Trends In Species Richness Research Articles

Contrasting vegetation change (1974–2015) in hedgerows and forests in an intensively used agricultural landscape

AbstractQuestionsHow did hedgerows and forests change in area between 1974 and 2015 and did hedgerows still show the same vegetation composition in 2015? To what degree did the vegetation change in hedgerows and how do these changes compare to changes in forests? What is the nature of the species that changed and, from these, can we make general inferences about possible drivers of change?LocationThe countryside in the municipality of Turnhout, province of Antwerp, northern Belgium.MethodsThrough a resurvey of 54 and 20 quasi‐permanent plots in hedgerows and forests, respectively, we investigated shifts in the herb layer over the period 1974–2015. The plot‐level mean Ellenberg Indicator Values (EIVs) were calculated and soil samples were taken in 2015. We compared diversity statistics and used used Generalized Linear Mixed‐Effects Models (GLMMs) to detect trends in species richness (SR) and EIVs. Via a non‐metric multidimensional scaling (NMDS) ordination based on the Sørensen dissimilarity, we compared shifts at the community level.ResultsOur study shows severe, but opposite changes in SR in forests and hedgerows. In forests, SR declined and a homogenization occurred. The shifts in EIVs indicate that forest vegetation evolved to more shade‐tolerant and nutrient‐demanding species, likely due to eutrophication combined with natural forest succession. In hedgerows, SR significantly increased. The species pool became more diverse and more heterogeneous. Changes in EIVs suggest a change towards more light‐demanding species, possibly caused by fragmentation of the network, and towards species indicative for nutrient‐rich habitats, benefiting from eutrophication.ConclusionsIn general, SR in hedgerows is higher than in forests in our studied region, being a suitable habitat for a wide range of plant species in the countryside. However, the loss of almost 30% of the hedgerow habitat in 41 years confronts us with the challenge of protecting the hedgerow remnants, in the interest of agro‐biodiversity.

Factors affecting species richness and distribution spatially and temporally within a protected area using multi‐season occupancy models

AbstractExploring trends in species richness and the distribution of individual species over time as well as the factors affecting these trends informs conservation priorities in protecting species and ecosystems as a whole. We used data from 41 park‐wide line transect surveys in 2009 and 2014 and multi‐season occupancy models with multi‐species data to explore trends in species richness and distribution of individual species and factors affecting these trends in Nyungwe National Park (NNP), Rwanda. Mammalian species richness and the distributional range of 5 of the 7 species increased between 2009 and 2014 in NNP. The probability of colonization of a species into a new area in 2014, where it was not present in 2009, was highest in sites with a lower probability of poaching activity, close to tourist trails, and at lower elevations. The probability of colonization with no poaching activity was about 50% but dropped to about 10% with a 100% chance of poaching activity. Duiker species had the largest increase in distribution during the study, while there was a decrease in the distribution of the eastern chimpanzee and blue monkey. Our results suggest that increased patrols could be implemented in areas of the park with low species richness and areas with a low probability of occurrence for species of conservation concern to combat poaching activity and thus increase the probability of a species moving into a new area. Our use of a single multi‐season model for multiple species explicitly accounts for imperfect detection and species‐specific identities, while allowing for inferences to be made about rarely detected species by sharing covariates with common species. These results can be used to improve conservation planning in NNP for species management and ranger patrol protocols, and our modelling framework is broadly applicable to any protected area with presence/absence species field data.

The strategy for protecting threatened forest species richness in the northeastern China from the effects of climate change

Climate change has the potential to severely threaten the plant species in the forests of northeastern China. The field surveys performed for this study spanned 4 years and identified the endangered species present in the forests of northeastern China. We conducted a detailed investigation of 2,884 study plots and selected 29 nationally protected plant species (sample sizes ≥ 5), namely, threatened species for further analysis. We modelled and mapped the potential distributions of these 29 threatened species, and found that threatened species richness hotspots are currently distributed in the eastern and northeastern areas of the studied region and will move geographically. This study focused on the strategy for protecting threatened forest species richness by analysing the change trend of species richness and planning of priority protection areas due to climate change.

The strategy for protecting threatened forest species richness in northeastern China from the effects of climate change

Climate change has the potential to severely threaten the plant species in the forests of northeastern China. The field surveys performed for this study spanned 4 years and identified the endangered species present in the forests of northeastern China. We conducted a detailed investigation of 2,884 study plots and selected 29 nationally protected plant species (sample sizes ≥ 5), namely, threatened species for further analysis. We modelled and mapped the potential distributions of these 29 threatened species, and found that threatened species richness hotspots are currently distributed in the eastern and northeastern areas of the studied region and will move geographically. This study focused on the strategy for protecting threatened forest species richness by analysing the change trend of species richness and planning of priority protection areas due to climate change.

Spatial and temporal effects of land use change as potential drivers of odonate community composition but not species richness

Land-use changes and land cover change are drivers of diversity. The effects of such drivers over the temporal trend in species richness and composition, particularly on invertebrate diversity in megadiverse countries, is controversial. One key animal group to clarify this controversy is that of odonate insects (dragonflies and damselflies), given their combined close water-land requirements. We have investigated whether changes in land use impact species richness and composition of odonates from 1980 to 1993 (period I) to 1994–2010 (period II) in Mexico. The effect of land use changes and land cover changes on species richness was analyzed using multiple diversity measures and at different spatial scales. In period II, an area reduction in original vegetation and increase in land use occurred. Responses to land use varied among spatial scales and measures of diversity but, overall, species richness in the transformed area was higher than in the original vegetation. However, species composition indicated a high species turnover inside hydrologic regions (watersheds) and across land uses classes, particularly between original and secondary vegetation. Our interpretation is that despite high land use conversion in Mexico, adult odonates seem resilient to land use change in terms of species richness, but not in species composition, which is in partial agreement with the intermediate disturbance hypothesis. Finally, we suggest that hydrologic region scale and use of entropy maximization (HCDT entropy), could provide a reliable biodiversity estimation of species loss associated with land use change.

The use of rarefaction and extrapolation as methods of estimating the effects of river eutrophication on macrophyte diversity

A study was carried out to estimate the effect of trophic degradation on the diversity of aquatic plants in rivers, with the application of rarefaction and extrapolation. The purpose of rarefaction was to standardise the uneven number of samples, while extrapolation enabled prediction of the real diversity considering the expected number of species undetected by the sampling effort. Both methods were based on three Hill’s numbers: q = 0 (species richness), q = 1 (Shannon index) and q = 2 (inverse Simpson index). The macrophyte survey was carried out at 96 river sites of a uniform abiotic type (medium lowland rivers with sandy substrate). Macrophyte diversity was evaluated based on survey data (the reference sample) as well as using a dataset standardised by rarefaction and extrapolation. Trends in species richness along the trophic gradient were depicted differently by analysis based on the reference sample and on the extrapolated dataset. Based on the reference sample, the increases of river trophy led to diminishing macrophyte richness, whereas use of the extrapolated dataset revealed that the highest plant diversity can be found in mesotrophic rivers. The extrapolated dataset showed that most oligotrophic pristine rivers were poorer in species than mesotrophic watercourses, and the most limited pool of macrophytes was found in highly eutrophic watercourses. Rarefaction/extrapolation methods enable the precise comparison of plant diversity across sites, by predicting the occurrence of rare species. Moreover, the extrapolation method allows assesses of the total biodiversity basing on a smaller number of trials (survey samples).

Inter-annual variation in species composition and richness after coppicing in a restored coppice-with-standards forest

AimsCoppice-with-standards (CWS) management was one of the most important disturbances in Central European forests in the past. As our knowledge about the effects of coppicing on species richness and composition needs to be enhanced, we carried out vegetation studies in the currently largest CWS project in Germany. In this article we focus on two issues: 1. Coppicing induced changes and trends in species richness and composition from year to year and 2. Development of species richness and composition in 19 years of CWS restoration. LocationSalzgitter Höhenzug mountains between Liebenburg and Goslar, Lower Saxony, Germany. Climate: subatlantic to subcontinental; soil: Limestone rendzina with low water storage capacity. MethodsIn 2013 we resurveyed the plant species composition of 12 permanent plots analysed every year from 1994 till 2002. The dates of coppicing were recorded for all of these plots, which enabled us to analyse the dynamics of species richness and composition after coppicing on a year to year basis. Differences in species richness and composition were analysed using ANOVA, H-test, DCA and GLMM. ResultsIn 19 years of CWS restoration mean plot species richness increased significantly, mainly attributed to the increase in woody species, such as Quercus robur and Sorbus torminalis. The Ellenberg indicator value for nutrients decreased significantly, whereas the indicator value for light increased significantly. The typical dynamic after coppicing consists of a continuous increase in shrub layer coverage and an increase in herb layer coverage with a maximum in years 3 and 4 after coppicing. Total species richness as well as richness of open habitat and forest species and true forest species also showed an increase with its maximum in years 3 and 4 after coppicing. ConclusionsOur results showed that the alternation of light and shaded phases had a positive impact on species richness, particularly on tree regeneration. Considering the trend of decreasing species richness level in Central European forests, CWS forests play a major role in the conservation of vascular plant species diversity. In contrast to other studies, the increase in species richness after coppicing did not result from an increase in weedy, nitrogen-demanding species. The so called “nitrogen time bomb” scenario (which other authors assumed to be happening after opening the canopy) did not occur in the studied area. The low water storage capacity of the limestone rendzina soil may be one reason, as there was not sufficient water and nitrogen for the more demanding species.

Eco-exergy based self-organization of the macrobenthic faunal assemblage during mangrove succession in Zhanjiang, China

Eco-exergy (ecological exergy) has been used to evaluate the health and self-organization of aquatic and wetland ecosystems following perturbation or natural succession. Although macrobenthic fauna are important components of mangrove ecosystems, their self-organization during mangrove succession is unclear. In this study, eco-exergy was used to quantify the self-organization processes of macrobenthic faunal assemblages in a mangrove chronosequence that included a primary (unvegetated shoal), early (Avicennia marina), middle (Aegiceras corniculatum), and late (Bruguiera gymnorrhiza + Rhizophora stylosa) community in Zhanjiang, China. Eco-exergy and biomass of the macrobenthic faunal community tended to decrease in the wet season during mangrove succession. The specific eco-exergy of the macrobenthic faunal community, in contrast, remained relatively constant in both wet and dry seasons during mangrove succession, although mollusk eco-exergy tended to decrease and arthropod eco-exergy tended to increase. Statistical analyses indicated that the self-organization of the macrobenthic faunal community during mangrove succession was mainly associated with the development of a suite of vegetation characteristics and sediment physicochemical properties, e.g., plant crown breadth, plant density, sediment ammonium nitrogen and sediment total nitrogen. Unlike the diversification trends of species richness and functional groups, this study confirmed the decreased self-organization trend of macrobenthic fauna assemblage mainly derived from biomass and genetic information. These results highlight the importance of conserving the macrobenthic faunal community in mangrove forests, especially in the late successional stages.

Urban bird trends in a rapidly growing tropical city

Long-term studies of urban birds are relatively scarce, especially in Africa. We analysed trends in species richness and bird species occurrence over a 32-year period in Kampala, Uganda, in order to assess changes in the bird community in a period that has shown rapid expansion of the city's human population. Given that species may respond to urbanisation according to their diet, we also analysed bird community trends of species groups defined according to predominant diet. There was an overall decline in species richness that was largely driven by declines in insectivores and granivores. General declines were evident also when the trends in the most common individual species in these two groups were considered. The occurrence of the commonest predator and scavenger species tended to increase over the period considered. Insectivorous species are likely to be especially affected by increasing urbanisation due to air pollution. Predators and scavengers are likely to have benefitted from the inability of municipal waste management to keep pace with growth in the human population, hence providing more potential food resources. Both insectivores and predators/scavengers are therefore good candidates for the development of urban indicators.

The longer the better: the effect of substrate on sessile biota in Arctic kelp forests

Kelps are ecosystem engineers and thus enhance biodiversity and subsidize food webs in nearshore areas. Numerous studies describing diversity and abundance of biota associated with kelp have focused on sub-tropical and temperate waters while kelp forests at high latitudes, where kelp is predicted to expand in distribution, remain mostly unexplored. Kelp forests contribute significantly to regional biodiversity, and associated fauna and the kelp themselves play ecologically important roles as habitat and feeding areas. Here, we report patterns in diversity, abundance and seasonal dynamics of fouling organisms associated with different regions of Saccharina latissima and nearby substrates (including stones of the barren ground). The study was conducted in Kongsfjorden, a high Arctic fjord on the west coast of Spitsbergen; and samples were taken five times between September 2013 and January 2015. Trends in species richness of epifauna were similar for stones and holdfasts: higher in winter (due the presence of rare species), and lower in spring and autumn. Species richness and abundance demonstrated a clear tendency to increase in accordance with substrate stability. Stones housed the most diverse biota compared to living substrates. Holdfasts demonstrated similar patterns in species composition and abundance as stones due their close spatial arrangement and presence of demersal larvae in most of fouling organisms. Similarly, assemblages on blades in prostrate kelp forests are influenced by the species inhabiting stones of the barren ground. Both biotic and abiotic factors, including habitat stability and proximity to source populations, contribute to these spatial and temporal patterns in faunal abundance and diversity.

Do marine faunas track lithofacies? Faunal dynamics in the Upper Cretaceous Pierre Shale, Western Interior, USA

Most studies examining faunal assemblages use their sedimentary context as a critical element in constraining and reconstructing their underlying environmental controls. This has resulted in the assumption that an absence of lithofacies change in a section should be reflected in a lack of environmental variation. This inference, however, has been placed into question by evidence that marine species are influenced by a broader range of environmental dynamics than just change in lithofacies. In this study, we examine the sensitivity of marine faunas to broadly defined environmental change within lithologically homogenous strata by examining concretionary fossil assemblages of the Baculites eliasi through B. clinolobatus biozones in monotonous, clay-rich strata of the Campanian-Maastrichtian Pierre Shale in Wyoming. We recognize five biofacies, which reflect different environmental conditions related to benthic oxygenation, substrate firmness, and water depth. Analyses of abundance patterns, raw species richness trends, and life-habit patterns display recurrent switching, upsection, between low- and high-diversity intervals. Our data reveal that samples with lower diversity show a strong relationship with intervals when water conditions were deepest, whereas higher diversity samples are associated with periods when shallow-water conditions prevailed in the study area. The distribution of taxa and diversity of the assemblages most likely reflect migrating oxygen- and substrate-controlled biofacies that were responding to changes in depth. This study shows that substantial changes in biofacies, diversity, and life habits can arise in response to variations in water depth with limited to no apparent change in lithofacies supporting the hypothesis that fossil taxa are much more sensitive indicators of environmental change than lithofacies.

Rapid Expansion of Melica przewalskyi Causes Soil Moisture Deficit and Vegetation Degradation in Subalpine Meadows

Invasive noxious plants have important impacts on community dynamics and ecosystem functions in grasslands. Since the 1960s, the noxious plant Melica przewalskyi has spread rapidly and formed different size of patches in subalpine meadows of the Qilian Mountains, Northwest China. In this study, the species richness, vegetation structure, and soil water content are investigated from the patch edge to the center in four sizes of M. przewalskyi patches (i.e., small patch, <100 cm in canopy diameter; middle patch, 100–200 cm; large patch, 200–300 cm; and the largest patch, >300 cm). The results show that while the patches grow continuously, the dominant species changes from Stipa krylovii to M. przewalskyi with an increasing trend in plant productivity and decreasing trend in species richness and soil water content. Plant height, density, coverage, and above‐ground biomass of M. przewalskyi population increases from the patch edge to the center in small, middle, and large patches, whereas it is precisely the opposite in the largest patch. Interestingly, soil water content exhibits a decreasing trend from the patch edge to the center in all patches. The results indicate that the rapid spread of M. przewalskyi may well alter vegetation pattern and cause a severe soil moisture deficit, which would further drive the degradation of ecosystem functioning in subalpine meadows.

Increased energy differentially increases richness and abundance of optimal body sizes in deep-sea wood falls.

Theoretical and empirical studies suggest that the total energy available in natural communities influences body size as well as patterns of abundance and diversity. But the precise mechanisms underlying these relationships or how these three ecological properties relate remain elusive. We identify five hypotheses relating energy availability, body size distributions, abundance, and species richness within communities, and we use experimental deep-sea wood fall communities to test their predicted effects both on descriptors describing the species-richness-body-size distribution, and on trends in species richness within size classes over an energy gradient (size-class-richness relationships). Invertebrate communities were taxonomically identified, weighed, and counted from 32 Acacia sp. logs ranging in size from 0.6 to 20.6kg (corresponding to different levels of energy available), which were deployed at 3,203m in the Northeast Pacific Ocean for 5 and 7yr. Trends in both the species-richness-body-size distribution and the size-class-richness distribution with increasing wood fall size provide support for the Increased Packing hypothesis: species richness increases with increasing wood fall size but only in the modal size class. Furthermore, species richness of body size classes reflected the abundance of individuals in that size class. Thus, increases in richness in the modal size class with increasing energy were concordant with increases in abundance within that size class. The results suggest that increases in species richness occurring as energy availability increases may be isolated to specific niches, e.g., the body size classes, especially in communities developing on discrete and energetically isolated resources such as deep sea wood falls.

Vanishing herpetofauna: 30 years of species relaxation in a wetland remnant of the Po plain (Northern Italy)

An analysis of a 30-year dataset (1985–2014) concerning a herpetofauna assemblage studied in a site of conservation concern (Northern Italy) is reported with the aim of evidencing a trend in species richness which may reveal the most sensitive ones (i.e., the first to go extinct locally). Our results point to a progressive loss of species (nested species relaxation) which were not replaced over the study period and consequently to a decline in species richness. Among the amphibians, two thresholds in mean species richness were evident in the mid and late 1990s, respectively, whereas reptiles showed a significant threshold only at the end of the 1990s. An inductive hypothesis to explain the abrupt relaxation in species richness in the mid and late 1990s may involve a combination of “pulse” or “press” perturbations at different scales. Moreover, although our long-term standardized study suffers from some limitations, our data clearly indicate a different species-specific sensitivity which could be useful to identify focal species of conservation concern. However, further comparisons with data set collected from long-term and wide-ranging studies are needed to confirm our temporal thresholds, in order to infer a more general model from this local pattern.

Biodiversity change is uncoupled from species richness trends: Consequences for conservation and monitoring

Abstract Global concern about human impact on biological diversity has triggered an intense research agenda on drivers and consequences of biodiversity change in parallel with international policy seeking to conserve biodiversity and associated ecosystem functions. Quantifying the trends in biodiversity is far from trivial, however, as recently documented by meta‐analyses, which report little if any net change in local species richness through time. Here, we summarise several limitations of species richness as a metric of biodiversity change and show that the expectation of directional species richness trends under changing conditions is invalid. Instead, we illustrate how a set of species turnover indices provide more information content regarding temporal trends in biodiversity, as they reflect how dominance and identity shift in communities over time. We apply these metrics to three monitoring datasets representing different ecosystem types. In all datasets, nearly complete species turnover occurred, but this was disconnected from any species richness trends. Instead, turnover was strongly influenced by changes in species presence (identities) and dominance (abundances). We further show that these metrics can detect phases of strong compositional shifts in monitoring data and thus identify a different aspect of biodiversity change decoupled from species richness. Synthesis and applications: Temporal trends in species richness are insufficient to capture key changes in biodiversity in changing environments. In fact, reductions in environmental quality can lead to transient increases in species richness if immigration or extinction has different temporal dynamics. Thus, biodiversity monitoring programmes need to go beyond analyses of trends in richness in favour of more meaningful assessments of biodiversity change.

Local and geographical factors jointly drive elevational patterns in three microbial groups across subarctic ponds

AbstractAimElevational biodiversity patterns are understudied in high‐latitude aquatic systems, even though these systems are important for detecting very early impacts of climatic changes on Earth. The aim of this study was to examine the elevational trends in species richness and local contribution to beta diversity (LCBD) of three biofilm microbial groups in freshwater ponds and to identify the key mechanisms underlying these patterns.LocationOne hundred and forty‐six ponds in subarctic Finland and Norway distributed across the tree line along an elevational gradient of 10–1,038 m a.s.l., spanning from forested landscape to barren boulder fields.Time periodJuly–August 2015.Major taxa studiedDiatoms, cyanobacteria and non‐cyanobacteria.MethodsGeneralized linear models were used to identify the most important pond variables explaining richness and LCBD. Structural equation models were used to explore the direct and indirect effects of multiscale drivers on richness and LCBD.ResultsDiatom and cyanobacteria richness showed unimodal elevational patterns, whereas non‐cyanobacteria richness decreased with increasing elevation. The LCBD–elevation relationship was U‐shaped for all three microbial groups. Diatom and cyanobacteria richness and LCBD were best explained by local pond variables, especially by pH. Non‐cyanobacteria richness and LCBD were related to pond variables, elevation as a proxy for climatic conditions, and normalized difference vegetation index as a proxy for terrestrial productivity.Main conclusionsAquatic autotrophs were primarily controlled by environmental filtering, whereas heterotrophic bacteria were also affected by terrestrial productivity and elevation. All studied aspects of microbial diversity were directly or indirectly linked to elevation; therefore, climatic changes may greatly alter aquatic microbial assemblages.

Consistency of effects of tropical-forest disturbance on species composition and richness relative to use of indicator taxa.

Lawton etal. (1998) found, in a highly cited study, that the species richness of 8 taxa each responds differently to anthropogenic disturbance in Cameroon forests. Recent developments in conservation science suggest that net number of species is an insensitive measure of change and that understanding which species are affected by disturbance is more important. It is also recognized that all disturbance types are not equal in their effect on species and that grouping species according to function rather than taxonomy is more informative of responses of biodiversity to change. In a reanalysis of most of the original Cameroon data set (canopy and ground ants, termites, canopy beetles, nematodes, and butterflies), we focused on changes in species and functional composition rather than richness and used a more inclusive measure of forest disturbance based on 4 component drivers of change: years since disturbance, tree cover, soil compaction, and degree of tree removal. Effects of disturbance on compositional change were largely concordant between taxa. Contrary to Lawton etal.'s findings, species richness for most groups did not decline with disturbance level, providing support for the view that trends in species richness at local scales do not reflect the resilience of ecosystems to disturbance. Disturbance affected species composition more strongly than species richness for butterflies, canopy beetles, and litter ants. For these groups, disturbance caused species replacements rather than just species loss. Only termites showed effects of disturbance on species richness but not composition, indicating species loss without replacement. Although disturbance generally caused changes in composition, the strength of this relationship depended on the disturbance driver. Butterflies, litter ants, and nematodes were correlated with amount of tree cover, canopy beetles were most strongly correlated with time since disturbance, and termites were most strongly correlated with degree of soil disturbance. There were moderately divergent responses to disturbance between functional feeding groups. Disturbance was most strongly correlated with compositional differences of herbivores within beetles and nematodes and humus feeders within termites. Our results suggest that consideration of the impact of different forms of disturbance on species and functional composition, rather than on net numbers of species, is important when assessing the impacts of disturbance on biodiversity.

Assessing and predicting shifts in mountain forest composition across 25 years of climate change

AbstractAimSpatial predictions of future communities under climate change can be obtained by stacking species distribution models (S‐SDM), but proper evaluation of community S‐SDM predictions across time with fully independent data has rarely been carried out. The aim of this study was to evaluate the predictive abilities of S‐SDMs for whole forest communities across the last 25 years in a mountain region.LocationThe western Swiss Alps.MethodsWe used past vegetation surveys (2,984 plots) and environmental data from the 1990s to calibrate SDMs for 364 plant species and predict changes in forest composition under contemporary conditions. These projections were then evaluated by resurveying a random subset of 92 forest plots in summer 2014.ResultsSpecies distribution models showed the same accuracy in the past (calibration data) and present (evaluation data). The S‐SDMs correctly predicted the general trends in species richness and shift of ecological conditions (i.e., temperature, moisture) at the regional level. However, it proved more difficult to identify precisely which forest communities or areas are most or least affected by climate change.Main conclusionOur results show that, across a period of a few decades, S‐SDMs can usefully predict trends in macroecological properties such as richness or average ecological conditions, but fail to accurately predict changes in composition. This is likely due to the combined effects of the stochasticity of local colonization and extinction events, dispersal limitations, community assembly rules (e.g., competition), observer bias, model and location errors and interannual variation. Furthermore, these models cannot account for potential species adaptations leading to persistence in sites predicted unsuitable. This highlights the need for developing more accurate forest community predictions as support to help prioritizing conservation actions.

Taxonomic survey compared to ecological sampling: are the results consistent for woodland epiphytes?

AbstractField survey by a taxonomist or specialist biologist (‘taxonomic survey’) provides a comprehensive inventory of species in a habitat. Common and conspicuous species are rapidly recorded and search effort can be targeted to inconspicuous or rare species. However, the subjective nature of taxonomic survey limits its usefulness in ecological monitoring and analysis. In contrast, ‘ecological sampling’, focused on the standardized use of repeated sub-units such as quadrats, is designed to quantify the observational error of results, allowing for more robust statistical treatment. Nevertheless, the spatial extent of recording will be lower during ecological sampling, and rarities might be missed. Despite their differences, these two approaches are often assumed to be congruent for decision making. Taxonomic survey is commonly used to identify priority sites for conservation (including species-rich sites, or those with many rare/threatened species) while ecological sampling is used to design conservation strategy by relating species richness or composition to habitat dynamics. If these contrasting approaches are indeed congruent, then trends in species richness and community composition, detected by ecological sampling, will mirror the results of taxonomic survey so that management confidently protects the attributes for which a site was prioritized. This study performed both taxonomic survey and ecological sampling for lichen epiphytes in 13 woodland study sites in Scotland. To understand the procedure of taxonomic survey, fieldwork by a professional taxonomist was structured by effort into 15-minute time intervals. As expected, taxonomic survey discovered more species per site, while ecological sampling (allowing a measure of species frequency) resolved greater variation in community composition. However, the patterns of richness and species composition obtained from the different methods were correlated, suggesting an overall high degree of congruence in identifying and then managing priority sites. Furthermore, when exploring the taxonomic survey in detail, we found that a minimum effort of 45 minutes was required to accurately determine species richness differences among contrasting woodland sites.

Assessing the burden of intestinal parasites affecting newly arrived immigrants in Qatar.

BackgroundIn the last decades, the enormous influx of immigrants to industrialized countries has led to outbreaks of parasitic diseases, with enteric infections being amongst the most frequently encountered. In its strategy to control such infection, Qatar has established the Pre-Employment Certificate (PEC) program which requires medical inspection before arrival in Qatar and which is mandatory for immigrant workers travelling to the country. To assess the reliability of the PEC, we conducted a survey of intestinal parasites, based on examination of stool samples provided by immigrant workers (n = 2,486) recently arrived in Qatar.ResultsOverall prevalence of helminths was 7.0% and that of protozoa was 11.7%. Prevalence of combined helminths was highest among the western Asians and the highest prevalence of combined protozoan parasites was among workers from North to Saharan Africa. Analysis of temporal changes showed an increasing trend of protozoan infections over the investigated 3 years. A major contribution to this temporal change in prevalence came from Blastocystis hominis as well as from other protozoan species: Giardia duodenalis and Endolimax nana. Analysis of the temporal trend in species richness of the protozoan species showed a significant increase in the mean number of species harboured per subject across this period.ConclusionThe increase of protozoan infections over recent years raises some concerns. It suggests that screening protocols for applicants for visas/work permits needs to be revised giving more careful attention to the intestinal protozoan infections that potential immigrants may harbor.