Changes In Species Richness Research Articles

Long-term recovery of Mediterranean ant and bee communities after fire in southern Spain

Wildfires play a determinant role in the composition and structure of animal communities, especially for groups closely associated with the vegetation and soil, such as bees or ants. The effects of fire on animal communities depend on the functional traits of each group. Here, we assessed the impacts of fire and time since fire on the taxonomic and functional responses of ant and bee communities. We sampled 35 pine forests in Andalusia (southern Spain) that had experienced fire in the past (0 to 41 years ago). Specifically, we explored whether a) fire increased taxonomic and functional diversity and changed community composition in communities in the short term and b) fire influence (increase or decrease) on ant communities would be dependent on time since fire. We found that ant and bee taxonomic richness increased regardless of time since fire. Different approaches gave the same result, such as taxonomic diversity indexes (ant abundance, ant richness and ant Shannon diversity index), the changes in species richness in ant and bee communities, as well as the higher number of ant and bee species prone to the burned habitat than to the unburned habitat, using the Ihabitat Index. Besides environmental variables (such as the effects of different Pinus species or elevation), time since fire changed the taxonomic composition of ant communities and the functional composition of bee communities. Moreover, six of the 13 ant functional traits explored differed between burned and unburned areas, with the degree of difference declining as time since fire increased. For example, burned areas contained ant communities with more ground-nesting species and strictly diurnal species, functional traits that are characteristic of open areas. In contrast, other traits persisted in burned areas over the long term, notably a higher degree of worker polymorphism and species monogyny. Our study shows how much short- and long-term effects of fire on ant and bee communities differ; while richness increases in the long-term, some functional traits are also filtered in the short-term. We suggest that fire in Mediterranean coniferous ecosystems could have a positive effect on these groups and should not be overlooked.

Biotic pressures and environmental heterogeneity shape beta‐diversity of seedling communities in tropical montane forests

Many theories have been proposed to explain the high diversity of plants in the tropics. However, we lack an understanding of the processes that drive plant diversity and community assembly at different spatial scales. Here, we applied beta‐diversity partitioning to test how biotic and abiotic factors are associated with seedling beta‐diversity in a tropical montane forest in southern Ecuador. We recorded seedling communities on 81 subplots in nine plots located at three elevations along a 2000 m elevational gradient. We measured biotic pressures (i.e. herbivory and fungal pathogen attacks) and environmental conditions (i.e. soil moisture and canopy closure) in all subplots and related them to species turnover and richness differences in seedling communities within and between elevations. We found that species turnover increased with differences in biotic dissimilarity within elevations, while differences in species richness within elevations increased with increasing environmental dissimilarity. Between elevations, species turnover increased with increasing environmental dissimilarity. Our findings show that species turnover and changes in species richness are related differently to abiotic and biotic factors, and that the importance of these factors for shaping seedling diversity is scale‐dependent. Our study contributes to better understand the processes driving seedling beta‐diversity and the assembly of plant communities in highly diverse tropical montane forests.

Climate change drives substantial decline of understorey species richness and abundance in Norway spruce forests during 32 years of vegetation monitoring

AbstractQuestionsObservations in permanent forest vegetation plots in Norway and elsewhere indicate that complex changes have taken place over the period 1988–2020. These observations are summarised in the “climate‐induced understorey change (CIUC)” hypothesis, i.e. that the understorey vegetation of old‐growth boreal forests in Norway undergoes significant long‐term changes and that these changes are consistent with the ongoing climate change as an important driver. Seven testable predictions were derived from the CIUC hypothesis.LocationNorway.MethodsVegetation has been monitored in a total of 458 permanently marked plots, each 1 m2, in nine old‐growth forest sites dominated by Picea abies at intervals of 5–8 years over the 32‐year study period. For each of the 52 combinations of site and year, we obtained response variables for the abundance of single species, abundance and species density of taxonomic–ecological species groups and two size classes of cryptogams, and site species richness. All of these variables were subjected to linear regression modelling with site and year as predictors.ResultsMean annual temperature, growing‐season length and the number of days with precipitation were higher in the study period than in the preceding ca. 30‐year period, resulting in increasingly favourable conditions for bryophyte growth. Site species richness decreased by 13% over the 32‐year study period. On average, group abundance of vascular plants decreased by 24% (decrease in forbs: 38%). Patterns of group abundance change differed among cryptogam groups: although peat‐moss abundance increased by 39%, the abundance of mosses, hepatics and lichens decreased by 13%, 49% and 67%, respectively. Group abundance of small cryptogams decreased by 61%, whereas a 13% increase was found for large cryptogams. Of 61 single species tested for abundance change, a significant decrease was found for 43 species, whereas a significant increase was found only for 6 species.ConclusionsThe major patterns of change in species richness, group species density and group abundance observed over the 32‐year study period accord with most predictions from the CIUC hypothesis and are interpreted as direct and indirect responses to climate change, partly mediated through changes in the population dynamics of microtine rodents. The more favourable climate for bryophyte growth explains the observed increase for a few large bryophyte species, whereas the decrease observed for small mosses and hepatics is interpreted as an indirect amensalistic effect, brought about by shading and burial in mats of larger species and accelerated by reduced fine‐scale disturbance by microtine rodents. Indirect effects of a thicker moss mat most likely drive the vascular plant decline although long‐term effects of tree‐stand dynamics and former logging cannot be completely ruled out. Our results suggest that the ongoing climate change has extensive, cascading effects on boreal forest ecosystems. The importance of long time‐series of permanent vegetation plots for detecting and understanding the effects of climate change on boreal forests is emphasised.

Climate as a determinant of dung beetle response to native forest replacement by cattle pastures in South America

AbstractAnthropogenic disturbance in natural ecosystems reduces the number of species in biological communities and homogenizes their composition across different regions. Climate is one of the main abiotic determinants of species distributions and different factors were proposed as the main climatic drivers. Here we explored the role of regional climate on the local response of dung beetle assemblages to the replacement of native forest by cattle pastures in South America by simultaneously contrasting three climatic hypotheses: energy, seasonality and heterogeneity. We compiled a database by searching published studies comparing dung beetle richness and composition between both native forests and cattle pastures. We calculated the proportional difference in species richness and composition between habitat types. As explanatory variables, we used seven abiotic variables grouped into the three climatic hypotheses. Energy/Productivity: mean annual temperature (°C/year) and total annual precipitation (mm/year). Seasonality: annual thermal amplitude (°C/year), the average coefficient of variation of monthly precipitation and the coefficient of average monthly variation in temperature. Heterogeneity: coefficient of variation of mean annual temperature, coefficient of variation of mean annual precipitation. Using regression analyses and a model selection procedure, we found differences in species richness between native forests and cattle pastures were explained by the coefficient of variation of mean annual precipitation, whereas changes in species composition were explained by total annual precipitation and the coefficient of variation of mean annual precipitation. The response of dung beetle assemblages to livestock grazing in South American forests was associated with precipitation variation. The heterogeneity hypothesis better explained changes in species richness following forest replacement by cattle pastures, while both energy/productivity and heterogeneity hypotheses explained the changes in species composition.

The effect of hypoxia on Daphnia magna performance and its associated microbial and bacterioplankton community: A scope for phenotypic plasticity and microbiome community interactions upon environmental stress?

The depletion of oxygen as a result of increased stratification and decreased oxygen solubility is one of the most significant chemical changes occurring in aquatic ecosystems as a result of global environmental change. Hence, more aquatic organisms will be exposed to hypoxic conditions over time. Deciphering the effects of hypoxia on strong ecological interactors in this ecosystem’s food web is critical for predicting how aquatic communities can respond to such an environmental disturbance. Here (sub-)lethal effects of hypoxia and whether these are genotype specific in Daphnia, a keystone species of freshwater ecosystems, are studied. This is especially relevant upon studying genetic responses with respect to phenotypic switches upon environmental stress. Further, we investigated the effect of hypoxia on the Daphnia microbial community to test if the microbiome plays a role in the phenotypic switch and tolerance to hypoxia. For this, two Daphnia genotypes were exposed for two weeks to either hypoxia or normoxia and host performance was monitored together with changes in the host associated and free-living microbial community after this period. We detected phenotypic plasticity for some of the tested Daphnia performance traits. The microbial community of the bacterioplankton and Daphnia associated microbial community responded via changes in species richness and community composition and structure. The latter response was different for the two genotypes suggesting that the microbiome plays an important role in phenotypic plasticity with respect to hypoxia tolerance in Daphnia, but further testing (e.g., through microbiome transplants) is needed to confirm this.

Climatic, geographic and anthropogenic factors shape the structure of bat–fruit networks in the Neotropical region

AbstractNatural and anthropogenic environmental gradients are associated with changes in species richness, abundance and resource use. There is increasing interest in understanding how the structure of interaction networks varies along environmental gradients, but most studies have focused on bird–plant networks, while studies on mutualistic networks formed by other vertebrate groups are scarce. Here, we compiled a database of 48 bat–fruit networks distributed in the Neotropical region and evaluated the influence of annual precipitation, annual mean temperature, latitude, altitude and human impacts on nestedness, modularity, specialization, interaction diversity and species richness. Furthermore, we characterized the distribution of the roles of bat species in networks of interactions inserted in different biomes of the Neotropical region. We found that annual mean temperature increased nestedness, but decreased modularity and diversity of interactions. In addition, the diversity of interactions was greater in areas with higher annual precipitation, with less human impact and in lower latitude regions. Plant richness increased in regions with higher annual precipitation, while latitude negatively affected both plant and bat richness. Regarding the role played by bat species, we observed that most species occupy peripheral positions and only 4% of the species acted as connectors. Consistent with previous studies that evaluated other mutualistic systems, we demonstrated that the structure of bat–fruit networks is influenced by climatic, geographic and anthropogenic factors. These findings enhance our understanding of how ecological communities are structured along an environmental gradient and allow us to understand how these systems can be affected by changes in climate and land use.

Magnitude and drivers of plant diversity loss differ between spatial scales in Scania, Sweden 1957–2021

AbstractQuestionsChanged land use, nitrogen deposition, climate change, and the spread of non‐native species have repeatedly been reported as the main drivers of recent floristic changes in northern Europe. However, the relevance of the geographical scale at which floristic changes are observed is less well understood and it has only rarely been possible to quantify biodiversity loss. Therefore, we assessed changes in species richness, species composition and mean ecological indicator values (EIVs) at three nested geographic scales during two different time periods, each ca 30 years, since the mid‐1900s.LocationTwo parishes in central Scania, southernmost Sweden.MethodsWe analyzed species presence/absence data from three inventories at ca 30‐year intervals over 1957–2021 and three geographic scales (157 m2, ca 7 km2 and ca 45 km2) to document temporal trends and differences between geographic scales in terms of species richness, species composition and mean EIVs.ResultsWe found shifts in species composition across all geographical scales. However, the magnitude of biodiversity loss and the main drivers of these changes were scale‐dependent. At the smallest spatial scale, we saw a dramatic loss of plant biodiversity with local species richness in 2021 being only 48% of that of 1960. In contrast, at the larger geographic scales no significant changes in species richness were observed because species losses were compensated for by gains of predominantly non‐native species, which made up at least 78% of the new species richness. At the smallest spatial scale, changed land use (ceased grazing/mowing and intensified forestry) appeared as the main driver, while an increasing proportion of non‐native species, as well as climatic changes and increasing nitrogen loads appeared relatively more important at larger geographic scales.ConclusionOur results highlight the precarious situation for biodiversity in the region and at the same time the fundamental importance of geographic scale in studies of biodiversity change. Both the magnitude and drivers of changes may differ depending on the geographic scale and must be considered also when previously published studies are interpreted.

Environmental drivers of earthworm communities along an elevational gradient in the French Alps

Elevational diversity gradients describe how species diversity and richness change with elevation. In this study, we tested for the effect of climate, resource quality and habitat heterogeneity on earthworm communities along an elevational gradient and around the treeline in the French Alps. Earthworm communities and environmental properties (i.e. climate, soil properties, vegetation structure and composition) were sampled at six elevations ranging from 1400 to 2400 m. Results were analysed through multi-table factorial analyses and structural equation modelling. We found average density, biomass and species richness in the range of that usually reported in comparable ecosystems. We found no monotonic decrease in species richness along the elevational gradient, which we explain by the species pool being dominated by taxa with high environmental tolerance and dispersal capacities. Instead, we highlighted the ecotone associated with the treeline as the primary driving factor of earthworm communities: at 1800–2000 m elevation, communities were more abundant and diverse, and had a greater variability in body mass. This result was largely explained by the structure and composition of the vegetation, whereas soil and climate appeared to have only indirect effects. Therefore, the treeline effect on earthworm communities can be explained both by the effect of environmental heterogeneity and of trophic resource quality that increases at the ecotone level.

Mechanisms underpinning community stability along a latitudinal gradient: Insights from a niche-based approach.

At large scales, the mechanisms underpinning stability in natural communities may vary in importance due to changes in species composition, mean abundance, and species richness. Here we link species characteristics (niche positions) and community characteristics (richness and abundance) to evaluate the importance of stability mechanisms in 156 butterfly communities monitored across three European countries and spanning five bioclimatic regions. We construct niche-based hierarchical structural Bayesian models to explain first differences in abundance, population stability, and species richness between the countries, and then explore how these factors impact community stability both directly and indirectly (via synchrony and population stability). Species richness was partially explained by the position of a site relative to the niches of the species pool, and species near the centre of their niche had higher average population stability. The differences in mean abundance, population stability, and species richness then influenced how much variation in community stability they explained across the countries. We found, using variance partitioning, that community stability in Finnish communities was most influenced by community abundance, whereas this aspect was unimportant in Spain with species synchrony explaining most variation; the UK was somewhat intermediate with both factors explaining variation. Across all countries, the diversity-stability relationship was indirect with species richness reducing synchrony which increased community stability, with no direct effects of species richness. Our results suggest that in natural communities, biogeographical variation observed in key drivers of stability, such as population abundance and species richness, leads to community stability being limited by different factors and that this can partially be explained due to the niche characteristics of the European butterfly assemblage.

Microbiome and Th cytokines association in chronic rhinosinusitis with or without nasal polyp.

Chronic rhinosinusitis (CRS), a common disease in otorhinolaryngology, seriously affects the life quality of patients. The existing therapy has certain limitations, and it is very urgent to deeply explore the pathogenesis and classification of CRS. Microbiome and inflammation are considered the causes of CRS, but the precise roles and the associations between these two factors in the pathogenesis of CRS remain controversial. Secretions were collected from the middle nasal canal, maxillary sinus and ethmoid sinus in CRS patients, then subjected to 16 S rRNA gene sequencing to profile microbiota community. Operational Taxonomic Units clustering and species annotation were adopted to obtain species diversity, prevalence rate and average relative abundance. Comparisons were performed at the level of microbial species and genus between CRS and control using NMDS, Anosim and MetaStat analysis. Th1 cytokines and Th2 cytokines were detected by ELISA. Spearman analysis were adopted to probe into the correlation between Th cytokines and microbial species in CRS. Thirty-seven patients were enrolled, among them 22 with CRS and 15 were controls. The most abundant genera were Corynebacterium and Staphylococcus no matter in CRS patients or control. Corynebacterium propinquum was significant decreased in CRS patients no matter with nasal polyp or not. The abundances of Prevotella birria and Carnobacterium maltaromaticum were significantly different between CRSsNP and CRSwNP group. The levels of cytokines IL-2, TNF-α, IFN-ɣ, IL-4, IL-6, IL-10 were all increased in CRS patients. The cytokines levels were associated with specific microbial species in nasal tissue. The changes of species richness and complexity in nasal microbiome were obvious in CRS patients with nasal polyps or not. The different cytokines levels and microbiome between CRS patients without nasal polyps and patients with nasal polyps suggest heterogeneity in pathogenesis of chronic rhinosinusitis. Distinct microbiota and different cytokines were strongly linked in CRS. NA.

Organization of planktonic Tintinnina assemblages in the Atlantic Ocean

Marine plankton have different biogeographical distribution patterns. However, it is not clear how the entire plankton assemblage is composed of these species with distinct biogeographical patterns. Tintinnina (tintinnids) is single-celled planktonic protozoa commonly used as model organisms in planktonic studies. In this research, we investigated the organization of Tintinnina assemblages along the Atlantic Meridional Transect (AMT) spanning over 90 degrees of latitude during the 29th AMT cruise (2019). Tintinnina with high frequency of occurrence was classified into four biogeographic distribution patterns (equatorial, gyre, frontal, and deep Chl a maximum) according to their vertical and horizontal distribution. All species falling within each distribution pattern formed a sub-assemblage. Equatorial sub-assemblage dominated in upper waters of the equatorial zone and gyre centres. Equatorial and frontal sub-assemblages co-dominated in upper waters of the frontal zones. Deep Chlorophyll a maximum Layer (DCM) sub-assemblage dominated in the DCM waters. Some Tintinnina species with high abundance could be used as indicator species of sub-assemblages. The Tintinnina assemblages in the northern and southern hemispheres exhibited asymmetry in terms of species composition. The latitudinal gradient of Tintinnina species richness was bimodal, which was shaped by the superposition of the species number of the four sub-assemblages with latitude. The result of this study contributes to the understanding of Tintinnina assemblage in the equatorial zone and subtropical gyres of the Pacific and Indian Ocean. It is also valuable for predicting the influence of global warming on changes in Tintinnina distribution and species richness.

Potential effects of future climate change on global reptile distributions and diversity

AbstractAimUntil recently, complete information on global reptile distributions has not been widely available. Here, we provide the first comprehensive climate impact assessment for reptiles on a global scale.LocationGlobal, excluding Antarctica.Time period1995, 2050 and 2080.Major taxa studiedReptiles.MethodsWe modelled the distribution of 6296 reptile species and assessed potential global and realm‐specific changes in species richness, the change in global species richness across climate space, and species‐specific changes in range extent, overlap and position under future climate change. To assess the future climatic impact on 3768 range‐restricted species, which could not be modelled, we compared the future change in climatic conditions between both modelled and non‐modelled species.ResultsReptile richness was projected to decline significantly over time, globally but also for most zoogeographical realms, with the greatest decreases in Brazil, Australia and South Africa. Species richness was highest in warm and moist regions, with these regions being projected to shift further towards climate extremes in the future. Range extents were projected to decline considerably in the future, with a low overlap between current and future ranges. Shifts in range centroids differed among realms and taxa, with a dominant global poleward shift. Non‐modelled species were significantly stronger affected by projected climatic changes than modelled species.Main conclusionsWith ongoing future climate change, reptile richness is likely to decrease significantly across most parts of the world. This effect, in addition to considerable impacts on species range extent, overlap and position, was visible across lizards, snakes and turtles alike. Together with other anthropogenic impacts, such as habitat loss and harvesting of species, this is a cause for concern. Given the historical lack of global reptile distributions, this calls for a re‐assessment of global reptile conservation efforts, with a specific focus on anticipated future climate change.

Changes in reef benthic communities in Sumba Timur, East Nusa Tenggara, Indonesia

Abstract. Utama RS, Hadi TA, Hermanto B, Giyanto, Budiyanto A. 2022. Changes in reef benthic communities in Sumba Timur, East Nusa Tenggara, Indonesia.Biodiversitas 23: 677-687. Anthropogenic impacts and coral bleaching due to rising sea surface temperature have been severe and often, as of late on the worldwide scale, influencing the composition of coral reef benthic communities from coral to algal-ruled reefs (phase shift). In any case, coral reef phase shift does not continuously happen, considering corals can recoup when stressors occur. This considers points to examine the alteration in coral reef benthic communities and the relationship among benthic categories. The study was carried out in 2018 and 2021 at 10 stations within East Sumba, and East Nusa Tenggara. Underwater photo transect (UPT) was used to examine benthic cover at a depth of 6 to 9 m in reef slope. The result demonstrated that the benthic communities were slightly altered, especially hard coral, sponge, and other biotas. A slight recovery of hard coral cover is shown in 2021, followed by the decline of sponge and fleshy seaweed cover, which is shown in most observation sites. Acropora spp., Seriatopora spp., and Stylophora spp. were the three genera that increased in cover. The study also found the relationship between the benthic gradient and species richness and the number of colonies, which is gradient changes in benthic composition were in line with the change in hard coral species richness and colony numbers. Although hard coral increase significantly changes over time, it's not altered the coral communities.

Increasing species richness along elevational gradients is associated with niche packing in bat assemblages.

The change in species richness along elevational gradients is a well-known pattern in nature. Niche theory predicts that increasing species richness in assemblages can either lead to denser packing of niche space ('niche packing') or an expansion into its novel regions ('niche expansion'). Traditionally, these scenarios have been studied using functional traits but stable isotopes provide advantages such as identifying the degree of resource specialisation, or niche partitioning among functionally similar species. In this study, we evaluate the relevance of niche packing versus niche expansion by investigating stable carbon and nitrogen isotopic niche width and overlap among 23 bat species from six functional groups across a 1500 m elevational gradient in the Himalaya. Our results suggest that an increase in species richness in the low elevation is accompanied by small niche width with high overlap, whereas the high elevation assemblage shows large niche width with low overlap among functional group members. At the functional group level, edge-space foraging, trawling, and active gleaning bats have the highest niche width while passive gleaning bats that are only found in high elevations are isotopic specialists showing low overlap with other groups. Edge and open-space foraging bats showed idiosyncratic changes in niche width across elevations. We also find that the niches of rhinolophid bats overlap with edge-space and open-space foraging bats despite their unique functional traits. These results support the idea that at low elevations high species richness is associated with niche packing while at high elevations strong niche partitioning prevails in dynamic and resource-poor environments. We conclude that although high elevation animal assemblages are often 'functionally underdispersed', that is show homogenous functional traits, our approach based on stable isotopes demonstrates niche partitioning among such functionally similar species.

The undetectability of global biodiversity trends using local species richness

Although species are being lost at alarming rates, previous research has provided conflicting results on the extent and even direction of global biodiversity change at the local scale. Here, we assessed the ability to detect global biodiversity trends using local species richness and how it is affected by the number of monitoring sites, sampling interval (i.e. time between original survey and re‐survey of the site), measurement error (error of the measurement of the local species richness), spatial grain of monitoring (a proxy for the taxa mobility) and spatial sampling biases (i.e. site‐selection biases). We use PREDICTS model‐based estimates as a proxy for the real‐world distribution of biodiversity and randomly selected monitoring sites to calculate local species richness trends. We found that while a monitoring network with hundreds of sites could detect global change in species richness within a 30‐year period, the number of sites for detecting trends doubled for a decade, increased 10‐fold within three years and yearly trends were undetectable. Measurement errors had a non‐linear effect on statistical power, with a 1% error reducing statistical power by a slight margin and a 5% error drastically reducing the power to reliably detect any trend. The ability to detect global change in local species richness was also related to spatial grain, making it harder to detect trends for sites sampled at smaller plot sizes. Spatial sampling biases not only reduced the ability to detect negative global biodiversity trends but sometimes yielded positive trends. We conclude that detecting accurate global biodiversity trends using local richness may simply be unfeasible with current approaches. We suggest that monitoring a representative network of sites implemented at the national level, combined with models accounting for errors and biases, can help improve our understanding of global biodiversity change.

Agricultural spider decline: long-term trends under constant management conditions

There is widespread evidence for a worldwide trend of insect decline, but we have much fewer data about recent temporal trends in other arthropod groups, including spiders. Spiders can be hypothesised to similarly decline because of trophic dependence on insects and being equally sensitive to local and global environmental changes. Background trends in arthropod populations can be verified if we decouple large-scale environmental transitions, such as climate change, from local factors. To provide a case study on baseline spider community trends, we observed changes in the spider community of an unsprayed alfalfa field and its margin 23 years apart under largely unchanged local conditions. We aimed to determine whether there are changes in spider abundance, species richness and mean species characteristics. Spider abundance per unit effort decreased dramatically, by 45% in alfalfa and by 59% in the margin, but species richness and most characteristics remained unchanged. Community composition in both habitats shifted and became more similar by the current study period. The population decline was especially marked in certain farmland species. We propose that in the absence of local causative factors, spider abundance decline in our study indicates a reduction of spider populations at landscape and regional scales.

Perception and appreciation of plant biodiversity among experts and laypeople

Abstract Plant biodiversity, which is fundamental for the delivery of ecosystem services, is in decline. Yet, knowledge about how plant biodiversity is perceived and appreciated is scarce. We studied biologists' and laypeople's perception and appreciation for plant communities that differ in plant biodiversity, using ranges of plant biodiversity known to affect ecosystem services. We investigate species richness, species turnover and species evenness. A questionnaire based on photographs displaying artificial plant communities was used. Perceived biodiversity was 12% more often congruent with actual biodiversity for biologists than for laypeople. Species richness was perceived congruently with actual species richness by 77% of all respondents, compared with 27% for species evenness and 29% for species turnover. Appreciation for the displayed communities correlated positively with their actual plant biodiversity, except for species turnover. Appreciation always correlated positively with perceived plant biodiversity and even stronger than with actual plant biodiversity. This was not the case for species richness, for which perceived and actual biodiversity were most often congruent. Our results suggest that plant biodiversity is perceived most accurately when changes in species richness are considered, while changes in species evenness and species turnover are perceived less accurately. The respondents' answers indicate that perceived higher plant biodiversity is appreciated more than perceived lower plant biodiversity, even when perceived and actual plant biodiversity are not congruent. We corroborate findings that people value plant biodiversity per se. But we also find that people largely perceive species evenness and turnover with low accuracy; and that people have low appreciation for these biodiversity dimensions that are lesser known but essential to ecosystem functioning. Our finding that biologists have higher accuracy in perceiving biodiversity suggests that biodiversity literacy is key to increasing people's awareness of changes in plant biodiversity. Read the free Plain Language Summary for this article on the Journal blog.

Effects of plant species richness on the structure of plant-bird interaction networks along a 3000-m elevational gradient in subtropical forests

Ecological community diversity and structure has implications for bird seed-dispersal networks that change with environmental conditions and plant species richness along elevational gradients. In this study, we examined how plant-bird interactions change with plant species richness at both the network and species level, along a 3000-m elevational gradient in a subtropical forest ecosystem. At the network level, Shannon diversity interactions (H2) decreased consistently with elevation, with a concomitant decrease in network specialization (H2′), likely due to lower plant and bird species richness at higher elevations. At the species level, the number of effective partners for both plants and birds decreased with increasing elevation, while the degree of specialization of both plants and birds on their partners increased with elevation. Specifically, we found a unimodal pattern where the effective partners of both birds and plants initially increased and then decreased with plant species richness. Furthermore, we found an inverted unimodal relationship between the degree of specialization and plant species richness, where the degree of specialization between birds and plants initially decreased and then increased with plant species richness. This study provides the first empirical evidence that changes in plant species richness with elevation can affect plant-bird interaction networks in subtropical forests.

Comprehensive Assessment of White-Tailed Deer Browse in the Presence of Beech Bark Disease at a Great Lakes National Park

In northern hardwood forests, white-tailed deer (Odocoileus virginianus) impact both tree regeneration and groundlayer composition, leading to a dominance of American beech (Fagus grandifolia), an unpalatable species, as well as a reduction of preferred groundlayer species. Deer become especially problematic in areas with beech bark disease, such as at Sleeping Bear Dunes National Lakeshore. We analyzed datasets from Sleeping Bear Dunes, collected in 2009 and 2018, to assess vegetation change in three management units: a mainland unit with a long history of deer occupancy, and two islands, one with high deer pressure and one with no known history of permanent deer presence. For each unit, we tested for change in species richness and mean coefficient of conservatism. We also examined the groundlayer, testing for change in indices of abundance and size of preferred and avoided species. Finally, we compared regeneration of palatable and unpalatable tree species. We found increased nonnative species richness, decreased number and abundance of preferred herbaceous species, as well as decreased height of a preferred species. We also detected increased sapling density of beech while that of palatable species declined. Our data provide further evidence of the impacts of white-tailed deer on the forest understory. Management goals should focus on maintaining deer densities at or below 5 deer km–2 in order to promote growth of the full suite of herbaceous species typical of the region and habitat and to allow adequate regeneration of the overstory.

Spatiotemporal effect reveal the abundance of the crab Paracleistostoma depressum negatively correlated with pneumatophore density in a tropical mangrove

The complexity of mangrove habitats, habitat heterogeneity, and the patchiness of crab assemblages could introduce potential confounding factors that make detection of physical disturbance impacts on mangrove crab assemblages difficult. This study categorized the effects of small-scale disturbance on mangrove crabs by examining changes in crab abundance and species richness in six mangrove sites at Merbok and Penang mangroves, North-west of Peninsular Malaysia across four months. Treatments that represented small-scale disturbance were introduced comprising control (Treatment 0), the removal of pneumatophores and detritus (Treatment 1) and trampling with size 9 boots (Treatment 2). Experimental design comprised of factors sampling Month (n = 4), Forest (n = 6), and Treatment (n = 3), with four plots as replicates. Sampling of mangrove crabs was conducted using a hand catch method. Seventeen species of crabs were identified, belonging to five families comprising Sesarmidae, Varunidae, Dotilidae, Camptandriidae and Ocypodidae. Several species of sesarmid crabs, and Paracleistostoma depressum from the family Camptandriidae were commonly found in all six sites, while some species from other families were found only in specific sites. The crab abundance was greater in Penang than in Merbok, although crab species richness was lower in Penang. Univariate analysis revealed there were significant effects of disturbance treatments in a specific month and forest on the abundance of the crab Paracleistostoma depressum (SNK Month × Forest × Treatment F(30,216)=1.55; p = 0.04). Paracleistostoma depressum was found to be the most abundant in Penang despite the removal of pneumatophores and detritus, with P. depressum abundance negatively correlating with the number of pneumatophores (r = −0.62, p = 0.03) and detrital biomass (r = −0.61, p = 0.03) in the Gurney site in Penang in September 2016. Thus, species-specific responses of crabs to physical disturbance should be analysed in detail to avoid misrepresentations of the role of habitat complexity in providing shelter for crab species.