Significant Increase In Species Richness Research Articles

Diatom assemblages in glacial-fed streams of Italian Western Alps

ABSTRACT The rate of glacier retreat has recently increased, with changes in the glacier discharge, river flow and water characteristics, creating specific environmental conditions for highly specialized organisms. We here investigated diatom communities in glacier-fed rivers of the Valle d’Aosta region (NW-Italy), analyzing data collected between 2010 and 2019 for the WFD monitoring programs. We present a complete checklist of the species inhabiting this region, many of which are classified as endangered in the diatom Red List. We found significant differences between sites with different catchment glacier cover (CGC), in terms of taxonomic composition, ecological guilds and abundance of Red List taxa. In particular, we observed a significant increase in species richness with the decrease in CGC, as well as significant differences in terms of taxonomic composition. We highlighted the role of Achnanthidium lineare as an indicator species for streams with the highest glacial influence, together with Hannaea arcus, Eucocconeis laevis and other oligotrophic low profile species that are well adapted to physical stress induced by glacier runoff. On the other hand, streams with lower glacial influence were characterized by motile species mostly belonging to the genera Navicula and Nitzschia, due to the nutrient increase. Didymosphenia geminata was recorded in streams with marginal glacier cover; recently observed blooms indicate that conditions may become increasingly favorable for the spread of this species in Alpine environments, as glaciers retreat. The abundance of Red List diatoms increased significantly with increasing glacier cover suggesting that glacier-fed rivers are niches for the conservation of diatom biodiversity.

Continuous Monitoring of Vegetation and Soil Recovery After Eucalyptus grandis Removal in Dense Trees and Shrubs Areas

ABSTRACTInvasion by invasive alien plants is a global challenge and South Africa has invested billions of Rands to manage invaders through the Working for Water programme. However, regular monitoring after alien plant clearing is hardly done, yet it forms the basis for assessing clearing programme effectiveness, particularly ecosystem recovery trajectories. I monitored both vegetation and soil recovery 6 years after Eucalyptus grandis clearing by Working for Water at Zvakanaka Farm in Limpopo Province of South Africa. Vegetation diversity and soil physical properties were surveyed in 2019 and re‐surveyed in 2022 on fell‐and‐removal and fell‐and‐stackburn cleared treatments and compared to the nearby uninvaded treatment. Results show a significant increase in species richness in 2022 compared to 2019 in the fell‐and‐removal treatment. Cover of both native trees and shrubs as well as forbs was significantly higher in 2022 compared to 2019 in the fell‐and‐removal treatment compared to the fell‐and‐stackburn treatment. Most secondary invaders such as Acacia mearnsii, E. cloeziana, Lantana camara and Rubus rigidus that frequently occurred in 2019 showed decreased occurrence in 2022 on both cleared treatments. Between the two sampling years, soil compaction improved on the fell‐and‐removal treatment only, whereas hydraulic conductivity increased significantly in 2022 compared to 2019 in both the fell‐and‐removal and fell‐and‐stackburn treatments. Soils that were strongly and severely repellent in 2019 in the fell‐and‐stackburn treatment were becoming slightly repellent in 2022. These results show varied vegetation and soil improvements between 2019 and 2022 in both the fell‐and‐removal and fell‐and‐stackburn cleared treatments an indication that recovery is moving towards a positive vegetation and soil recovery trajectory in the direction of the uninvaded treatment. Recommendations for successful passive restoration such as secondary invasion follow‐up clearing are discussed.

Reverse-engineered exclusive enteral nutrition in pediatric Crohn's disease: A pilot trial.

In pediatric Crohn's disease (CD), commercial formulas used as exclusive enteral nutrition (EEN) are effective at inducing remission. This study aims to assess the impact of a whole-food blended smoothie as EEN on CD activity and the intestinal microbiome. A 4-week prospective trial assessed the impact of EEN with a whole-food smoothie on newly diagnosed mild-to-moderate active pediatric CD. The smoothie with a multivitamin were developed to meet age-appropriate nutritional requirements. Assessment over 4 weeks included Pediatric Crohn's Disease Activity Index (PCDAI), serum laboratories, fecal calprotectin (FCP), and stool collection for metagenomic shotgun sequencing and microbiota composition analysis. Clinical remission was defined as PCDAI ≤ 10 at week 4. Ten participants were enrolled with median age 14.5 years, and 8 completed the trial. Baseline mean PCDAI was 26.3 ± 9.1 and mean FCP 1149 ± 718 µg/g. At week 4, 80% of participants achieved clinical remission. FCP decreased by over half in 60% of participants, with FCP below 250 µg/g in 60% and below 100 µg/g in 40%. Microbiome analysis showed a significant increase in species richness over 4 weeks (p = 0.01). Compared to baseline, the relative abundance at week 2 and at week 4 was significantly increased for Bifidobacterium and Streptococcus and decreased for Blautia (p < 0.05 for all). A whole-food blended smoothie was effective for inducing clinical remission and decreasing FCP in pediatric CD similar to commercial EEN formulas. Further research may give insight into data-driven whole-food dietary approaches for CD management. gov NCT03508193.

Metagenomic insight to apprehend the fungal communities associated with leaf blight of Welsh onion in Taiwan.

Plants are associated with a large diversity of microbes, and these complex plant-associated microbial communities are critical for plant health. Welsh onion (Allium fistulosum L.) is one of the key and oldest vegetable crops cultivated in Taiwan. The leaf of the Welsh onion is one of the famous spices in Taiwanese cuisine, thus, it is crucial to control foliar diseases. In recent years, Welsh onion cultivation in Taiwan has been severely threatened by the occurrence of leaf blight disease, greatly affecting their yield and quality. However, the overall picture of microbiota associated with the Welsh onion plant is still not clear as most of the recent etiological investigations were heavily based on the isolation of microorganisms from diseased plants. Therefore, studying the diversity of fungal communities associated with the leaf blight symptoms of Welsh onion may provide information regarding key taxa possibly involved in the disease. Therefore, this investigation was mainly designed to understand the major fungal communities associated with leaf blight to identify key taxa potentially involved in the disease and further evaluate any shifts in both phyllosphere and rhizosphere mycobiome assembly due to foliar pathogen infection by amplicon sequencing targeting the Internal Transcribed Spacer (ITS) 1 region of the rRNA. The alpha and beta-diversity analyses were used to compare the fungal communities and significant fungal groups were recognized based on linear discriminant analyses. Based on the results of relative abundance data and co-occurrence networks in symptomatic plants we revealed that the leaf blight of Welsh onion in Sanxing, is a disease complex mainly involving Stemphylium and Colletotrichum taxa. In addition, genera such as Aspergillus, Athelia and Colletotrichum were abundantly found associated with the symptomatic rhizosphere. Alpha-diversity in some fields indicated a significant increase in species richness in the symptomatic phyllosphere compared to the asymptomatic phyllosphere. These results will broaden our knowledge of pathogens of Welsh onion associated with leaf blight symptoms and will assist in developing effective disease management strategies to control the progress of the disease.

Enhancing ecological complexity in soft‐bottom coastal ecosystems: the impact of introducing hard substrates

Coastal ecosystems globally face pressures, with natural coastal habitats being replaced by engineered structures. While hard structures for navigation‐purposes and coastal defense can negatively impact native communities, they can also be applied in ecological restoration as artificial reefs. This way substrates may facilitate establishment of biogenic (shellfish) reefs and provide habitat heterogeneity in soft‐sediment ecosystems. In a 1.5‐year experiment, we introduced six different types of natural or biodegradable hard substrates in a subtidal soft‐sediment system. We compared the substrates with surrounding soft sediment and evaluated differences among substrate types using biodiversity indices, community composition analyses, and food web indicators. This offers a comprehensive understanding of how the introduced hard substrates affect ecosystem complexity. Overall ecological complexity indicators were higher in the second year of the experiment. We found a significant increase in species richness, community composition, and link density (number of feeding interactions per species) on hard substrates compared to the surrounding sediment. However, Shannon diversity index and food web connectance (measure of food web saturation) did not differ between substrates and the surrounding sediment. Although differences among types of hard substrates were small, certain species were uniquely associated with specific substrates with wood and granite performing best. While there was no establishment of epibenthic shellfish reefs within 1.5 years, we conclude that introducing hard substrates effectively enhances ecological complexity in soft‐bottom coastal ecosystems within that timeframe. We recommend the use of substrates with a historical ecological relevance in the system for scaling up introduction of substrates for ecological restoration.

Effect of 15 days -6° head-down bed rest on microbial communities of supragingival plaque in young men.

The microgravity environment astronauts experience during spaceflight can lead to an increased risk of oral diseases and possible changes in oral microecology. In this study, we aimed to assess changes in the microbial community of supragingival plaques to explore the effects of spaceflight microgravity environment on oral microecology. Sixteen healthy male volunteers were recruited, and supragingival plaque samples were collected under -6° head-down bed rest (HDBR) at five-time points: day 1 before HDBR; days 5, 10, and 15 of HDBR; and day 6 of recovery. Bacterial genomic DNA was sequenced using gene sequencing technology with 16S ribosomal ribonucleic acid V3-V4 hypervariable region amplification and the obtained data were analyzed bioinformatically. Alpha diversity analysis showed a significant increase in species richness in supragingival plaque samples on day 15 of HDBR compared with that at pre-HDBR. Beta diversity analysis revealed that the community composition differed among the groups. Species distribution showed that, compared with those at pre-HDBR, the relative abundances of Corynebacterium and Aggregatibacter increased significantly during HDBR, while those of Veillonella, Streptococcus, and Lautropia decreased significantly. Moreover, compared with those at pre-HDBR, the relative abundance of Leptotrichia increased significantly on day 6 of recovery, whereas the relative abundances of Porphyromonas and Streptococcus decreased significantly. Network analysis showed that the interaction relationship between the dominant genera became simpler during HDBR, and the positive and negative correlations between them showed dynamic changes. Phylogenetic investigation of communities by reconstruction of unobserved states analysis showed that the amino acid metabolism function of plaque microorganisms was more enriched during HDBR. In summary, in a 15-day simulated microgravity environment, the diversity, species distribution, interaction relationship, and metabolic function of the supragingival plaque microbial community changed, which suggests that microgravity may affect the oral microecosystem by changing the balance of supragingival plaque microbial communities and further leading to the occurrence and development of oral diseases.

Microbes and their Role in Atrial Fibrillation: A Literature Review

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia observed in clinical practice. The gut microbiota (GM) and their byproducts have the potential to activate the autonomic nervous system, which plays a crucial role in the development and maintenance of AF. Recent hypotheses suggest that bacterial infections, such as Helicobacter pylori and Chlamydia pneumonia might play a role in the development of AF. The emerging evidence suggested that certain patients might develop AF due to bacterial infections. AF patients exhibited a significant increase in species richness and diversity. Specifically, opportunistic pathogenic bacteria such as Klebsiella, Haemophilus, Streptococcus and Enterococcus were significantly higher, while symbiotic bacteria such as Agathobacter and Butyrivibrio were significantly lower in AF patients. Likewise, the development of AF has been linked to infections caused by viruses that have an affinity for the heart. Chronic hepatitis C virus infection appears to be linked to an elevated risk of incidental AF, likely due to the shared underlying pathology of chronic inflammation. Numerous studies have explored the arrhythmogenic effects of SARS-CoV-2, particularly its impact on mortality and its association with AF. Influenza infection was found to be significantly linked to the development of AF, resulting in an 18% increased risk. However, in cases where AF is present and dengue infection is suspected, it is advisable to exercise caution when considering the use of anticoagulants, ensuring that specific serological tests have excluded the presence of this infection.

Compositional shifts of alpine plant communities across the high Andes

AbstractAimClimate change is transforming mountain summit plant communities worldwide, but we know little about such changes in the High Andes. Understanding large‐scale patterns of vegetation changes across the Andes, and the factors driving these changes, is fundamental to predicting the effects of global warming. We assessed trends in vegetation cover, species richness (SR) and community‐level thermal niches (CTN) and tested whether they are explained by summits' climatic conditions and soil temperature trends.LocationHigh Andes.Time periodBetween 2011/2012 and 2017/2019.Major taxa studiedVascular plants.MethodsUsing permanent vegetation plots placed on 45 mountain summits and soil temperature loggers situated along a ~6800 km N‐S gradient, we measured species and their relative percentage cover and estimated CTN in two surveys (intervals between 5 and 8 years). We then estimated the annual rate of changes for the three variables and used generalized linear models to assess their relationship with annual precipitation, the minimum air temperatures of each summit and rates of change in the locally recorded soil temperatures.ResultsOver time, there was an average loss of vegetation cover (mean = −0.26%/yr), and a gain in SR across summits (mean = 0.38 species m2/yr), but most summits had significant increases in SR and vegetation cover. Changes in SR were positively related to minimum air temperature and soil temperature rate of change. Most plant communities experienced shifts in their composition by including greater abundances of species with broader thermal niches and higher optima. However, the measured changes in soil temperature did not explain the observed changes in CTN.Main conclusionsHigh Andean vegetation is changing in cover and SR and is shifting towards species with wider thermal niche breadths. The weak relationship with soil temperature trends could have resulted from the short study period that only marginally captures changes in vegetation through time.

Local environmental conditions influence species replacement in Great Lakes interdunal wetland macroinvertebrate communities

Abstract Understanding the role of environmental filtering and spatial processes along environmental gradients in assembling and maintaining aquatic communities in rare habitats is crucial for land management and biological conservation. We investigated the relative roles of environmental and spatial factors influencing beta (β) diversity of aquatic macroinvertebrate assemblages in 36 interdunal wetlands from five freshwater sand dune areas across two ecoregions spanning the latitudinal gradient of Lake Michigan. We hypothesised that aquatic macroinvertebrate diversity and composition would vary along the coastline because of an underlying environmental gradient. We predicted high species replacement correlated with environmental (local and regional) conditions and increasing species diversity with decreasing latitude. We calculated sample completeness, obtained diversity estimates based on Hill numbers and used abundance‐based β partitioning and multivariate analysis to examine β diversity, and its replacement and nestedness components in relation to local and regional predictors. Despite a short latitudinal gradient, we detected a significant increase in species richness with decreasing latitude, underpinned by a strong temperature and precipitation gradient. Species replacement (balanced variation in abundance) was high at all spatial scales (wetland, dune area, ecoregion and coastline), and correlated with local and regional environmental variables. Community dissimilarity showed no marked increase with spatial extent, which suggests a system where local‐scale environmental filtering prevents dispersal driven homogenisation. Both local and bioclimatic factors were correlated with aquatic macroinvertebrate dissimilarity, but local factors played a larger role. This study simultaneously examined the response of alpha and β diversity to geographical and environmental variables. Our results indicate that macroinvertebrates respond to abiotic factors by tracking suitable environmental conditions among locally variable interdunal wetlands. Thus, high dispersal along the coastline conveys resiliency to a hydrologically dynamic wetland system, which allows aquatic macroinvertebrates to contribute an integral portion of sand dune biodiversity within the Laurentian Great Lakes region. The high species turnover found suggests that conservation strategies should consider coastline connectivity among dune areas to maintain freshwater biodiversity.

The Plant Species Composition of an Abandoned Meadow as an Element of an Ecosystem Mosaic within an Urban-Industrial Landscape

The absence of traditional management in grasslands is responsible for the consequent changes in plant community species composition and diversity of this habitat in Europe. The common reason for these changes is the spread of expansive native species such as Calamagrostis epigejos (L.) Roth and their subsequent dominance over other component species. The aim of the study was to determine the effect of management treatments (e.g., mowing, harvesting biomass) and their frequency of application (e.g., once or twice a year) on the cover abundance of C. epigejos (L.) Roth and the subsequent changes in component grassland species richness and diversity (Shannon–Wiener index) of an abandoned meadow in Silesia in S. Poland. A difference in species richness was found after five years of mowing, but an increase in species diversity appeared only after seven years of the treatments. Significant increases in species richness and Shannon–Wiener index and a significant decrease in cover abundance of C. epigejos (L.) Roth were recorded after different periods and for different treatments.

Long-term forest vegetation dynamics in Nanda Devi Biosphere Reserve, Indian west Himalaya: evidence from repeat studies on compositional patterns.

It has been established that resurvey of historical vegetation stands, even those not marked permanently, could foster our understanding of vegetation dynamics and changes in structure and composition over time. However, such studies are poorly available, particularly in remote landscapes of the Indian Himalaya. There exists a complete lack of resurveys, which has limited our ability to provide reliable evidence of changes over the decades. This study, for the first time in the Indian Himalaya, considered repeat surveys (nearly after 25years) of vegetation stands in eleven forest communities of the buffer zone of NDBR (Nanda Devi Biosphere Reserve). Thirty historical forest stands, earlier studied in 1988-1990, were revisited during 2012-2014 and investigated using the same survey methods as used in the previous study. We found that previously reported dominant tree species, i.e., Alnus nepalensis, Acer cappadocicum, Quercus floribunda, Quercus semecarpifolia, Hippophae salicifolia, and Betula utilis, in nine out of eleven communities in the study area are continuing to exhibit dominance in the community. However, a significant increase in species richness and density in the seedling and sapling layer in Quercus floribunda, Quercus semecarpifolia, Rhododendron arboreum, and Abies pindrow is indicative of the ongoing process of change in forest composition. The compositional features of plant communities, when analyzed through Community Change Sensitivity (CCS) approach, identified Quercus floribunda, mixed Quercus-deciduous spp., Hippophae salicifolia, and Abies pindrow as the most change-sensitive communities in the study area and thus can be prioritized as the long-term ecological monitoring sites in the west Himalaya to understand intensity and patterns of changes. The potential changes based on the ecological information from two time period compositional data sets, having conservation and management implications, should be accommodated in the long-term perspective plans of the reserve.

Changes in the root fungal microbiome of strawberry following application of residues of the biofumigant oilseed radish

Biofumigation has been proposed as an environmentally friendly method of plant protection against soil-borne pathogens, but its effects on microbial communities are still incompletely understood. Using high throughput DNA sequencing, we investigated the effects of oilseed radish residues on the root fungal microbiome of strawberry in the presence of a soil-borne fungal pathogen, Verticillium dahliae. Results of our greenhouse study show that early flowering occurred in response to residue addition, suggesting a plant stress-response and there was a significant decrease in berry yield. The fungal microbiome of roots was significantly restructured by both biofumigation and inoculation with Verticillium. In particular, the abundance of root endophyte- and arbuscular mycorrhizal functional guilds was reduced significantly as a result of biofumigant and V. dahliae addition, whereas the abundance of saprotrophs increased significantly when both treatments were applied together. Alpha diversity analyses of fungi associated with roots indicated a significant increase in species richness following Verticillium inoculation, whereas the biofumigant alone or in the presence of V. dahliae resulted in no significant effect, suggesting that apparently some rare taxa may have been enriched/stimulated in the presence of the pathogen. Further investigations should reveal whether negative effects of biofumigation on potentially beneficial root associated endophytes and arbuscular mycorrhizal fungi are host genotype- or soil-dependent.

How Surface Water Management Can Benefit Fish Conservation in Urban Streams

Abstract We analyzed 33 y of fish community data collected from a low-order, urban stream in central Illinois, USA, to determine the effects of municipal wastewater management projects and urbanization on fish communities. From 1985 to 2017, species richness, number of pollution-intolerant species, and alternative index of biotic integrity significantly increased at sites across this system. Species diversity likewise increased, but was mostly significant only at sites downstream of the effluent outflow. Ceasing the chlorination of wastewater in 1990 resulted in significant increases in fish community metrics both upstream and downstream of effluent outflow, although effects varied from site to site. Completing a combined sewer overflow abatement project in 2008 resulted in some significant increases in species richness, diversity, and number of pollution-intolerant species at sites downstream of effluent outflow. From 2001 to 2016, the change in the number of pollution-intolerant species correlated inversely with the increased percentage of impervious cover in the study system. There was no significant correlation of other metrics with the change in percent impervious surfaces. These results suggest that urbanization at upstream sites limited to some extent the benefits of water management interventions that improved fish community metrics at downstream sites.

Comparative impacts of grazing and mowing on the floristics of grasslands in the buffer zone of Polesie National Park, eastern Poland

Most European grasslands are semi-natural and require proper management to preserve their high natural value. They are habitats for many rare and endangered species of plants and animals. The aim of the study was to determine patterns of changes in the flora of grasslands induced by the introduction of extensive mowing and grazing treatments and to answer the following questions: (1) Do species richness and the number and occurrence of ecological groups plants differ depending on management schemes? (2) Is grazing or mowing more beneficial for the conservation of plant diversity? (3) Is the duration of land management a determinant of flora characteristics? The study was carried out in permanent grasslands located in the buffer zone of Polesie National Park in 2015–2018. The flora comprised 189 vascular plant species representing six ecological groups. The most numerous groups were meadow species (M) – 85, grassland species (G) – 35, and segetal species (S) – 31. Trees and shrubs (T) – 10 made up the smallest share of the flora, followed by ruderal (R) – 13 and aquatic (W) – 17 vegetation. The study showed that extensive grazing and mowing induced quantitative and qualitative changes in the flora of the research plots and were the key determinants of the flora dynamics. The first two years of use were crucial for the dynamics of the flora present in the plots. During that time a significant increase in species richness and the emergence of ecological groups was noted. Stabilization of the features analysed was noted in subsequent years. Significant differences were noted in species richness (SR) and the number of meadow (M), grassland (G), segetal (S), ruderal (R), water (W) and tree and shrub (T) species in favour of the managed plots compared with the abandoned sites. Grazing significantly decreased the number of emerging trees and shrubs, while mowing facilitated the preservation and regeneration of water and waterside vegetation. The use of local cattle breeds for grazing in valuable nature areas protects meadow habitats, prevents succession of trees and shrubs, and preserves and protects farm animal genetic resources.

Recolonization patterns of benthic assemblages after relict sand dredging in the central Tyrrhenian sea

AbstractRecolonization patterns of benthic assemblages after relict sand dredging were investigated in an area offshore of Capo d’Anzio (central Tyrrhenian Sea). Surveys were performed before, during, and after dredging in 2007. Sampling stations were located within and outside the dredging site in water depths between 40 and 56 m. Defaunation due to sand extraction was the main impact observed in the inner stations and in stations located in proximity of the dredging site. At the inner stations, 9 months after dredging, a significant increase in species richness and diversity was observed: the sediment removal led to an increase of the sandy sediment fraction, favouring the settlement of sabulicolous species. A decrease in number of individuals and species was also observed in most of the outer stations, probably due to fine sediment redeposition. Recolonization of macrobenthic assemblages was essentially achieved at inner stations both in terms of abundance and species richness, while at outer stations it was still in progress. Results of this study, providing a picture of recovery times and processes in the Tyrrhenian Sea, could be used to develop predictions of the effects of future offshore sand dredging projects in comparable areas. Monitoring programs and research have a key role to provide a more detailed overview of biological recovery processes and times in different regions and with different dredging intensity.

Temporal Dynamics of Fishing Affect the Biodiversity of Macrobenthic Epifaunal Communities in the Coastal Waters of Ningbo, East China Sea

Spatio-temporal patterns of macrobenthic epifaunal communities with fishing disturbances indicate that the fishing process directly leads to a decrease in diversity and substratum sediment homogenization. However, it has not yet been explored exclusively at the community reconstruction dynamic level with fishing changes over time. This study monitored the macrobenthic epifaunal communities during the implementation of a fishing moratorium policy in order to elucidate the fishing-driven variations in the macrobenthic epifaunal communities. Bottom trawl surveys were conducted before (BEF), during (DUR), and after (AFT) a summer fishing moratorium. During each survey, macrobenthic species and surface sediment samples were collected from two transects located at two different depths. The results showed that the communities in the DUR phase were undisturbed, while the communities were disturbed in both the BEF and AFT phases. Compared with the BEF and AFT phases, there was an abundance of peak spawning species as well as the impact on macrobenthic communities in relation to the lightened fishing disturbance, significant increases in species richness, abundance, and biomass were observed in the DUR phase. Prohibition of fishing during summer facilitates the resilience of macrobenthic communities by maximizing spawning and reducing bottom disturbance to larval, thereby enhancing overall fishery resources.

Vegetation changes in temperate ombrotrophic peatlands over a 35 year period.

Global changes in climate and land use are occurring at an unprecedented rate, often triggering drastic shifts in plant communities. This study aims to reconstruct the changes that occurred over 35 years in the plant communities of temperate bogs subjected to indirect human-induced disturbances. In 2015-17, we resurveyed the vascular flora of 76 plots located in 16 bogs of southern Québec (Canada) first sampled in 1982. We evaluated changes in species richness, frequency of occurrence and abundance, while considering species shade-tolerance and preferential habitat. We calculated beta diversity as between-site similarities in composition, and evaluated differences between the two surveys using tests for homogeneity in multivariate dispersion. We found a significant increase in species richness and beta diversity over the last 35 years associated with major species turnovers, indicating a biotic differentiation of the Sphagnum-bog plant communities. These changes were mostly associated with an increase in the abundance and frequency of shade-tolerant and facultative species, suggesting a global phenomenon of woody encroachment. Because the observed changes occurred in a few decades on sites free of in situ human disturbances, we suggest that they were likely induced by the synergic effect of the agricultural drainage occurring in the surrounding mineral soils, climate warming, and nitrogen atmospheric depositions. We also believe that further changes are to be expected, as the triggering factors persist. Finally, our results highlight the need for increased bog conservation or restauration efforts. Indeed, a rise in beta diversity due to the introduction of nearby terrestrial species could induce biotic homogenization of the bog flora with that of surrounding habitats and ultimately impoverish the regional species pool.

Verification of the biomass transfer hypothesis under moderate grazing across the Tibetan plateau: a meta-analysis

We aimed to explore the general response patterns of plant biomass allocation to grazing disturbance and to test two important hypotheses, optimal partitioning and isometric allocation, for explaining potential mechanisms by which grazing controls biomass distribution in an alpine grassland on the Tibetan Plateau. We identified 57 relevant papers about grazing on the Tibetan Plateau, from which 366 data sets suitable for the meta-analysis were extracted. Effect sizes were assessed by computing natural log-converted response ratios of response variables. Percentage change relative to control was used for each estimate of grazing effects. The aboveground biomass, soil water content (SWC), soil organic carbon, soil total nitrogen, and soil total phosphorus significantly decreased with increased grazing intensities, while plant species richness (SR), soil bulk density (SBD) and the ratio of root to shoot exhibited the opposite tendency. Belowground biomass (BGB) showed no significant differences under light and high grazing intensities while apparently increased under moderate grazing intensity (MG) that verifies the biomass transfer hypothesis. BGB was positively related to SBD and SR but was negatively associated with SWC. The biomass transfer in MG supports the optimal partitioning hypothesis that plants partition biomass among various organs to maximize growth rate responding to environmental stress. The findings suggest that the primary mechanisms leading to the enhancement of BGB in MG are compensatory growth of individual plants, a dwarfing tendency within the plant community, a significant increase in species richness, and changes in soil microbial communities resulting from grazing.

Nematodes of Meiobenthos and Periphyton in Rybinsk Reservoir Tributaries

In various biotopic groups of invertebrates of small rivers, the species richness and nematode abundance vary. Periphyton is poorer than meiobenthos. Along with common species, a number of worms are found only in biofouling or only in meiobenthos. A significant increase in species richness, diversity of ecological groups, and abundance of worms in meiobenthos and periphyton of small rivers is observed in zones contaminated with organic substances of anthropogenic and zoogenic origin. The biocenotic and functional role of nematodes in these groups depends to a higher extent on the level of food availability than on a number of other environmental factors that limit their development.

The effects of the invasive thief ant, Solenopsis papuana, on ground-dwelling invertebrates in mesic forests of Hawaiʻi

Invasive predators are often hypothesized to negatively affect native invertebrates, but impacts have not been measured for most invaders. We quantified the effects of Solenopsis papuana, an invasive thief ant that is widespread in Hawaiʻi, on invertebrate communities via an experimental manipulation study. We established six pairs of plots in the Waiʻanae Mountains of Oʻahu, suppressed S. papuana in half of the plots, and measured the responses of invertebrates 6 months and 1 year later. Leaf litter and pitfall sampling revealed that ground-dwelling invertebrate communities were highly invaded, with native species comprising 24% of the taxa and only ~ 1–2% of the individuals captured. Relatively few taxonomic groups increased significantly in abundance following suppression of S. papuana, and responses were generally inconsistent between the two sampling periods. Significant increases in species richness in ant-suppressed plots were more common, particularly in pitfall samples. Most of the significant changes involved non-native species, but several native species also appear to be impacted by S. papuana. Although statistically significant responses were relatively uncommon, nearly all taxonomic groups exhibited non-significant increases in abundance and species richness in response to S. papuana suppression, and there were no significant decreases in either abundance or species richness for any taxonomic group. This suggests that in their current highly invaded states, mesic forest ground-dwelling invertebrate communities are broadly but relatively weakly affected by S. papuana. This conclusion may be tempered by the difficulty of accurately measuring effects on rare species, many of which may now be absent from these communities.