首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
This paper presents the results of wood charcoal analysis carried out on material from Theopetra cave in central Greece. The sequence dates from prior to 130–8 ka bp and is made up of layers of both anthropogenic and geogenic origins. The study of the wood charcoal samples from these layers sets out to distinguish changes in the local vegetation through time, to correlate these with broader environmental conditions and to discuss how they may relate to differences in the frequency and intensity of human occupation of the cave from shortly before the last interglacial to the Holocene. Changes in the presence and frequency of Prunus sp., Juniperus sp. as well as taxa needing temperate, thermophilous or riverine conditions in successive layers reflect a pattern of vegetation succession that can be correlated with the pollen and marine isotope stage (MIS) records. The earliest human occupation took place in an open park-woodland environment dominated by Prunus during the late MIS 6–6/5 transition. This was followed by a succession of temperate woodlands with deciduous Quercus, Carpinus and Fraxinus, reflecting the optimal conditions of the last interglacial (MIS 5e), followed by more open vegetation during subsequent cooling events. Middle Palaeolithic hunter-gatherers visited the cave repeatedly during the last interglacial, in contrast to more sporadic human presence during the following climatic deterioration. This was characterized by Juniperus dominated steppe and open vegetation and/or riparian woods, reflecting the harsh and unstable climatic conditions of the pleniglacial. Finally, the expansion of Pistacia and re-establishment of temperate woodland points to climatic amelioration during the Holocene from which there is evidence of regular use of the cave by Mesolithic and Neolithic people. The dominant role of Prunus observed in several periods provides important complementary information to the pollen evidence from the late Pleistocene.  相似文献   

2.

Background, aim, and scope

The rise in wood fuel consumption, particularly of charcoal, has been associated with increased deforestation in Ghana. Plantation developments from teak (Tectona grandis), bamboo (Bambusa balcooa), and Acacia auriculiformis are now being promoted to produce sustainable biomass for charcoal production. While all species have comparable charcoal quality, there is limited available data to elucidate the environmental impacts associated with their plantation development and use as biomass sources for producing charcoal. Therefore, this study quantified and compared the cradle-to-gate environmental impacts of producing charcoal from T. grandis, A. auriculiformis, and B. balcooa.

Methods

The study was conducted in accordance with ISO 14040/14044, an international procedural framework for performing life cycle analysis (LCA). For this study, the functional unit of charcoal used was 1 MJ energy produced from three species: T. grandis, A. auriculiformis, and B. balcooa. Data on B. balcooa plantations was collected from a B. balcooa-based intercropping system set up by the International Network for Bamboo and Rattan in Sekyere Central District, Ghana. Input data for A. auriculiformis and T. grandis came from the Forestry Commission of Ghana plantations established within the forest agroecological zone of Ghana. All input data came from primary local sources. Pollutant emissions were also calculated in order to analyze the contribution of all the flow processes to the emissions. The analysis used Simapro version 8, as well as life cycle inventory (LCI) databases of Ecoinvent V3 and Idemat 2015 (a database developed by Delft University of Technology, the Netherlands). The emissions were expressed as eco-costs and used as indicators in an impact assessment.

Results and discussion

The results showed that relative to B. balcooa, the total eco-cost (comprising of human health, ecosystem, resource depletion, and global warming eco-costs) of a cradle-to-gate production of 1 MJ of charcoal will be 140% higher with T. grandis and 113% higher with A. auriculiformis. The increased environmental impacts associated with T. grandis and A. auriculiformis occurred at their biomass production stage. As these species use comparatively large quantities of pesticides, weedicides, and fertilizers with high acidification, ozone depletion, and global warming potentials, their biomass production stage accounted for approximately 85% of their total eco-cost.

Conclusions

The study results suggest that B. balcooa plantations are the most environmentally viable option. In cases where T. grandis or A. auriculiformis plantations are widespread, improvement options at the biomass production stage are required in order to reduce their environmental costs.
  相似文献   

3.
Little is known about the vegetation and fire history of Sardinia, and especially the long-term history of the thermo-Mediterranean belt that encompasses its entire coastal lowlands. A new sedimentary record from a coastal lake based on pollen, spores, macrofossils and microscopic charcoal analysis is used to reconstruct the vegetation and fire history in north-eastern Sardinia. During the mid-Holocene (c. 8,100–5,300 cal bp), the vegetation around Stagno di Sa Curcurica was characterised by dense Erica scoparia and E. arborea stands, which were favoured by high fire activity. Fire incidence declined and evergreen broadleaved forests of Quercus ilex expanded at the beginning of the late Holocene. We relate the observed vegetation and fire dynamics to climatic change, specifically moister and cooler summers and drier and milder winters after 5,300 cal bp. Agricultural activities occurred since the Neolithic and intensified after c. 7,000 cal bp. Around 2,750 cal bp, a further decline of fire incidence and Erica communities occurred, while Quercus ilex expanded and open-land communities became more abundant. This vegetation shift coincided with the historically documented beginning of Phoenician period, which was followed by Punic and Roman civilizations in Sardinia. The vegetational change at around 2,750 cal bp was possibly advantaged by a further shift to moister and cooler summers and drier and milder winters. Triggers for climate changes at 5,300 and 2,750 cal bp may have been gradual, orbitally-induced changes in summer and winter insolation, as well as centennial-scale atmospheric reorganizations. Open evergreen broadleaved forests persisted until the twentieth century, when they were partly substituted by widespread artificial pine plantations. Our results imply that highly flammable Erica vegetation, as reconstructed for the mid-Holocene, could re-emerge as a dominant vegetation type due to increasing drought and fire, as anticipated under global change conditions.  相似文献   

4.
Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests (Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species (Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso-mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees (Fagus sylvatica, Ilex aquifolium) dominated in the natural or quasi-natural forests of the oro-mediterranean belt. Forests were repeatedly opened for agricultural purposes. Fire activity was closely associated with farming, providing evidence that burning was a primary land use tool since Neolithic times. Land use and fire activity intensified during the Early Neolithic at 5000 bc, at the onset of the Bronze Age at 2500 bc and at the onset of the Iron Age at 800 bc. Our data and previous studies suggest that the large majority of open land communities in Sicily, from the coastal lowlands to the mountain areas below the thorny-cushion Astragalus belt (ca. 1,800 m a.s.l.), would rapidly develop into forests if land use ceased. Mesophilous Fagus-Ilex forests developed under warm mid Holocene conditions and were resilient to the combined impacts of humans and climate. The past ecology suggests a resilience of these summer-drought adapted communities to climate warming of about 2 °C. Hence, they may be particularly suited to provide heat and drought-adapted Fagus sylvatica ecotypes for maintaining drought-sensitive Central European beech forests under global warming conditions.  相似文献   

5.
This study concerns the stand-scale palaeoecological reconstruction of the subsequent stages of late Holocene vegetation development on habitats recently covered by beech-dominated woodland in the southern Baltic region. The data, based on pollen, non-pollen palynomorphs, macrofossil and charcoal analyses from two close-lying sites, demonstrated that each of the subsequent late Holocene shifts in dominating forest communities took place because of human impact coupled with climatic events or episodic human-made disturbances. Shifts from the Tilia dominated forest to the Quercus-Corylus plant community at around 3300 bc was most probably driven by the coupled effect of climate change and human activity. Human impact was the primary driver of the final Corylus decline and concurrent major Carpinus expansion at c. 460 bc, and the Carpinus decline followed by Fagus expansion at c. ad 900. Carpinus had been lingering on the edge of a major expansion in the local forest for at least 2,500 years while Fagus had persisted in a small admixture for no fewer than 1,500 years before becoming important forest constituents. Our data illustrate the role of episodic disturbances as turning points that initiate long-term vegetation changes.  相似文献   

6.
Investigation during the period of 3 years from 2007 to 2010 on the malacofauna of Chilika lake revealed the occurrence of 126 molluscan taxa belonging to 56 families, 18 orders of three classes in the bottom sediment. Of these 61 species belonged to Bivalvia, 64 species belonged to Gastropoda and one species belonged to Polyplacophora. Maximum Bivalvia and Gastropoda taxa were found in the outer channel region of the lake. The dominating species were Crassostrea cuttackensis, Saccostrea cucullata, Brachidontes undulatus, Meretrix meretrix among bivalves and Cerethideopsilla cingulata, Bullia vittata, Nassarious stolatus, Indothias lacera, Natica tigrina, Turritella attenuata were from the gastropods. Occurrence of a large number of marine taxa is most probably associated with the opening of new lagoon during 1st August 2008.  相似文献   

7.
Aquatic vegetation of Hydrochari-Lemnetea and Potametea classes in the Danube-Tisza-Danube hydrosystem (Hs DTD) was studied in 2009–2012, by applying the standard Braun-Blanquet method. The canal network vegetation comprises 14 associations, with Trapetum natantis and Ceratophylletum demersi being the most widely distributed. Hs DTD is also a habitat for several important endangered species, which serve as edificators of the following phytocenoses: Nymphaeetum albae, Nymphaeetum albo-luteae, Nymphoidetum peltatae, Trapetum natantis, Lemno-Spirodeletum, Salvinio-Spirodeletum polyrrhizae, Lemno-Utricularietum vulgaris, Potametum nodosi, Myriophyllo-Potametum and Najadetum marinae. In the studied vegetation, we also found an invasive phytocenosis Elodeetum canadensis that did not have an expanding tendency, and Ceratophyllo demersi-Vallisnerietum spiralis that had this tendency, which made monitoring its stands necessary. Physico-chemical analyses of water, conducted at localities in which the studied phytocenoses thrive, revealed that the development and distribution of most phytocenoses is closely linked with specific habitat conditions. Among the studied parameters, the most significant for the phytocenoses differentiation were: pH, alkalinity, COD-MnO4, BOD5, NO 3 ? , NO 2 ? , PO 4 3? and the concentration of total phosphorus.  相似文献   

8.
Investigations were carried out in June–August 2012 and 2013 in broadleaf forests and planted stands of the northern red oak Quercus rubra in Kiev. The ant visitation rates of 3–6 most abundant plant species within each vegetation layer were analyzed. In all, 16 species of ants were found in the broadleaf forest (Quercus robur + Acer spp. + Carpinus betulus), with the dominance of three species: Formica rufa, Lasius fuliginosus, and L. emarginatus. Eight ant species occurred in Q. rubra stands with the undergrowth of Acer campestre and A. platanoides; the dominant species were Lasius fuliginosus and L. emarginatus. The northern red oak stands with conspecific undergrowth had only four ant species with no dominants among them. Plants with the highest ant visitation rates in the herbage layer of the broadleaf forest were the invasive Impatiens parviflora and the native Aegopodium podagraria. Ants were rare or absent on the remaining herbs: Impatiens noli-tangere, Carex sylvatica, Stellaria holostea, and Galium odoratum. The herbage layer was mostly visited by influents, the dominants being represented only by Lasius emarginatus. Within the shrub layer, ants most frequently visited the undergrowth of the maple Acer platanoides, often harboring colonies of the aphid Periphyllus lyropictus; the highest visitation rates were recorded in the dominants L. emarginatus and L. fuliginosus. The arboreal layer had the highest visitation rate and was most often visited by the dominants Lasius fuliginosus, L. emarginatus, and F. rufa. The common oak Q. robur was the most visited tree in broadleaf forests. In addition to providing ants with food (colonies of the aphids Lachnus roboris and Stomaphis quercus, and also phytophagous insects and other invertebrates), these trees were used for nesting by the dominants L. fuliginosus and L. emarginatus. The presence of aphid colonies was also typical of ripe trees and undergrowth of the maple A. platanoides, the second-visited tree in broadleaf forests. The common hornbeam Carpinus betulus was the least frequently visited, though some ant species, usually L. emarginatus, nested in the trunks and branches of old trees. The vertical distribution of ants in broadleaf forests and red oak stands formed two clusters: the influents occupied the lower (herbage and shrub) vegetation layers, while the subdominants and dominants occupied the upper (shrub and arboreal) ones. The smallest number of ant species (1 or 2) in all the vegetation layers was recorded in the areas with F. rufa; areas with L. fuliginosus had twice as many species; the greatest numbers of ant species were found in the areas with L. emarginatus and in those without dominants. This pattern may result from different territoriality of the dominants: the strongest in F. rufa (defending the whole territory) and the weaker in the other two species (defending only a part of the territory). Plants of all the vegetation layers varied in their attractiveness to ants. As a result, the layers had a mosaic structure in their vertical (between-layer) and horizontal (between different plant species within one layer) arrangement. From 60 to 100% of plants of certain species were visited by ants while plants of other species were not visited at all. The main reason for visiting plants by ants was the presence of aphid colonies.  相似文献   

9.
This paper describes the present-day vegetation, stratigraphy and developmental history of the mire of Egelsee-Moor (Salzburg, Austria; 45°45′N, 13°8.5′E, 700 m a.s.l., 15 ha in area) since the early Late Glacial on the basis of 4 transects with 14 trial borings across the peatland. We present a vegetation map of the mire, a longitudinal section through the peat body based on six cores showing the peat types, overview macrofossil diagrams of six cores showing the local mire development and two pollen diagrams covering the Late Glacial and Holocene. The chronology of the diagrams depends on biostratigraphic dating for the Late Glacial and early Holocene and radiocarbon dating for the remaining Holocene. The northern part of the mire originated through terrestrialisation of nutrient-rich, mostly inundated fen and the southern part through paludification of wet soils. The very small lake of today was a reservoir until recently for providing water-power for timber rafting (‘Holztrift’). The mire vegetation today is a complex of forested parts (mainly planted Pinus sylvestris and Thuja occidentalis, but also spontaneous Picea abies, Betula pubescens and Frangula alnus), reed-lands (Phragmites) and litter meadows (Molinietum, Schoenetum, etc.). The central part has hummock-hollow complexes with regionally rare species of transitional mires (Drosera anglica, D. intermedia, Lycopodiella inundata, Scorpidium scorpioides, Sphagnum platyphyllum, S. subnitens). The results indicate that some of the mid-Holocene sediments may have been removed by the timber-rafting practices, and that water extraction from the hydrological catchment since 1967 has resulted in a partial shift of transitional mire to ombrotrophic bog. The latter potentially endangers the regionally rare species and was used as an argument to stop further water extraction.  相似文献   

10.
Charcoal rot disease, a root and stem disease caused by the soil-borne fungus Macrophomina phaseolina (Tassi) Goid., is a major biotic stress that limits sorghum productivity worldwide. Charcoal rot resistance-related parameters, e.g., pre-emergence damping-off%, post-emergence damping-off%, charcoal rot disease severity, and plant survival rates, were measured in a structured sorghum population consisting of 107 landraces. Analysis of variance of charcoal rot resistance-related parameters revealed significant variations in the response to M. phaseolina infection within evaluated accessions. Continuous phenotypic variations for resistance-related parameters were observed indicating a quantitative inheritance of resistance. The population was genotyped using 181 simple sequence repeat (SSR) markers. Association analysis identified 13 markers significantly associated with quantitative trait genes (QTLs) conferring resistance to charcoal rot disease with an R2 value ranging between 9.47 to 18.87%, nine of which are environment-specific loci. Several QTL-linked markers are significantly associated with more than one resistance-related parameter, suggesting that those QTLs might contain genes involved in the plant defense response. In silico analysis of four novel major QTLs identified 11 putative gene homologs that could be considered as candidate genes for resistance against charcoal rot disease. Cluster analysis using the genotypic data of 181 SSR markers from 107 sorghum accessions identified 12 main clusters. The results provide a basis for further functional characterization of charcoal rot disease resistance or defense genes in sorghum and for further dissection of their molecular mechanisms.  相似文献   

11.
Pollen analyses of spider web samples, collected from the recently planted Tectona grandis (T. grandis, teak)-dominated tropical deciduous forest of Bhulsidih Village, Korba District (Chhattisgarh, central India), shed light on the relationship between the extant vegetation and pollen rain. The study revealed the dominance of pollen of herbs and trees, whereas shrubs, fern spores and algal remains are meagre. Among the tree taxa, Sapotaceae, Syzygium, Holoptelea, Lannea coromandelica, Shorea robusta and Grewia are dominating with moderate to low and intermittent presence of Madhuca indica, Terminalia, Mitragyna, Schleichera, Anacardiaceae, Diospyros, Emblica officinalis and Flacourtia. However, the rest of the forest constituents are either not represented at all despite their presence in the floristics, which could be attributed to their low pollen productivity owing to entomophily as well as their poor pollen preservation pattern. On the other hand, the ground vegetation is represented by the very high frequency of grasses (Poaceae) along with Tubuliflorae, Chenopodiaceae/Amaranthaceae and Cerealia, however, Artemisia, Xanthium, Malvaceae, Caryophyllaceae and Justicia in moderate to lower values. Ferns, which occur abundantly along the adjoining stream banks, are marked by the sporadic retrieval of trilete spores that could be ascribed to the prevailing damp condition around the sampling provenance. The study, in addition to understanding the pollen–vegetation relationship, could also be helpful in aerobiological study, especially in assessing the allergenicity of various pollen grains/spores in the area of investigation, causing bronchial asthma, hay fever (allergic rhinitis/pollinosis), naso-bronchial allergy and other respiratory disorders along with conjunctivitis, contact dermatitis, eczema, food allergies and other health disorders.  相似文献   

12.
Archaeobotanical analyses of charred seeds, fruit and wood charcoal from the residential part of the ez-Zantur area at Petra, Jordan, provide new data on the agricultural economy and use of the landscape in this famous merchant Nabataean city from the middle of the 2nd century bc to the beginning of the 5th century ad. The study is based on analyses of 7,640 whole and fragmented seeds, pips and fruit stones and 624 charcoal fragments sampled from household deposits. The results show that the food supply was based on common Mediterranean cultivated taxa such as cereals (Hordeum vulgare, Triticum aestivum/durum), pulses (Lens culinaris) and fruit (Olea europaea, Ficus carica, Vitis vinifera), which were probably cultivated both in the city and its hinterland. The by-products from the processing of cereals and fruit trees played a significant role in fuel supply, supplementing woody wild plants obtained from rocky slopes and the desert valley. The variety of fuel resources shows a major capacity to manage complex supply networks and perhaps the rarity of natural woodland cover. The existence of orchards within the city centre and notably olive groves is indicated in the Early Nabataean period (mid 2nd century to mid 1st century bc) but they expanded during the Classical Nabataean period (mid 1st century bc to 1st century ad), probably reflecting specialised fruit growing. Unusual plant remains such as Prunus armeniaca (apricot), P. persica (peach) and Juglans regia (walnut) are considered to be social indicators of prosperity. These archaeobotanical results fit with others from this region and match with the urbanization and social dynamics of the city of Petra.  相似文献   

13.
Understanding terrestrial vegetation dynamics is a crucial tool in global change research. The Loess Plateau, an important area for the study of Asian monsoons and early agriculture, poses a controversial question on the potential vegetation and its pattern. Fossil charcoal as direct evidence of wood provides precision in species identification and hence vegetation reconstruction. Charcoals from the Dadiwan and Xishanping sites suggest a great variety of plants between 5200 and 4300?cal. b.p. in the valley area of the western Loess Plateau. The deciduous broad-leaf wood from Quercus, Ulmus, Betula, Corylus and Acer is very frequent and makes up almost half the total abundance ratio of the represented taxa. Meanwhile, some typical subtropical taxa such as Liquidambar formosana, Eucommia ulmoides, Toxicodendron and Bambusoideae, are present at the two study sites. The high abundance of Picea appearing between 5200 and 4300?cal. b.p. suggests the development of Picea forests in the valley of the western Loess Plateau. The assemblages of charcoal indicate that the mixed forest of evergreen deciduous and conifer-deciduous broadleaved trees developed in the valley of the Loess Plateau during the Holocene optimum. Precipitation is the main controlling factor for forest development. The increasing precipitation is the probable reason for the appearance of north-subtropical forests between 5200 and 4300?cal. b.p.  相似文献   

14.
Ground beetles were sampled in a broadleaved deciduous forest in Kaluga Province in April–October 1995 using 90 traps grouped in 18 experimental plots. Three types of pitfall traps were used: glass jars, white plastic cups, and cylindrical containers made of transparent plastic bottles. Two types of cover put above the traps were tested: transparent and black. Altogether, 72 carabid species were found, of which only 10 species were shared by all the experimental plots: Leistus terminatus, Carabus hortensis, C. glabratus, Cychrus caraboides, Pterostichus niger, P. oblongopunctatus, P. strenuus, P. melanarius, Calathus micropterus, and Badister lacertosus. The Jaccard binary similarity index between the experimental plots amounted to 37–68% while the Bray-Curtis similarity index was 66–89%. Both the trap type and the cover color significantly affected the similarity of the species structure and species composition of the samples. Plastic cups provided the highest catches of beetles, but this was due to the most abundant species, P. oblongopunctatus. Containers provided the highest catches of C. glabratus. The total abundance was higher for the traps with transparent covers than for those with black covers. Traps with transparent covers provided significantly higher catches of L. terminatus, P. oblongopunctatus, Asaphidion flavipes, and Harpalus rufipes. An adequate assessment of the species composition of a particular habitat requires at least 30 pitfall traps.  相似文献   

15.
In the large caldera of Mt. Aso, Japan, artificial grasslands were converted into forests of different species due to the decline of the livestock industry in this region. These changes in species composition are thought to have changed not only the transpiration rates (E), but also the responses in E to variations in environmental conditions. For three introduced forest types, we monitored E using sap flux sensors and computed E with a multilayer model parameterized by independently obtained leaf-scale ecophysiological traits. Modeled E replicated the time series of measured E reasonably well, but did not reproduce a decrease in E lasting 20 days after a short rainless period in conifer plantation. Mean leaf-scale stomatal conductance of two deciduous broadleaved tree species was as low as that of trees under dry conditions in other studies, possibly an adaptation for the avoidance of excessive E during rainless periods. These results suggest that land use change influenced E and its response to the rainfall patterns of the region and that drought plays an important role in influencing species-specific E characteristics in this rainy region. The multilayer model in combination with sap flux measurements was found to be a useful tool not only for the extrapolation of E, but also for the detection of the unexpected events, as long as the measured parameter values capture the species-specific seasonality in leaf ecophysiological traits.  相似文献   

16.
In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (Psat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, Psat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest Psat at saturating irradiance and the highest leaf N content. This N content was higher and Psat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, Psat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by δ13C, showed the same range reported for temperate tree species. The ranking of δ13C values for the different tree types was conifers < evergreen broadleaved<deciduous, suggesting tighter stomatal closure and higher water use efficiency for the evergreen types, confirming trends found elsewhere. No relevant differences of δ13C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (δF/Fm’), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .δF/Fm’ along the altitudinal gradient correlated well with the reported altitudinal distribution of the species.  相似文献   

17.
18.
The present study shows that, from 300 Lactobacillus strains isolated from the oral cavity and large intestine of 600 healthy people, only 9 had high antagonistic activity against pathogens and opportunistic pathogens. All antagonistic strains of lactobacilli have been identified by 16S rRNA sequencing and assigned to four species: Lactobacillus fermentum, Lactobacillus rhamnosus, Lactobacillus plantarum, and Lactobacillus casei. In addition, these lactobacilli appeared to be nonpathogenic and had some probiotic potential: the strains produced lactic acid and bacteriocins, showed high sensitivity to broad-spectrum antibiotics, and were capable of forming biofilms in vitro. With the help of PCR and specific primers, the presence of genes for prebacteriocins in L. plantarum (plnEF, plnJ, plnN) and L. rhamnosus (LGG_02380 and LGG_02400) has been revealed. It was found that intestinal strains of lactobacilli were resistant to hydrochloric acid and bile. Lactobacilli isolated from the oral cavity were characterized by a high degree of adhesion, whereas intestinal strains were characterized by average adhesion. Both types of lactobacilli had medium to high rates of auto-aggregation and hydrophobicity and could coaggregate with pathogens and opportunistic pathogens. Additionally, the ability of the lactobacilli strains to produce gasotransmitters, CH4, CO2, C2H6, CO, and NH3, has been revealed.  相似文献   

19.
The microbiota of whole crop corn silage and feces of silage-fed dairy cows were examined. A total of 18 dairy cow feces were collected from six farms in Japan and China, and high-throughput Illumina sequencing of the V4 hypervariable region of 16S rRNA genes was performed. Lactobacillaceae were dominant in all silages, followed by Acetobacteraceae, Bacillaceae, and Enterobacteriaceae. In feces, the predominant families were Ruminococcaceae, Bacteroidaceae, Clostridiaceae, Lachnospiraceae, Rikenellaceae, and Paraprevotellaceae. Therefore, Lactobacillaceae of corn silage appeared to be eliminated in the gastrointestinal tract. Although fecal microbiota composition was similar in most samples, relative abundances of several families, such as Ruminococcaceae, Christensenellaceae, Turicibacteraceae, and Succinivibrionaceae, varied between farms and countries. In addition to the geographical location, differences in feeding management between total mixed ration feeding and separate feeding appeared to be involved in the variations. Moreover, a cow-to-cow variation for concentrate-associated families was demonstrated at the same farm; two cows showed high abundance of Succinivibrionaceae and Prevotellaceae, whereas another had a high abundance of Porphyromonadaceae. There was a negative correlation between forage-associated Ruminococcaceae and concentrate-associated Succinivibrionaceae and Prevotellaceae in 18 feces samples. Succinivibrionaceae, Prevotellaceae, p-2534-18B5, and Spirochaetaceae were regarded as highly variable taxa in this study. These findings help to improve our understanding of variation and similarity of the fecal microbiota of dairy cows with regard to individuals, farms, and countries. Microbiota of naturally fermented corn silage had no influence on the fecal microbiota of dairy cows.  相似文献   

20.
Coniferous forests are a significant feature in the natural vegetation of the Mediterranean mountains, but most stands are rather degraded and the present distribution is just a fraction of its potential natural area. The Parnonas range (Peloponnese, Greece) ranks among the most extensive areas with a well-preserved mountain coniferous forest in the Mediterranean. The present paper aims at describing the conifer-dominated vegetation of this mountain and the ecological roles of the prevailing speciesAbies cephalonica, Pinus nigra, andJuniperus drupacea. For comparison, a survey is provided of theAbies cephalonica forests in the total distribution area, using all published relevés. Species composition and abundance, together with structural and abiotic parameters were recorded in 118 relevés distributed throughout Mt. Parnon. The phytosociological classification reveals 8 interpretable vegetation types well separated by groups of diagnostic species and presented in a synoptic table. The ecology and distribution of the units are outlined, and they are assigned to 4 associations within theAbietion cephalonicae (Helictotricho convoluti-Abietetum cephalonicae, Junipero drupaceae-Abietetum cephalonicae, Lilio chalcedonicae-Abietetum cephalonicae, Pyrolo chloranthae — Pinetum nigrae). The syntaxonomy and nomenclature of these associations, two of which are described as new, are discussed. The most important gradients in the data matrix found by detrended correspondence analysis (DCA) are related to altitude/climate and rockiness/soil. The communities are well segregated in the ordination space, and the fairly distinct clusters of the three conifer species are discussed. These conifers may be arranged along a gradient of decreasing drought tolerance fromJuniperus throughAbies toPinus. The latter is predominant and most vital essentially on schistose soils, or else reflects previous disturbance by, e.g., wildfires.Juniperus drupacea is a subordinate low tree or shrub in Tripolitza limestoneAbies forest. The vitality ofAbies cephalonica as expressed by tree height and structure is best in theLilio-Abietetum, between 1300 and 1600 m. The community variation within the total area of theAbietion cephalonicae reflects a principal differentiation in xerophytic and mesophytic stands. This pattern is encountered in various mountains and suggests that water supply is the crucial factor governing the floristic variation in the mountain coniferous forests.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号