scholarly journals Directional trends in species composition over time can lead to a widespread overemphasis of year‐to‐year asynchrony

2020 ◽  
Vol 31 (5) ◽  
pp. 792-802 ◽  
Author(s):  
Enrique Valencia ◽  
Francesco de Bello ◽  
Jan Lepš ◽  
Thomas Galland ◽  
Anna E‐Vojtkó ◽  
...  
Keyword(s):  
Species Composition ◽  
Over Time

scholarly journals Ichthyological Differentiation and Homogenization in the Pánuco Basin, Mexico

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 187 ◽  
Author(s):  
Norma Martínez-Lendech ◽  
Ana P. Martínez-Falcón ◽  
Juan Jacobo Schmitter-Soto ◽  
Humberto Mejía-Mojica ◽  
Valentino Sorani-Dalbón ◽  
...  
Keyword(s):  
Species Composition ◽  
Native Species ◽  
Ecosystem Change ◽  
Species Introductions ◽  
Fish Collection ◽  
Species Groups ◽  
Conservation Concern ◽  
Key Aspects ◽  
Independent Species ◽  
Over Time

Species introductions and extirpations are key aspects of aquatic ecosystem change that need to be examined at large geographic and temporal scales. The Pánuco Basin (Eastern Mexico) has high ichthyological diversity and ecological heterogeneity. However, freshwater fish (FWF) introductions and extirpations since the mid-1900s have modified species range and distribution. We examine changes in FWF species composition in and among four sub-basins of the Pánuco by comparing fish collection records pre-1980 to 2018. Currently, the FWF of the Pánuco includes 95 species. Fishes in the Poeciliidae, Cyprinidae, and Cichlidae, respectively, comprised most records over time. Significant differences in species composition were found between the first (pre-1980) and last (2011–2018) study periods, but not for periods in-between. Eight independent species groups were key for explaining changes in Pánuco river ichthyofauna; one group was dominated by invasive species, and saw increases in the number of records across study periods (faunal homogenization). Another group was formed by species with conservation concern with a declining number of records over time. Thirteen (2 native and 11 non-native) species were responsible for temporal turnover. These results strongly suggest high rates of differentiation over time (via native species loss) following widespread non-native species introductions.

Mites in dried figs of Turkey: diversity, species composition and density

2019 ◽  
Vol 24 (6) ◽  
pp. 992-997 ◽  
Author(s):  
Hulya Dizlek ◽  
Mehmet Karagoz ◽  
Farid Faraji ◽  
Ibrahim Cakmak
Keyword(s):  
Species Composition ◽  
Mite Species ◽  
Predatory Mite ◽  
Infestation Rate ◽  
Pest Species ◽  
Tyrophagus Putrescentiae ◽  
Acarus Siro ◽  
Blattisocius Tarsalis ◽  
Cheyletus Eruditus ◽  
Over Time

This study was conducted to determine mite species in dried figs in Aydin, Turkey between August 2014 and November 2016. A total of 141 dried fig samples were taken from producers’ storage, commercial storages and fig processing factories in Buharkent, Germencik, Incirliova, Kocarli, Kosk, Kuyucak, Merkez, Nazilli, Sultanhisar and Yenipazar districts. In addition, 24 dried fig samples were kept in storage for 8 months and the changes in mite species composition and their densities in stored figs were determined. As a result, 8 mite species belonging to 3 orders and 5 families were identified from the dried figs. Acarus siro L., Carpoglyphus lactis (L.), Glycyphagus destructor (Schrank), G. domesticus (De Geer) and Tyrophagus putrescentiae (Schrank) as pest species, and Blattisocius tarsalis (Berlese), B. mali (Oudemans) and Cheyletus eruditus (Schrank) as predatory mite species were found. Out of 141 samples, 133 were infested with mites and the infestation ratio was 94.3%. Tyrophagus putrescentiae was the most common pest species with an infestation rate of 72.3%, followed by C. lactis with 34.8%, A. siro, G. destructor and G. domesticus with 0.7% contamination, respectively. Carpoglyphus lactis was found to have the highest density with 10,488 individuals/kg in contaminated fig samples. Blattisocius tarsalis was the most common predatory mite species with an infestation rate of 77.3%. Blattisocius mali and C. eruditus were found in 9.2% and 4.3% of dried figs, respectively. This study showed that the dried fig samples kept in storage were always vulnerable to contamination with mites. Mite species composition and their densities also fluctuated over time.

scholarly journals Richness and zoogeography of ascidians (Tunicata: Ascidiacea) in eastern Canada

2017 ◽  
Vol 95 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Kevin C.K. Ma ◽  
Don Deibel ◽  
Kenneth K.M. Law ◽  
Mai Aoki ◽  
Cynthia H. McKenzie ◽  
...  
Keyword(s):  
Species Composition ◽  
Nonindigenous Species ◽  
Indigenous Species ◽  
Eastern Canada ◽  
Online Databases ◽  
Invading Species ◽  
Over Time

Managers and policymakers in eastern Canada embrace science-based management of nonindigenous species and may benefit from having comprehensive regional species checklists at subnational jurisdictional levels. In this paper, regional checklists provide an account of the richness of ascidians in eastern Canada. Records of 58 ascidians resulted from reviewing 108 published sources, accessing data from two online databases, and collecting some common indigenous ascidian specimens. Analysis comparing the similarity of species among nine regions indicates that there is greater similarity in species composition between contiguous regions than between noncontiguous regions and suggests that there are four zoogeographic clusters in eastern Canada. Our checklists can inform managers and policymakers of the diversity of the ascidian taxa and can minimize taxonomic uncertainties of established nonindigenous and prospective invading species, for example, by identifying indigenous species that are congeners of nonindigenous species. The maintenance of checklists can be a valuable tool for the management of nonindigenous species as baselines to estimate changes in richness and to document the invasion status of nonindigenous species over time. For example, more importance can be placed on the spread of nonindigenous ascidians from one zoogeographic cluster to another than spread within the same cluster.

Restoration for Resistance to Invasion by Giant Reed (Arundo donax)

2009 ◽  
Vol 2 (4) ◽  
pp. 279-291 ◽  
Author(s):  
Lauren D. Quinn ◽  
Jodie S. Holt
Keyword(s):  
Species Composition ◽  
Community Composition ◽  
Environmental Parameters ◽  
Invasion Success ◽  
Giant Reed ◽  
Planting Density ◽  
Late Winter ◽  
Community Resistance ◽  
Natural Recruitment ◽  
Over Time

AbstractThe relationship between plant community composition and invasibility has been studied extensively but seldom in the context of ecosystem restoration. Experimental riparian restoration plots differing in species composition and density were established and evaluated for susceptibility to invasion by giant reed, a common riparian invader in California, and natural recruitment by riparian species over time. Plots were planted in 2002 with cuttings of common threesquare (a sedge), seepwillow (a shrub), and Goodding's willow (a tree) at two densities in monoculture and all possible mixture combinations. Giant reed rhizomes were introduced into half of the plots in the spring of 2003, while the remaining plots were allowed to undergo natural recruitment for an additional year. In late winter 2004, giant reed rhizomes were planted in the remaining plots. Both planting groups were followed for one growing season to evaluate giant reed establishment, survival, and growth. Community composition affected giant reed performance, particularly in 2003 before natural recruitment occurred. In that year, plots containing seepwillow + willow had the lowest giant reed shoot production, growth, and survival. All plots containing seepwillow were resistant to colonization by natural recruitment in 2004, but none of the planting treatments affected giant reed success in that year. Giant reed was more successful overall in 2004 despite deeper shade and drier soils. This pattern could be attributed to larger initial rhizome size in 2004, which allowed giant reed to overcome environmental stress during establishment. Planting density did not impact giant reed or natural recruitment independently, but may affect environmental parameters and warrants further study as a potential contributor to restoration success. Our results indicate that choice of species composition in restoration might impact giant reed invasion success initially, but community resistance might not be sustainable and maintenance-free over time.

scholarly journals Sampling efficiency of a protocol to measure Odonata diversity in tropical streams

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248216
Author(s):  
Joana Darc Batista ◽  
Victor Rennan Santos Ferreira ◽  
Helena Soares Ramos Cabette ◽  
Lourivaldo Amancio de Castro ◽  
Paulo De Marco ◽  
...  
Keyword(s):  
Species Composition ◽  
Environmental Monitoring ◽  
Sampling Effort ◽  
Sampling Efficiency ◽  
Sampling Protocol ◽  
Future Studies ◽  
Different Types ◽  
Local Species ◽  
Over Time ◽  
Local Species Pool

Odonata can be sampled following different types of protocols. In Brazil, the most used protocol is the scanning in fixed areas method, where a 100-meter transect is delimited in one of the stream margins, subdivided into 20 segments measuring 5 meters. Despite being universally used, the methodological efficiency or limitations of this protocol for Odonata has never been tested. In this scenario, our objective was to assess the efficiency of the sampling protocol to measure the richness and composition of Odonata in three fundamental aspects: the time of sampling and sampling effort over time and space. We show that the best sampling efficiency was achieved in collections performed at noon, in transects measuring 100 meters, requiring at least two samplings in the same location, supporting the procedures traditionally adopted by many studies with the group. While comparing species composition, we did not see any implication between the different treatments on the capture of the local species pool. However, we highlight and discuss some possible methodological flaws when using this protocol to sample specific Odonata groups. We believe the results obtained are fundamental in the inventory of species and to conduct future studies, as well as to aid conservative measures that use the order Odonata as a tool for environmental monitoring.

scholarly journals Bryophyte Conservation in Managed Boreal Landscapes: Fourteen-Year Impacts of Partial Cuts on Epixylic Bryophytes

2021 ◽  
Vol 4 ◽  
Author(s):  
Jeffrey Opoku-Nyame ◽  
Alain Leduc ◽  
Nicole J. Fenton
Keyword(s):  
Species Composition ◽  
Coarse Woody Debris ◽  
Black Spruce ◽  
Woody Debris ◽  
Permanent Plots ◽  
Old Growth ◽  
Clear Cut ◽  
Old Growth Forest ◽  
Old Growth Forests ◽  
Over Time

Clear cut harvest simplifies and eliminates old growth forest structure, negatively impacting biodiversity. Partial cut harvest has been hypothesized (1) to have less impact on biodiversity than clear cut harvest, and (2) to encourage old growth forest structures. Long-term studies are required to test this hypothesis as most studies are conducted soon after harvest. Using epixylic bryophytes as indicators, this study addresses this knowledge gap. Fourteen years after harvest, we examined changes in epixylic bryophyte community composition richness and traits, and their microhabitats (coarse woody debris characteristics and microclimate) along an unharvested, partial cuts and clear cuts harvest treatment in 30 permanent plots established in the boreal black spruce (Picea mariana) forests of northwestern Quebec, Canada. Our results were compared to those of an initial post-harvest study (year 5) and to a chronosequence of old growth forests to examine species changes over time and the similarity of bryophyte communities in partial cut and old growth forests. Coarse woody debris (CWD) volume by decay class varied among harvest treatments with partial cuts and clear cuts recording lower volumes of early decay CWD. The epixylic community was richer in partial cuts than in mature unharvested forests and clear cuts. In addition, species richness and overall abundance doubled in partial and clear cuts between years 5 and 14. Species composition also differed among treatments between years 5 and 14. Furthermore, conditions in partial cut stands supported small, drought sensitive, and old growth confined species that are threatened by conditions in clear cut stands. Lastly, over time, species composition in partial cuts became more similar to old growth forests. Partial cuts reduced harvest impacts by continuing to provide favorable microhabitat conditions that support epixylic bryophytes. Also, partial cut harvest has the potential to encourage old growth species assemblages, which has been a major concern for biodiversity conservation in managed forest landscapes. Our findings support the promotion of partial cut harvest as an effective strategy to achieve species and habitat conservation goals.

Container Type Affects Mosquito (Diptera: Culicidae) Oviposition Choice

2020 ◽  
Vol 57 (5) ◽  
pp. 1459-1467
Author(s):  
Allison T Parker ◽  
Kelsey McGill ◽  
Brian F Allan
Keyword(s):  
Species Composition ◽  
Mosquito Species ◽  
Habitat Preferences ◽  
Oviposition Preference ◽  
Oviposition Choice ◽  
Source Reduction ◽  
Incomplete Removal ◽  
Wide Range ◽  
Over Time ◽  
Container Habitats

Abstract Larvae of container-breeding mosquitoes develop in a wide range of container habitats found in residential neighborhoods. Different mosquito species may exhibit preference for different container types and sizes. Due to phenological differences, species composition in container habitats may change over time. We first conducted weekly neighborhood container surveys to determine the types of container habitats found in residential neighborhoods, and to determine mosquito species composition over time within these habitats. We then conducted an oviposition choice field assay to determine whether female mosquitoes of different species preferentially oviposit in different container types commonly found in neighborhoods. Halfway through the experiment, the largest container was removed at half the sites to test the hypothesis that incomplete source reduction alters oviposition preference among the remaining containers. In the neighborhood surveys, large containers had the greatest mosquito densities and the highest species richness. Aedes albopictus (Skuse), the most commonly collected mosquito, was found in all container types. The oviposition experiment indicated that Culex spp. females preferentially oviposit in large containers. When the largest container was removed, the total number of egg rafts decreased. Aedes spp. females preferred to oviposit in large- and medium-sized containers, but the total number of eggs laid did not change when the large container was removed. These results confirm that understanding habitat preferences of container-breeding mosquitoes is important to control efforts targeting vector species and that incomplete removal of container habitats may have unpredictable consequences for the distribution of juveniles among remaining habitats.

Long-term changes of epiphytic lichen species composition over landscape gradients: an 18 year time series

2008 ◽  
Vol 40 (05) ◽  
pp. 437-448 ◽  
Author(s):  
Jiří LIŠKA ◽  
Tomáš HERBEN
Keyword(s):  
Air Pollution ◽  
Species Composition ◽  
Pollution Sources ◽  
Rate Of Change ◽  
Lichen Species ◽  
Tree Bark ◽  
Data Set ◽  
Local Conditions ◽  
Epiphytic Lichen ◽  
Over Time

Abstract:The study aimed to determine how the response of the epiphytic lichen vegetation to sulphur air pollution is affected by interaction with other factors (distance from pollution sources, habitat, altitude, initial eutrophication of the tree bark). It was based on a series of four successive recordings taken over a period of 18 years with increasing pollution levels and on the same set of 139 solitary trees. Relationships between habitat variables and lichen community composition are assessed using canonical correspondence analysis. The data set comprised 69 lichen species. Ordination of initial species composition on trees revealed two major gradients: eutrophication and acidity.The species composition significantly changed with time, with a general decrease of the total number of lichen species per tree. In general, species sensitive to air pollution decreased, while tolerant species increased in number. Change over time differed depending on the position of the tree within the landscape (relative to one major source of pollution, the town of Tábor, whereas the distance to the other source, Sezimovo Ústí, was not significant) and on the initial species composition found on the tree. Trees under the effect of eutrophication changed their species composition less, indicating that the effect of eutrophication (mainly increased bark pH) may ameliorate the effects of air pollution; a local effect of eutrophication also seems to play an important role. Distance to pollution sources had only a small impact on the rate of change and perhaps other local conditions (sheltered or humid position, altitude) play a role in this interaction. There was a decrease of the overall heterogeneity of the data set over time. This means that the gradients in species composition attributable to these variables became less important over time. Therefore, one of the effects of air pollution is also a general homogenization of the lichen vegetation of the solitary trees.

Changes in species composition of the demersal fish community in nearshore waters of Kodiak Island, Alaska

2000 ◽  
Vol 57 (6) ◽  
pp. 1169-1180 ◽  
Author(s):  
Franz J Mueter ◽  
Brenda L Norcross
Keyword(s):  
Species Composition ◽  
Major Part ◽  
Fish Community ◽  
Demersal Fish ◽  
Trawl Survey ◽  
Data Set ◽  
Forage Fishes ◽  
Kodiak Island ◽  
Trends Over Time ◽  
Over Time

We examined the species composition of the demersal fish and shrimp community in seven different areas in the nearshore waters of Kodiak Island based on trawl survey data. A major part of the variability in the data set was attributed to trends over time, indicating a significant change in species composition in the early 1980s. Results agree with work by others and show a shift from a community dominated by shrimp and small forage fishes to one dominated by large piscivorous gadid and flatfish species. The shift occurred rather abruptly in most areas between 1980 and 1982, but the pattern of change differed significantly among areas. Correlations between trends in the two groups of species were weak but were consistent with the hypothesis that the decline in shrimp and forage fishes followed, rather than preceded, the increase in large piscivorous fishes. The results suggest predation as a possible mechanism to explain the observed changes.

scholarly journals Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance

2016 ◽  
Vol 55 (1) ◽  
pp. 47-62 ◽  
Author(s):  
M. Walsh ◽  
J.P. Hanrahan ◽  
L. O’Malley ◽  
R. Moles
Keyword(s):  
Species Composition ◽  
Ground Cover ◽  
Ground Level ◽  
Bare Soil ◽  
Performance Criteria ◽  
Individual Plant ◽  
Negative Consequences ◽  
Blanket Bog ◽  
Ewe Lamb ◽  
Over Time

Abstract The frequency of individual plant species at ground level and the species composition of the unimproved vegetation on a western hill farm, stocked with Scottish Blackface sheep, were monitored from 1995 to 2008. Performance criteria of the flock that relied totally, or almost totally, on this vegetation for sustenance from 1994 to 2011 were evaluated. The frequency of vegetation increased over time (from 65% to 82% of the surface area; P < 0.05), with a corresponding decline in the frequency of bare soil, thus reducing vulnerability to soil erosion. This increased incidence of vegetation cover reflected increases in ‘other forbs’(P < 0.01), heather(P < 0.05)and grass (P < 0.08).A significant change (P < 0.05) also occurred in the species composition of the vegetation, reflecting an increase in the proportions of ‘other forbs’ (P < 0.05) and heather (P = 0.14), and a decline in the proportion of sedges (P = 0.14). A similar pattern occurred in the two main habitats: blanket bog and wet heath. Annual stocking rate (ewes per hectare, based on actual ewe grazing days) on the unimproved hill grazing averaged 0.9 (0.13 livestock units) per hectare prior to 1999 and 0.78 (0.11 livestock units) per hectare subsequently. There was no trend in weight gain of replacement females while confined to the unimproved hill area between weaning (14 weeks old) and first joining at 18 months of age. A negative trend (P < 0.01) occurred in the pre-weaning growth rate of lambs on the hill. The average number of lambs reared per ewe joined (reflecting fertility, litter size and ewe/lamb mortality) was 1.0, and this showed no evidence of change over time. The study flock performed 10% to > 60% better, depending on the variable, than similar flocks in the National Farm Survey at comparable stocking rates. A well-defined rational management system can sustain a productive sheep enterprise on unimproved hill land without negative consequences for the frequency or composition of the vegetation.

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