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opencc-zeroDec 2022View details →

Experimental extensification of mountain grasslands restores plant species richness but not species composition in the mid-term

<ol> <li>The traditional grasslands that characterize the cultural landscapes of the palaeartic mountain massifs represent biodiversity hotspots. Yet, they are currently threatened by the intensification of farming practices, notably excesses in fertilization and irrigation.</li> <li>We experimentally investigated the passive restoration of montane and subalpine hay meadows after six years of management intensification, with different levels of fertilization and irrigation, followed by five years of release of intensive management, i.e. extensification. More specifically, relying on a full randomized block-design replicated at 11 Swiss study sites constituted of extensively-managed meadows, we exposed during six years (2010-2015) four 20 m diameter plots to three levels of intensification (low, medium and high inputs), while a fourth plot served as a control (no inputs). In the second phase of the experiment (2016-2020), all study meadows underwent farming extensification.</li> <li>We monitored total species richness and plant diversity (Simpson diversity), indicator plant species as well as the composition and variability of the plant communities based on Bray-Curtis dissimilarity distances.</li> <li>We found that total species richness decreased in the most intensified plots after six years of intensification, but all plots retrieved their baseline species richness after five years of re-extensification. Additionally, we found no difference between the years in plant diversity (Simpson diversity) among the treatments. Yet, intensification led to different plants communities' compositions in all three levels of intensification in 2015 compared to the extensive plots, and this structural difference remained after five years of re-extensification.</li> <li>Synthesis and applications. Land-use intensification induces a rapid impoverishment of the flora of mountain meadows. Our results demonstrate the potential of mountain hay meadows to passively restore plant species richness after re-extensification, however plants communities did not fully recover. We recommend maintaining fertilization inputs as low as possible and operating active restoration on grasslands formerly intensified.</li> </ol>

opencc-zeroJan 2023View details →

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.

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

1. 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. 2. In this study, we evaluate the relevance of niche packing vs. 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. 3. 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. 4. 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', i.e. show homogenous functional traits, our approach based on stable isotopes demonstrates niche partitioning among such functionally similar species.

Data for: Species richness and assemblages of bats along a forest elevational transect in Papua New Guinea

Over the past decades, elevational gradients have become a powerful tool with which to understand the underlying cause(s) of biodiversity. The Mt. Wilhelm elevational transect is one such example, having been used to study the birds, insects, and plants of Papua New Guinea (PNG). However, a survey of mammals from this forest elevational transect was lacking. We thus aimed to investigate patterns in the community structure and species richness of bats (Chiroptera) along the transect, link the species to available regional data, and explain the observed patterns by including environmental characteristics. Bat assemblages were surveyed between 200 m and a timberline at 3,700 m a.s.l. at eight study sites separated by 500 m in elevation. We conducted mist-netting and acoustic surveys to detect and identify species at each site. Regional data were compiled to compare local with regional diversity. Finally, biotic (i.e., food availability, habitat features) and abiotic (i.e., mean daily temperature) factors were included in our analyses to disentangle the ecological drivers underlying bat diversity. Results revealed that species richness decreases with ascending elevation and was best explained by a corresponding decrease in temperature. We observed both turnover and nestedness of the species composition at regional scale whereas turnover was dominant at local scale. Extensions and shifts of bat elevational ranges were also found in Mt. Wilhelm. Consequently, despite that the study was restricted to one mountain in PNG, it demonstrates how basic inventory surveys can be used to address ecological questions in other similar and undisturbed tropical mountains.

Data from: Habitat heterogeneity determines species richness on small habitat islands in a fragmented landscape

Aim: The small-island effect (SIE), as an exception to the species-area relationship, has received much attention in true island systems. However, the prevalence and related patterns of the SIE have not been well evaluated in habitat island systems. Here, we aimed to identify the existence of SIE for habitat islands in fragmented landscapes and determine the key factors influencing species richness on small habitat islands. Location: Inner Mongolia Autonomous Region, China. Taxon: Vascular plants. Methods: Based on 78 grassland fragments in fragmented landscapes of the agro-pastoral ecotone of northern China, we used piecewise regression, path analysis, and null models to investigate the SIE of the species-area relationship. We then used a multi-model selection to evaluate the impacts of four influencing factors (instability, isolation, habitat heterogeneity, and surrounding productivity) on species richness (including habitat specialists and generalists) on small habitat islands within the range of SIE. Results: We found an obvious threshold of 5.1 ha in the species-area relationship, below which habitat island area had no direct and indirect effects on species richness. Small habitat islands (< 5.1 ha) host a lower percentage of habitat specialists and a higher percentage of generalists. On small habitat islands, species richness was positively affected by habitat heterogeneity while negatively affected by instability and isolation. Habitat heterogeneity had the strongest effect on species richness, positively affecting specialist richness while negatively affecting generalist richness. Main conclusions: There is a SIE in fragmented landscapes of the agro-pastoral ecotone of northern China, which should be considered in biodiversity conservation. Habitat heterogeneity had a key role in determining the pattern of species richness, especially for small islands. Habitat specialists and generalists had different SIE-related patterns. Our study highlights the importance of considering different ecological groups of species to improve our understanding of the SIE in fragmented habitats.

Data from: Acoustic indices estimate breeding bird species richness with daily and seasonally variable effectiveness in lowland temperate Białowieża forest

Biodiversity monitoring is important to follow temporal changes of the environment. We examined whether acoustic indices can be used as a rapid and easy-to-apply tool for bird biodiversity estimation in one of the least changed European lowland forests – the Białowieża Forest. We collected soundscape recordings in early and late spring at 84 randomly chosen recording points. At each recording point, we analysed 72 1-min sound samples to evaluate how well acoustic indices predict bird species richness from the perspective of a single sound sample, single survey, and recording point, and how they follow the daily pattern of singing activity. For each 1-min sound sample, we prepared a list of vocalizing bird species and calculated three acoustic indices: Bioacoustic Index (BI), Acoustic Complexity Index (ACI), and Acoustic Diversity Index (ADI). We found that from the perspective of a single 1-min sound sample, BI best predicts the bird species richness, independently of time in the season but variably across the day, while ACI and ADI showed weaker and seasonally and daily variable dependency. The correlation between each index and the number of bird species was stronger in the early survey than in the late survey. All acoustic indices followed daily bird activity patterns, yet they provided greater values before the peak of the species richness estimated by manual spectrogram scanning and listening to recordings. We showed that acoustic indices correlate moderately to strongly with the bird species richness obtained by manual spectrogram scanning and listening to recordings by humans. Therefore, acoustic indices can be used as a tool for rapid estimation of bird biodiversity in temperate forests. However, daily and seasonal variation in effectiveness of acoustic indices should be taken into account in the analysis.

opencc-by-4.0Apr 2013View details →

Fig. 28 in Terrestrial mollusc species richness and diversity in Omo Forest Reserve, Ogun State, Nigeria

Fig. 28. Dendrogram of Bray-Curtis similarity between plots in sites I and II.

opencc-by-4.0Apr 2013View details →

Fig. 2 in Terrestrial mollusc species richness and diversity in Omo Forest Reserve, Ogun State, Nigeria

Fig. 2. Rank abundance curve for terrestrial snails from Omo Forest Reserve in Ogun State, Nigeria.

opencc-zeroMar 2023View details →

Data from: High vascular plant species richness in the Usumacinta River Basin: a comprehensive floristic checklist for a natural region in the Mesoamerican biodiversity hotspot

Background: Mesoamerica is one of the most important biodiversity hotspots on the planet. Despite significant efforts made over two centuries to contribute to the floristic knowledge of this region, our understanding of its flora is still scattered and uneven. Questions: What is the magnitude of the vascular plant species richness in the Usumacinta River Basin? Study site and dates: Usumacinta River Basin (Guatemala and Mexico), 1838–2018. Methods: We compiled the checklist by systematizing the floristic information acquired from various sources derived from numerous floristic and ecological studies. Results: We recorded 6,977 species, 1,892 genera, and 274 families. The largest numbers of species (5,746) and records (58,859) correspond to the Mexican portion of the Usumacinta River Basin, compared to its Guatemalan counterpart (4,445 species and 19,952 records). The most species-rich families were Orchidaceae (598 species), Fabaceae (512), and Asteraceae (476). The prevalence of these and all other families with significant contributions to the flora varied among three elevation-defined sectors into which the Usumacinta River Basin was subdivided (lower, middle, and upper basin). Conclusions: The Usumacinta River Basin is a strategic region for plant biodiversity conservation as it hosts almost one-third of all vascular plant species known for Mesoamerica and ca. 6 % of the entire flora in the Americas. Further botanical exploration should focus on those areas of the basin for which little or no information is available in order to gain a better appreciation of its flora.

opencc-zeroMar 2023View details →

Seed limitation interacts with biotic and abiotic factors to constrain novel species' impact on community biomass and richness

Seed limitation can narrow down the number of coexisting plant species, limit plant community productivity, and can also constrain community responses to changing environmental and biotic conditions. In a 10-year full-factorial experiment of seed addition, fertilisation, warming, and herbivore exclusion, we tested how seed addition alters community richness and biomass, and how its effects depend on seed origin and biotic and abiotic context. We found that seed addition increased species richness in all treatments, and increased plant community biomass depending on nutrient addition and warming. Novel species, originally absent from the communities, increased biomass the most, especially in fertilised plots and in the absence of herbivores, while adding seeds of local species did not affect biomass. Our results show that seed limitation constrains both community richness and biomass, and highlight the importance of considering trophic interactions and soil nutrients when assessing novel species immigrations and their effects on community biomass.

opencc-by-4.0Apr 2023View details →

Vector species richness predicts local mortality rates by Chagas disease

Vector species richness may drive the prevalence of vector-borne diseases by influencing pathogen transmission rates. The dilution effect hypothesis predicts that higher biodiversity reduces disease prevalence, but with inconclusive evidence. In contrast, the amplification effect hypothesis suggests that higher vector diversity may result in greater disease transmission by increasing and diversifying the transmission pathways. The relationship between vector diversity and pathogen transmission remains unclear and requires further study. Chagas disease is a vector-borne disease most prevalent in Brazil and transmitted by multiple species of Triatominae insect vectors, yet the drivers of spatial variation in its impact on human populations remain unresolved. We tested whether triatomine species richness, latitude, bioclimatic variables, human host population density, and socioeconomic variables predict Chagas disease mortality rates across over 5000 spatial grid cells covering all of Brazil. Results show that species richness of triatomine vectors is a good predictor of mortality rates caused by Chagas disease, which supports the amplification effect hypothesis. Vector richness and the impact of Chagas disease may also be driven by latitudinal components of climate and human socioeconomic factors. We provide evidence that vector diversity is a strong predictor of disease prevalence and give support to the amplification effect hypothesis.

opencc-by-4.0Apr 2023View details →

Species richness and nativity of ants (Hymenoptera: Formicidae) in urban and suburban areas of Kingston, Jamaica

The dataset contains the raw data for the paper on the species richness and nativity of ants in urban and suburban areas of Kingston, Jamaica.

opencc-zeroJun 2023View details →

Large-scale restoration of species-rich dry grasslands on arable land: Environmental filtering drives successful species establishment over a period of 10 years

Sowing of regionally specific seed mixtures on former arable land is increasingly used to restore species-rich grasslands, but it often faces important obstacles in environmental conditions and colonisation from preserved surrounding grasslands. Long-term landscape scale studies, which explore the processes governing plant establishment from seed mixtures and later colonisation from the surrounding landscape are scarce. We studied the species and functional trait composition of 32 grasslands restored 1–11 years before the first sampling by sowing regional seed mixtures in the White Carpathian Mts (SE Czech Republic). We compared them with 23 well-preserved permanent grasslands in their surroundings. In each grassland we estimated plant species cover in three plots of 25 m2, in restored grasslands in 2009, 2014 and 2019, in permanent grasslands in 2009. The species composition of the restored grasslands converged towards the permanent grasslands due to expansion of dry grassland species and retreat of mesic grassland and weed species. The majority (60–71%) of the vegetation cover of restored grasslands was formed by sown species, while the species number was mainly determined by colonising unsown species (61–63%). The species number of restored grasslands remained lower than that in permanent grasslands. Functional trait composition (Community Weighted Mean) of the sown seed mixtures, permanent grasslands and restored grasslands overlapped in all three samplings. With increasing grassland age, species with resource-retaining traits of low specific leaf area and high leaf dry matter content, lower stature, higher seed mass, and lower capacity for clonal reproduction expanded. Functional trait diversity of the plots was mostly lower than expected by null model randomisations of community, which indicates strong environmental filtering. Comparison of newly colonising species and extinct species indicated that mainly species with traits similar to the rest of the community are able to colonise the grasslands successfully. Synthesis and applications. Sowing of regionally specific seed mixtures was successful and demonstrated to be a fast way of grassland restoration, particularly in terms of functional trait composition. The resulting species diversity depended on the colonisation processes, which are controlled by the functional composition of the local communities.

opencc-zeroJul 2023View details →

Aridity and soil fertility, not species richness, interact to affect temporal stability along a large natural gradient in Northern China

There is mounting evidence from experimental studies that drought and nutrient enrichment can interact to impact the biodiversity and productivity of terrestrial ecosystems. Whether such interactive effect influence plant diversity and the temporal stability of community productivity of natural ecosystems is unknown. To fill this knowledge gap, we combined a field survey of plant diversity and soil conditions with remote sensing temporal estimates of primary productivity in grasslands along a natural gradient in northern China. We found that aridity and soil ammonium (NH4+-N) interacted to influence temporal stability of NDVI. That is, the relationship between ammonium and temporal stability of NDVI shifted from positive to negative due to increased standard deviation of NDVI with increasing aridity. Species richness was not related to temporal stability because it influenced the mean and standard deviation of NDVI proportionally. As a result, soil fertility outweighed the contribution of species richness to temporal stability. Our study demonstrates the synergistic effect of aridity and soil fertility, but not species richness, on temporal stability along a large natural gradient. Predicting how environmental drivers affect diversity and the stable provisioning of ecosystem services in real-world ecosystems therefore requires a better understanding of the complex interactions among environmental drivers.

opencc-zeroSep 2023View details →

Ancient human colonization explains dung beetle species richness in the Mediterranean and Macaronesian islands

Aim: Different hypothesis have been proposed to explain differences in species richness among islands. However, few studies have attempted to compare the explanatory power of multiple hypotheses using a large data set. Here we analyse how different types of predictors (energetic/climatic, environmental heterogeneity, island biogeography and anthropogenic) affect variation in dung beetle species richness on Mediterranean and Macaronesian islands. Location: Mediterranean and Macaronesian islands. Taxon: Dung beetles. Methods: Using a large dataset of islands (n = 147), we extracted the species richness of dung beetles on each island using 362 bibliographic reference sources. We performed GLMs to analyse the relationship between the species richness of dung beetles and eleven explanatory variables (temperature, evapotranspiration, aridity, area, maximum elevation, connection to continent during LGM, geological origin, distance from continent, nearest continent, years since first human colonization and human density) representing four types of causal hypotheses. We also included as a covariate the number of published papers studying dung beetles as a surrogate of the survey/study effort carried out in each island. Results: GLMs suggest that the years since first human colonization, the number of published papers, and island area were the predictors with a higher explanatory capacity. The volcanic character of the islands and the distance from the mainland had some relevance in the case of Scarabaeinae and Geotrupinae, and maximum elevation appeared relevant in the species richness of Scarabaeinae and Aphodiidae. The anthropogenic and island biogeography hypotheses on the variation in species richness were the ones that have the strongest explanatory capacity, regardless of the inclusion of the surrogate of survey effort as a covariate in the models. Main conclusions: The long history of human movements and agricultural activities has facilitated the colonization of dung beetles and provided trophic resources for their persistence, leading to increased species richness. Thus, the importance of anthropogenic factors in shaping the biodiversity patterns of island biogeography cannot be ignored. These human-induced influences may play a fundamental role in altering the biogeographic patterns of islands, even overriding the importance of other variables. Consequently, our findings underline the profound impact of historical human actions on islands biodiversity.

opencc-zeroSep 2023View details →

The functioning of alpine grassland ecosystems: climate outweighs plant species richness

<ol> <li>The biodiversity–ecosystem functioning relationship has received significant attention in recent decades. It has been widely demonstrated that plant diversity plays a crucial role in enhancing the functioning of terrestrial ecosystems. However, few studies have tested the influence of plant species richness in mediating the impacts of climate on ecosystem functions at large spatial scales. </li> <li>To address this gap, we utilized data from field surveys across broad climatic gradients at the Qinghai-Tibetan Plateau, China. Our goal was to examine the importance of plant species richness for the functioning of alpine grassland ecosystems, specifically productivity and soil carbon sequestration. </li> <li>Our results showed strong positive correlations between ecosystem functioning and growing season precipitation as well as species richness. In contrast, there was a negative correlation with growing season temperature. Notably, the positive effect of growing season precipitation on ecosystem functioning outweighed the negative effect of growing season temperature. The indirect effects of growing season precipitation and temperature on ecosystem functioning through changes in species richness were weak. Furthermore, the inclusion of climate factors in the model weakened the relationships between species richness and ecosystem functioning.</li> <li>Synthesis. Our findings demonstrate that climate factors are more important than species richness for the provisioning of ecosystem functions at large spatial scales. In summary, our study underscores the importance of considering climate factors alongside species richness when assessing ecosystem functioning across extensive geographical areas.</li> </ol>

opencc-zeroOct 2023View details →

Tree species richness around urban red maples reduces pest abundance but does not enhance biological control

Urban trees often host greater insect pest abundance than trees in rural forests. This may be due, in part, to differences in tree diversity and canopy cover between these settings. Urban trees are often planted in isolation or monoculture, which favors pest accumulation. The gloomy scale, Melanaspis tenebricosa Comstock, is a pest of urban red maples (Acer rubrum L.) that is abundant where impervious surfaces dominate the local landscape. Increasing tree diversity and canopy cover around urban red maples may reduce gloomy scale abundance by supporting natural enemy communities. We investigated the effect that surrounding tree species richness and tree canopy cover had on gloomy scale abundance, natural enemy abundance, and biological control in red maple trees in Raleigh, NC, USA. We collected scales and natural enemies from red maples that spanned a gradient of tree species richness, canopy cover, and impervious surface values. We also measured gloomy scale parasitism and predation of sentinel prey in red maple canopies. Greater tree species richness and canopy cover were associated with lower gloomy scale density. Red maples in diverse settings also hosted fewer scales per natural enemy. Parasitoids were less common in maples in diverse settings, but generalist predator abundance was unaffected by tree diversity. Finally, tree species richness and canopy cover did not increase biological control of scales or sentinel prey. Our findings suggest that higher tree diversity and greater canopy cover may reduce gloomy scale density, but this is not entirely explained by the effects of natural enemies and biological control.

opencc-by-4.0Oct 2023View details →

Insect biomass shows a stronger decrease than species richness along urban gradients

Anthropogenic land cover change is a major driver of biodiversity loss, with urbanisation and farmland practices responsible for some of the most drastic modifications of natural habitats. The relative importance of different land covers for shaping insect communities, however, is unclear. This study examines the effect of urban and farmland covers, along with land cover heterogeneity, at a landscape scale on species richness, evenness and biomass of flying insects using citizen science carnet sampling across Denmark. Increasing urban cover had a negative effect on insect richness but an even stronger negative effect on biomass. Increased land cover heterogeneity did not mitigate the negative effect of urban cover. Insect assemblages also became more even with increased urban cover. Farmland cover had no significant effect on insect richness, evenness or biomass. Based on our findings, the urban cover has a strong negative impact on insect communities, indicating that urbanisation could contribute to insect declines. Moreover, our findings indicate that insect loss occurs more through loss of biomass than loss of species, which may affect the ecosystem‐level consequences of urbanisation.

opencc-zeroOct 2023View details →

Widespread sympatry in a species-rich clade of marine fishes (Carangoidei)

A universal paradigm describing patterns of speciation across the tree of life has been debated for decades. In marine organisms, patterns of speciation are largely unknown due to the deficiency of species-level phylogenies and information on species' distributions, as well as conflicting relationships between species' dispersal, range size and co-occurrence. Most research on global patterns of marine fish speciation has focused on coral reef or pelagic species. Carangoidei is an ecologically important clade of marine fishes that utilize both coral reef and pelagic environments. We used sequence capture of 1314 ultraconserved elements (UCEs) from 154 taxa to generate a phylogeny of Carangoidei and its parent clade, Carangiformes. Age-range correlation analyses of the geographic distributions and divergence times of sister species pairs reveal widespread sympatry, with 73% of sister species pairs exhibiting a sympatric geographic distribution, regardless of node age, and most species pairs co-existing across large portions of their ranges. We also observe greater disparity in body size and water column depth utilization between sympatric than allopatric sister species. These and other ecological or behavioral attributes likely facilitate sympatry among the most closely related carangoids.