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Search Results: 1 - 10 of 9032 matches for " Invasive community "
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Asteretum lanceolati: Xenospontaneous community on wet and riparian habitats
Obratov-Petkovi? Dragica,Bjedov Ivana,Sko?aji? Dragana,?unisijevi?-Bojovi? Danijela
Glasnik ?umarskog Fakulteta , 2011, DOI: 10.2298/gsf1103073o
Abstract: Invasive species Aster lanceolatus grows on moist habitats on the whole territory of Serbia. In Belgrade, this species is recorded with a higher degree of presence at a number of localities. With the aim to investigate the community in which this species is dominant, the wide area of Serbia was researched, and 8 localities on the territory of Belgrade were chosen for the analysis of the community. Floristic structure of the community was determined by the standard Braun-Blanquet method (1964), phytogeographical analysis was performed according to Gaji (1980, 1984), and determination of life forms according to Raunkier (Ellenberg, Mueller-Dombois, 1967). pH soil analysis and electric conductivity (EC) were performed at all investigated localities. It was established that the community dominates the moist habitats of Belgrade. It is composed of 104 species and among them Aster lanceolatus Willd., Cichorium intybus L., Agropyrum repens (L.) Beauv., Calystegia sepium (L.) R. Br., Cirsium arvense (L.) Scop., Symphytum officinale L. and Rumex obtusifolius L. are the most frequent. In relation to life forms, the community has hemicriptophytes character, and in relation to phytogeography Euroasian and Middle Europaean floral elements are dominant, with a high presence of cosmopolitan and adventive floral elements. On the locialities Veliko Ratno ostrvo (island) and Maki , EC values point to the fact that the amount of nutrient in the soil is higher than at other localities.
Insights into Ecological Effects of Invasive Plants on Soil Nitrogen Cycles  [PDF]
Congyan Wang, Hongguang Xiao, Jun Liu, Lei Wang, Daolin Du
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.61005
Abstract: The increasing degree of plant invasion is an expanding problem that affects the functioning and composition of forest ecosystems with increasing anthropogenic activities, particularly soil nitrogen (N) cycles. Numerous studies have revealed that one of the main factors for successful plant invasion is that plants could pose significant effects on soil N cycles via direct and/or indirect ways, such as changes in soil microbial communities, litter decomposition rates, and/or soil physicochemical properties. We thereby summarize the ecological effects of invasive plants on soil N cycles, including the aforementioned changes, to understand the mechanism of successful invasion. We also discuss the needs for further research on the relationship between invasive plants and soil N cycles.
Presence of Sargassum horneri at Todos Santos Bay, Baja California, Mexico: Its Effects on the Local Macroalgae Community  [PDF]
Giuliana I. Cruz-Trejo, Silvia E. Ibarra-Obando, Luis E. Aguilar-Rosas, Miriam Poumian-Tapia, Elena Solana-Arellano
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.617271
Abstract: To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.
Invasion of Langebaan Lagoon, South Africa, by Mytilus galloprovincialis – effects on natural communities
T.B. Robinson,C.L. Griffiths
African Zoology , 2011,
Abstract: In 1992 the invasive musselMytilus galloprovincialis began establishing beds on the centre sandbanks of Langebaan Lagoon. This global invader had previously been restricted to rocky shores along the South African coastline. In order to investigate the effect of the invasion on naturally-occurring communities, a comparative study between invaded areas and areas clear of invasion was conducted. Communities in these areas differed significantly (ANOSIM, R = 0.685, P < 0.01). The biomass supported in invaded areas (53 262 g/m2), was significantly greater than that in clear areas (1133 g/m2), (Mann-Whitney, U
The remaining challenges of pneumococcal disease in adults
E. Ludwig,P. Bonanni,G. Rohde,A. Sayiner
European Respiratory Review , 2012,
Abstract: Pneumococcal disease can be divided into invasive disease, i.e. when bacteria are detected in normally sterile body fluids, and noninvasive disease. Pneumococcal disease occurs more frequently in younger children and older adults. It is estimated that, in 2050, 30.3% of the European population will be ≥65 yrs old, compared with 15.7% in 2000. Preventive medicine, including vaccination, is essential for the promotion of healthy ageing. Uptake rates for influenza vaccination in the elderly are generally low, despite recommendations in many countries. In addition, it has been reported that influenza infections can make people more susceptible to pneumococcal infections. Despite pneumococcal vaccination, case fatality rates for patients hospitalised with invasive pneumococcal disease have remained at around 12% since the 1950s. Even when effective antibiotic therapy is administered, mortality can be high amongst immunocompetent patients in intensive care. Timely and accurate diagnosis of pneumococcal disease and identification of patients at high risk of poor outcome is essential to ensure that adequate treatment, including hospitalisation when necessary, is implemented as early as possible. Improved diagnostic techniques and more efficacious treatments may help to reduce the burden of pneumococcal disease, but preventive measures, such as influenza and pneumococcal vaccination, should be promoted in order to avoid preventable disease, particularly in the elderly.
Molecular analyses of Fusarium isolates recovered from a cluster of invasive mold infections in a Brazilian hospital
Scheel Christina M,Hurst Steven F,Barreiros Gloria,Akiti Tiyomi
BMC Infectious Diseases , 2013, DOI: 10.1186/1471-2334-13-49
Abstract: Background Invasive fusariosis (IF) is a rare but often fatal fungal infection in immunosuppressed patients. In 2007, cases of IF above the expected epidemiologic baseline were detected in the hematology ward of a hospital in Rio de Janeiro, Brazil. Possible sources of infection were investigated by performing environmental sampling and patient isolate collection, followed by molecular typing. Isolates from dermatology patients with superficial fusariosis were included in the study for comparison to molecular types found in the community. Methods Environmental sampling focused on water-related sources in and around the hematology ward. Initially, we characterized 166 clinical and environmental isolates using the Fusarium translation elongation factor 1α (EF-1α) genetic locus. Isolates included 68 collected from water-related sources in the hospital environment, 55 from 18 hematology patients, and 43 from the skin/nails of 40 outpatients seen at the hospital dermatology clinic. Multi-locus sequence typing was performed on Fusarium solani species complex (FSSC) species 1 and 2 isolates to investigate their relatedness further. Results Most of the hematology samples were FSSC species 2, with species type FSSC 2-d the most commonly isolated from these patients. Most of the outpatient dermatology samples were also FSSC 2, with type 2-d again predominating. In contrast, environmental isolates from water sources were mostly Fusarium oxysporum species complex (FOSC) and those from air samples mostly Fusarium incarnatum-equiseti species complex (FIESC). A third of the environmental samples were FSSC, with species types FSSC 1-a and FSSC 1-b predominating. Conclusions Fusarium isolate species types from hematology patient infections were highly similar to those recovered from dermatology patients in the community. Four species types (FSSC 1-a, 1-b, 2-d and 2-f) were shared between hematology patients and the environment. Limitations in environmental sampling do not allow for nosocomial sources of infection to be ruled out. Future studies will focus on environmental factors that may have influenced the prevalence of FSSC fusariosis in this hematology ward.
The effects of removing dominant herbaceous species on woody seedling growth in Chromolaena odorata+Digitaria ciliaris community in Xishuangbanna,Southwest China
清除优势草本植物对西双版纳飞机草-马唐群落中木本幼苗的影响

SHEN Wei,CAO Min,Key Laboratory of Tropical Forest Ecology,Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla,China Graduate University of Chinese Academy of Sciences,Beijing,China,
沈维
,曹敏

生态学报 , 2010,
Abstract: Early successional communities in abandoned agricultural fields are often dominated by herbaceous species. To study the effects of dominant herbaceous species on woody seedlings and microenvironmental factors, and to contrast these effects between invasive species and native species, we conducted a species\|removal experiment in an early successional community dominated by invasive species (Chromolaena odorata) and native species (Digitaria ciliaris) in Xishuangbanna, southwest China. After the removal treatment, we investigated the recruitment, growth and mortality of woody seedlings. We also measured microenvironmental factors in the community. We found that the seedling height increment was substantially greater in removal plots than in control plots, the mortality of woody seedlings decreased, and the number of new seedlings increased after removal treatments. The effect of removing dominant species on height increment and seedling mortality was larger on 0-50 cm seedlings than on seedlings taller than 50 cm. The removal treatments increased the diffuse non\|interceptance value (DIFN) significantly but had little effects on soil moisture or soil nutrient status. Both the invasive species and the native species formed dense canopies and inhibited the growth of woody seedlings by competing for light, with no significant difference between these two species. The seedlings of pioneer tree species were found in the study area but they were subjected to severe inhibition by dominant herbaceous species; both the invasive and the native weed species. Therefore, attention should be paid to both invasive species and native weeds in managing dominant herbaceous species in early successional communities.
Prevention of pneumococcal diseases in the post-seven valent vaccine era: A European perspective
Weil-Olivier Catherine,van der Linden Mark,de Schutter Iris,Dagan Ron
BMC Infectious Diseases , 2012, DOI: 10.1186/1471-2334-12-207
Abstract: Background The burden of invasive pneumococcal disease in young children decreased dramatically following introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). The epidemiology of S. pneumoniae now reflects infections caused by serotypes not included in PCV7. Recently introduced higher valency pneumococcal vaccines target the residual burden of invasive and non-invasive infections, including those caused by serotypes not included in PCV7. This review is based on presentations made at the European Society of Pediatric Infectious Diseases in June 2011. Discussion Surveillance data show increased circulation of the non-PCV7 vaccine serotypes 1, 3, 6A, 6C, 7 F and 19A in countries with routine vaccination. Preliminary evidence suggests that broadened serotype coverage offered by higher valency vaccines may be having an effect on invasive disease caused by some of those serotypes, including 19A, 7 F and 6C. Aetiology of community acquired pneumonia remains a difficult clinical diagnosis. However, recent reports indicate that pneumococcal vaccination has reduced hospitalisations of children for vaccine serotype pneumonia. Variations in serotype circulation and occurrence of complicated and non-complicated pneumonia caused by non-PCV7 serotypes highlight the potential of higher valency vaccines to decrease the remaining burden. PCVs reduce nasopharyngeal carriage and acute otitis media (AOM) caused by vaccine serotypes. Recent investigations of the interaction between S. pneumoniae and non-typeable H. influenzae suggest that considerable reduction in severe, complicated AOM infections may be achieved by prevention of early pneumococcal carriage and AOM infections. Extension of the vaccine serotype spectrum beyond PCV7 may provide additional benefit in preventing the evolution of AOM. The direct and indirect costs associated with pneumococcal disease are high, thus herd protection and infections caused by non-vaccine serotypes both have strong effects on the cost effectiveness of pneumococcal vaccination. Recent evaluations highlight the public health significance of indirect benefits, prevention of pneumonia and AOM and coverage of non-PCV7 serotypes by higher valency vaccines. Summary Routine vaccination has greatly reduced the burden of pneumococcal diseases in children. The pneumococcal serotypes present in the 7-valent vaccine have greatly diminished among disease isolates. The prevalence of some non-vaccine serotypes (e.g. 1, 7 F and 19A) has increased. Pneumococcal vaccines with broadened serotype coverage are likely to continue de
Nuevas plantas alóctonas relevantes para la Comunidad Valenciana
Emilio Laguna Lumbreras,Pedro Pablo Ferrer Gallego
Flora Montiberica , 2012,
Abstract: Se indica la presencia en la Comunidad Valenciana de diversas especies vegetales alóctonas de las que no existían hasta ahora citas o datos georreferenciados.SUMMARY: The presence of several exotic plants in the Valencian Community (Spain), eithout former citations or geo-referenced indications, are given.
Network complexity and species traits mediate the effects of biological invasions on dynamic food webs
Miguel Lurgi,Núria Galiana,Bernat C. López,Lucas N. Joppa,José M. Montoya
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00036
Abstract: Biological invasions are a major threat to natural communities worldwide. While several species traits have been identified as important determinants of invasion success, a systematic exploration of the effects of invasions on native communities, and the role of species and community features on community robustness in the face of invasion is lacking. We present a theoretical approximation considering food web structure and species population dynamics to study the effects of invasions on complex food webs. We find that less complex (i.e., less connected) food webs are more resistant to invasions. Simulated invasions promote profound changes in several food web properties and stability measures, such as decreases in modularity and the number of food chains from basal to top species; and a decoupling of community- and population-level temporal variability. Additionally, species traits such as body size and diet breadth are strong determinants of invasion success across several trophic levels, with larger and more generalist species being more successful invaders in general. Our work complements species-centered invasion studies by adding a more holistic and systematic perspective to the study of invasions on species interaction networks.
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