Reduced Species Richness Research Articles

Systematic Review: The Gut Microbiome and Its Potential Clinical Application in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing–remitting systemic disease of the gastrointestinal tract. It is well established that the gut microbiome has a profound impact on IBD pathogenesis. Our aim was to systematically review the literature on the IBD gut microbiome and its usefulness to provide microbiome-based biomarkers. A systematic search of the online bibliographic database PubMed from inception to August 2020 with screening in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. One-hundred and forty-four papers were eligible for inclusion. There was a wide heterogeneity in microbiome analysis methods or experimental design. The IBD intestinal microbiome was generally characterized by reduced species richness and diversity, and lower temporal stability, while changes in the gut microbiome seemed to play a pivotal role in determining the onset of IBD. Multiple studies have identified certain microbial taxa that are enriched or depleted in IBD, including bacteria, fungi, viruses, and archaea. The two main features in this sense are the decrease in beneficial bacteria and the increase in pathogenic bacteria. Significant differences were also present between remission and relapse IBD status. Shifts in gut microbial community composition and abundance have proven to be valuable as diagnostic biomarkers. The gut microbiome plays a major role in IBD, yet studies need to go from casualty to causality. Longitudinal designs including newly diagnosed treatment-naïve patients are needed to provide insights into the role of microbes in the onset of intestinal inflammation. A better understanding of the human gut microbiome could provide innovative targets for diagnosis, prognosis, treatment and even cure of this relevant disease.

Buzzing Homes: Using Citizen Science Data to Explore the Effects of Urbanization on Indoor Mosquito Communities.

Simple SummaryMany mosquito species can transmit pathogens and may pose a risk to human health. With increasing urbanization and alteration of natural habitats, the composition of mosquito communities is changing, with some species thriving particularly well in and adjacent to human settlements. In the present study, indoor mosquito collections submitted to the citizen science project ‘Mückenatlas’ were used to investigate the composition, abundance, and diversity of species of different urbanization levels, and to detect preferences for less or more urbanized areas. We found that species richness and diversity decreases with increasing urbanization, and some important vector species are captured most frequently in densely urbanized regions. Our results highlight the importance of long-term mosquito monitoring to learn how these vectors respond to habitat change caused by humans. Only with sufficient knowledge about the ecology of mosquitoes can we assess risks, plan counter strategies, and take action.Urbanization has been associated with a loss of overall biodiversity and a simultaneous increase in the abundance of a few species that thrive in urban habitats, such as highly adaptable mosquito vectors. To better understand how mosquito communities differ between levels of urbanization, we analyzed mosquito samples from inside private homes submitted to the citizen science project ‘Mückenatlas’. Applying two urbanization indicators based on soil sealing and human population density, we compared species composition and diversity at, and preferences towards, different urbanization levels. Species composition between groups of lowest and highest levels of urbanization differed significantly, which was presumably caused by reduced species richness and the dominance of synanthropic mosquito species in urban areas. The genus Anopheles was frequently submitted from areas with a low degree of urbanization, Aedes with a moderate degree, and Culex and Culiseta with a high degree of urbanization. Making use of citizen science data, this first study of indoor mosquito diversity in Germany demonstrated a simplification of communities with increasing urbanization. The dominance of vector-competent species in urban areas poses a potential risk of epidemics of mosquito-borne diseases that can only be contained by a permanent monitoring of mosquitoes and by acquiring a deeper knowledge about how anthropogenic activities affect vector ecology.

Evolutionary simulations clarify and reconcile biodiversity-disturbance models.

There is significant geographic variation in species richness. However, the nature of the underlying relationships, such as that between species richness and environmental stability, remains unclear. The stability-time hypothesis suggests that environmental instability reduces species richness by suppressing speciation and increasing extinction risk. By contrast, the patch-mosaic hypothesis suggests that small-scale environmental instability can increase species richness by providing a steady supply of non-equilibrium environments. Although these hypotheses are often applied to different time scales, their core mechanisms are in conflict. Reconciling these apparently competing hypotheses is key to understanding how environmental conditions shape the distribution of biodiversity. Here, we use REvoSim, an individual-based, eco-evolutionary system, to model the evolution of sessile organisms in environments with varying magnitudes and scales of environmental instability. We demonstrate that when environments have substantial permanent heterogeneity, a high level of localized environmental instability reduces biodiversity, whereas in environments lacking permanent heterogeneity, high levels of localized instability increase biodiversity. By contrast, broad-scale environmental instability, acting on the same time scale, invariably reduces biodiversity. Our results provide a new view of the biodiversity–disturbance relationship that reconciles contrasting hypotheses within a single model and implies constraints on the environmental conditions under which those hypotheses apply. These constraints can inform attempts to conserve adaptive potential in different environments during the current biodiversity crisis.

Differential effects of nutrient addition and woody plant encroachment on grassland soil, litter and plant dynamics across a precipitation gradient

Interactions between woody plant encroachment and nutrient availability may vary along precipitation gradients. Furthermore, with predicted increases in N deposition due to increasing industrial emissions and changes in land use, potential increases in N storage and cycling are expected. We conducted a two-year field experiment that tested whether nitrogen (N) and phosphorus (P) addition and woody plant encroachment had independent effects on grasslands along a precipitation gradient. We added these nutrients to adjacent encroached and open grasslands (ranging from 300 to 1500 mm mean annual precipitation). We compared differential responses to fertilizer addition and encroachment in terms of soil N stocks and soil P, litter % N and C:N ratio (index of decomposition), plant productivity and species richness. In addition, we determined whether there were trends in responses to increased nutrient availability for encroached versus open grasslands across the above-mentioned precipitation gradient. Soil N stocks were on average 15 times higher in the high precipitation sites regardless of nutrient addition or encroachment status. Larger variation in soil P was noted at the high precipitation sites, with some evidence of P-limitation in the encroached area with the highest precipitation. Fertilization increased grass biomass and reduced species richness in the high precipitation sites only. Overall, increased nutrient availability was found to be of importance in high precipitation sites only, possibly due to water scarcity at the low precipitation sites. We found significant positive effects of encroachment on litter % N (quality), C:N ratios and forb cover across the precipitation gradient. The purportedly beneficial effects of encroachment on litter and plant species richness was more pronounced at the high-precipitation sites.

Together we stand, divided we fall: Effects of livestock grazing on vegetation patches in a desert community

AbstractQuestionsVegetation patches formed by interacting xeric species are the main drivers of dryland structure and function. Plant aggregation enhances microclimatic conditions and triggers abiotic and biotic processes, such as nutrient cycling and accumulation, and species interactions. However, vegetation patches may be modified by disturbances in unpredictable ways. We tested whether livestock grazing affects vegetation structure and plant spatial associations in a desert community, by considering the role of plant species in ecological succession.LocationPatagonian Monte Desert, Argentina.MethodsWe used high‐quality standardized photographs along transects to characterize plant community structure (i.e., cover, abundance, richness), spatial patterns (i.e. plant‐plant associations), and classified species based on their successional role (i.e. early, intermediate and late species). We used regression models and network analysis to evaluate the effect of grazing on vegetation.ResultsIn general, grazing modified community structure, reducing total cover, abundance and richness. Grazing modulated community spatial patterns, simplifying and removing vegetation patches. The impact of grazing depended on the species successional role. The abundance and cover of early species were less affected by grazing than intermediate and late species, the latter being the most affected. However, species richness significantly decreased with increasing stocking rates, regardless of their successional role. Late species were present in most plant spatial associations, indicating a major contribution to multi‐specific vegetation patches formation.ConclusionsThe reduction in species richness and low abundance of late species highlights the need to prevent irreversible degradation caused by overgrazing. Late species emerge as key structures of vegetation in desert rangelands facilitating the establishment and protecting other plant species. Due to the critical role of vegetation patches in maintaining desert ecosystem functioning, conservation and management practices should focus on late species, while early species, responsible for vegetation patch formation in overgrazed situations, should be preferred for restoration practices.

Plant community responses to integrating livestock into a reduced‐till organic cropping system

AbstractThe problems with herbicide‐ and tillage‐based weed management in agriculture are well documented and have precipitated research into finding alternatives. Integrating livestock grazing into organic agroecosystems has benefits and is a viable method for terminating cover crops, yet its impacts on weed communities are largely unknown. This lack of knowledge is particularly true in semi‐arid environments, including the Northern Great Plains, where we conducted our research. We compared weed community responses (biomass, species richness, Simpson’s diversity, composition) of a sheep‐grazed organic cropping system with those of two contrasting cropping systems (high input conventional no‐till, tilled organic) across a five‐year crop rotation (safflower, sweet clover, winter wheat, lentils, winter wheat). We found that the conventional no‐till and tilled organic systems suppressed weed biomass and reduced species richness and diversity, while the grazed organic resulted in higher weed biomass, species richness, and diversity. During the first two years of the study, the composition of the two organic communities were distinct from the conventional no‐till communities but were indistinguishable from one another. Over the final three years of the study, grazed organic communities were tightly grouped and became distinct from both the tilled and conventional communities. We found that weed biomass and diversity were highest in the sweet clover and lowest in the winter wheat. The spring annual crops, safflower and lentil, demonstrated similar weed biomass, species richness, and composition. Our findings indicate that integrating livestock into cropping systems alters plant communities and increases the agroecosystem plant biodiversity of semi‐arid organic farming and that specific crops interact with cropping systems to alter agroecosystem plant communities. However, the increase in weed biomass associated with our grazing treatment makes this approach impractical as the sole weed management strategy and necessitates that integrating livestock into semi‐arid organic cropping systems must be part of a larger integrated weed management program.

Warming drives cryptic declines of amphibians in eastern Brazil

The global amphibian extinction crisis has challenged scientists around the globe for decades. Robust long-term time-series data to detect such population declines are key to understanding how species respond to climatic variations. Thus, we assessed the species' richness and abundance of an anuran assemblage in the Atlantic Forest in Brazil, where average temperatures were rising over the last 30 years. A series of models were applied to a long time-series of amphibian standardized monitoring (2010–2019) to assess the impact of a combination of a series of local climatic factors, and species life-history traits, to detect any variation on species abundance and richness. We observed a significant reduction in species abundance and a trend of reduction in species richness over time. Temperature had a stronger influence on species abundance and richness compared to precipitation. Furthermore, the most resilient species were generalist and peri-anthropic ones. Although more robust data is needed to pinpoint climate change-related variation on species decline, anticipating amphibian sensitivity to climate shift, and the limited time to act, our results are concerning. We suggest further studies to evaluate other aspects that could be influencing this local population decline and highlights that a broader amphibian monitoring program should be implemented in the Atlantic forest to detect other equally silent gradual declines.

The composition of the gut microbiome differs among community dwelling older people with good and poor appetite.

BackgroundAnorexia of ageing is common and important in the development of sarcopenia in older individuals. Links have been proposed between the gut microbiota and sarcopenia. Disordered gut function is also recognized in anorexia of ageing, but how this may relate to resident gut microbiota is unexplored. Understanding this relationship may provide a basis for novel interventions for anorexia of ageing and sarcopenia. This study explores compositional differences of the gut microbiota between community dwelling healthy older adults with good or poor appetite, and associated differences in sarcopenia.MethodsWe assessed appetite by the Simplified Nutritional Appetite Questionnaire (SNAQ) in members of the TwinsUK cohort aged ≥65 years. Using a pool of 776 individuals with existing microbiome data estimated from 16S rRNA sequencing data, we identified 102 cases (SNAQ score < 14) (95% female, mean age 68 years) matched to controls (SNAQ > 14) on body mass index, gender, age, diet, calorie consumption, frailty, antibiotic use, socio‐economic status, and technical variables to minimize confounding microbiota associations. Species abundance and diversity, compositional differences, and paired differences in taxa abundance were compared between cases and controls. Additionally, we compared case and controls for sarcopenia as measured by muscle mass (appendicular lean mass/height2) and strength (chair stand time in seconds).ResultsCases with poor appetite had reduced species richness and diversity of their gut microbiome (adjusted OBSERVED: beta = −0.2, P < 0.001; adjusted SHANNON: beta = −0.17, P = 0.0135), significant compositional differences (adjusted non‐parametric multivariate analysis of variance, P = 0.0095), and significant differences in taxa abundance including reduction of genus Lachnospira (logFC = −1.015, q = 0.023). In all‐female subgroup analysis, cases with poor appetite demonstrated reduction in muscle strength (11.03 s vs. 9.26 s, P = 0.02).ConclusionsThis study is the first to observe differences in the composition of gut microbiota between healthy community dwelling older individuals with good and poor appetite. We found female individuals with reduced muscle strength had poor appetite compared with those with normal strength. These associations require further examination to understand causality and mechanisms of interaction, to inform potential strategies targeting the gut microbiota as a novel intervention for anorexia of ageing and sarcopenia.

Mega-dams and extreme rainfall: Disentangling the drivers of extensive impacts of a large flooding event on Amazon Forests.

Extreme weather events and the presence of mega-hydroelectric dams, when combined, present an emerging threat to natural habitats in the Amazon region. To understand the magnitude of these impacts, we used remote sensing data to assess forest loss in areas affected by the extreme 2014 flood in the entire Madeira River basin, the location of two mega-dams. In addition, forest plots (26 ha) were monitored between 2011 and 2015 (14,328 trees) in order to evaluate changes in tree mortality, aboveground biomass (AGB), species composition and community structure around the Jirau reservoir (distance between plots varies from 1 to 80 km). We showed that the mega-dams were the main driver of tree mortality in Madeira basin forests after the 2014 extreme flood. Forest loss in the areas surrounding the reservoirs was 56 km2 in Santo Antônio, 190 km2 in Jirau (7.4–9.2% of the forest cover before flooding), and 79.9% above that predicted in environmental impact assessments. We also show that climatic anomalies, albeit with much smaller impact than that created by the mega-dams, resulted in forest loss along different Madeira sub-basins not affected by dams (34–173 km2; 0.5–1.7%). The impact of flooding was greater in várzea and transitional forests, resulting in high rates of tree mortality (88–100%), AGB decrease (89–100%), and reduction of species richness (78–100%). Conversely, campinarana forests were more flood-tolerant with a slight decrease in species richness (6%) and similar AGB after flooding. Taking together satellite and field measurements, we estimate that the 2014 flood event in the Madeira basin resulted in 8.81–12.47 ∙ 106 tons of dead biomass. Environmental impact studies required for environmental licensing of mega-dams by governmental agencies should consider the increasing trend of climatic anomalies and the high vulnerability of different habitats to minimize the serious impacts of dams on Amazonian biodiversity and carbon stocks.

Gut microbiota and motoric-cognitive frailty in hospitalized older persons.

In older people, many systems spontaneously change without diseases. Because of the ageing process, the gut microbiota undergoes a reduced species richness, altered balance between species, with an increased interindividual variability. The result is the reduced resilience in the presence of diseases and medications. These changes are more evident in older persons with neurodegenerative diseases and cognitive-motoric frailty. A relationship between liver alteration, gut microbiota and the presence of viruses and gram-bacteria is conceivable. They determine the acceleration of neurodegenerative diseases with cognitive and motoric frailty. Hospitalization represents one of the stressors for the gut microbiota, producing dysbiosis and increasing the representation of pathobionts. The gut microbiota alterations during hospitalization may be associated with negative clinical outcomes. This phenomenon together with liver dysfunction could produce an acceleration of the trajectory of cognitive-motoric frailty towards disability and mortality. The observation that predisability is associated of both losses of cognition and motoric performance, has allowed introducing a new syndrome, the motoric-cognitive risk syndrome, which is a condition of increased risk of dementia and mobility-disability. The interaction between liver and gut microbiota may accelerate the neurodegenerative diseases and represents a promising marker of prognostic trajectories in older patients.

Immediate effects of the 2019 oil spill on the macrobenthic fauna associated with macroalgae on the tropical coast of Brazil

The 2019–2020 Brazil oil spill disaster affected several ecosystems and species-rich areas. The shallow-water reefs of Paiva beach are among the best-preserved coastal environments in the State of Pernambuco (NE Brazil), but were severely affected by oil arrival at the end of 2019. The reefs are densely covered by macroalgae as important biogenic substrates for benthic fauna. Based on that, herein, we provide a baseline assessment of the immediate impacts of the oil spill on the structure of epifaunal communities associated with the algae Jania capillacea and Penicillus capitatus. The benthic communities in both algae simplified (reduction of species richness and abundance) soon after oil arrival, while opportunistic taxa increased. After two months, the macrofaunal communities restructured to almost pre-disaster levels. However, polychaeta diversity remained low. Despite the apparently fast recovery of reef macrobenthos, a more detailed, long-term monitoring is necessary to evaluate the chronic effects.

Continental‐scale 1 km hummingbird diversity derived from fusing point records with lateral and elevational expert information

Anthropogenic change is affecting mountain regions worldwide. Managing this change and advancing biodiversity information for research requires spatially detailed information on species distributions which often is incomplete. Here, we provide a model‐based approach for the integration of expert‐based elevational range information with expert range maps and point occurrences to address this need. These integrated models use expert knowledge on elevational and distributional ranges as offset in a Poisson point process species distribution model (SDM). We use this approach to model the distribution of 276 hummingbird Trochilidae species at 1 km resolution and validate model performance with extensive survey data (presence–absence inventories). Models including expert elevation information consistently outperformed those lacking this information. Improvements were greatest when the number of available occurrences was small, highlighting the added value from expert elevation information, especially for data‐poor species. Separate validation data indicated significant increases in true skill statistics, based on higher specificity and slightly improved sensitivity. SDMs that included expert range information out‐performed presence‐only models based only on occurrence data in 92.5% of cases and had higher sensitivity, lower false positive rates and smaller predicted range sizes. Generally, the integrated models removed unsuitable areas from range estimates and decreased overestimates in geographic range size (false presences) inherent in expert maps and in models lacking elevation information. By stacking SDM output we provide a first, hemispheric map of predicted hummingbird species richness modelled at 1 km resolution and identify southwest Colombia as a richness hotspot. Our study highlights the value gained from integrating multiple data types in a single framework. The presented approach improved high‐resolution range predictions for single species (reducing false presences) and aggregate biodiversity patterns (e.g. reducing species richness overestimates). The method is now being implemented and expanded in Map of Life.

Seasonal impoundment alters patterns of tidal wetland plant diversity across spatial scales

AbstractUnderstanding patterns of biodiversity is a key goal of ecology and is especially pressing in the current human‐caused biodiversity crisis. In wetland ecosystems, human impacts are centered around hydrologic manipulation including the common practice of wetland diking and impoundment. Constraining how wetland management influences plant biodiversity patterns across spatial scales will provide information on how best to modify actions to preserve biodiversity and ecosystem function in managed wetlands. Here, we compare patterns of plant diversity and species presence, abundance, and community composition at several spatial scales among tidal wetlands along an estuarine salinity gradient and managed wetlands that were formerly tidal. Managed impounded wetlands had decreased alpha and gamma diversity of rare species, with less than 60% of the species richness found in tidal brackish wetlands at several spatial scales. There was little change in the overall pattern of alpha, beta, and gamma diversity for common species in impounded wetlands; however, dominant tidal brackish species, primarily perennial rhizomatous graminoids, were replaced with management target plants and non‐native annual grasses in impounded wetlands. This species replacement led to over 60% of impounded sites being classified as containing novel plant assemblages. An additional 25% of impounded sites were classified as containing tidal saline plant assemblages, suggesting potential soil salinization. Along the estuarine gradient, patchiness and codominance of common plant species drove high diversity and turnover in tidal brackish wetlands, while it remains unclear whether tidal fresh or brackish wetlands maximize rare plant diversity. With reduced species richness, altered functional dominants, and novel or saline assemblages, impounded brackish wetlands may require careful water management to balance native plant biodiversity, associated ecosystem processes, and waterfowl requirements.

Freshwater gastropod richness patterns along an urbanization gradient in tropical India

Abstract Data on the urbanization impact on freshwater biota and ecosystem function are limited from many developing countries despite being recognized as a driver for biodiversity loss. To study these impacts, we analysed the species richness and diversity patterns of freshwater gastropods along a gradient of urbanization in a river system around Pune city, India. We observed a significant reduction in species richness, faunal similarity and an increased proportion of non-native species with increasing urbanization. These impacts were prominent in highly urbanized sites of the rivers suggesting biotic homogenization. Our results underscore the great impacts of urbanization on freshwater biota, highlighting the need for further studies in developing regions.

Alarming decline of bovids in Kasanka National Park, Zambia: A case study of the puku antelope (Kobus vardonii)

AbstractKnowledge about antelope populations and their status is a key for conservation. In November 2019, we used distance sampling to perform a re‐survey of the bovid species in Kasanka National Park, Zambia, with a focus on the puku (Kobus vardonii). Data collection and subsequent analyses were of the same design as in a previous survey in 2009–2010. This allowed for the direct comparison between survey periods, especially for the data collected in November 2010 and 2019. The estimated puku population size decreased from 5,038 (range 3,268–7,238) animals in 2009–2010 to 819 (range 250–2,708) animals in 2019, representing an 84% decline. Smaller group sizes were observed. Changes in population structure (decline in male abundance, fewer male groups) and spatial distribution (decline in population density, especially along the park boundaries) of puku showed signs of increased poaching activities in Kasanka National Park. Also, puku became more vigilant and demonstrated significantly longer flight distances in 2019 in comparison with 2010. A strong decline in puku in combination with clear signs of poaching, as well as the reduced species richness and sightings of other bovids, should become an agenda for long‐term conservation of Kasanka National Park.

Environmental factors structuring the assemblage of aquatic insects in an epigean and hypogean stretch of a Neotropical karst stream

The aim of the present study was to identify which variables structure the assemblage of aquatic insects in the subterranean environment, because knowledge about how subterranean communities are structured in rivers with hypogean sections is still emerging. In addition to identifying whether the hypogean assemblage is structured in the same way as the epigean assemblage, we sought to identify whether the environmental restrictions caused by the subterranean habitat resulted in reduced species richness and abundance compared with the epigean habitat. We sampled a 345-m stretch of a stream in Brazil and collected aquatic insects from both the epigean and hypogean environments. In the stream stretch investigated, there was a positive relationship between richness and the percentage of immersion, fine substrate and organic matter, and a negative relationship between richness and conductivity. We also verified differences between the epigean and hypogean environments regarding composition. The variables that best explained the overall assemblage structure included the epigean–hypogean environment and the percentage of coarse and fine substrate. Given the differences between these environments, we emphasise the need for management actions in karst regions that consider the discontinuity of these regions’ river communities to conserve all components of diversity.

Introduction of woody and herbaceous legumes influences productivity, diversity and soil properties in a degraded grassland

AbstractMedicago sativa (herbaceous plant) and Caragana korshinskii (woody plant) are the most important legume species planted in semiarid grassland on the Loess Plateau, China. However, the effects of introducing these legumes on the productivity, diversity and soil fertility of native grassland are not well understood. The effects of planting M. sativa and C. korshinskii on the productivity, diversity and soil properties of native grassland on the Loess Plateau were assessed over a 10‐year period. A 20‐ha area of grassland was selected for planting in 2009 and subdivided into 18 1‐ha plots with three treatments: 1) a non‐planted control (GN); 2) M. sativa (GM) and 3)C. korshinskii (GC) both planted individually, with six replicates. Ten subplots were established in each plot from which plant and soil samples were collected in August 2019. Compared with GN, GM and GC increased vegetative cover by 12.1 and 9.0%, respectively. Soil organic carbon (OC), total nitrogen (TN), ammonium nitrogen (NH4+‐N), nitrate‐nitrogen (NO3−‐N) and total phosphorus (TP) were also higher (p &lt;.05) in the GM and GC treatments. Compared with GN, GM had no effect on native grassland productivity but did reduce species richness and evenness. In contrast, GC increased grassland productivity and maintained species richness and evenness. This suggests that C. korshinskii is the preferred legume species for grassland restoration on the Loess Plateau.

Changes in the ceca microbiota of broilers vaccinated for coccidiosis or supplemented with salinomycin

The objective of this study was to characterize differences in the cecal microbiota of chickens vaccinated for coccidiosis or receiving salinomycin in the diet. In this study, 140 male 1-day-old broiler chickens were divided in 2 groups: vaccine group (live vaccine) vaccinated at the first day and salinomycin group (60 ppm/kg since the first day until 35 d of age). Each treatment was composed for 7 replicates of 10 birds per pen. At 28 d, the cecal content of one bird per replicate was collected for microbiota analysis. The genetic sequencing was conducted by the Miseq Illumina platform. Vaccine group showed lower body weight, weight gain, and poorer feed conversion in the total period (P < 0.05). Bacterial 16S rRNA genes were classified as 3 major phyla (Bacteroidetes, Firmicutes, and Proteobacteria), accounting for more than 98% of the total bacterial community. The microbiota complexity in the cecal was estimated based on the α-diversity indices. The vaccine did not reduce species richness and diversity (P > 0.05). The richness distribution in the salinomycin group was larger and more uniform than the vaccinated birds. Salinomycin group was related to the enrichment of Bacteroidetes, whereas Firmicutes and Proteobacteria phyla were in greater proportions in the vaccine group. The last phylum includes a wide variety of pathogenic bacteria. The vaccine did not decrease the species richness but decreased the percentage of Bacteroidetes, a phylum composed by genera that produce short-chain fatty acids improving intestinal health. Vaccine group also had higher Proteobacteria phylum, which may help explain its poorer performance.

Effects of long-term removal of sheep-grazing in a series of British upland plant communities: Insights from plant species composition and traits

Environmental and management pressures are considered a threat for preserving plant communities worldwide. Identification of long-term impacts of changing management practices on plant community composition must, therefore, be a major priority to ensure improvement in conservation value. Land abandonment/wilding is one topical area where there is little available information on long-term impacts. To address this, here, we describe plant species compositional change over relatively long-time scales in a range of four British upland communities (high-level grasslands, intermediate grasslands, blanket bogs and high-level bogs) and its relationships with a series of life-history and plant trait variables. Our aims were to determine whether the business-as-usual sheep grazing practice was maintaining these communities, and if grazing was to be removed as part of abandonment/wilding strategies, would there be a conservation benefit. We used a series of long-term experimental grazing-exclosure studies at twelve sites (>40 years) on the Moor House National Nature Reserve in northern England. Each site consisted of paired plots; i.e. sheep-grazed versus ungrazed. Our results showed that there was relatively little change in dominant plant species with most change occurring within sub-dominant species. Similarly, different temporal responses in plant species richness were detected between the experiments (richness was reduced in three experiments, only one increased). In any case, the vegetation temporal trajectories were moving in similar direction in grazed and ungrazed plots at most sites. Interestingly, blanket bog experiments showed a clear compositional convergence for both grazed and ungrazed plots, although, the between-site differences related to a combination of elevation and past burning testament. Finally, the bryophytes (especially liverworts) and lichens were the groups that contributed most to the reductions in species richness. Moreover, implementation of a no-stock grazing strategy under a land abandonment/wilding approach will not bring about much plant change in the short-term in the plant communities studied here.

Prescribed burning reduces species richness of wood-decay fungi in the forests of northwest Arkansas.

The present study, which was carried out at three localities in the Ozark Mountains of northwest Arkansas, investigated the effects of prescribed burning on wood-decomposing fungi using samples of decaying woody debris (DWD) placed in plastic incubation chambers. One of the localities had not been subjected to recent prescribed burning, whereas the other localities contained both an unburned area as well as an area recently subjected to burning. In all three localities, small pieces of decaying woody debris (DWD) were collected, placed in the incubation chambers and the latter kept moist for any extended period of time. Pieces of DWD collected in the areas subjected to burning typically displayed evidence of considerable charring. Fruiting bodies appearing in the incubation chambers were removed and identified by sequencing of ribosomal DNA region. A total of 101 specimens representing 80 different taxa were recorded in the entire investigation, but the numbers of both specimens and taxa were appreciably higher for the unburned collecting sites. As such, the data obtained indicate that prescribed burning lowers the species richness of the wood-decomposing fungi associated with DWD at a particular locality. The unique aspect of the present study was the use of incubation chambers to characterize the taxa of fungi associated with CWD.