Richness Patterns Research Articles

Global meta-analysis reveals overall higher nocturnal than diurnal activity in insect communities

Insects sustain key ecosystem functions, but how their activity varies across the day–night cycle and the underlying drivers are poorly understood. Although entomologists generally expect that more insects are active at night, this notion has not been tested with empirical data at the global scale. Here, we assemble 331 quantitative comparisons of the abundances of insects between day and night periods from 78 studies worldwide and use multi-level meta-analytical models to show that insect activity is on average 31.4% (CI: −6.3%–84.3%) higher at night than in the day. We reveal diel preferences of major insect taxa, and observe higher nocturnal activity in aquatic taxa than in terrestrial ones, as well as in warmer environments. In a separate analysis of the small subset of studies quantifying diel patterns in taxonomic richness (31 comparisons from 13 studies), we detect preliminary evidence of higher nocturnal richness in tropical than temperate communities. The higher overall (but variable) nocturnal activity in insect communities underscores the need to address threats such as light pollution and climate warming that may disproportionately impact nocturnal insects.

Expert‐based range maps cannot be replicated using data‐driven methods but macroecological conclusions arising from them can

AbstractAimAnswering many fundamental and applied scientific questions relies on accurate geographic range maps for species, such as those compiled by experts working with the International Union for Conservation of Nature (IUCN). However, these maps are resource demanding to produce and only available for a limited number of organisms. Here, we test to what extent standardized, data‐driven methods based on publicly available occurrences can reproduce expert‐based IUCN range maps and the macroecological conclusions drawn from them.LocationGlobal.Time PeriodPresent.TaxaBirds.Materials and MethodsWe estimated the geographic ranges for 7385 non‐marine bird species which either were non‐migratory or had spatially connected breeding and wintering ranges from publicly available, georeferenced point occurrences. We then quantified the spatial overlap between these range estimates and the IUCN expert‐derived range estimates. Finally, we compared global species richness patterns and the environmental correlates that emerge from both approaches.ResultsWe find that range estimates based on point occurrence records overlap on average 52% with expert range estimates for the same species. The global species richness patterns estimated under both approaches are overall similar but show local and regional differences, for example, in the tropical Andes of northern South America and the Central Arc region of Africa. The estimated global drivers of richness are similar.Main ConclusionsExpert‐derived estimates of species distributions are not reproducible by data‐driven approaches relying on currently available public records, even for well‐documented taxa such as birds. However, these discrepancies do not substantially change our macroecological understanding of global drivers of bird diversity.

Climbing mechanisms as a central trait to understand the ecology of lianas across the tropics

AbstractAimsLianas are a central component of tropical forests. However, how the type of climbing mechanisms is related to the functional and taxonomic diversity of lianas across the tropics, remains largely unresolved. Here, we tested two main hypotheses: (i) the functional diversity of lianas differs with climbing mechanism (active and passive) and (ii) the association between taxonomic diversity with contemporary climate, paleoclimate, forest structure and phylogeny differ between climbing mechanisms.LocationTropical forests.Time PeriodPresent.Major Taxa StudiedTerrestrial plants.MethodsWe assembled functional traits and the type of climbing mechanism for 702 liana species and used the World Checklist of Vascular Plants (WCVP v.2.0) to standardize species names, map geographical distribution and estimate taxonomic richness. We used kernel density n‐dimensional hypervolume to estimate the functional diversity of each type of climbing mechanism. We compared the environmental response of taxonomic richness of each type of climbing mechanism, active and passive, to the response of overall liana species richness. We assessed the magnitude and direction of the environmental response considering variables of climate, soil fertility and forest structure.ResultsWe found that active climbing exhibits a higher functional richness than passive climbing. Richness patterns of active and passive climbing mechanisms were mainly driven by contemporary climate, paleoclimate and phylogenetic relatedness. More importantly, paleoclimate was negatively associated with active climbing and positively associated with passive climbing.Main ConclusionsOur study highlights differences in functional diversity (richness, dispersion, evenness and originality) between active and passive climbing species, likely reflecting their distinct ecological strategies for resource use, stress tolerance and dispersal. Integrating taxonomic and functional diversity metrics with information about the type of climbing mechanism provides deeper insights into the ecology and response of lianas to climate change.

Unraveling biogeographical patterns and environmental drivers of soil fungal diversity at the French national scale

Abstract. The fungal kingdom is among the most diversified kingdoms on Earth, with estimations of up to 12 million species. However, it remains poorly understood, with only 150 000 fungal species currently described. Given the major ecological role of fungi in ecosystem functioning, these numbers stress the importance of investigating fungal diversity description across different ecosystem types. Here, we explored the spatial distribution of the soil fungal diversity on a broad geographical scale, using the French Soil Quality Monitoring Network that covers the whole French territory (2171 soils sampled along a systematic grid). Fungal alpha diversity was assessed directly from soil DNA using a meta-barcoding approach by targeting the 18S rDNA gene. The total accumulated fungal diversity across France included 136 219 operational taxonomic units (OTUs), i.e., about 1 % of worldwide soil fungal diversity (based on a maximum diversity estimate of 12 million) for a territory representing only 0.3 % of the terrestrial surface on Earth. Based on this dataset, the first extensive map of fungal alpha diversity was drawn and showed a heterogeneous and spatially structured distribution in large biogeographical patterns of 231 km radius for richness (Hill diversity of order 0) and smaller patterns of 36 km radius for dominant fungi (Hill diversity of order 2). As related to other environmental parameters, the spatial distribution of fungal diversity (Hill numbers based on different orders of diversity) was mainly influenced by local filters such as soil characteristics and land management and also by global filters such as climate conditions with various relative influences. Interestingly, cropped soils exhibited the highest pool of fungal diversity relative to forest and vineyard soils. To complement this, soil fungal OTU network interactions were calculated for the different land uses across France. They varied hugely and showed a loss of 75 % of the complexity in crop systems and grasslands compared to forests and up to 83 % in vineyard systems. Overall, our study revealed that a nationwide survey with a high spatial-resolution approach is relevant for deeply investigating the spatial distribution and determinism of soil fungal diversity. Our findings provide novel insights for a better understanding of soil fungal ecology across the 18S rDNA gene and upgrade biodiversity conservation policies by supplying representative repositories dedicated to soil fungi.

Unveiling the hypotheses of endemic richness: A study case in the Southwestern Alps

Areas where range-restricted species are concentrated are of importance for conservation. However, most of the studies aim at identifying areas rich in endemics for conservation planning, while few studies aim at understanding the causal factors of endemic richness. Here, our goal is to identify the determinants of endemic richness within a centre of endemism, the Southwestern European Alps, by testing four non-mutually exclusive hypotheses that have been proposed to explain patterns of endemic richness. In particular, we examined to what extent temporal and spatial climatic stability and environmental heterogeneity are related to endemic richness. Almost all hypotheses partially support the observed patterns of plant endemics richness within the SW Alps. In general, most of the relationships between environmental variables and endemic richness are statistically significant. However, the highest effect in explaining endemic richness is found for climate change velocity and standard deviation of slope, two factors affecting the possibility of species to disperse. This is in line with the idea that endemics are strongly limited by dispersal and not only by climate. Our results suggest that in regions where the effects of past climate changes were less dramatic endemic richness results from the interaction of species dispersal with regional and specific historical factors.

Predicting time‐at‐depth weighted biodiversity patterns for sharks of the North Pacific

Depth is a fundamental and universal driver of ocean biogeography but it is unclear how the biodiversity patterns of larger, more mobile organisms change as a function of depth. Here, we developed a predictive biogeography model to explore how information of mobile species' depth preferences influence biodiversity patterns. We employed a literature review to collate shark biotelemetry studies and used open‐access tools to extract 283 total records from 119 studies of 1133 sharks from 35 species. We then matched field guide reported depth ranges and IUCN habitat associations for each shark species to use as covariates in a hurdle variant of ensemble random forests. We successfully fit this model (R2 = 0.63) to the noisy time‐at‐depth observations and used it to predict the time budgets of the northeast Pacific shark regional pool (n = 52). We then assessed how occurrence diversity patterns, informed by minimum and maximum depth of occurrence, compared to time‐at‐depth weighted diversity patterns. Time‐at‐depth weighted richness was highest between 0 and 25 m and at the upper part of the mesopelagic zone, 250–300 m; resulting in little similarity to common depth or elevational biodiversity patterns while the occurrence‐weighted richness pattern was similar to the ‘low‐plateau' pattern. In the phylogenetic and functional dimensions of biodiversity and over three different distance metrics, we found strong but haphazard differences between the occurrence‐ and time‐at‐depth weighted biodiversity patterns. The strong influence of time budgets on biodiversity led us to conclude that occurrence data alone are likely insufficient or even misleading in terms of the depth‐driven biogeographic patterns in the open ocean. Utilizing the increasing amount of time‐at‐depth information from biotelemetry studies in predictive biogeographic models may be critical for capturing the preferences of pelagic, mobile species occupying the largest biome on the planet.

Future changes in society and climate may strongly shape wild large-herbivore faunas across Europe.

Restoring wild communities of large herbivores is critical for the conservation of biodiverse ecosystems, but environmental changes in the twenty-first century could drastically affect the availability of habitats. We projected future habitat dynamics for 18 wild large herbivores in Europe and the relative future potential patterns of species richness and assemblage mean body weight considering four alternative scenarios of socioeconomic development in human society and greenhouse gas emissions(SSP1-RCP2.6, SSP2-RCP4.5, SSP3-RCP7.0, SSP5-RCP8.5). Under SSP1-RCP2.6, corresponding to a transition towards sustainable development, we found stable habitat suitability for most species and overall stable assemblage mean body weight compared to the present, withan average increase in species richness (in 2100: 3.03 ± 1.55 compared to today's 2.25 ± 1.31 species/area). The other scenarios are generally unfavourable for the conservation of wild large herbivores, although under theSSP5-RCP8.5 scenario there would be increase in species richness and assemblage mean body weight in some southern regions (e.g. + 62.86 kg mean body weight in Balkans/Greece). Our results suggest that a shift towards a sustainable socioeconomic development would overallprovide the best prospect of our maintaining or even increasing the diversity of wild herbivore assemblages in Europe, thereby promoting trophic complexity and the potential to restore functioning and self-regulating ecosystems. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Altitudinal variation in soil nematode communities in an alpine mountain region of the eastern Tibetan plateau

Distribution patterns of species diversity in high mountains have received considerable attention in scientific research and conservation efforts. However, our understanding of the corresponding altitudinal patterns of soil fauna across spatial scales, particularly on high-altitude plateaus, remains limited. To address this gap, we conducted a case study on Balang Mountain, located at the eastern margin of the Tibetan Plateau. Our focus was on soil nematodes within an altitudinal range of approximately 3000 to 4000 m. We collected climate, soil, and vegetation data to test multiple hypotheses, including the effects of energy, water availability, productivity, soil resource availability, and pH constraints on nematode communities. Dominance analysis and commonality analysis were employed to determine the relative support of these hypotheses in explaining nematode abundance, diversity, and composition. Beta-diversity, which links local alpha-diversity and regional gamma-diversity, was decomposed into distinct components to elucidate ecological processes along altitude and across diversity facets. Our findings revealed distinct yet significant altitudinal patterns in nematode abundance (concave-down), richness (monotonous decrease), and evenness (concave-up). Water and soil resource availability emerged as dominant factors influencing nematode abundance, while energy and pH played pivotal roles in determining nematode richness. Additionally, water and productivity were identified as the most significant drivers shaping nematode community composition. Furthermore, a significant influence of pH on gamma- and beta-diversities was observed, surpassing the impact of other predictors at a coarse level. Upon decomposing beta-diversities into different components, we discovered that taxa substitution (turnover) and individual substitution (balance-variation) were the primary contributors to community dissimilarity among altitudes, indicating strong effects of environmental sorting or spatial and historical constraints on soil nematode communities. These findings contribute to our understanding of the distribution patterns and processes of soil nematode communities along altitude in alpine ecosystems. Moreover, they offer valuable insights into soil biodiversity distribution and conservation in high-mountain environments.

Environment and management jointly shape the spatial patterns of plant species diversity of moist grasslands in the mountains of Northeastern Yunnan

Grasslands account for about a quarter of the Earth’s land area and are one of the major terrestrial ecosystems, with significant ecological and economic value. The influence of environmental factors and management types on grassland biodiversity has garnered considerable attention. This study investigated how patterns of species richness are influenced by geographical distance, environmental gradients, and management type in the grasslands of northeastern Yunnan, China. We used structural equation modeling to disentangle the impacts of environment and management on phylogenetic community structure, and partial Mantel tests to estimate the roles of dispersal limitation and environmental filtering on taxonomic and phylogenetic beta diversity of three types of grasslands. Our results show that taxonomic alpha diversity increased in grazed grasslands and decreased in mowed grasslands, compared with protected grasslands. However, the phylogenetic structure of both grazed and mowed grassland communities was clustered, whereas that of protected communities was random. Moreover, both grazing and mowing significantly reduced the taxonomic and phylogenetic beta diversity of grasslands, with the lowest values observed in mowed grasslands. Both taxonomic and phylogenetic beta diversity were dominated by species turnover under different management types. The taxonomic and phylogenetic beta diversities of protected and grazed grasslands were simultaneously affected by environmental filtering and dispersal limitation, with the later playing a stronger role. In addition, mowing and related management measures had a stronger filtering effect on grassland community structure, as reflected by changes in community composition.

Distribution and abundance of herbivorous reef fishes on a barrier reef system in the Florida Keys and Dry Tortugas, Florida

Herbivorous reef fishes control algal growth and are critical for maintaining reef health. Grazing effects vary due to community composition, so a diverse herbivore community is important for preventing phase shifts from coral to algal-dominated reefs. However, herbivore communities and grazing effects vary spatially, resulting in non-uniform distribution of algal mitigation across the seascape. Therefore, understanding how habitat influences herbivore communities is essential for predicting the spatial distribution of these species' ecological services. This study used underwater visual surveys (n = 5455) to examine how habitat influences spatial patterns of herbivorous fish densities and species richness in the Florida Keys and Dry Tortugas, Florida. Herbivorous fishes were ubiquitous, and communities were dominated by small herbivores such as damselfishes (Pomacentridae), gobies (Gobiidae), surgeonfishes (Acanthuridae), and small- to medium-bodied parrotfishes (subfamily Scarinae). A suite of factors influenced herbivorous fish communities but boosted regression tree results showed that habitat relief, depth, and spatial location within the Florida Keys and Dry Tortugas were the most important factors. In general, herbivore occurrence, density, and species richness increased as percent of low relief hardbottom habitat (<0.2 m high) decreased. In addition, density and occurrence of herbivores generally increased at shallower depths. Spatial location influenced the density of herbivores with potential hotspots predominantly located in the Upper Keys and the Dry Tortugas Bank. These data provide a valuable understanding of the spatial distribution of herbivorous reef fishes, and aid management decisions regarding the protection and sustainability of herbivore resources and the ecosystems that rely on them.

A novel hybrid beachgrass is invading U.S. Pacific Northwest dunes with potential ecosystem consequences

AbstractInvasive plants formed via hybridization, especially those that modify the structure and function of their ecosystems, are of particular concern given the potential for hybrid vigor. In the U.S. Pacific Northwest, two invasive, dune‐building beachgrasses, Ammophila arenaria (European beachgrass) and A. breviligulata (American beachgrass), have hybridized and formed a new beachgrass taxa (Ammophila arenaria × A. breviligulata), but little is known about its distribution, spread, and ecological consequences. Here, we report on surveys of the hybrid beachgrass conducted across a 250‐km range from Moclips, Washington to Pacific City, Oregon, in 2021 and 2022. We detected nearly 300 hybrid individuals, or an average of 8–14 hybrid individuals per km of surveyed foredune. The hybrid was more common at sites within southern Washington and northern Oregon where A. breviligulata is abundant (75%–90% cover) and A. arenaria is sparse and patchy. The hybrid displayed morphological traits such as shoot density and height that typically exceeded its parent species suggesting hybrid vigor. We measured an average growth rate of 30% over one year, with individuals growing faster at the leading edge of the foredune, nearest to the beach. We also found a positive relationship between hybrid abundance and A. arenaria abundance, suggesting that A. arenaria density may be a controlling factor for hybridization rate. The hybrid showed similar sand deposition and associated plant species richness patterns compared with its parent species, although longer term studies are needed. Finally, we found hybrid individuals within and near conservation habitat of two Endangered Species Act‐listed, threatened bird species, the western snowy plover (Charadrius alexandrinus nivosus) and the streaked horned lark (Eremophila alpestris strigata), a concern for conservation management. Documenting this emerging hybrid beachgrass provides insights into how hybridization affects the spread of novel species and the consequences for communities in which they invade.

Cultural Echoes in Modern Design: Assessing Young Consumers’ Perceptions of Traditional Bamboo Weaving Patterns

This study, employing convenience sampling of art specialists, investigates the emotional resonance of young consumers with Chinese bamboo patterns, underscoring their significance in the realm of contemporary design. Through the lens of Kansei engineering, we delve into the intricate world of bamboo weaving patterns, scrutinizing their perceptual evaluations and user preferences among 104 art university students aged 18–23. Our analysis not only identifies pivotal factors for innovative redesign but also underscores the pivotal role of these traditional patterns in enhancing the emotional and aesthetic appeal of products for the younger generation. The findings illuminate a notable appreciation among this demographic for the ecofriendly and culturally rich bamboo patterns, positioning them as essential elements in modern lifestyle products. The study advances the discourse on integrating cultural heritage into product innovation, advocating for designs that resonate with the aesthetic sensibilities and environmental values of today’s youth. This aligns with the critical insights into the various categories of patterns and their diverse applications in contemporary design, addressing the cognitive gap between designers and consumers and highlighting the importance of cultural motifs in product development.

Seed bank and aboveground vegetation of Atlantic Forest re‐growing on mining tailings in Mariana: Highlighting diversity patterns of functional groups

AbstractNatural regeneration after mining activities depends largely on the soil seed bank (SSB) and aboveground vegetation (AGV) richness and composition. We evaluated the species diversity pattern of the SSB and AGV on soil and technosol across second‐growth Atlantic Forests (SGFs) after mining tailings deposition in Mariana, southeastern Brazil. Two second‐growth Atlantic seasonal semideciduous forests of different stand ages were selected: a 3‐year‐old stand of SGF re‐growing on tailings (SGF tailings) and a 30‐year‐old stand of native reference forest not affected by tailings (SGF nontailings). Overall, the results showed significant differences in forest attributes (species richness and composition) in the SSB and AGV between the two forest patches evaluated (SGF tailings and SGF nontailings). Moreover, both nonzoochoric and zoochoric dispersed species of AGV showed significant differences between second‐growth forests, with higher variability of community‐weighted mean in SGF tailings. The result shows smaller differences in species richness between forest types for both SBB (ranging 85 and 90 species) and AGV (~55 species). Despite the time difference between the secondary forest and the absence of zoochoric species in the tailings seed bank, the AGV that are re‐growing on mining tailings presented a high proportion of zoochoric species. This pattern of species richness and community composition variability observed in the technosol seed bank, and AGV that are re‐growing after the deposition of mining tailings are important recovery indicators for plant communities affected.

Scale-to-scale energy flux in the oceanic global circulation models

Lewis Fry Richardson proposed his famous picture of turbulent flows in 1922, where the kinetic energy is transferred from large-scale to small-scale structures until the viscosity converts it into heat. This cascade idea, also known as the forward energy cascade, is now widely accepted and is treated as the cornerstone of not only turbulent modeling, but also global circulation models of the ocean and atmosphere. In this work, the Filter-Space-Technique is applied to the oceanic flow field provided by the CMEMS reanalysis model to quantify the scale-to-scale energy flux. A rich dynamical pattern associated with different scales is observed. More precisely, either positive or negative fluxes are observed, indicating the direction of the energy cascade, where the energy is transferred from large-scale structures to small-scale ones or vice versa. High-intensity energy exchange is found mainly in the Western Boundary Current Systems and Equatorial Counter Currents. For the latter case, a wavelike pattern is observed on the westward travel. Moreover, strong seasonal variation is evident for some scales and regions. These results confirm the existence of forward and inverse cascades and rich regional dynamics.

Farm management and landscape context shape plant diversity at wetland edges in the Prairie Pothole Region of Canada.

Evaluating the impacts of farming systems on biodiversity is increasingly important given the need to stem biodiversity loss, decrease fossil fuel dependency, and maintain ecosystem services benefiting farmers. We recorded woody and herbaceous plant species diversity, composition, and abundance in 43 wetland-adjacent prairie remnants beside crop fields managed using conventional, minimum tillage, organic, or perennial cover (wildlife-friendly) land management in the Prairie Pothole Region. We used a hierarchical framework to estimate diversity at regional and local scales (gamma, alpha), and how these are related through species turnover (beta diversity). We tested the expectation that gamma richness/evenness and beta diversity of all plants would be higher in remnants adjacent to perennial cover and organic fields than in conventional and minimum tillage fields. We expected the same findings for plants providing ecosystem services (bee-pollinated species) and disservices (introduced species). We predicted similar relative effects of land management on alpha diversity, but with the expectation that the benefits of organic farming would decrease with increasing grassland in surrounding landscapes. Gamma richness and evenness of all plants were highest for perennial cover, followed by minimum tillage, organic, and conventional sites. Bee-pollinated species followed a similar pattern for richness, but for evenness organic farming came second, after perennial cover sites, followed by minimum tillage and conventional. For introduced species, organic sites had the highest gamma richness and evenness. Grassland amount moderated the effect of land management type on all plants and bee-pollinated plant richness, but not as expected. The richness of organic sites increased with the amount of grassland in the surrounding landscape. Conversely, for conventional sites, richness increased as the amount of grassland in the landscape declined. Our results are consistent with the expectation that adopting wildlife-friendly land management practices can benefit biodiversity at regional and local scales, in particular the use of perennial cover to benefit plant diversity at regional scales. At more local extents, organic farming increased plant richness, but only when sufficient grassland was available in the surrounding landscape; organic farms also had the highest beta diversity for all plants and bee-pollinated plants. Maintaining native cover in agroecosystems, in addition to low-intensity farming practices, could sustain plant biodiversity and facilitate important ecosystem services.

Evolutionary causes of global patterns of species richness in regional fern floras across the world

AbstractAimGlobally, biodiversity is unevenly distributed, as a result of varying environmental conditions and regionally different historical processes. The influence of the latter on current diversity patterns is poorly understood. We explore geographic patterns of matches and mismatches between phylogenetic relatedness metrics measuring different depths of evolutionary history and investigate the effects of evolutionary legacy at different evolutionary depths on species density of ferns.MethodsWe divided the globe into 392 geographic regions on land, and collated species lists of ferns for each geographic region. We related species richness to phylogenetic metrics reflecting different depths of evolutionary history (standardized effect sizes of mean nearest taxon distance and mean pairwise distance, MNTDses and MPDses, respectively) for ferns in regional floras across the world.LocationGlobal.Time PeriodCurrent.TaxonFerns.ResultsWe show that different centers of fern diversity have strikingly different phylogenetic composition. We find that overall fern species diversity is negatively correlated with both MNTDses and MPDses, so that regions with high species diversity tend to have clustered species assemblages, whereas species‐poor regions tend to have overdispersed species assemblages. At the global extent, MNTDses and MPDses together explained 62.2%, 19.3%, and 65.7% of the variation in species diversity for all ferns as a whole, non‐polypod ferns, and polypods, respectively.Main ConclusionsOur study suggests that current geographic patterns of fern species richness are driven, at least in part, by evolutionary history of ferns, which varies among biogeographic regions.

Species Diversity and Conservation of Typhlocybinae (Heteroptera: Cicadellidae) in China

Abstract Species diversity is undergoing rapid reductions globally. Identifying the causes underlying species diversity patterns and biodiversity hotspots is critical for developing conservation strategies. In this study, the 4,594 occurrence records of 854 Typhlocybinae (Heteroptera: Cicadellidae) species in China were used to investigate the factors affecting species richness and endemism patterns as well as identify species diversity hotspots to establish their conservation status. Generalized linear models and hierarchical partitioning were used to assess the effects of 6 environmental factors on species richness and endemism. Species diversity hotspots were obtained by integrating the 10 grids with highest levels of species richness and endemism; the conservation status of these hotspots was assessed via gap analysis. We found that species richness and endemism distribution of Typhlocybinae in China were heterogeneous, mainly concentrated in southern and central areas. The results also showed that plants were the most important environmental factors affecting species richness and endemism patterns, followed by niche conservatism. The 10 hotspots were identified; however, they were not fully protected by the existing nature reserves. This study highlights the importance of plants and niche conservatism in shaping species richness and endemism patterns of Typhlocybinae. Moreover, establishment of new nature reserves in hotspot areas with a conservation gap is required.

Temporal pattern-aware QoS prediction by Biased Non-negative Tucker Factorization of tensors

Dynamic quality of service (QoS) data contain rich temporal patterns of user-service interactions, which are vital for better understanding user behaviors and service conditions. Canonical polyadic (CP)-based latent factorization model has proven to be capable of capturing such patterns. However, it models the relations among latent features of user, service and time in a rigid and unnatural way, causing its failures in capturing the complex patterns when the target QoS data become massive. To address that issue, this paper proposes a Biased Non-negative Tucker Factorization of 3D tensors (BNTucF) model with the four-fold ideas: (1) utilizing a core tensor for modeling the complex interactions among latent features; (2) incorporating linear biases into the model for accurate descriptions on QoS fluctuation; (3) constraining the model to be non-negative for describing QoS non-negativity; (4) deducing a single latent factor-dependent, multiplicative updating scheme for training the model in an efficient density-oriented way. Empirical studies demonstrate that the proposed BNTucF can learn complex dynamic user-service interaction patterns more accurately, hence achieving accurate predictions on missing QoS data.

Current and past climate co-shape community-level plant species richness in the Western Siberian Arctic.

The Arctic ecosystems and their species are exposed to amplified climate warming and, in some regions, to rapidly developing economic activities. This study assesses, models, and maps the geographic patterns of community-level plant species richness in the Western Siberian Arctic and estimates the relative impact of environmental and anthropogenic factors driving these patterns. With our study, we aim at contributing toward conservation efforts for Arctic plant diversity in the Western Siberian Arctic. Western Siberian Arctic, Russia. We investigated the relative importance of environmental and anthropogenic predictors of community-level plant species richness in the Western Siberian Arctic using macroecological models trained with an extensive geobotanical dataset. We included vascular plants, mosses and lichens in our analysis, as non-vascular plants substantially contribute to species richness and ecosystem functions in the Arctic. We found that the mean community-level plant species richness in this vast Arctic region does not decrease with increasing latitude. Instead, we identified an increase in species richness from South-West to North-East, which can be well explained by environmental factors. We found that paleoclimatic factors exhibit higher explained deviance compared to contemporary climate predictors, potentially indicating a lasting impact of ancient climate on tundra plant species richness. We also show that the existing protected areas cover only a small fraction of the regions with highest species richness. Our results reveal complex spatial patterns of community-level species richness in the Western Siberian Arctic. We show that climatic factors such as temperature (including paleotemperature) and precipitation are the main drivers of plant species richness in this area, and the role of relief is clearly secondary. We suggest that while community-level plant species richness is mostly driven by environmental factors, an improved spatial sampling will be needed to robustly and more precisely assess the impact of human activities on community-level species richness patterns. Our approach and results can be used to design conservation strategies and to investigate drivers of plant species richness in other arctic regions.

Biogeographical patterns of species richness in stream diatoms from southwestern South America.

The latitudinal diversity gradient (LDG) hypothesis has been validated for many taxon groups, but so far, stream diatoms have not conformed to this pattern. Research on diatoms that includes data from South America is lacking, and our study aims to address this knowledge gap. Previous studies have successfully explained stream diatom species richness by considering niche dimensionality of physicochemical variables. Moreover, in southwestern South America, the observed biogeographical pattern differs from LDG and has been shown to be determined by historical factors. We used a dataset comprising 373 records of stream diatom communities located between 35° S and 52° S latitude, southwestern South America. The dataset included physicochemical river water variables, climate data, and ice sheet cover from the Last Glacial Maximum. We explored geographical patterns of diatom species richness and evaluated 12 different causal mechanisms, including climate-related theories, physicochemical and climatical exploratory analyses, historical factors, and niche dimensionality. A metacommunity analysis was conducted to evaluate the possible nested structure due to historical factors. We observed an increase in diatom species richness from south to north. Models containing both physicochemical and climatic predictors explained the highest proportion of variation in the data. Silica, which was correlated with latitude, and flow velocity, which did not show any spatial pattern, were the most important predictors. Historical factors and nested structure did not play any role. Contrary to what has been reported in the literature, we found no support for climate-related explanations of species richness. Instead, theories related to niche dimensionality and local factors provided better explanations, consistent with previous related research. We suggest that the increase in diatom richness in the north of our study region is due to a higher nutrient supply in these rivers, rather than a due to larger species pool in the area.