Proportion Of Invasive Species Research Articles

Soil bacterial activity and functional diversity as indicators of recultivation of alkaline settlements of a ‘Solvay’ process

PurposeMany industries continuously produce large volumes of alkaline residues. After recultivation, former landfills can be an important element providing ecosystem services in highly urbanised areas.Materials and methodsWe studied the relationship between vegetation and soil bacterial characteristics using Biolog® ECO plates on recultivated areas of the Solvay heaps, and participation of invasive species in plant community in progressive succession.Results and discussionBacterial activity and functional diversity indices were correlated with soil physicochemical properties (soil organic matter content, water holding capacity, total phosphorus content, and soil pH). Plots with a higher total number of vascular plant species, including forest floor species, and a higher Shannon–Wiener index of vegetation diversity H'plant, were characterised by a higher amino acid utilisation by soil bacteria. Soil bacteria CLPP (community-level physiological profiles) were most influenced by soil physical and chemical properties, but also by the proportion of invasive species in the total number of plant species. In conclusion, soil physical and chemical properties dominate vegetation characteristics in shaping the functional diversity of soil bacteria. Invasive species may be an influential component of ecosystems during spontaneous succession of degraded soils.

Assessment of Fish Species in Wanlv Lake, the Largest Drinking Water Source in South China, by Environmental DNA Metabarcoding Technology

As the largest lake in South China, Wanlv Lake is also an important drinking water source for Guangdong and Hong Kong and is responsible for water supplying of more than 40 million people in the Guangdong-Hong Kong-Macao Greater Bay Area. The study of fish diversity in Wanlv Lake can help us to effectively understand the changes and states of its aquatic ecosystem and provide scientific basis for natural ecological protection, biodiversity, sustainable use and scientific management of fishery resources. However, research on the lake’s fish is scarce. The high throughput environmental DNA metabarcoding technology (eDNA technology) of the mitochondrial 12S rRNA gene sequence was herein used to conduct a preliminary exploration of Wanlv Lake fish diversity. A total of 10 sampling sites were set up to monitor fish diversity and analyze the composition and richness of the species. The results revealed a total of 83 genera in 42 families and 17 orders of fish in the lake, with the highest proportion found in Cypriniformes (38 species), accounting for 45.24% of the total. Five alien species and eight rare and endangered species were also detected. The proportion of invasive species was 5.95%, and the combined proportion of rare and endangered species was 9.52%. The results indicated that Wanlv Lake serves as an important drinking water source, and overall, the condition of fish is satisfactory. However, proactive measures should be implemented to control the overpopulation of invasive species, as their unchecked proliferation may lead to a decline in species abundance, particularly among endangered species. This was the first overall assessment report on fish of the Wanlv Lake via 12S rRNA; the results herein lay a foundation for water quality assessment of Wanlv Lake as a drinking water source.

Great Lakes coastal fish habitat classification and assessment

Abstract Basin-scale assessment of fish habitat in Great Lakes coastal ecosystems would increase our ability to prioritize fish habitat management and restoration actions. As a first step in this direction, we identified key habitat factors associated with highest probability of occurrence for several societally and ecologically important coastal fish species as well as community metrics, using data from the Great Lakes Aquatic Habitat Framework (GLAHF), Great Lakes Environmental Indicators (GLEI) and Coastal Wetland Monitoring Program (CWMP). Secondly, we assessed whether species-specific habitat was threatened by watershed-level anthropogenic stressors. In the southern Great Lakes, key habitat factors for determining presence/absence of several species of coastal fish were chlorophyll concentrations, turbidity, and wave height, whereas in the northern ecoprovince temperature was the major habitat driver for most of the species modeled. Habitat factors best explaining fish richness and diversity were bottom slope and chlorophyll a. These models could likely be further improved with addition of high-resolution submerged macrophyte complexity data which are currently unavailable at the basin-wide scale. Proportion of invasive species was correlated primarily with increasing maximum observed inorganic turbidity and chlorophyll a. We also demonstrate that preferred habitat for several coastal species and high-diversity areas overlap with areas of high watershed stress. Great Lakes coastal wetland fish are a large contributor to ecosystem services as well as commercial and recreational fishery harvest, and scalable basin-wide habitat models developed in this study may be useful for informing management actions targeting specific species or overall coastal fish biodiversity.

Invasive flora within urban railway areas: a case study from Lublin (Poland) and Lviv (Ukraine)

Heterogeneous and disturbed habitats within railway areas create an ideal environment for establishment of invasive plant species. In this study, we compared the invasive species composition and abundance within railway areas of two cities, Lublin, SE Poland and Lviv, W Ukraine. In total, 70 invasive species were recorded. The invasive species list was similar for the two cities, with the most invasive species occurring at both (81.4%), 8.5% occurring only in Lublin and 10% only in Lviv. The proportion of invasive species in the total flora was almost 1.5-fold higher at Lviv compared to Lublin. Invasive species have originated mainly from continental America (45.7%), followed by Asia and Eurasia. The participation of invasive plants derived from Asia and Eurasia at Lviv is higher than at Lublin. The invasive flora includes a wide range of taxonomic groups, with a predominance of Asteraceae and Poaceae. The ecological attributes of invasive species on railway areas are: mainly annual therophytes, mostly wind- and insect pollination modes, a predominance of generative reproduction, anthropochorous and anemochorous dispersal and short-term persistent, long-term persistent or transient seed banks.

Spatial and Temporal Variation in Brackish Wetland Seedbanks: Implications for Wetland Restoration Following Phragmites Control

Chesapeake Bay tidal wetlands are experiencing a broad-scale, aggressive invasion by the non-native, clonal grass Phragmites australis. The grass is often managed with herbicides in efforts to restore native plant communities and wildlife habitat. Management efforts, however, can act as a disturbance, resulting in increased light availability, potentially fostering reinvasion from soil seedbanks. If native vegetation establishes quickly from seedbanks, the site should have greater resiliency against invasion, while disturbed sites where native plants do not rapidly establish may be rapidly colonized by P. australis. We surveyed the soil seedbank of three vegetation cover types in five Chesapeake Bay subestuaries: areas where P. australis had been removed, where P. australis was left intact, and with native, reference vegetation. We determined the total germination, the proportion of the seedbank that was attributable to invasive species, the richness, the functional diversity, and the overall composition of the seedbanks in each of the cover types (i.e., plots). After 2 years of herbicide treatment in the P. australis removal plots, vegetation cover type impacted the total germination or the proportion of invasive species in the seedbank. In contrast, we also found that seedbank functional composition in tidal brackish wetlands was not influenced by vegetation cover type in most cases. Instead, plots within a subestuary had similar seedbank functional composition across the years and were composed of diverse functional groups. Based on these findings, we conclude that plant community recovery following P. australis removal is not seed-limited, and any lack of native vegetation recruitment is likely the result of yet-to-be-determined abiotic factors. These diverse seedbanks could lead to resilient wetland communities that could resist invasions. However, due to the prevalence of undesirable species in the seedbank, passive revegetation following invasive plant removal may speed up their re-establishment. The need for active revegetation will need to be assessed on a case-by-case basis to ensure restoration goals are achieved.

Invasive plant species in the West Indies: geographical, ecological, and floristic insights.

The level of invasion (number or proportion of invasive species) in a given area depends on features of the invaded community, propagule pressure, and climate. In this study, we assess the invasive flora of nine islands in the West Indies to identify invasion patterns and evaluate whether invasive species diversity is related to geographical, ecological, and socioeconomic factors. We compiled a database of invasive plant species including information on their taxonomy, origin, pathways of introduction, habitats, and life history. This database was used to evaluate the similarity of invasive floras between islands and to identify invasion patterns at regional (West Indies) and local (island) scales. We found a total of 516 alien plant species that are invasive on at least one of the nine islands studied, with between 24 to 306 invasive species per island. The invasive flora on these islands includes a wide range of taxonomic groups, life forms, and habitats. We detected low similarity in invasive species diversity between islands, with most invasive species (>60%) occurring on a single island and 6% occurring on at least five islands. To assess the importance of different models in predicting patterns of invasive species diversity among islands, we used generalized linear models. Our analyses revealed that invasive species diversity was well predicted by a combination of island area and economic development (gross domestic product per capita and kilometers of paved roadways). Our results provide strong evidence for the roles of geographical, ecological, and socioeconomic factors in determining the distribution and spread of invasive species on these islands. Anthropogenic disturbance and economic development seem to be the major drivers facilitating the spread and predominance of invasive species over native species.

Floristic diversity, composition and invasibility of riparian habitats with Amorpha fruticosa: A case study from Belgrade (Southeast Europe)

Amorpha fruticosa L. represents one of the most dangerous invasive neophytes spreading quickly in many countries and cities of southeastern Europe where it aggressively penetrates into newly invaded sites and establishes permanently. It prefers moist and periodically flooded terrains, being therefore a serious threat for fragile wet habitats. Considering this, the main aim of this research was to determine the floristic diversity, composition and level of invasibility of urban and suburban riparian forests and open habitats with domination of A. fruticosa at the mouth of the Sava and Danube Rivers in Belgrade, and to assess the impact of all invasive neophytes in the analyzed habitats. Two hundred fifty seven (257) relevés, made according to Braun-Blanquet (1964) methodology, were subjected to different statistical analyses. The obtained results showed that urban wet habitats with domination of A. fruticosa were differentiated into 7 coenological groups, with the total of 222 registered taxa, out of which 29 (13.06%) were invasive neophytes. These coenoses are developed within willow and poplar habitats, wet lowland meadows and reedbed habitats. We found a direct negative correlation between the change in the number of species and the proportion of invasive species i.e. their coverage indexes in the analysed stands. The identified coenological group with domination of Rubus caesius and A. fruticosa represents the most dangerous hotspot of invasive species, which might seriously threaten native species and their urban riparian habitats, as well as similar habitats downstream.

Employing indicators for prioritization of fish assemblage with a view to manage freshwater fish diversity and ecosystem health in the tributaries of Ganges basin, India

The major tributaries of the river Ganges basin are currently threatened by various anthropogenic activities which are hampering the ecosystem stability and fish biodiversity of the basin. Multiple indicators were used to prioritize the fish assemblages in the tributaries and to develop an index that is responsive to human-induced environmental changes. A high percentage of invasive species was described with the orgin index at the most disturbed sites of rivers Gomti and Betwa which also represented a substantial amount of biological disturbance. The Fisheries Assessment Integrity Index based on ecological integrity of different segments of the rivers was used to prioritize different sampling sites of the tributaries. Some of the sampling sites in Gomti and Betwa rivers are reflecting disturbed fish assemblages, a very low Fisheries Assessment Integrity Index score, few threatened species, and a high proportion of invasive species. Principal components analysis of the sampling sites, along with fish assemblage, reflected the influence of the habitat parameters on structuring the assemblage pattern. This study identified depth, flow, water quality and land uses in shaping fish assemblages. The combination of various indices in this study should provide more accurate measures in identifying sites of high conservation value.

Freshwater mollusc assemblages and habitat associations in the Danube River drainage, Hungary

Abstract Native freshwater mollusc diversity has been declining over the past decades. For developing efficient conservation management plans for molluscs, it is especially important to identify areas with high native biodiversity. The River Danube is one of the most important freshwater ecosystems in Europe and should receive special attention. The main objective of this work was to characterize the composition, diversity and conservation status of freshwater molluscs occurring in the Hungarian Danube River Drainage in five river habitat types (main channel of the Rivers Danube and Tisza, side channels of River Danube, tributaries of Rivers Danube and Tisza). In total, 53 mollusc species were identified including 10 invasive species and 12 species of conservation concern. The main determining factors of mollusc composition were sediment characteristics, current velocity and oxygen content. Nitrate–nitrogen, ammonium–nitrogen, and calcium content also play a key role. Overall, density, species richness and diversity showed significant differences between habitat types. The highest diversity values were detected in the side channels, but the highest proportion of threatened species was observed in the tributaries. The highest number and proportion of invasive species was detected in the main channel of the Danube. Most of the recorded invasive species were previously documented in side channels and the adjacent wetlands, but did not invade the tributaries. Tributaries may provide refuges for native molluscs and could be considered as ‘source’ populations, which may be critically important in the regional maintenance of threatened species. Tributaries are still less disturbed and less invaded; and should be given priority in future conservation management plans. Copyright © 2015 John Wiley & Sons, Ltd.

Origin of British and Irish mammals: disparate post-glacial colonisation and species introductions

Origin of British and Irish mammals: disparate post-glacial colonisation and species introductions

A benefit analysis of screening for invasive species - base-rate uncertainty and the value of information

1.. Implementation of the full spectra of screening tools to prevent the introduction of invasive species results in a need to evaluate the cost-efficiency of gathering the information needed to screen for these species. 2. We show how the Bayesian value of information approach can be used to derive the benefit of a screening model based on species traits, which in combination with the base rate of invasiveness, i.e. the proportion of invasive species among those introduced and established, predicts species-specific invasiveness. 3. A pre-posterior Bayesian analysis demonstrated that the benefit of the screening model of invasiveness depends on both the accuracy in predictions and the uncertainty in the base rate of invasiveness. However, even though increasing model accuracy always generates higher model benefit, acknowledging or neglecting the uncertainty in the base rate of invasiveness does not. This means that uncertainty in the base rate is important to consider in the cost-benefit analysis of the screening model. 4. As an example, we derived the benefit of basing decisions on a screening model trained for a data set on species traits of invasive and non-invasive marine macroalgae introduced into Europe. The benefit ranged from 0.6% to 19% of the loss of introducing an invasive species, where the actual value can be estimated if we know the monetary values of impacts from introducing invasive and not introducing non-invasive species. 5. Cost-benefit analyses of screening models for invasive species is one means to reach efficient management of the risks of non-indigenous species. Value of information is a useful tool for benefit analysis of predictive models with respect to decision-making, which goes beyond the investigations of model accuracy. Here, we use value of information analysis to evaluate which sources of uncertainty that is most worth while to reduce and how to set the cost of gathering further species-specific information which will improve the accuracy of a screening.

TWO DECADES OF CHANGE IN DISTRIBUTION OF EXOTIC PLANTS AT THE DESERT LABORATORY, TUCSON, ARIZONA

A gridline survey for exotic plant species was undertaken in 1983 and repeated in 2005 at the Desert Laboratory, a 352-ha natural area just west of downtown Tucson, Arizona, USA. Coordinate data gathered during the surveys were used to plot distributions, determine frequencies (number of coordinate locations), and assess percent change. Fifty-two exotic species were encountered in all, 34 in the first survey, 44 in the second. The proportion of ornamental exotics doubled over time, reaching 50% in 2005. Casual, naturalized, and invasive exotics comprised 44%, 40%, and 15% of species found during the surveys. Minimum residence time increased significantly from casual to naturalized to invasive species, suggesting that the longer a species was present, the more likely it was to surmount barriers to naturalization and invasion. In both 1983 and 2005, casual, naturalized, and invasive species differed in mean frequency by an order of magnitude, with casual species having the lowest frequencies and invasive species the highest. Between surveys, frequency of 18 species decreased; most other species increased in frequency. The recent surge in ornamental exotics, combined with temporal trends in invasiveness, indicates that the proportion of invasive species in the flora will increase with time.