native habitat, still enable them to become established. Our results highlight the importance of understanding the regionally-specific factors that allow an exotic species to become established, which is key to predicting their expansion beyond areas of introduction.

Overview of the Distribution, Habitat Association and Impact of Exotic Ants on Native Ant Communities in New Caledonia

Ants are among the most ubiquitous and harmful invaders worldwide, but there are few regional studies of their relationships with habitat and native ant communities. New Caledonia has a unique and diverse ant fauna that is threatened by exotic ants, but broad-scale patterns of exotic and native ant community composition in relation to habitat remain poorly documented. We conducted a systematic baiting survey of 56 sites representing the main New Caledonian habitat types: rainforest on ultramafic soils (15 sites), rainforest on volcano-sedimentary soils (13), maquis shrubland (15), Melaleuca-dominated savannas (11) and Acacia spirorbis thickets (2). We collected a total of 49 species, 13 of which were exotic. Only five sites were free of exotic species, and these were all rainforest. The five most abundant exotic species differed in their habitat association, with Pheidole megacephala associated with rainforests, Brachymyrmex cf. obscurior with savanna, and Wasmannia auropunctata and Nylanderia vaga present in most habitats. Anoplolepis gracilipes occurred primarily in maquis-shrubland, which contrasts with its rainforest affinity elsewhere. Multivariate analysis of overall ant species composition showed strong differentiation of sites according to the distribution of exotic species, and these patterns were maintained at the genus and functional group levels. Native ant composition differed at invaded versus uninvaded rainforest sites, in the absence of differences in habitat variables. Generalised Myrmicinae and Forest Opportunists were particularly affected by invasion. There was a strong negative relationship between the abundance of W. auropunctata and native ant abundance and richness. This emphasizes that, in addition to dominating many ant communities numerically, some exotic species, and in particular W. auropunctata, have a marked impact on native ant communities.

Do environmental attributes, disturbances and protection regimes determine the distribution of exotic plant species in Bangladesh forest ecosystem?

Introduction of exotic plant species in the tropics has occurred since the colonial period, and has mostly been for timber production. However, due to uncontrolled distribution and lack of awareness, many of these species became invasive, and have been increasingly reported as a source of threats to native ecosystems. We investigated the exotic species richness, their traits, and biogeographic origin in the Satchari Forest in the north-eastern region of Bangladesh, one of the very few intact terrestrial ecosystems remaining in the country. Boosted Regression Trees and Detrended Correspondence Analysis were performed to determine the contribution of various environmental attributes, protection regimes, and disturbances to explain the distribution of exotic species within Satchari Forest. Among the environmental variables, native species richness, elevation gradient, and soil nutrient parameters were found as good predictors of both exotic species’ presence and richness in the area. In our analysis, number of exotic species showed a unimodal relationship with native species in the reserved forest, where the relationship was negative in the surrounding area. An increase in exotic species with the presence of higher anthropogenic disturbance events, thereby with lower conservation restrictions as well as with lower protection status, was also evident. Our study suggests that enforcing greater protection status and preventing human use can be the best ways to protect native species composition in forest ecosystems with greater conservation values in tropical developing countries.

Avian dispersal of exotic shrubs in an archipelago

The distribution of exotic species bearing fruits may depend in part on their palatability to birds, because species attracting a more diverse array of dispersers should broadcast seed to a wider range of habitats, including those otherwise assumed to represent refuges from exotic species invasion, such as small islands. To test these ideas, we compared the palatability of 11 exotic shrub species to their occurrence on 91 islands of varying size and isolation in the Gulf Islands of British Columbia, Canada and the San Juan Islands of Washington, USA. The estimated palatability of fruits for 10 common frugivorous birds was positively related to the number of islands on which they occurred. Rubus armeniacus and R. laciniatus were the most widely consumed exotic species and the only such species prevalent on small islands, suggesting that they have benefited by attracting a wide array of frugivores that have, in turn, facilitated their rapid colonization of the region. Our results suggest that protecting small islands from human visitation will be insufficient to prevent exotic species establishment and the loss of native biodiversity.

Assessing the influence of environmental and human factors on native and exotic species richness

Understanding the ecological determinants of biological invasions is a key issue for predicting the spread of exotic species over broad geographical extents. The goal of this study was to investigate independent and combined effects of climatic and human-related factors on native and exotic plant species richness in Great Britain. We used multiple and partial regression techniques and spatial methods to investigate the effect of these variables on species richness. The highest plant richness was found in southeastern Great Britain and the lowest in the North for both native and exotic species. We found that energy input was the best predictor of either native or exotic plant richness, followed by water availability. Richness increased linearly with energy input for native plants, but exponentially for exotics. This is probably due to the lower chances of exotic species to succeed in low-energy sites, and/or to the lower species saturation of more productive ecosystems. The low portion of richness variance explained by human footprint was probably due to the study scale and to the overlapping between climatic and human factors. We conclude that the environment–human models are robust to enhance our understanding of the factors controlling the distribution of exotic species. Models containing water–energy measures can be a key component for explaining the broad-scale patterns of exotic species.

Patterning the distribution of threatened crayfish and their exotic analogues using self-organizing maps

SUMMARYAbility to demonstrate statistical patterns of distribution by threatened species and by their potential competitors will determine success in forecasting locations at greatest risk, and ability to target management efforts. A self-organizing map algorithm (SOM) was used to derive probabilities of presence of native (Austropotamobius pallipes) and exotic (Orconectes limosus, Pacifastacus leniusculus and Procambarus clarkii) crayfish species with respect to physical and land-cover variables in a large stream system, using a simple presence-absence dataset of species. Crayfish were sampled at 128 sites representing 86 rivers. The probability of occurrence of the native species increased at higher elevations above sea level and lower temperatures; populations appeared to be mostly confined to headwater streams where exotic competitors were unable to withstand the colder conditions. The distribution of exotic species was correlated with anthropogenic factors, such as the degree of urbanization and agricultural land area. Complementary modelling tools, such as GIS and SOMs, can help to maximize the information extracted from available data in the context of biological conservation.

Vegetation Structure of Field Margins and Adjacent Forests in Agricultural Landscapes of the North Carolina Piedmont

Irregularly disturbed forests surrounding crop fields in agricultural landscapes often serve as ecological buffers that separate undesirable agricultural elements such as agrichemicals and weedy species from adjacent ecosystems. However, the nature of this interface between fields and forests remains little studied, particularly within the context of how species composition changes with field distance and how far exotic species penetrate into forest interiors. In three agricultural landscapes in the North Carolina Piedmont, we surveyed plant communities in multi-scale, nested quadrats arrayed along transects perpendicular to field boundaries and penetrating .200 m into adjacent forests. Rates of species turnover, patterns of species richness, and the distribution of exotic species were assessed for 18 transects. Plant communities exhibited high rates of compositional turnover within 50 m of field boundaries, but species turnover was considerably reduced beyond this threshold. Vegetation composition within borders immediately adjacent to cornfields was dominated by a relatively predictable set of weedy forb and graminoid species, of which a substantial proportion was exotic. Composition of surrounding forest communities more reflected local environmental conditions and contained few exotic species overall. Species richness was not influenced by field proximity. We suggest that agricultural influences on landscape-scale vegetation patterns are most apparent in plant communities located very close (,50 m) to continuous agricultural operations. Although weed communities associated with agricultural management are represented by a large pool of exotic species, relatively few of these species are able to penetrate forest boundaries.

Functional grouping and establishment of distribution patterns of invasive plants in China using self-organizing maps and indicator species analysis

In the present study, we introduce two techniques - self-organizing maps (SOM) and indicator species analysis (INDVAL) - for understanding the richness patterns of invasive species. We first employed SOM to identify functional groups and then used INDVAL to identify the representative areas characterizing these functional groups. Quantitative traits and distributional information on 127 invasive plants in 28 provinces of China were collected to form the matrices for our study. The results indicate Jiangsu to be the top province with the highest number of invasive species, while Ningxia was the lowest. Six functional groups were identified by the SOM method, and five of them were found to have significantly representative provinces by the INDVAL method. Our study represents the first attempt to combine self-organizing maps and indicator species analysis to assess the macro-scale distribution of exotic species.

Human-related processes drive the richness of exotic birds in Europe

Both human-related and natural factors can affect the establishment and distribution of exotic species. Understanding the relative role of the different factors has important scientific and applied implications. Here, we examined the relative effect of human-related and natural factors in determining the richness of exotic bird species established across Europe. Using hierarchical partitioning, which controls for covariation among factors, we show that the most important factor is the human-related community-level propagule pressure (the number of exotic species introduced), which is often not included in invasion studies due to the lack of information for this early stage in the invasion process. Another, though less important, factor was the human footprint (an index that includes human population size, land use and infrastructure). Biotic and abiotic factors of the environment were of minor importance in shaping the number of established birds when tested at a European extent using 50 x 50 km2 grid squares. We provide, to our knowledge, the first map of the distribution of exotic bird richness in Europe. The richest hotspot of established exotic birds is located in southeastern England, followed by areas in Belgium and The Netherlands. Community-level propagule pressure remains the major factor shaping the distribution of exotic birds also when tested for the UK separately. Thus, studies examining the patterns of establishment should aim at collecting the crucial and hard-to-find information on community-level propagule pressure or develop reliable surrogates for estimating this factor. Allowing future introductions of exotic birds into Europe should be reconsidered carefully, as the number of introduced species is basically the main factor that determines the number established.

Thinking Locally for Urban Forest Restoration: A Simple Method Links Exotic Species Invasion to Local Landscape Structure

Abstract Restoring urban forests often involves eradicating exotic species and diligently guarding against future invasions. Understanding how landscape structure contributes to the distribution of exotic species may inform these management efforts. To date, the distribution of exotic species in forested patches has been correlated with the type of development surrounding the patch, with those surrounded by agricultural or urban development often more highly invaded. Yet, previous studies have categorized land use types and have not examined more local‐scale changes in land use. These local changes may be particularly important in urban areas where forested patches are immediately surrounded by diverse land use types. Our study examined how two key aspects of landscape structure, patch size and adjacent land use, may influence patterns of exotic species invasion of riparian buffers within Raleigh and Cary, North Carolina, United States. We found that large patch size alone, in our case, wide riparian buffers, does not protect against exotic species invasion. Patches surrounded by higher canopy‐cover landscapes (e.g., forests and older residential developments with mature canopy) were more likely to be invaded than those surrounded by less canopy cover (e.g., shopping malls and other commercial development). We attribute these results, in part, to increased pressure from exotic propagules from adjacent forests. When restoring urban forests, attention should be paid to local land use to better plan for successful, long‐term eradication of exotic species.