Changes In Species Diversity Research Articles

Bee discovery suggests the importance of urban gardens in a changing world

AbstractThe diversity and distribution of wild bees are dramatically changing due to habitat fragmentation, agricultural intensification and climate change. In cities, urban gardens are proposed ‘island’ habitats for bees offering floral and nesting resources. Yet, it is largely unclear how gardens play a role in changes in species diversity and distribution. This paper reports on the discovery of a bee species to our knowledge previously undocumented in the region of Berlin, Germany. We discovered Lasioglossum limbellum in a community garden created on concrete slabs of annual and perennial vegetation. As a cavity nester in soft rock cliffs—a natural habitat functionally not existent in urban areas—the life history of this species makes this discovery particularly interesting, and an opportunity to explore the role of urban gardens in biodiversity change. This report aims to spur future research, reporting and discussion on the changes in diversity and distribution of wild bees specifically in urban areas.

Long-term changes in floristic diversity, composition and stand structure in Acacia auriculiformis plantation in Mount Makiling Forest Reserve, Philippines

Abstract. Hernandez JO, Ata JP, Combalicer MS. 2022. Long-term changes in floristic diversity, composition and stand structure in Acacia auriculiformis plantation in Mount Makiling Forest Reserve, Philippines. Biodiversitas 23: 3631-3638. There have been continuous debates about whether exotic tree plantation facilitates vegetation succession. In the Philippines, the potential for the re-establishment of native plant communities and improvement of the plant community structure under exotic tree plantations has not yet been evaluated adequately. Thus, the study investigated the dynamics in floristic diversity, composition and stand structure of a reforested area using Acacia auriculiformis Benth. in Sitio Kay Inglesia, Mount Makiling Forest Reserve (MMFR), Philippines. The changes in basal area, stem density, biomass growth, species diversity, species evenness and richness, and canopy closure were determined between two study periods, i.e., 1993-2008 and 2009-2019. Results revealed significant changes in stem density (i.e., 1324 to 2135 trees ha-1) and canopy closure (i.e., 18% to 10%) for mature trees and seedlings/saplings in 2009-2019. The changes in basal area and aboveground biomass were not significant between the two study periods. The species richness was significantly higher in 2009-2019 (i.e., 55 species) than in 1993-2008 (i.e., 22 species). The species diversity also significantly increased from low (i.e., H' = 1.99, S = 23) to moderate (i.e., H' = 2.88, S = 55). Moreover, the number of exotics decreased (i.e., 60 to 40% or 15 to 9 species) as the number of native ones increased (i.e., 27 to 72% or 15 to 40 species). Therefore, the findings of the present study show that re-establishment of native species is possible when restoring degraded land with A. auriculiformis plantation. However, monitoring studies on other key ecosystem attributes (e.g., ecosystem functionality, external exchanges, structural diversity) of the plantation are recommended to enhance our understanding of the species' potential for restoration.

Fish Species Diversity From Someșul Cald River: 50Years After Cascade Dam Constructions

In the present study, changes in fish species composition, distribution, and diversity caused by cascade dam constructions on Someșul Cald River, Romania, were analyzed. Cascade dam constructions may act as a freshwater stressor both on short and long term. The river was divided into two sections according to the positioning of the cascade dams (T1-inferior section, respectively T2-superior section). In the T1 and T2 sections, 8 and 12 sampling stations were established, respectively. A total number of 1789 specimens grouped in 12 species and 8 families were sampled from August to September 2018. The most abundant species in both sections was S. trutta. The most abundant family was Salmonidae, with 66.2%. Alpha diversity (species richness) in the T2 section was higher than in T1 (T2 = 12 species vs T1 = 9 species). The Kruskal-Wallis test indicated no significant differences (p > 0.05) for beta diversity of T1 vs T2 (Sørensen coefficient). The species that contributed most to the dissimilarities between the two river sections were T. thymallus, B. carpathicus, C. gobio, and S. cephalus, their summed contribution to the dissimilarity being larger than 50%. The analyzed environmental variables influenced the distribution of some fish species. Alpha and beta diversity distribution on elevation gradient showed that stations close to reservoirs had more species (both in T1 and T2 sections) than the other stations, clearly showing that the distance from lake/reservoir is influencing species richness. The effect of dams from Someșul Cald River on fish species distribution was analyzed by comparing previous data (before 1968) to recent collected data.

Contribution of Sheep Grazing to Plant Diversity in Natural Grasslands

Global climate change and overgrazing have led to the degradation of natural grasslands and seriously threaten the diversity of grassland plant species, as plant species richness is very sensitive to natural grassland degradation. Therefore, we conducted a sheep grazing experiment in Zinniquan pasture on the northern slope of Xinjiang Tianshan Mountains to test the effects of grazing on plant species diversity in natural grasslands through the spatial and temporal characteristics of the foraging behavior of grazing sheep and the plant species composition on the grazing trajectories. Data on sheep grazing tracks were collected based on GPS, vegetation composition around the tracks was investigated and seeds were collected from sheep manure to determine germination rates by simulating rumen fistula uptake tests in sheep. We found that sheep grazing can bring seeds from agricultural fields to grow on natural grasslands, causing changes in plant species diversity and community structure. The results of this study provide new insights into natural grassland species restoration and offer a range of new strategies that can be applied to the management of natural grassland plant ecological restoration.

Plant beta-diversity across biomes captured by imaging spectroscopy

Monitoring the rapid and extensive changes in plant species distributions occurring worldwide requires large-scale, continuous and repeated biodiversity assessments. Imaging spectrometers are at the core of novel spaceborne sensor fleets designed for this task, but the degree to which they can capture plant species composition and diversity across ecosystems has yet to be determined. Here we use imaging spectroscopy and vegetation data collected by the National Ecological Observatory Network (NEON) to show that at the landscape level, spectral beta-diversity—calculated directly from spectral images—captures changes in plant species composition across all major biomes in the United States ranging from arctic tundra to tropical forests. At the local level, however, the relationship between spectral alpha- and plant alpha-diversity was positive only at sites with high canopy density and large plant-to-pixel size. Our study demonstrates that changes in plant species composition and diversity can be effectively and reliably assessed with imaging spectroscopy across terrestrial ecosystems at the beta-diversity scale—the spatial scale of spaceborne missions—paving the way for close-to-real-time biodiversity monitoring at the planetary level.

Changes in Species and Functional Diversity of the Herb Layer of Riparian Forest despite Six Decades of Strict Protection

The herb layer of temperate forests contributes to long-term forest ecosystem functioning and provisioning of ecosystem services. Therefore, a thorough understanding of its dynamics in the face of environmental changes is essential. This paper focuses on the species and functional diversity of the herb layer of riparian forests to verify how these two community components changed over time and under strict protection. The understory vegetation was surveyed on 42 semi-permanent plots in three time periods between 1960 and 2020. The overall pattern in vegetation changes that related to species richness and diversity, functional structure, and habitat conditions was analyzed using ordination and permutation techniques. We found significant changes in species composition and the functional structure of herbaceous vegetation over the last six decades. Forests were enriched with nutrient-demanding and alien species. A significant increase in functional diversity and the proportion of species with high SLA and canopy height was also observed, whereas changes in habitat conditions were insignificant. The observed trends indicate that the strict protection of forest communities within small and isolated reserves does not fully protect their species composition. Forest reserves should be surrounded by unmanaged forests and spatially connected to allow species mobility.

Fire Compromises the Recovery of a Managed Forest in Tapajós National Forest, Eastern Amazon, Brazil

Logged forests are more prone to fire, shifts in species composition, and losses in biodiversity. In this work changes in the horizontal structure and species composition of a managed forest in the Tapajós National Forest, Eastern Amazon, Brazil, along 31 years (1981-2012) was evaluated. The disturbances included logging (1982), thinning of non-commercial species (1993/1994), and fire (1997). Data were obtained in 36 0.25-ha permanent plots split in 12 plots per each one of three harvesting treatments. In 1997, 16 plots were reached by an accidental superficial fire. The changes in species composition and diversity between the last measurement after logging and before fire (1995) and the last measurement (2012) were compared. PERMANOVA, considering the relationship between the NMDS axes and the treatment variable (logging / control + unburnt / burnt) differed in species composition, among treatments before fire (1995) and 15 years after fire (2012). The post-hoc test for PERMANOVA showed great similarity among logged forests before and after fire. The forest pre-disturbance conditions were important drivers in forest recovery, since logged forests under heavy thinning presented more losses in basal area and alterations in species composition. Therefore, stronger and more frequent disturbances can compromise the forest resilience.

Fire Compromises the Recovery of a Managed Forest in Tapajós National Forest, Eastern Amazon, Brazil

Logged forests are more prone to fire, shifts in species composition, and losses in biodiversity. In this work changes in the horizontal structure and species composition of a managed forest in the Tapajós National Forest, Eastern Amazon, Brazil, along 31 years (1981-2012) was evaluated. The disturbances included logging (1982), thinning of non-commercial species (1993/1994), and fire (1997). Data were obtained in 36 0.25-ha permanent plots split in 12 plots per each one of three harvesting treatments. In 1997, 16 plots were reached by an accidental superficial fire. The changes in species composition and diversity between the last measurement after logging and before fire (1995) and the last measurement (2012) were compared. PERMANOVA, considering the relationship between the NMDS axes and the treatment variable (logging / control + unburnt / burnt) differed in species composition, among treatments before fire (1995) and 15 years after fire (2012). The post-hoc test for PERMANOVA showed great similarity among logged forests before and after fire. The forest pre-disturbance conditions were important drivers in forest recovery, since logged forests under heavy thinning presented more losses in basal area and alterations in species composition. Therefore, stronger and more frequent disturbances can compromise the forest resilience.

Effects of Dietary Carbohydrases on Fecal Microbiome Composition of Lactating Sows and Their Piglets.

Corn-soybean meal diets are commonly used in the pork industry as a primary source of energy and protein. However, such a diet generally contains non-starch polysaccharides (NSPs) which present a challenge in finding ways to improve their availability and digestibility. Dietary multi-carbohydrases (MCs) have been proposed as an efficient approach to utilize NSPs, and can result in improved growth performance and host intestinal fitness. In this study, we evaluated the effects of MC in lactation diets on gut microbiota composition of lactating sows and their litters. The experimental design contained two dietary treatments, a diet based on corn-soybean meal (CON), and CON supplemented with 0.01% multigrain carbohydrases (MCs). Sow and piglet fecal samples were collected on days 7 and 28 after farrowing. Based on the results from 16S rRNA gene amplicon sequencing, MC led to changes in species diversity and altered the microbial compositions in lactating sows and their piglets. Specifically, the MC treatment induced an increase in the proportions of Lactobacillus in piglets. Clostridium and Spirochaetaceae showed a significantly reduced proportion in MC-treated sows at day 28. Our results support the beneficial effects of dietary carbohydrases and their link with improved production due to better host fitness outcomes and gut microbiota composition.

Elevational patterns in tropical bryophyte diversity differ among substrates: A case study on Baru volcano, Panama

AbstractQuestionsBryophytes attain their highest diversity in tropical mountain forests. Although distribution patterns have been described, little emphasis has been placed on comparing patterns among substrates (e.g., terrestrial, epiphytic). Understanding these patterns is important, because they determine not only the pool of genetic resources, but also the functioning of these forest ecosystems. Therefore, we studied how bryophyte species diversity changes with elevation, how elevational patterns differ between substrate types, and how elevational trends relate to environmental drivers.LocationBaru volcano, Panama.MethodsAt each of eight elevations, between 1900 and 3300 m, bryophytes were collected in 600‐cm2 plots from six substrate types with four replicates. Species cover was registered as a measure of relative abundance. Species richness and community structure were determined and related to elevation, substrate types, and environmental drivers at three scales (plots, sets of four replicate plots per substrate per elevation, and all plots at each elevation).ResultsBryophyte species richness decreased towards higher elevations, at all three scales and on all substrates except bryophytes on soil, for which, at the plot scale, richness peaked at higher elevations than on the other substrates. Relative humidity explained richness slightly better than elevation. Communities at the lowest elevations had the most uneven compositions, due to the presence of many small species with low abundance.ConclusionsIn studies on the spatial distribution of bryophyte diversity, it is essential to consider different substrates and spatial scales separately. If substrates differ in their elevational species richness patterns, climate and land‐use change may affect bryophyte diversity patterns not only directly, but also indirectly via changes in substrate availability. Therefore, a better understanding of the spatial variation in bryophyte diversity in mountains is essential to elucidate the effects of environmental change on this important group of plants and their implications for ecosystem functioning.

Fire severity assessment on peatland vegetation diversity

Forest fires have a significant impact on peatland ecosystem, including its vegetation diversity. Several approaches applied for forest fire severity assessment are available in the literature. This study aimed to implement field-based and spatial-aware fire severity assessments and to compare both approaches. Peat swamp forests of Ogan Komering Ilir, South Sumatera Province, for field assessment and Siak, Riau Province, for spatial assessment were selected in this research. Field-based fire severity assessment used indicators of vegetation analyses (individual tree damages, burned vegetation severity, and diversity index), which were measured and analyzed from sample plots in both burned and unburned areas. Spatial analyses of fires severity assessment employed Sentinel-2 satellite imagery with Normalized Burn Ratio (NBR) approach. The research revealed a significant change in tree species diversity, indicating a lower diversity in burned areas than the ones in pristine fields. Magnitude of changes in diversity was influenced by fire severity levels in burned areas and pre-fire condition of burned areas. Spatial analyses indicated low to high fire severity with burned area estimation for each fire severity class. Both approaches have their own benefits and challenges. Field-based severity assessment is beneficial for a detailed assessment of fire damages and losses, whereas spatial analyses would be considered for a broader estimation of fire severity. Both assessments are mutually implemented. Field-based assessment can serve as a verification tool for spatial assessment.

Predictable shifts in diversity and ecosystem function in phytoplankton communities along coastal salinity continua

AbstractSalinity is a major environmental predictor of phytoplankton species richness and composition. We hypothesize that the variation in phytoplankton richness along coastal salinity gradients is reflected in essential ecosystem functions like resource use efficiency (RUE)—the proportion of limiting resource that is converted into biomass. To test the hypothesis, we analyzed time series of phytoplankton and environmental variables from the Chesapeake Bay and the Baltic Sea. We analyzed the relationship among salinity, diversity, and RUE in bivariate and interaction association, and in structural equation model (SEM)—a form of path analysis to resolve multivariate relationships among interrelated variables. We concluded that the intrusion of marine water will lead to rapid change in species diversity on the fresh side. Despite diversity drop, individual community functions, like RUE, remain relatively resilient, reflecting functional redundancy. We propose that the salinity gradient also reflects trophic complexity, allowing stable resource use at reduced diversity.

Climate change linked to functional homogenization of a subtropical estuarine system.

Climate change causes marine species to shift and expand their distributions, often leading to changes in species diversity. While increased biodiversity is often assumed to confer positive benefits on ecosystem functioning, many examples have shown that the relationship is specific to the ecosystem and function studied and is often driven by functional composition and diversity. In the northwestern Gulf of Mexico, tropical species expansion was shown to have increased estuarine fish and invertebrate diversity; however, it is not yet known how those increases have affected functional diversity. To address this knowledge gap, two metrics of functional diversity, functional richness (FRic) and functional dispersion (FDis), were estimated in each year for a 38‐year study period, for each of the eight major bays along the Texas coast. Then, the community‐weighted mean (CWM) trait values for each of the functional traits are calculated to assess how functional composition has changed through time. Finally, principal component analysis (PCA) was used to identify species contributing most to changing functional diversity. We found significant increases in log‐functional richness in both spring and fall, and significant decreases in functional dispersion in spring, suggesting that although new functional types are entering the bays, assemblages are becoming more dominated by similar functional types. Community‐weighted trait means showed significant increases in the relative abundance of traits associated with large, long‐lived, higher trophic level species, suggesting an increase in periodic and equilibrium life‐history strategists within the bays. PCA identified mainly native sciaenid species as contributing most to functional diversity trends although several tropical species also show increasing trends through time. We conclude that the climate‐driven species expansion in the northwestern Gulf of Mexico led to a decrease in functional dispersion due to increasing relative abundance of species with similar life‐history characteristics, and thus the communities have become more functionally homogeneous.

Prospective observational study of the role of the microbiome in BCG responsiveness prediction (SILENT-EMPIRE): a study protocol

IntroductionThe human microbiota, the community of micro-organisms in different cavities, has been increasingly linked with inflammatory and neoplastic diseases. While investigation into the gut microbiome has been robust, the urinary...

Speciation in a metapopulation model upon environmental changes

We propose a metapopulation model to investigate the role of environmental changes in shaping species diversity. The model is studied under the framework of the Fisher geometric model, which assumes the existence of an optimal phenotype in each patch. The phenotypic distance rules out the survivorship of the individuals in a patch to the optimal phenotype. Additionally, we provide our model a genetic ground, such that changes in phenotype are associated with mutational events. One simulates environmental changes as shifts of the optimum phenotype. Quite surprisingly, we find that the pattern of speciation depends only on the net effect of the environmental disturbances in a given time interval, no matter the rate at which the events occur. We also observe that migration has a pivotal role in shaping diversity due to its substantial effects on the genetic distance among individuals at small and intermediate values of the strength of selection.

N-Induced Species Loss Dampened by Clipping Mainly Through Suppressing Dominant Species in an Alpine Meadow.

Nitrogen addition and clipping can exert substantial impact on species diversity but their interactions and the underlying mechanisms still remain unclear. Resource competition theory holds that sufficiently strong competitive ability of dominant species can lead to the losses of subordinate species through competitive exclusion, while niche differentiation theory suggests that the persistence of subordinate species in competitive systems can be promoted by guaranteeing positive growth rates of rare species. Taking advantage of a field experiment with nitrogen addition (10 g N m–2 year–1) and different clipping intensities (2, 15, and 30 cm) treatments in a Tibetan alpine meadow across 2015–2020, we assessed the relative importance of competitively dominant species and niche differentiation in driving species diversity changes via using community weighted mean (CWM) and variation coefficient of nearest neighbor distance (CV_NND) of functional traits including height, specific leaf area (SLA) and leaf dry matter content (LDMC). We show that nitrogen enrichment drove a strong plant diversity loss (P < 0.001). Clipping at different intensities had little effect on species diversity, but it can reduce the N-induced diversity loss. Nitrogen addition and clipping caused changes in community diversity were mainly indirectly attributed to their effects on community functional composition, and the competitive ability of dominant species. Nitrogen increased the CWM of functional traits to improve the competitive ability of dominant species. In contrast, clipping influenced species diversity positively by decreasing CWMheight (P < 0.001), and also negatively by increasing CWMSLA (P < 0.001) and decreasing CV_NNDSLA (P < 0.05). Interacting with N addition, clipping resulted in a neutral effect on species diversity, because clipping could offset the negative effects of nitrogen addition through an opposite effect on CWMheight. This study provides new insights into the mechanisms of diversity maintenance with respect to nitrogen addition and clipping. Thus, clipping is recommended as a useful management strategy to alleviate the species loss caused by nutrients enrichment and maintain the diversity of grassland ecosystems.

Plant Diversity and Soil Nutrients in a Tropical Coastal Secondary Forest: Association Ordination and Sampling Year Differences

Studying the patterns of changes in species diversity and soil properties can improve our knowledge of community succession. However, there is still a gap in understanding how soil conditions are related to plant diversity in tropical coastal secondary forests. We sampled plant diversity and soil nutrients spanning two different years (2012 and 2019) to assess the patterns of species diversity and relationships of soil nutrients and species diversity on Hainan Island, southern China. Results showed that the soil pH and total nitrogen (TN) significantly decreased while the soil organic matter (OM) and total phosphorus (TP) significantly increased from 2012 to 2019. Plant species diversity was significantly higher in 2012 than in 2019, and the dominant species significantly changed in two different years. Using multiple regression analysis, we determined that soil TP and TN were significantly related to plant diversity in 2012 and 2019, respectively. Using CCA analysis, TN and OM were the strongest predictors for dominant species in 2012, whereas the soil TP and TN were the strongest predictors for dominant species in 2019. Our findings show a significant change in plant diversity and dominant species after 7 years of development in the tropical coastal secondary forest. The patterns of plant diversity and soil nutrients increase our knowledge of forest restoration in coastal areas.

Intraspecific more than interspecific diversity plays an important role on Inner Mongolia grassland ecosystem functions: A microcosm experiment

Biodiversity changes in terrestrial communities continue in the context of global changes. However, the interactive effects of the changes in diversity at inter- and intraspecific levels as well as cascading effects from plant to soil microorganisms on ecosystem functioning under climate changes remains largely unexplored. Using grassland species in the semi-arid Inner Mongolia Steppe, we conducted a microcosm experiment to assess how drought treatment (non-drought and drought conditions), species diversity (2, 4, and 7 species) and genotypic diversity of the dominant species Leymus chinensis (1, 3, and 6 genotypes) affected ecosystem functions directly or indirectly via regulating plant community functional structure [community-weighted mean (CWM) and functional dispersion (FDis)] and soil microbial diversity (Shannon–Wiener index). Drought treatment, species and genotypic diversity significantly and interactively affected soil N, P cycle and soil multifunctionality as well as soil microbial diversity. Drought treatment significantly affected biomass, soil C cycle, CWM and soil microbial diversity. Species diversity significantly affected soil N cycle, CWM and FDis, and genotypic diversity significantly affected all soil functions and soil microbial diversity. CWM regulated the responses of all ecosystem functions except soil N cycle to the changes in soil moisture and species diversity, which supports the mass ratio hypothesis. The cascading effect from genotypic diversity to soil microbial diversity was significant on belowground biomass but not on any of the other ecosystem functions observed in this study. These findings highlight the importance of genotypic diversity of the dominant species L. chinensis in affecting belowground ecosystem functioning as well as soil microbial diversity, which should not be ignored for grassland protection and management. This study provides further insights into biodiversity and ecosystem functioning mechanisms in semi-arid grasslands in the context of global climate changes.

Effects of Soil Physico-Chemical Properties on Plant Species Diversity Along an Elevation Gradient Over Alpine Grassland on the Qinghai-Tibetan Plateau, China.

Elevation gradient can reflect the effects of soil physico-chemical properties on plant species diversity. Alpine grassland on the QTP has suffered from a serious decline in plant species diversity. In this study, we investigated 112 sites recording plant community characteristics and collecting soil samples along an elevation gradient (3,500–5,200 m asl) in alpine meadow on the QTP. We analyzed the effects of soil physico-chemical properties on plant species composition and diversity by canonical ordination and spatial regression along an elevation gradient. The results showed that species richness of the overall plant communities decreased with the increasing elevation, and the Simpson dissimilarity index (βsim) had a maximum at low elevation (3,500–4,000 m) with the value of 0.37. Soil available nitrogen content was the primary soil parameter affecting plant species composition and diversity in alpine grassland. The effect of soil available nitrogen content on plant species richness varied at different elevations. For Gramineae plants (G), plant species richness declined with the increase in soil available nitrogen content at low elevation (3,500–4,000 m), but rose at middle elevation (4,000–4,500 m). Soil available nitrogen content had a more significant limiting effect on species richness at high elevation (>4,500 m). These findings increase our understanding about the drivers of plant species diversity changes in alpine grassland on the QTP, and will provide insights into grassland restoration and sustainable management.

Rediscovering the mosquito fauna (Diptera: Culicidae) of Estonia: an annotated checklist with distribution maps and DNA evidence.

Female mosquitoes (Diptera: Culicidae) affect their hosts in numerous negative ways and are crucial to the spread of vector-borne pathogens. It is, therefore, important to have a detailed overview of regional mosquitoes, to be able to detect changes in species diversity and identify possible health threats. The aim of this study was to update the checklist of the mosquito fauna of Estonia for the first time since 1957. For this purpose, 24,344 adult mosquitoes (94% females) were collected in Estonia from 2008 to 2020 using various trapping methods. Specimens were primarily identified by morphological characteristics, but DNA barcoding based on the partial cytochrome c oxidase subunit 1 gene (COI) was also used. Species were included in the checklist based on historical records as well as new collections, while also considering reports from neighboring countries. Species records are supplemented with voucher specimens, distribution maps and DNA evidence. The updated checklist includes 34 species, 27 of which were confirmed with recently collected material. All in all, Aedes communis (de Geer, 1776) proved to be the most common mosquito in Estonia, accounting for 30.1% of the specimens collected. This is noteworthy, as this species has been implicated in the transmission of multiple disease agents present in the area. New evidence revealed the presence of Ae. hexodontus Dyar, 1916, Ae. sticticus (Meigen, 1838), Anopheles messeae Falleroni, 1926 and Culiseta bergrothi (Edwards, 1921) in Estonia.