Species Diversity Of Communities Research Articles

Microbial Community Response to Alpine Meadow Degradation and Its Impact on Soil Nutrient Cycling

The degradation of alpine meadows on the Qinghai–Tibet Plateau is a major issue affecting both the ecology and the economy. Microorganisms play an important role in soil nutrient cycling and the regulation of ecosystem function. This study aimed to investigate the species composition and diversity of microbial communities and understand the response of microbial communities to changes in physicochemical properties resulting from meadow degradation. In this study, the soil bacterial and fungal communities’ composition and diversity of alpine meadows of degradation gradient were sequenced by high-throughput sequencing. During the process of grassland degradation, there were 59 bacterial taxa and 29 fungal taxa showing significant differences. The relative abundance of meadow pathogenic fungi significantly increased (p < 0.05). PICRUSt2 analysis showed a decrease in synthesis-related functional gene abundance and an increase in metabolism-related functional gene abundance. FUNGuild analysis showed that symbiotic and saprophytic nutrient fungi decreased significantly (p < 0.05). The soil nutrient cycling was mainly influenced by the beta diversity of microbial communities. Grassland degradation affects soil structure, thereby affecting the diversity of soil microbial composition and functional soil nutrient content. This work reveals the response of microbial communities to the degradation of alpine meadows and their impact on nutrient cycling, providing theoretical support for the protection and sustainable development of alpine meadows.

Response of Soil Fungal Community to Biochar Application Under Different Irrigation Water Salinity

Saline water irrigation can alleviate the shortage of freshwater resources in the northwest arid zone, but long-term saline water irrigation can damage the soil fungal community structure. To alleviate the harm caused by salinity, biochar is used as a soil amendment to improve the soil fungal community structure. To investigate the intrinsic link between biochar application and the structural diversity of fungal communities in saline soils, two irrigation water salinity levels were set:0.35 dS·m-1 (fresh water) and 8.04 dS·m-1 (saline water). At each irrigation water salinity, two levels of biochar application were set:0 t·hm-2 (no application) and 3.7 t·hm-2 (application). High-throughput sequencing results showed that compared to that under fresh water irrigation, saline water irrigation increased fungal community species diversity and decreased fungal community species richness; biochar application under saline water irrigation reduced soil fungal community species diversity and species richness. The dominant fungal phyla in the soils of each treatment were Ascomycota, Mortierellomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Rozellomycota, and Cysticercales, and the dominant genera were Gibberella, Chaetomium, Sarocladium, Stachybotrys, and Fusarium. Compared to that under freshwater irrigation, saline water irrigation significantly increased the relative abundance of Basidiomycota and Chytridiomycota and significantly decreased the relative abundance of Ascomycota and Rozellomycota. The application of biochar under saline irrigation significantly increased the relative abundance of Ascomycota and Sarocladium but significantly decreased the relative abundance of Basidiomycota, Chaetomium, and Fusarium. LEfSe analysis showed that under the condition of no biochar application, saline irrigation reduced the number of potential biomarkers of fungal communities, whereas the application of biochar under the condition of saline irrigation increased the number of potential biomarkers of fungal communities. These results indicated that the application of biochar can improve the saline soil environment and fungal community structure and provide a theoretical basis for reasonable brackish water irrigation and soil fertilization in arid areas.

Overgrazing on unmanaged grassland interfered with the restoration of adjacent grazing-banned grassland by affecting soil properties and microbial community.

A "grazing ban" policy has been implemented in some pastoral areas in China to fence degraded grasslands for restoration. However, fencing increased grazing pressures in unmanaged grasslands. Based on the mechanism of negative edge effect, we investigated whether overgrazing on unmanaged grassland interfered with the restoration of adjacent grazing-banned grassland by affecting soil properties and microbial community using a sample in Hulun Buir of Inner Mongolia, in order to optimize the "grazing ban" policy. Plant and soil were sampled in areas 30 m away from the fence in unmanaged grassland (UM) and in areas 30 m (adjacent to UM) and 30-60 m (not adjacent to UM) away from the fence in the grazing-banned grassland (F-30 m and F-60 m). The species richness and diversity of plant communities and the ASV number of fungal communities significantly decreased in F-30 m and UM, and the Simpson index of the bacterial community significantly decreased in F-30 m compared with F-60 m. The abundance of fungi involved in soil organic matter decomposition significantly decreased and the abundance of stress-resistant bacteria significantly increased, while the abundance of bacteria involved in litter decomposition significantly decreased in UM and F-30 m compared with F-60 m. The simplification of plant communities decreased in soil water and total organic carbon contents can explain the variations of soil microbial communities in both UM and F-30 m compared with F-60 m. The results of PLS-PM show that changes in plant community and soil microbial function guilds in UM may affect those in F-30 m by changing soil water and total organic carbon contents. These results indicate that overgrazing on unmanaged grassland interfered with the restoration of adjacent grazing-banned grassland by affecting soil properties and microbial community. The grazing-banned grasslands should be adjusted periodically in order to avoid negative edge effects.

Species diversity and distribution-pattern determinants of African rivulines (Cyprinodontiformes: Nothobranchiidae) in rainforest streams of southern Cameroon

Understanding the community structure and ecology of fish populations in rainforest streams is a prerequisite for any actions towards their exploitation, management or conservation. We examined the community structure and species diversity of nothobranchiids (African rivulines) in rainforest streams of Cameroon’s southern plateau and part of the coastal plain, using data on 19 environmental variables for ecological indices and multivariate analyses. In total, 1 019 individual cyprinodontiforms assigned to 14 species (largely species of Aphyosemion) were collected, for a global sampling effort of 78.6%. The presence of nothobranchiids in the study area was associated with several local environmental factors common to all sampling sites, mainly canopy cover above the watercourse and physicochemical characteristics of the stream habitat. Distribution of the species was strongly spatially structured, driven by the site’s elevation and the water temperature, and influenced primarily by the riparian vegetation, substrate type, water conductivity and flow velocity. However, fish species richness did not differ significantly between the five sectors sampled and by elevation. The nothobranchiid communities were highly diverse (Shannon’s H′ = 2.28 ± 0.05; Pielou’s J = 0.87) and the species evenly distributed. Seven species were exclusive to a single sector, others were prevalent in multiple sectors, and no species was common to all sectors. Affinities between species were relatively few, though there were exceptions, and most species tended to exclude each other. These findings highlight nothobranchiids as local fish assemblages having high biotic integrity and responsiveness to environmental degradation. In tropical Africa, these fishes often occupy fragile habitats influenced by anthropogenic activities. A better understanding of the unifying role of habitat in ecology will assist management efforts to promote biodiversity conservation.

ОСОБЕННОСТИ МИКРОБНОЙ КОЛОНИЗАЦИИ КОНСТРУКЦИОННЫХ МАТЕРИАЛОВ, ИСПОЛЬЗУЕМЫХ В КОСМИЧЕСКОЙ ТЕХНИКЕ, ПРИ ИХ МНОГОЛЕТНЕМ ЭКСПОНИРОВАНИИ В СРЕДЕ ОБИТАНИЯ МЕЖДУНАРОДНОЙ КОСМИЧЕСКОЙ СТАНЦИИ

The paper presents the results of studying quantitative dynamics, changes in composition and species diversity (Shannon diversity index, SDI) of the cultivable microbial community on samples of structural materials in the course of long-term exposure inside the International space station (space experiment Biorisk). It was found that the total number and species diversity of microorganisms changed in waves but the general trend was downward. In all, over the period of the experiment we detected, after cultivation in nutrient media, 20 bacterial species and 5 species of microscopic fungi grown on the samples of structural materials. Among bacteria, dominating species belonged to genus Bacillus, and species of the normal cutaneous and mucous microbiota belonged to genus Staphylococcus and Micrococcus. Genus Aspergillus and Penicillium dominated among fungi. Species diversity of the cultivable microbial community was maximal for textured glass and minimal for polyvinylchloride. SDI was 2.99 and 1.72 respectively. Also, these materials were populated by the largest (11) and least (5) numbers of cultivable microorganisms. The low microbial load on all types of materials after different periods of exposure suggests eco-safety of the ISS environment and effectiveness of the respective control measures.

Sampling origins and directions affect the minimum sampling area in forest plots

AbstractQuestionsThe minimum sampling area (minimum area) is the smallest space that reflects species composition and characteristics of a plant community. The quantitative concept of minimum area is often estimated using species–area relationships (SARs) and has become the classical foundation for managing protected areas. However, sampling designs to determine the minimum area in different forest types have not been systematically evaluated.LocationChina.MethodsWe used tree census data from three forest dynamic plots, each with a size of 25–60 ha, in different climatic zones in China to determine the minimum areas of woody plants and to analyze the effects of species richness and topographic heterogeneity on the minimum areas by changing sampling origin and direction.ResultsWe found that mainly sampling design affects the estimation of woody plant species richness and required minimum area in different forest types. The estimated size of the minimum areas required was several hectares and varied significantly with sampling origin and direction, and showed a difference of approximately 1.5–2 times in the forest plots. Topographic heterogeneity significantly affected the minimum area through changes in species composition.ConclusionsSampling origin and direction should be considered when using SARs to estimate the minimum area and species diversity in communities. Such a comprehensive approach of sampling can contribute to a better understanding of vegetation characteristics and the minimum area required for a conservation census in heterogeneous environments.

Ecological state of the natural park “Ivano-Arakhleisky”

The article presents the results of studies of the biodiversity of pyrogenically disturbed areas in the forest communities of the Ivano- Arakhleisky natural park, the identification of rare and specially protected plant species listed in the Red Book of the Trans-Baikal Territory and the Russian Federation. The lakes of the Ivano-Arakhlei system are located in the southeastern part of the Vitim plateau of the Osinovy and Yablonovy ridges. The territory of the park is characterized by the ecological value of natural areas, and is also a popular recreation area for citizens. Aquatic and terrestrial ecosystems are subject to anthropogenic impacts. Currently, digressive processes are dominant in the development of vegetation cover, leading to a simplification of the structure and a decrease in the species diversity of communities. Synanthropic plant species were recorded in the studied flora. The volume of ecosystem services provided directly depends on the biodiversity of the natural park. The general ecological condition of the study area is deteriorating due to an increase in anthropogenic pressure - forest fires, illegal logging, uncontrolled “wild” tourism, procurement of medicinal raw materials, and collection of beautiful flowering plants in bouquets.

Diurnal versus nocturnal pollination in a subalpine wetland: From network structure to plant reproduction

Diurnal and nocturnal pollinators are fundamental for the functioning of natural ecosystems and food security. However, differences between diurnal and nocturnal pollination networks and the contribution of these pollinators to plant fecundity have not been assessed comprehensively within a community context. In the Dajiuhu subalpine wetland of central China, we supplemented data from an intensive field survey with the analysis of pollen loads carried by diurnal and nocturnal pollinators to compare the structures of diurnal and nocturnal pollination networks using network parameters. Simultaneously, we compared the contribution of diurnal and nocturnal pollinators to plant reproduction of the nine dominant species based on stigma pollen placement. We found that although diurnal and nocturnal pollination networks exhibited a similar structural organisation, the diurnal network displayed greater stability and broader interaction with pollinators and plants compared to the nocturnal network. However, nocturnal pollinator species tended to establish less generalised interactions with the available floral resources. Both diurnal and nocturnal pollinators played a significant role in plant reproduction, and nocturnal pollination can result in greater pollen germination. In terms of stability, the lower redundancy of links within nocturnal networks suggests they may be more vulnerable to the temporary or permanent disappearance of plant resources in the study area. Our findings highlight the differences in the contributions of diurnal and nocturnal pollinators to plant reproduction at the community level, demonstrating that nocturnal pollinators are not redundant in maintaining species diversity in communities. This knowledge should play a pivotal role in preventing future pollination declines and improving pollinator conservation efforts.

The ecological niche characteristics and interspecific associations of plant species in the alpine meadow of the Tibetan Plateau affected plant species diversity under nitrogen addition.

Plant species diversity is of great significance to maintain the structure and function of the grassland ecosystem. Analyzing community niche and interspecific associations is crucial for understanding changes in plant species diversity. However, there are few studies on the response of plant species diversity, species niche characteristics, and interspecific relationships to nitrogen addition in alpine meadows on the Qinghai-Tibet Plateau. This study investigates the effects of different levels of nitrogen addition (0, 15, 30, 45, and 60 g N m-2) on plant species diversity, functional group importance values, niche width, niche overlap, and interspecific associations in an alpine meadow. 1) Compared with the control (CK), the Shannon-Weiner index and species richness index significantly increased by 11.36% and 30.77%, respectively, with nitrogen addition at 30 g N m-2, while both indices significantly decreased by 14.48% and 23.08%, respectively, at 60 g N m-2. As nitrogen addition increased, the importance value of grasses showed an upward trend, whereas the importance value of sedges showed a decline. 2) The niche width of Poa pratensis L., Elymus nutans Griseb., and Stipa purpurea Griseb. are increased with higher nitrogen addition. As nitrogen addition increases, the niche overlap values also show a rising trend. At 60 g N m-2, the overall community association in the alpine meadow exhibited a significant negative correlation. These findings suggest that grasses exhibit strong ecological adaptability under high nitrogen addition and gain a competitive advantage in spatial competition, increasing their niche width. Moreover, as nitrogen levels increase, the importance values of grasses rise significantly, and their ecological characteristics become more similar, resulting in reduced niche overlap among plant species. Furthermore, high nitrogen addition intensifies interspecific competition between grasses, sedges, and forbs, disrupting the original balance and reducing species diversity. These insights provide a valuable understanding of changes in species diversity and competitive dynamics in alpine meadow plant communities under high nitrogen addition.

Morphological Classification, Species Diversity, and Ecological Functions of Ciliate Communities

Morphological Classification, Species Diversity, and Ecological Functions of Ciliate Communities

Community structure and species diversity of rotifers in five connected lakes in Hanyang water network, Wuhan

Community structure and species diversity of rotifers in five connected lakes in Hanyang water network, Wuhan

Investigation of fish community structure and species diversity in two river estuary ecosystems, the Taehwa River and Changwon Stream, based on conventional survey and eDNA metabarcoding

Investigation of fish community structure and species diversity in two river estuary ecosystems, the Taehwa River and Changwon Stream, based on conventional survey and eDNA metabarcoding

Effects of Different Degrees of Xanthium spinosum Invasion on the Invasibility of Plant Communities in the Yili Grassland of Northwest China.

Studying the effects of different degrees of exotic plant invasion on native plants' community structure and plant diversity is essential for evaluating the harm caused to ecosystems by plant invasion. In this study, we investigated the effects of Xanthium spinosum, a widespread invasive species, on plant community species diversity and community stability in the Ili River Valley area of Xinjiang, China, under three invasion levels (no invasion and low, moderate, and heavy invasion), and the competitive advantage index, invasion intensity, and contribution of plant community species diversity to community stability and invasibility were determined for the prickly fungus under different degrees of invasion. The results show that there were significant differences (p < 0.05) in the species diversity and community stability of plant communities caused by different degrees of invasion of X. spinosum. The species diversity and stability of plant communities were negatively correlated with the community invasibility, competitive advantage, and invasion intensity of X. spinosum (p < 0.05); therefore, the competitive advantage and invasion intensity of X. spinosum increase with the increase of its invasion degree. On the contrary, community species diversity and stability decreased with the increase of its invasion degree, ultimately leading to differences in community invasibility under different invasion degrees. The Shannon-Wiener and Simpson's indices were the greatest contributors to community stability and invasibility, respectively. Moderate and heavy levels of invasion by X. spinosum reduced the diversity and stability of local plant communities, increased the invasibility of communities, and substantially affected the structures of plant communities. Therefore, the continued invasion by X. spinosum will have an immeasurable impact on the fragile ecosystems and diversity of indigenous species in Xinjiang. We recommend that this invasive species be controlled and eradicated at the early stages of invasion to prevent further harm.

Characteristics and Species Diversity of Semi-Natural Plant Communities on Langqi Island.

(1) Background: Islands are relatively independent and fragile ecosystems with unique habitats. Studying the relatively stable semi-natural plant communities on islands can enrich island vegetation data and provide an understanding of the factors affecting species diversity and distribution. (2) Methods: The semi-natural plant communities on Langqi Island (LI) in Fujian Province were sampled, and the redundancy method was used to analyze the correlation between species diversity, community distribution, and environmental factors. (3) Results: (i) There were 432 species of vascular plants, with 306 genera and 110 families; (ii) the semi-natural plant communities consisted of three vegetation types, 10 formations, and 10 clusters; (iii) the species diversity indices of the semi-natural plant communities presented a trend of gradually decreasing along the shrub, tree, and herb layers. Different formations varied in terms of the species diversity index; and (iv) the soil total potassium and nitrogen contents significantly affected the species diversity of the LI semi-natural plant communities, whereas the pH, soil TN content, organic matter content, AK content, and altitude significantly affected the community distribution. (4) Conclusions: Selecting appropriate tree species for mixed forests based on plant characteristics and regional conditions, together with regulating the soil nutrient content, can improve the species diversity of semi-natural plant communities.

Effect of grazing and climatic factors on biodiversity-ecosystem functioning relationships in grassland ecosystems -a case study of typical steppe in Inner Mongolia, China.

Biodiversity underpins grassland ecological functions and productive capacities. By studying the mechanisms for the maintenance of species diversity in animal communities, we can provide important theoretical guidance for the optimization of grazing management and biodiversity protection. The typical grassland of Xilingol in Inner Mongolia, China, was used as the experimental area, and a grazing intensity experiment was set up. This consisted of four gradient levels that were grazed by sheep, which were available for continuous monitoring, namely control standard sheep unit·day·hectare-1·year-1 (CK, 0 SSU·d·hm-2y-1), light grazing (LG, 170 SSU·d·hm-2·y-1), moderate grazing (MG, 340 SSU·d·hm-2·y-1), and high grazing (HG, 510 SSU·d·hm-2·y-1). Nine consecutive years of multi-indicator monitoring of vegetation was carried out from 2014-2022, using monitoring data coupled with time series and inter-annual climatic (relative moisture index, RMI) fluctuations. This was done to analyze the impacts of disturbances, such as grazing use and climatic fluctuations, on the diversity of species and above-ground productivity of the community, thereby exploring the relationship between diversity and productivity, and provide possible explanations for the emergence of a range of ecological responses. The statistical analysis methods used were One-way Analysis of Variance (ANOVA), general linear regression and mixed-effects models. The main conclusions of this study are as follows: (1) The grassland in the experimental area under CK had the highest diversity and productivity and the ecosystem was better able to buffer the negative impacts of climatic drought. Furthermore, the effect of climate on productivity and diversity weakened as the intensity of grazing increased. (2) LG to MG had a constant diversity. (3) Grazing utilization changed the relationship between community species diversity and aboveground productivity by releasing spatial community resources, altering the structure of plant communities, weakening competitive exclusion, and strengthening complementary effects. However, under all of the conditions there is a brief stage in the time series when diversity is stimulated to increase, and the higher the grazing intensity, the earlier this occurs.

Species richness and diversity of grassland plant communities and effects of nitrogen addition on some plant species

From 2009-2022, we have in the vegetation communities of the long-term vegetation monitoring of the plant ecology and plant economy laboratory of the Institute of Botany in 3 settlements of the meadow steppe in the area of Mungunmorit sum of Tuv province, the dry steppe in the area of Tumentsogt sum of Sukhbaatar province, and the desert steppe plant community in the area of Dalanjargalan sum of Dornogovi province. A total of 108 plots of 1m2 were tested in three versions. In doing so, it was calculated to increase nitrogen in two different amounts: 28.57 g (N1) and 57.14 g (N2). The plots were fertilized with ammonium nitrate twice a year, during the first period of plant growth in May and during the peak period in July, to increase the richness and diversity of community species compared to the non-fertilized (N0) field. As a result of the research, in 2022, the species richness of the sedge field community in the N2 scenario with nitrogen supplementation was 1.2 times lower than the control N0 field (N0-S=75, N2-S=60), and the species diversity was 1.14 times (N0- H’=3.15, N2-H’=3.61) larger. In the dry steppe community, species richness is 1.1 times lower (N0-S=41, N2-S=37) and species diversity is 1.04 times lower (N0- H’=3.29, N2-H’=3.16) than the control N0 site. The species richness in the N1 scenario is 1.28 times lower (N0-S=9, N1-S=7) than in the N0 site of the barren steppe community, while the species richness is 1.2 times higher in the N2 scenario, and the species diversity is 1.2 times higher in the nitrogen N2 scenario (N0-H’= 1.86, N2- H’=2.2) increased respectively. 6 species of meadow steppe (Astragalus adsurgens, Carex pediformis, Chrysanthemum zawadskii, Cymbaria dahurica, Leuzea uniflora, Potentilla leucophylla), 3 species of dry steppe (Galium verum, Bassia prostrata, Potentilla strigosa), 2 species of desert steppe (Allium ramossum, Convolvulus ammanii) The addition of nitrogen had a statistically significant effect on the plant cover. In our study, the N2 scenario had a greater effect on the canopy of the above plants. Хээрийн ургамал бүлгэмдлүүдийн зүйлийн баялаг, олон янз байдал ба зарим зүйлийн ургамалд азотын нэмэгдлийн үзүүлэх нөлөө Хураангуй. Бид 2009-2022 онд тус хүрээлэнгийн Ургамалжлын экологи, ургамлын эдийн засгийн лабораторийн ургамалжлын урт хугацааны мониторингийн 3 суурингийн Төв аймгийн Мөнгөнморьт сумын нутаг дахь нугажуу хээр, Сүхбаатар аймгийн Түмэнцогт сумын нутаг дахь хуурай хээр болон Дорноговь аймгийн Даланжаргалан сумын нутаг дахь цөлөрхөг хээрийн ургамал бүлгэмдлүүдэд 1*1м2 хэмжээтэй нийт 108 талбайд 3 хувилбараар туршилт судалгааг явуулав. Ингэхдээ азотыг 28.57 г (N1) ба 57.14 г (N2) гэсэн 2 өөр хэмжээтэй нэмэгдүүлэхээр тооцож ургамал ургалтын эхний үе буюу 5-р сард, оргил үе буюу 7-р сард жилдээ 2 удаа аммоны нитратаар бордож, бүлгэмдлийн зүйлийн баялаг ба олон янз байдалд хэрхэн нөлөөлж байгааг бордоогүй (N0) талбайтай харьцуулан судлав. Судалгааны үр дүнд 2022 онд нугажуу хээрийн бүлгэмдлийн зүйлийн баялаг азотын нэмэгдэлтэй N2 хувилбарт хяналтын N0 талбайгаас 1.2 дахин бага (N0-S=75, N2-S=60), зүйлийн олон янз байдал нь 1.14 дахин (N0- H’=3.15, N2- H’=3.61) их байна. Хуурай хээрийн бүлгэмдэлд хяналтын N0 талбайгаас N2 хувилбарт зүйлийн баялаг 1.1 дахин бага (N0-S=41, N2-S=37), зүйлийн олон янз байдал нь 1.04 дахин (N0- H’=3.29, N2- H’=3.16) буурч байна. Цөлөрхөг хээрийн бүлгэмдлийн N0 талбайгаас N1 хувилбарт зүйлийн баялаг 1.28 дахин бага (N0-S=9, N1-S=7), харин N2 хувилбарт зүйлийн баялаг 1.2 дахин их, зүйлийн олон янз байдал азотын N2 хувилбарт 1.2 дахин (N0-H’=1.86, N2-H’=2.2) тус тус нэмэгдсэн байна. Нугажуу хээрийн 6 зүйл (Astragalus adsurgens, Carex pediformis, Chrysanthemum zawadskii, Cymbaria dahurica, Leuzea uniflora, Potentilla leucophylla), хуурай хээрийн 3 зүйл (Galium verum, Bassia prostrata, Potentilla strigosa), цөлөрхөг хээрийн 2 зүйл (Allium ramossum, Convolvulus ammanii)-ийн ургамлын тусгагийн бүрхцэд азотын нэмэгдэл статистикийн хувьд нөлөө үзүүлсэн. Бидний судалгаанд дээрх ургамлуудын тусгагийн бүрхцэд N2 хувилбар илүү нөлөө үзүүлж байв. Түлхүүр үгс: нугажуу хээр, хуурай хээр, цөлөрхөг хээр, азот, зүйлийн баялаг, олон янз байдал

DNA from non-viable bacteria biases diversity estimates in the corals Acropora loripes and Pocillopora acuta

BackgroundNucleic acid-based analytical methods have greatly expanded our understanding of global prokaryotic diversity, yet standard metabarcoding methods provide no information on the most fundamental physiological state of bacteria, viability. Scleractinian corals harbour a complex microbiome in which bacterial symbionts play critical roles in maintaining health and functioning of the holobiont. However, the coral holobiont contains both dead and living bacteria. The former can be the result of corals feeding on bacteria, rapid swings from hyper- to hypoxic conditions in the coral tissue, the presence of antimicrobial compounds in coral mucus, and an abundance of lytic bacteriophages.ResultsBy combining propidium monoazide (PMA) treatment with high-throughput sequencing on six coral species (Acropora loripes, A. millepora, A. kenti, Platygyra daedalea, Pocillopora acuta, and Porites lutea) we were able to obtain information on bacterial communities with little noise from non-viable microbial DNA. Metabarcoding of the 16S rRNA gene showed significantly higher community evenness (85%) and species diversity (31%) in untreated compared with PMA-treated tissue for A. loripes only. While PMA-treated coral did not differ significantly from untreated samples in terms of observed number of ASVs, > 30% of ASVs were identified in untreated samples only, suggesting that they originated from cell-free/non-viable DNA. Further, the bacterial community structure was significantly different between PMA-treated and untreated samples for A. loripes and P. acuta indicating that DNA from non-viable microbes can bias community composition data in coral species with low bacterial diversity.ConclusionsOur study is highly relevant to microbiome studies on coral and other host organisms as it delivers a solution to excluding non-viable DNA in a complex community. These results provide novel insights into the dynamic nature of host-associated microbiomes and underline the importance of applying versatile tools in the analysis of metabarcoding or next-generation sequencing data sets.

Variability in precipitation influences the water sourcing and adaptive strategies of key plant species within the desert steppe ecosystem

The composition and species diversity of desert plant communities exhibit high sensitivity to changes in precipitation. From the perspective of plant community dynamics, alterations in precipitation levels result in increased complexity in water absorption and utilization strategies, consequently leading to diversified adaptation strategies. Focusing on the desert steppe within the transitional zone between agriculture and animal husbandry in northern China, this study investigates the mechanisms through which variations in precipitation impact plant species' water absorption and utilization strategies in desert steppes. In this study, a controlled precipitation experiment was conducted on site in a natural desert steppe setting with three precipitation treatments: 50 % reduction in precipitation (PE), normal precipitation (CK), and 50 % increase in precipitation (PD). By analysing the δ2H and δ18O values of plants, soil, and precipitation, as well as indicators such as plant species composition, biomass, specific leaf area (SLA), and δ13C values, the changes in plant community species and the main plant species' water sources and strategies under different precipitation conditions were studied. The results show that (1) Within each treatment, the variability of soil δ2H and δ18O in the 0–20 cm soil layer was greater than that in the 20–60 cm soil layer. The slope of the soil δ2H and δ18O fitting line in the PE treatment was larger than that in the PD and CK treatments. (2) Except for Leymus secalinus, the dominant plant species, including Lespedeza potaninii, Polygala tenuifolia, Convolvulus ammannii, Kali collinum, and Stipa breviflora, exhibited an increase in water absorption from deeper soil layers as precipitation decreased. The diversity in water sources among the dominant plant species decreased with increasing precipitation, while the overlap index of soil moisture utilization across different soil layers initially increased and then decreased with increasing precipitation levels. (3) The root-to-shoot ratio (RS) of L. potaninii and P. sibirica shows an extremely significant negative correlation with SWC, while the RS of C. ammannii and K. collinum exhibits a significant negative correlation with SWC. The δ13C values of S. breviflora demonstrate an extremely significant negative correlation with SWC, while those of L. secalinus, C. ammannii, and S. breviflora show a significant negative correlation. In contrast, the δ13C values of K. collinum exhibit an extremely significant positive correlation with SWC. The SLA of all six plants exhibits an extremely significant positive correlation with SWC. The water source diversity of L. potaninii, C. ammannii, K. collinum, and S. breviflora demonstrates an extremely significant positive correlation with SWC, while that of P. sibirica and L. secalinus shows a significant positive correlation with SWC. Conclusion: As precipitation decreases, soil water evaporation becomes more pronounced. The primary plant species within the community exhibit flexibility in absorbing moisture from different soil layers in response to changes in precipitation levels. Differential water utilization strategies among different plants have led to hydrological niche separation, intensifying competition for soil moisture, particularly during extremely arid conditions. Plant water utilization strategies tend to become more conservative as precipitation decreases, and they demonstrate the ability to adapt by altering their water use strategies in response to varying precipitation levels.

국립공원 육상생태계 생태·환경적 차이에 따른 탄소저장량 특성 연구

This study aimed to assess carbon storage by establishing 222 fixed survey plots in 22 national parks and analyzing the plant ecological characteristics of the survey areas to determine any relationships. To achieve this, we analyzed plant community structure and species diversity indices based on survey information for each plot. Initially, the plant communities for the entire survey plots were classified into four types. Group I was characterized as the Taxus cuspidata-Abies koreana community, Group II as the Acer pictum community, Group III as the Quercus-Pinus densiflora community, and Group IV as the Pinus strobus community. Among these four types, Groups I, II, and III were distinguished by elevation, and we observed a linear arrangement along the second axis as the carbon storage in the deciduous layer increased, indicating that Groups I, II, and III could be differentiated based on carbon storage in the deciduous layer. Soil carbon storage showed a similar trend, while woody carbon storage did not exhibit a clear group-based trend. Furthermore, when examining the relationship between carbon storage and species diversity, we found a weak positive correlation between soil carbon storage and species diversity, but no significant correlation with vegetation carbon storage. However, it's important to note that these results only reflect the findings based on the survey results for trees with a diameter at breast height of 6 cm or larger and sub-canopy layer trees. Additional data collection for shrub and ground cover plant species is necessary to further develop these findings.

Divergent successions to shrubs- and forbs-dominated meadows decrease ecosystem multifunctionality of hillside alpine meadow

Global climate change and overgrazing pressure both affects the community succession, and multifunctionality of grassland ecosystems. Alpine meadows cover 1/3 of the Qinghai-Tibetan Plateau of China’s climate sensitive area and major pastures, which is the main grassland ecosystem. However, the responses of ecosystem multifunctionality during climate change and overgrazing induced divergent community succession to shrubs- and forbs-dominated community remains poorly understood in alpine meadow ecosystem. Here, we examined five ecological functions, including above- and below-ground productivity, soil water holding capacity, soil organic carbon stocks and soil erosion resistance capacity of the native Kobresia-dominated alpine meadow ecosystem during the divergent succession to shrubs- and forbs-dominated meadow located on the Qinghai-Tibetan Plateau, and identified the key factors contributing to the changes of ecosystem multifunctionality during the divergent succession. Results showed that the divergent succession to shrubs- and forbs-dominated meadow both significantly reduced community species diversity and richness, changed community structure, especially the decreasing of the Sedges and Leguminous functional groups. Meanwhile, the ecological functions including below-ground productivity, soil water holding capacity, and soil organic carbon stocks are greatly decreased along shrubs and forbs encroachment in hillside alpine meadows. Taken together, our results demonstrate that climate warming and overgrazing induced divergent successions to the shrubs-encroached and the forbs-encroached communities both decreased the ecosystem multifunctionality of hillside alpine meadows. The ecosystem multifunctionality of hillside alpine meadow ecosystem might therefore be decreased continuously under ongoing and future climate warming and overgrazing by herbivores.