Variation In Species Diversity Research Articles

Groundfish and invertebrate community shift in coastal areas off Iceland

Biodiversity is a key concept for conservation and management and is fundamental for ecosystem-based approaches. It is of importance to consider whole areas in which communities and their ecological processes can be maintained. To effectively manage ecosystems for sustainable use and conservation, it is important to understand changes in the ecosystems. The objective of this study was to investigate the species diversity of groundfish and invertebrates, including both commercially exploited species as well as unexploited species, and identify long-term changes in the composition and abundance of the groundfish community and the northern shrimp (Pandalus borealis) in six fjords off Iceland in the period from 1995 to 2016 using data from annual shrimp survey. The results showed a strong indication of species replacement during the study period and a top-down control, where the abundance of cod and haddock increased at the same time as the abundance of northern shrimp, eelpouts, blennies and flatfish species decreased. Moreover, the increase in gadoid abundance seemed to have less effect in more open systems, which showed greater variability in species diversity and evenness compared with more closed ecosystems.

城市湿地公园生物多样性设计与评估——以六盘水明湖国家湿地公园为例

PDF HTML阅读 XML下载 导出引用 引用提醒 城市湿地公园生物多样性设计与评估——以六盘水明湖国家湿地公园为例 DOI: 10.5846/stxb201812052666 作者: 作者单位: 北京大学建筑与景观设计学院,北京土人城市规划设计股份有限公司 北京;北京大学建筑与景观设计学院,北京大学建筑与景观设计学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划（2016YFC0401105）；国家自然科学基金面上项目（51678002） Design and assessment of biodiversity in urban wetland parks: Take liupanshui minghu national wetland park as an example Author: Affiliation: College of Architecture and Landscape of Peking University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:由于中国城市化进程加快，湿地公园中的生物多样性也随之受到影响，科学合理的设计和评估生物多样性对城市中同类型的湿地公园建设或维护有着重要的参考价值。研究选取基于人工设计的贵州省六盘水明湖国家湿地公园为例，从生境多样性与物种多样性两个方面对生物多样性进行评估。得出以下结论：（1）公园生境单元类型较丰富，公园中面状、现状要素饱和度指数都超50%，生境多样性状况良好。（2）公园建成5年后场地内乔灌木植物的种类明显增多，其中丁香、香樟、蜡梅、榆树等植物成为新的优势种群，表现在园区的西部、南部与东部；草本水生植物种类也明显增多，优势种群结构并没有发生太大改变，集中表现在园区的西南部、南部与中部。（3）影响生物多样性变化的两大因素一是优势群落的自然演替恢复速度效果明显，二是人为干扰严重的地区生物多样性减少。 Abstract:As the process of urbanization in China is accelerating, the biodiversity in wetland parks will also be affected. Scientific and rational assessment of biodiversity provides an important reference value for the construction or maintenance of the same types of wetland parks in cities. In this study, we selected the 5-year-old Liupanshui Minghu National Wetland Park in Guizhou Province and analyzed its biodiversity from habitat and species diversity. The former categorizes the "habitat units" in wetland parks into categories:punctual elements, linear elements, and planar elements, and calculates the corresponding area. The latter uses a sample method to investigate the number of species of vascular plants in the park and uses the Shannon-Wiener index for calculation, based on the diversity index of the two. ArcGIS overlay analysis was used to obtain the spatial coupling relationship between habitat diversity and species diversity. Subsequently, the corresponding habitat elements that affected the variation of species diversity were analyzed and optimized protection measures were proposed. 参考文献 相似文献 引证文献

Small mammal diversity of Mt. Kenya based on carnivore fecal and surface bone remains.

Ecological dynamics and faunal diversity documentation is normally conducted by direct observation and trapping of live animals. However, surveys of carnivore scat prey and surface bone remains, which are relatively inexpensive, can provide complementary data that expand carnivore diet breadth and may improve accuracy regarding inferences of the ecological dynamics of a given ecosystem. We used this inexpensive method to document species diversity variation with elevation on the leeward (Sirimon) and windward (Chogoria) areas of Mt. Kenya. Bone and fecal specimens were opportunistically collected by walking 2 km in opposite directions from transect points selected at 200-m intervals along the elevational gradient of the study areas. We collected a total of 220 carnivore fecal and owl pellet specimens from both study sites, which were mainly deposited by the spotted hyena (Crocuta crocuta), leopard (Panthera pardus), serval (Leptailurus serval), genet (Genetta sp.), and Mackinder’s Cape owl (Bubo capensis mackinderi). Serval scats were the most common, followed by those of the spotted hyena. Scats and bones were found at the lowest density at the lowest elevations, peaked at mid-higher elevations, and then declined at the highest elevations. Based on skeletal analysis only, there were more species in Sirimon (19) than in Chogoria (12). Small fauna (rodents to duiker size bovids) formed the bulk of the identified remains, representing 87.9% of the Sirimon fauna and 90.9% of the Chogoria fauna. The genus Otomys was the dominant prey of the owl and serval in both sites. Three giraffe teeth were found at 3 500 m a.s.l. in Chogoria on the edge of Lake Ellis, suggesting that it is an occasional visitor to such high elevations. This study underscores the value of fecal and bone surveys in understanding the diet and diversity of mammals in ecological ecosystems, but such surveys should be complemented with analysis of hairs found in scats to obtain a more complete list of carnivore prey at Mt. Kenya.

Freshwater fish fauna of rivers of the southern Western Ghats, India

Abstract. The Western Ghats of India is a UNESCO World Heritage Site and is one of the eight “hotspots” of biological diversity in the world. It is also referred to as the “Great Escarpment of India”. This paper provides information on the diversity of freshwater fish fauna of six river systems of the southern Western Ghats. The study area has been identified geographically using a GPS, and the respective topographic map has been digitized using ArcGIS software. The fish fauna were collected from various streams and rivers using cast nets, dip nets, gill nets and drag nets. Among the 31 georeferenced sites sampled from the rivers of the southern Western Ghats, a total of 64 species, belonging to 6 orders, 14 families and 31 genera, were recorded. Among them, the order Cypriniformes was dominant, with 3 families, 18 genera and 49 species (76.6 %). Principal component analysis and cluster analysis were performed to express the contribution of the variables and their influence on the species diversity. Interestingly, of the 31 sites, Thunakadavu stream, Gulithuraipatti, Athirapally, Naduthotam, Nadathittu, Mullaithodu, Thonanthikla, Noolpuzha and Sinnaru exhibited high variation in species diversity. Nearly 15 species were found to be threatened in the Western Ghats. Garra periyarensis and Cirrhinus cirrhosus are known to be vulnerable and Hemibagrus punctatus is critically endangered because of various anthropogenic activities. The study clearly indicates that certain timely measures have to be taken immediately to protect the fish fauna in the southern Western Ghats (https://doi.org/10.1594/PANGAEA.882214).

Sounding out ecoacoustic metrics: Avian species richness is predicted by acoustic indices in temperate but not tropical habitats

Affordable, autonomous recording devices facilitate large scale acoustic monitoring and Rapid Acoustic Survey is emerging as a cost-effective approach to ecological monitoring; the success of the approach rests on the development of computational methods by which biodiversity metrics can be automatically derived from remotely collected audio data. Dozens of indices have been proposed to date, but systematic validation against classical, in situ diversity measures are lacking. This study conducted the most comprehensive comparative evaluation to date of the relationship between avian species diversity and a suite of acoustic indices. Acoustic surveys were carried out across habitat gradients in temperate and tropical biomes. Baseline avian species richness and subjective multi-taxa biophonic density estimates were established through aural counting by expert ornithologists. 26 acoustic indices were calculated and compared to observed variations in species diversity. Five acoustic diversity indices (Bioacoustic Index, Acoustic Diversity Index, Acoustic Evenness Index, Acoustic Entropy, and the Normalised Difference Sound Index) were assessed as well as three simple acoustic descriptors (Root-mean-square, Spectral centroid and Zero-crossing rate). Highly significant correlations, of up to 65%, between acoustic indices and avian species richness were observed across temperate habitats, supporting the use of automated acoustic indices in biodiversity monitoring where a single vocal taxon dominates. Significant, weaker correlations were observed in neotropical habitats which host multiple non-avian vocalizing species. Multivariate classification analyses demonstrated that each habitat has a very distinct soundscape and that AIs track observed differences in habitat-dependent community composition. Multivariate analyses of the relative predictive power of AIs show that compound indices are more powerful predictors of avian species richness than any single index and simple descriptors are significant contributors to avian diversity prediction in multi-taxa tropical environments. Our results support the use of community level acoustic indices as a proxy for species richness and point to the potential for tracking subtler habitat-dependent changes in community composition. Recommendations for the design of compound indices for multi-taxa community composition appraisal are put forward, with consideration for the requirements of next generation, low power remote monitoring networks.

Floristic list, ecological features and biological spectrum of district Nowshera, Khyber Pakhtunkhwa, Pakistan

A survey was carried out to evaluate the Phytosociological and ethnobotanical features of district Nowshera, Khyber Pakhtunkhwa, Pakistan. The study was performed in different seasons of 2013–2015. The plant diversity comprised of 222 species belonging to 72 families. Among the total reported plant species, Poaceae (28 spp) was the dominant family, followed by Brassicaceae (15 spp.) and Papilionaceae (13 spp) while other families had less than 09 species each. Hydrophytes had 44 species (19.8%); xerophytes had the share of 157 species (70.72%), while 21 species (9.45%) were amphibious in nature. However, plant species possessing simple leaves were 170 (76.57%) species having compound leaves were 23 (10.36%). There were 24 species (10.81%) with dissected leaves and 05 species (2.25%) were aphyllous. Seasonal variation of species diversity indicated 173 species (77.92%) in spring, followed by summer with 120 species (54.5%), winter with 90 species (40.54%) and autumn with 84 species (37.83%). Meanwhile, the biological spectrum showed that therophytes were dominant life form and were represented by 110 species (50.1%), followed by microphanerophytes with 24 species (10.58%). Nanophylls were the leading leaf size spectra with 94 species (42.23%), followed by microphylls with 75 species (33.78%), while leptophyllous had 32 species (14.41%), mesophylls had 16 species (7.20%) and aphyllous were 05 species (2.25%).

Modelling the spatial distribution of aquatic insects (Order Hemiptera) potentially involved in the transmission of Mycobacterium ulcerans in Africa

BackgroundBiting aquatic insects belonging to the order Hemiptera have been suggested as potential vectors of Mycobacterium ulcerans in endemic areas for Buruli ulcer (BU). If this is the case, these insects would be expected to co-exist with M. ulcerans in the same geographical areas. Here, we studied the geographical distribution of six aquatic Hemiptera families that are thought to be vectors of M. ulcerans and explored their potential geographical overlapping with communities reporting BU cases in endemic countries.MethodsWe have developed ensemble ecological models of predicted distribution for six families of the Hemiptera (Naucoridae, Belostomatidae, Notonectidae, Nepidae, Corixidae and Gerridae) applying a robust modelling framework over a collection of recorded presences and a suite of environmental and topographical factors. Ecological niche factor analysis (ENFA) was first used to identify factors that best described the ecological niches for each hemipteran family. Finally, we explored the potential geographical co-occurrence of these insects and BU in two endemic countries, Cameroon and Ghana.ResultsSpecies of the families Naucoridae and Belostomatidae, according to our models, are widely distributed across Africa, although absent from drier and hotter areas. The other two families of biting Hemiptera, the Notonectidae and Nepidae, would have a more restricted distribution, being more predominant in western and southern Africa. All these four families of biting water bugs are widely distributed across coastal areas of West Africa. They would thrive in areas where annual mean temperature varies between 15–22 °C, with moderate annual precipitation (i.e. 350–1000 mm/annual) and near to water courses. Species of all hemipteran families show preference for human-made environments such as agricultural landscapes and urbanized areas. Finally, our analysis suggests that M. ulcerans and species of these aquatic insects might coexist in the same ecological niches, although there would be variation in species diversity between BU endemic areas.ConclusionsOur findings predict the geographical co-existence of some species of aquatic hemipteran families and BU. Considering the existing biological evidence that points to some of these aquatic insects as potential phoretic vectors of M. ulcerans, its presence in BU endemic areas should be considered a risk factor. The ecological models here presented may be helpful to inform future environmental based models intended to delineate the potential geographical distribution of BU in the African region.

Aboveground biomass and root/shoot ratio regulated drought susceptibility of ecosystem carbon exchange in a meadow steppe

Nitrogen deposition and altered precipitation regime are likely to change plant growth, biomass allocation and community structure, which may influence susceptibility of ecosystem functions (i.e. ecosystem carbon exchange) to extreme climatic events, such as drought. In a meadow steppe, we deployed a drought treatment on a long-term water and nitrogen addition experiment to investigate resource abundance changes induced variation in the sensitivity of ecosystem carbon exchange to extreme drought. Compared to the control plots, long-term water and nitrogen addition caused a strong increase in biomass, and a reduction in diversity and root/shoot ratio. Net ecosystem CO2 exchange (NEE) in water and nitrogen addition plots were more sensitive to drought stress than the control plots. The enhanced NEE drought sensitivity (SNEE) in nitrogen fertilization habitat is associated with changes in aboveground biomass and root/shoot ratio, rather than variation in species diversity, while SNEE in the unfertilized plots was controlled by root/shoot ratio. Compared to the water and nitrogen addition plots, the control plots had the highest percentage recovery of ecosystem carbon exchange (RNEE) during the rehydration period. RNEE is likely determined by aboveground biomass and level of damage in the photosynthetic organ. These findings suggest that long-term changes in precipitation regimes and nitrogen deposition may significant alter the susceptibility of key ecosystem processes to drought stress.

Spatial Distribution of Species Diversity of Clavarioid Mycobiota in West Siberia

The results of a 20-year study of the spatial distribution of clavarioid mycobiota in the West Siberian Plain (WSP) are discussed. The species structure has been studied on two scales: regional (an area of 100000 km2) and local (100 km2). In the studied area, 121 species of clavarioid fungi are found. The patterns of spatial variability of species diversity on the plain are revealed. On the regional scale, the maximum species richness of fungi is observed in hemiboreal forests (104 species); on the local scale it ranges from the middle boreal to hemiboreal (54.3–54.5 species). With the increasing pessimality of the hydrothermal regime, the number of species decreases sharply on both scales in the direction of the tundra and steppes. The study of the distribution of diversity among the localities reveals changes not only along the latitudinal gradient, but also in the longitude sectors: in the forest zone, the richest localities are located on the western and eastern edges of the plain, while in the extensive marshy areas in the center the number of species is lower (p < 0.05). A map of the spatial distribution of species diversity for the local scale is constructed. The correspondence of the spatial distribution of the studied fungi group to a global latitudinal gradient is discussed. The main abiotic factors forming a variety of the studied group of fungi in the region are revealed.

Geographic and Seasonal Variation in Species Diversity and Community Composition of Frugivorous Drosophila (Diptera: Drosophilidae) and their Leptopilina (Hymenoptera: Figitidae) Parasitoids.

Many studies have investigated species diversity patterns across space and time, but few have explored patterns of coexistence of tightly interacting species. We documented species diversity patterns in a host-parasitoid system across broad geographic location and seasons. We calculated species diversity (H and eH ') and compared the relationship between community similarity and geographic distances of frugivorous Drosophila host (Diptera: Drosophilidae) and Leptopilina parasitoid (Hymenoptera: Figitidae) communities across Eastern North America, from New Hampshire to Florida, at two time points during the breeding season. We also analyzed the influence of environmental factors on species assemblages via constrained correspondence analysis and lastly calculated cluster dendrograms to identify potential host-parasitoid interactions. We found that the composition of Drosophila-Leptopilina communities varied significantly with latitude. Interestingly, diversity increased with increasing latitude, a trend counter to latitudinal patterns of diversity observed in many other taxa. We also found seasonal effects of monthly temperature range and precipitation on host biodiversity patterns across geographic locations. Cluster dendrograms nominated potential parasitoid-hosts and competitive interactions to be validated in the future studies. The present study fills an important gap of knowledge in North American Drosophila-Leptopilina species diversity patterns and lays the groundwork for future ecological and evolutionary studies in this system.

Variation in species diversity of deep-water megafauna assemblages in the Caribbean across depth and ecoregions.

Diversity patterns of the deep-sea megafauna in the Caribbean Basin and the Guiana ecoregion were analyzed in order to test the hypothesis of species richness variation as a function of depth and the hypothesis of non-differences between ecoregions by analyzing spatial patterns of five taxa and a merged assemblage. Collections of five taxa (corals, sea stars, sea urchins, sea lilies and gastropods) were obtained from seven oceanographic expeditions aboard the R/V Pillsbury at 310 stations between 60 and 7500 m depth. Data were sorted according to depth zones and ecoregions and were analyzed in order to estimate species richness, changes in species composition and distinction of β-diversity by species turnover or by nestedness. The observed patterns of diversity were consistent between taxa and their assemblage: Species richness increased from the continental shelf (60–200 m deep) to the slope (200–2000 m deep), followed by a decrease at the continental rise-abyssal zone. We detected marked changes in species composition according to depth ranges. Changes in species composition in relation to ecoregions were also detected. In general, the Caribbean Basin lacks important physical barriers, causing high deep-sea ecosystem connectivity; however, variation in composition could be related to changes in environmental conditions associated with productivity and/or continental influences.

Tree species diversity promotes soil carbon stability by depressing the temperature sensitivity of soil respiration in temperate forests

The diversity-stability interrelationship suggests that high diversity can buffer fluctuations in environmental conditions such as temperature; we thus hypothesize that tree species diversity will lower the temperature sensitivity of soil respiration (Rs), known as Q10 value. Our hypothesis was tested in a deciduous broad-leaf and a coniferous-broad-leaf mixedwood stand in the warm temperate region in China. We measured soil respiration and indices of tree species diversity including species richness (S), the Berger-Parker index (d), the Simpson index (λ), the Shannon index (He′), and the Pielou evenness index (Je). Our results generally confirm our hypothesis that Q10 was positively correlated to λ, but negatively related to He′, d, and Je, and independent of S, in both stands. However, Rs was independent of the diversity indices. These findings imply that tree species diversity promotes soil carbon stability by depressing the Q10. Furthermore, different biotic and abiotic variables explained the variations of species diversity and Q10 in the broad-leaf and mixedwood forests, suggesting that the mechanisms underlining the effects of tree species diversity on Q10 are different between the two forest types. We conclude that sustainable forest management that improves tree species diversity will increase soil carbon stability and benefit our efforts to mitigate climate change.

Diatom diversity at multiple scales in urban reservoirs in Southern Brazil reveals the likely role of trophic state

Diatoms grow under very specific physical and chemical conditions, and eutrophication may cause community variation. We aimed to describe spatial and temporal variation in diatom community diversity in two urban reservoirs of different throphic status at different spatial scales. We collected samples of epiphytic diatoms from aquatic macrophytes from six sites in each reservoir in the metropolitan region of Curitiba, Southern Brazil, in fall and in spring. We assessed the variation in cell density and taxa richness (considering the lower taxonomic level possible) between the reservoirs and periods using t-tests, and the differences in community composition using PERMANOVA. Principal coordinates analysis (PCoA) was used to observe the change in floras between reservoirs and periods. We also partitioned gamma diversity into alpha and beta diversities using Additive Partitioning. In this case, variation components at different spatial scales were generated for each period. Beta diversities at different scales were also divided into turnover and nestedness components. We identified 132 infrageneric taxa in each reservoir. Spatial and temporal variation in species diversity and composition occurred in both reservoirs at different scales. Even so variation between reservoirs is a component that cannot be expected by a null model, indicating a possible role of eutrophication in community variation. Community variation at different scales was higher in the more eutrophic reservoir, in line with the positive relationship between beta diversity and productivity. Turnover was always the main component of beta diversity considering all spatial and temporal community variation. Nestedness occurred particularly in community variation among time periods at a same location, in line with studies suggesting community stability in urban reservoirs. Taken together, our results highlight the key role of nutrient availability in determining species composition, community variation within reservoirs, and community variation over time.

Simulated tri-trophic networks reveal complex relationships between species diversity and interaction diversity.

Most of earth’s biodiversity is comprised of interactions among species, yet it is unclear what causes variation in interaction diversity across space and time. We define interaction diversity as the richness and relative abundance of interactions linking species together at scales from localized, measurable webs to entire ecosystems. Large-scale patterns suggest that two basic components of interaction diversity differ substantially and predictably between different ecosystems: overall taxonomic diversity and host specificity of consumers. Understanding how these factors influence interaction diversity, and quantifying the causes and effects of variation in interaction diversity are important goals for community ecology. While previous studies have examined the effects of sampling bias and consumer specialization on determining patterns of ecological networks, these studies were restricted to two trophic levels and did not incorporate realistic variation in species diversity and consumer diet breadth. Here, we developed a food web model to generate tri-trophic ecological networks, and evaluated specific hypotheses about how the diversity of trophic interactions and species diversity are related under different scenarios of species richness, taxonomic abundance, and consumer diet breadth. We investigated the accumulation of species and interactions and found that interactions accumulate more quickly; thus, the accumulation of novel interactions may require less sampling effort than sampling species in order to get reliable estimates of either type of diversity. Mean consumer diet breadth influenced the correlation between species and interaction diversity significantly more than variation in both species richness and taxonomic abundance. However, this effect of diet breadth on interaction diversity is conditional on the number of observed interactions included in the models. The results presented here will help develop realistic predictions of the relationships between consumer diet breadth, interaction diversity, and species diversity within multi-trophic communities, which is critical for the conservation of biodiversity in this period of accelerated global change.

The contribution of broadscale and finescale habitat structure to the distribution and diversity of birds in an Alpine forest-shrub ecotone

In a mountain context, the forest-shrub ecotone is an area of high biodiversity. Relatively little is known about the habitat requirements of birds in this habitat, yet it is facing potential threats from changes in grazing practices and climate change. Moreover, it is not clear at which scale habitat associations should be assessed in Alpine birds. Further information on key habitat components affecting bird communities of the ecotone is needed in order to inform management strategies to counteract potential habitat loss, and to better inform predictions of how bird communities may be affected by future environmental change. Data on bird occurrence and broadscale (land cover) and finescale (vegetation structure and shrub species composition) habitat variables were collected in an Alpine forest-shrub ecotone in Val Troncea (northwestern Italian Alps) in order to address two objectives: to identify the key habitat variables associated with the occurrence of individual species and with the diversity of the bird community; and, to assess which scale of habitat measurement (broadscale, finescale or both combined) is needed to model bird occurrence. Broadscale variables, or combinations of broadscale and finescale variables, tended to have the best performing models. When combined models performed best, shrub species identity was included in many cases. Shrubs also played an important role in explaining variations in species diversity and richness. Vegetation structure was of relatively little importance, either for individual bird species or for species richness and diversity. These findings suggest that management should strive to maintain a mosaic of habitats whilst minimizing forest encroachment, which could be achieved through targeted grazing. Broadscale habitat data and data on shrub species composition should provide a sufficient basis for identifying relevant species-specific habitat parameters in a mountain environment in order to model future scenarios of effects of habitat change on the bird community of the alpine forest-shrub ecotone.

A six-year grazing exclusion changed plant species diversity of a Stipa breviflora desert steppe community, northern China.

Excluding grazers is one of most efficient ways to restore degraded grasslands in desert-steppe communities, but may negatively affect the recovery of plant species diversity. However, diversity differences between grazed and fenced grasslands in desert-steppe are poorly known. In a Stipa breviflora desert steppe community in Northern China, we established six plots to examine spatial patterns of plant species diversity under grazed and fenced conditions, respectively. We addressed three aspects of species diversity: (1) The logistic, exponential and power models were used to describe the species-area curve (SAR). Species richness, abundance and Shannon diversity values change differently with increasing sampling areas inside and outside of the fence. The best fitted model for SAR was the logistic model. Excluding grazers had a significant impact on the shape of SAR. (2) Variograms was applied to examine the spatial characteristics of plant species diversity. We found strong spatial autocorrelations in the diversity variables both inside and outside the fence. After grazing exclusion, the spatial heterogeneity decreased in species richness, increased in abundance and did not change in Shannon diversity. (3) We used variance partitioning to determine the relative contributions of spatial and environmental factors to plant species diversity patterns. Environmental factors explained the largest proportion of variation in species diversity, while spatial factors contributed little. Our results suggest that grazing enclosures decreased species diversity patterns and the spatial pattern of the S. breviflora desert steppe community was predictable.

Variability within the dominant microbiota of sliced cooked poultry products at expiration date in the Belgian retail

Sliced cooked poultry products are susceptible to bacterial spoilage, notwithstanding their storage under modified-atmosphere packaging (MAP) in the cold chain. Although the prevailing bacterial communities are known to be mostly consisting of lactic acid bacteria (LAB), more information is needed about the potential variation in species diversity within national markets. In the present study, a total of 42 different samples of sliced cooked poultry products were collected in the Belgian retail and their bacterial communities were analysed at expiration date. A total of 629 isolates from four different culture media, including plate count agar for the total microbiota and de Man-Rogosa-Sharpe (MRS), modified MRS, and M17 agar as three selective agar media for LAB, were subjected to (GTG)5-PCR fingerprinting and identification by gene sequencing. Overall, Carnobacterium, Lactobacillus, and Leuconostoc were the dominant genera. Within each genus, the most encountered isolates were Carnobacterium divergens, Lactobacillus sakei, and Leuconostoc carnosum. When comparing samples from chicken origin with samples from turkey-derived products, a higher dominance of Carnobacteria spp. was found in the latter group. Also, an association between the dominance of lactobacilli and the presence of added plant material and lactate salts was found.

Spatial variations in species diversity of mid-subtropical evergreen broad-leaved forest community in Gutianshan National Nature Reserve

Spatial variations in species diversity of mid-subtropical evergreen broad-leaved forest community in Gutianshan National Nature Reserve

桂西北喀斯特常绿落叶阔叶混交林物种多样性分布格局的尺度效应

PDF HTML阅读 XML下载 导出引用 引用提醒 桂西北喀斯特常绿落叶阔叶混交林物种多样性分布格局的尺度效应 DOI: 10.5846/stxb201709231713 作者: 作者单位: 中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,中国科学院亚热带农业生态研究所,广西壮族自治区木论国家级自然保护区管理局,中国科学院亚热带农业生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2016YFC0502405）；广西重点研发计划项目（桂科AB16380255，桂科AB17129009）；国家自然科学基金项目（31770495）；广西特聘专家项目 Scale-dependent spatial patterns for species diversity in a karst evergreen and deciduous broad-leaved mixed forest of northwest Guangxi Author: Affiliation: Institute of Subtropical Agriculture Chinese Academy of Sciences,Institute of Subtropical Agriculture Chinese Academy of Sciences,Institute of Subtropical Agriculture Chinese Academy of Sciences,Institute of Subtropical Agriculture Chinese Academy of Sciences,Institute of Subtropical Agriculture Chinese Academy of Sciences,,Institute of Subtropical Agriculture Chinese Academy of Sciences Fund Project: Dthe National Key Research and Development Program ( 2016YFC0502405), the Guangxi Key Research and Development Program (AB17129009, AB16380255), the National Natural Science Foundation of China (31370485, 31370623, 31400412), and the Guangxi Program of Distinguished Expert 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:物种多样性的空间分布格局及其与尺度的关系研究对于了解群落物种多样性形成机制具有重要意义。为了探讨喀斯特地区物种多样性空间分布格局的尺度效应，以喀斯特常绿落叶阔叶混交林25 hm2样地的（胸径DBH≥1）木本植物为研究对象，分析了6个空间尺度（5 m×5 m，10 m×10 m，20 m×20 m，50 m×50 m，100 m×100 m，250 m×250 m）上的多度、物种丰富度、Shannon-Wiener指数、Simpson指数以及Pielou均匀度指数的变化规律。结果表明：物种多样性指数的空间分布均表现出较高的空间异质性；物种多样性指数的方差随取样尺度增加呈现单峰分布特征，并且在100 m×100 m尺度上达到最大值；物种多样性指数的变异系数随尺度的增加呈线性下降趋势，其中，Shannon-Wiener指数、Simpson指数以及Pielou均匀度指数均在5 m×5 m至20 m×20 m尺度上明显减小；在大于50 m×50 m的尺度上，物种丰富度与多度的正相关性不显著（P > 0.05）。喀斯特常绿落叶阔叶混交林物种多样性的空间分布格局与不同空间尺度密切相关，深入解析物种多样性随空间尺度的变化模式，需要在类似的森林生态系统做更多的研究。 Abstract:Spatial distribution patterns of species diversity and their relationships with scale are of great significance to understand the mechanism of community species diversity formation. Here, a field survey was conducted to assess the variation in species diversity along spatial scales in a karst evergreen and deciduous broad-leaved mixed forest, Southwest China. Based on the dataset of woody plants (DBH ≥ 1) from a 25 hm2 plot, the spatial distribution patterns of species abundance, species richness, and Shannon-Wiener, Simpson, and Pielou's evenness indices were analyzed at six spatial scales-5 m×5 m, 10 m×10 m, 20 m×20 m, 50 m×50 m, 100 m×100 m, and 250 m×250 m. The results showed that spatial distributions of species diversity indices were highly heterogeneous. The variance of species diversity indices changed with spatial scale following a unimodal pattern, i.e., with a maximum value at the 100 m×100 m scale. Variation coefficients of species diversity decreased linearly with increasing scale. The Shannon-Wiener, Simpson, and Pielou's evenness indices decreased sharply at the 5 m×5 m and 20 m×20 m scales. No significant positive relationship was found between species richness and abundance at scales over 50 m×50 m (P > 0.05). Our results suggest that the spatial pattern of species diversity in this evergreen and deciduous broad-leaved mixed karst forest is closely related to spatial scale. To better understand spatial variation of species diversity across spatial scales, more such studies in other similar forest ecosystems are needed. 参考文献 相似文献 引证文献

山西吕梁山亚高山草甸物种多样性的时空变化格局

PDF HTML阅读 XML下载 导出引用 引用提醒 山西吕梁山亚高山草甸物种多样性的时空变化格局 DOI: 10.5846/stxb201803300667 作者: 作者单位: 太原师范学院地理科学学院,太原师范学院地理科学学院,太原师范学院地理科学学院,太原师范学院地理科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 山西省应用基础研究计划项目（2016021136）；山西省高等学校重点学科建设项目（晋教研函〔2016〕4号）；山西省高等学校科技创新项目（晋教科函〔2016〕4号） Spatial and temporal patterns of species diversity of subalpine meadows in the Lvliang Mountains, Shanxi Province Author: Affiliation: Taiyuan Normal University,Taiyuan Normal University,Taiyuan Normal University,Taiyuan Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在山西吕梁山系按照纬度从北向南依次选取马伦草原、荷叶坪、云顶山作为研究区，于2015、2016、2017年7月下旬进行亚高山草甸植被群落多样性调查，研究吕梁山亚高山草甸物种多样性不同年份、不同纬度的时空变化格局。结果表明：（1）吕梁山亚高山草甸群落中矮嵩草（Kobresia humilis）和珠芽蓼（Polygonum viviparum）、线叶嵩草（Kobresia capillifolia）和珠芽蓼、车前草（Plantago asiatica）和披碱草（Elymus dahuricus）分别为马伦草原、荷叶坪、云顶山的优势种，不同山地植物优势种和次优势种均以菊科（Asteraceae）、蔷薇科（Rosaceae）、莎草科（Cyperaceae）、禾本科（Gramineae）植物为主。（2）吕梁山亚高山草甸物种多样性在不同年份分布较为稳定，Pielou指数在连续3年内均无较大变化；Shannon-Wiener指数、Simpson指数和Patrick指数在2016年最高，同时该年份的降水天数也是最多，表明吕梁山亚高山草甸物种多样性在时间上呈现出受降水条件影响较大的变化格局。（3）吕梁山偏南部的云顶山多样性指数高于偏北部的马伦草原和荷叶坪，表明吕梁山亚高山草甸物种多样性在空间上表现出由北向南逐渐升高的变化格局。因此，吕梁山亚高山草甸物种多样性在时空上呈现出受降水条件影响较大，且由北向南逐渐升高的变化格局，降水条件和纬度梯度对该山地亚高山草甸物种多样性的时空变化格局产生了重要影响。 Abstract:Based on latitude from north to south in the Lvliang Mountains, Shanxi Province, Malun Grassland, Heyeping, and Yunding Mountain were selected as study areas in this research. In 2015, 2016, and 2017, the species diversity of subalpine meadows was surveyed to determine the spatial and temporal patterns of different years and latitudes of subalpine meadow species in the Lvliang Mountains. The results showed that:(1) Kobresia humilis and Polygonum viviparum, Kobresia capillifolia and Polygonum viviparum, Plantago asiatica and Elymus dahuricus were the dominant species of Malun Grassland, Heyeping, and Yunding Mountain. The dominant and subdominant species in different regions were mainly from Compositae, Rosaceae, Cyperaceae, Gramineae, and the life forms were mainly perennial herbs; (2) the species diversity distribution was stable in different years. There was no visible difference in the Pielou index in three years. The Shannon-Wiener, Simpson, and Patrick indexes were the highest in 2016, which indicated that the species diversity of subalpine meadows in the Lvliang Mountains were affected by temporal variations in precipitation; (3) in the Lvliang Mountains, the species diversity of Yunding Mountain in the southern section was higher than that in Malun Grassland and Heyeping in the northern section. This indicated that the variation of species diversity of subalpine meadows in the Lvliang Mountains gradually increased from north to south. Therefore, the spatial and temporal patterns of species diversity of subalpine meadows in the Lvliang Mountains were obviously affected by precipitation and gradually increased from north to south. 参考文献 相似文献 引证文献