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1.
2.
Zizania latifolia is a perennial herb belonging to the family Gramineae that has been used as a health food in Asian countries. In this study, we investigated the antimicrobial effect of Z. latifolia, which increased human beta-defensin 2 (hBD2) expression in HaCaT cells. hBD2 expression was further increased in cells treated with Z. latifolia extracts and subsequently infected with Staphylococcus aureus. Inversely, S. aureus infection decreased after treatment. The induction of hBD2 in HaCaT cells was mediated by the Toll-like receptor 2 (TLR2) signaling pathway, including the activation of extracellular signal-regulated kinase (ERK) and activator protein 1 (AP-1). Further study using siRNA revealed that hBD2 played an important role in the inhibition of S. aureus infection in HaCaT cells. Our data suggest that Z. latifolia extracts can be used as an antimicrobial ingredient for skin treatment formulas.  相似文献   

3.
To examine the effects of soil fertility on biomass production, plant species diversity, and early vegetation development, we performed a mesocosm experiment using soil seed bank under three soil fertility levels (ombrotrophic, mesotrophic, and eutrophic). Biomass production linearly increased (P < 0.01), whereas plant species diversity significantly decreased (P < 0.001) as soil fertility increased. Soil fertility seemed to play a role as an environmental sieve in early vegetation development, in turn, lead the patterns of biomass production and plant species diversity. Several Poaceae species which are forming tall and dense canopy, such as Phalaris arundinacea, Miscanthus sacchariflorus, and Zizania latifolia, showed higher importance values under fertilized condition, whereas relatively small macrophytes of Eleocharis acicularis, Carex dickinsii, and Isachne globosa mainly survived under ombrotrophic condition. Although plant species richness decreased as soil fertility increased, the percentages of perennials and exotics increased rather than annuals and natives. Predominance of perennials and exotics under eutrophic condition in early vegetation development seemed to lead a continuous decrease in plant species diversity as a result of competitive effect. A significant negative relationship between plant species diversity and biomass production (P < 0.0001) was obtained when all experimental plots are included in correlation analysis.  相似文献   

4.
While hybridization between Native and Introduced Phragmites australis has not been documented across much of North America, it poses an ongoing threat to Native P. australis across its range. This is especially true for native populations in the biologically rich, but sparsely distributed wetlands of the southwest United States, which are among the most imperiled systems in North America. We identified multiple Hybrid P. australis stands in the Las Vegas Wash watershed, NV, a key regional link to the Colorado River basin. Rapid urbanization in this watershed has caused striking changes in water and nutrient inputs and the distribution of wetland habitats has also changed, with urban wetlands expanding but an overall reduction in wetland habitats regionally. Native P. australis has likely been present in the Wash wetland community in low abundance for thousands of years, but today Hybrid and Native plants dominate the shoreline along much of the Wash. In contrast, Introduced P. australis is rare, suggesting that opportunities for novel hybridization events remain uncommon. Hybrid crosses derived from both the native and introduced maternal lineages are widespread, although the conditions that precluded their establishment are unknown and we did not find evidence for backcrossing. Spread of Hybrid plants is likely associated with flooding events as well as restoration activities, including revegetation efforts and construction for erosion control, that have redistributed sediments containing P. australis rhizomes. Downstream escape of Hybrid plants to Lake Mead and wetlands throughout the lower Colorado River basin is of management concern as these Hybrids appear vigorous and could spread rapidly.  相似文献   

5.
Seedlings’ successful establishment is of importance in the preemption process of pioneers in wetlands. Although Typha orientalis Presl has been reported as a pioneer in Asia countries, studies on the seedling phase of T. orientalis are not available yet. A mesocosm experiment was conducted to understand the effects of biotic (initial density) and abiotic (nutrient and water level regime) factors on the seedling survival and growth of T. orientalis. Most seedlings survived under low initial density (93.8%) and eutrophic (95.5%) rather than high initial density (64.3%) and ombrotrophic (62.5%). Seedlings under low initial density, eutrophic, and flooded conditions showed relatively higher growth in shoot height. The final number of ramets showed an adverse tendency compared to the survival rate and shoot height particularly depending on the water level regime. T. orientalis compensated its biomass production with producing less but longer shoots under the flooded condition, indicating the phenotypic plasticity of T. orientalis as a deep water species. However, the compensation seemed to be guaranteed only under the condition of sufficient nutrients. Asian T. orientalis seemed not to be a pioneer but a weak-competitor not only in mature plant stage but also in juvenile seedling stage unless sufficient nutrients are guaranteed.  相似文献   

6.
In cleared landscapes, wetlands can represent important reservoirs of native plant diversity, which include terrestrial species. Depending on study aims, non-wetland plants might be removed before analysis, affecting conclusions around biodiversity and community structure. We compared the native plant communities of seasonal wetlands in a predominately agricultural landscape as defined geographically (including all species) with that of the obligate wetland assemblage. We were primarily concerned with determining how this design decision affects ecological and conservation conclusions. We analysed a survey database containing >12,900 flora records from South Australia, developing a new area-based method to remove sampling bias to include only wetlands with a near-complete census. We modelled occupancy, species-area relationships, β-diversity and nestedness under our contrasting community definitions. Terrestrial species were 57.4 % of total richness. Removing these species reduced wetland α-diversity by 45 %, but did not affect the scaling of richness with area (power-law species-area relationship z = 0.21 ± 0.01). Occupancies for wetland plants were relatively uniform, but were heavily dominated by rare (satellite) species when terrestrial plants were included, and this also increased β-diversity. Nestedness for terrestrial species occupancies was marginally lower than predicted under null models, suggesting that rare species often do not co-occur with common species. An implication of these occupancy patterns is that twice as many wetlands (and 50 % more wetland area) would be needed to include every native species within at least one wetland compared with wetland-only species.  相似文献   

7.
This study investigated vegetation and soil properties in a beaver-created freshwater wetland located on the Coastal Plain of Virginia near Washington, DC. We focused on the associations among floristic quality, soil physicochemistry, denitrification, and hydrologic conditions of the wetland to understand links between the effects of beaver engineering and ecosystem function. The floristic quality assessment index (FQI) and denitrification are two important indicators often used to examine overall habitat quality and ecosystem functioning of a wetland. Samples were collected from ten plots (10 m × 10 m each) in August 2014. Vegetation attributes included total percent cover, species richness (S), diversity, FQI, and prevalence index (PI). Soil attributes included organic matter (OM), total carbon, total nitrogen, gravimetric moisture (GM), pH, bulk density (Db), and denitrification potential (DP). FQI was greater in the higher of the two standing water level categories, where Db was lower, and was negatively associated with Db but no other soil nutrient properties. DP was positively associated with soil nutrients, OM, and GM, but not with measured vegetation attributes nor standing water levels. We found higher soil GM, lower plant community PI, and lower plot S in this study compared to our previous study, with no changes to other vegetation or soil attributes, indicating enduring beaver activity and a resilient plant community. The outcome of the study includes regression models that best explain the association between structural and functional attributes of the ecosystem, which can be applicable to the study of other beaver-created wetlands. The study also provides partial evidence for the notion that low-lying areas dug out by beaver positively impact the FQI of wetlands.  相似文献   

8.
Overabundant growth of emergent lacustrine plants can cause biodiversity, ecosystem service and economic loss. The two-basined Wuchang Lake is a typical small shallow lake within the Yangtze River floodplain. Expansion of the emergent macrophyte Zizania latifolia at Wuchang Lower Lake (to 49 km2 in area, c. 87.0% of Lower Lake) has increasingly denied the local community open water for fishing since the 1980s. To better understand the causes of these changes and potential remediation, we used annual Landsat imagery from 1975 to 2012 to determine the patterns of expansion between years as well as the effects of water levels in different seasons and trophic status on the annual extent of macrophytes in the Lower Lake. These analyses showed that: (1) Z. latifolia progressively covered the Lower Lake, while remaining confined to one inlet in the Upper Lake; (2) despite the generally increasing trend, there were obvious annual variations in area of Z. latifolia; (3) variation of water level in spring contributed to between-year variation in area and was significantly negatively correlated with expansion in Z. latifolia. Based on these results, to reduce the expansion in Z. latifolia, we recommend maintaining spring Lower Lake water levels above at least at 11.6 m and better at 12 m, cutting shoots in June and July, with subsequent shoot removal in autumn.  相似文献   

9.
Zizania latifolia is a common emergent macrophyte that plays an important role in the ecological restoration of lakes in the middle and lower reaches of the Yangtze River basin. To understand the mechanisms behind the relative changes in the distribution of Z. latifolia in the field, we analyzed the effects of water depth and substrate type on rhizome bud sprouting (RBS) and growth in Z. latifolia through simulation experiments. Four water depths (0, 30, 60, and 90 cm) and three substrate types (sandy loam, clay loam, and silt) were used. The results showed that: (1) water depth significantly affected the RBS, and the RBS percentage significantly decreased with increasing water depth. However, substrate type and its interaction with water depth had no effect on RBS. (2) Two-way analysis of variance (ANOVA) showed that plant height, stem diameter, and root length were significantly affected by water depth, with the highest values observed at a water depth of 0 cm. Only root length was significantly affected by substrate type and its interaction with water depth, and it was highest in silt. (3) Both water depth and its interaction with substrate type had significant effects on total biomass and the root:shoot ratio in Z. latifolia, but no significant effect was found when it came to subtrate type. The results of this study will be useful for the ecological restoration of lakes in the middle and lower reaches of the Yangtze River basin.  相似文献   

10.
Three of the five European species of Branchinecta have a disjunct distribution. In this study, we analyze populations of B. ferox and B. orientalis for mitochondrial (cox1) and nuclear (ITS2) molecular markers. We compare intraspecific genetic divergences between geographically distant populations of B. orientalis, from its only known Spanish population (originally described as B. cervantesi) and from a Hungarian population (assigned to B. orientalis since its discovery), with data from two relatively close Iberian populations of B. ferox. Results indicate that isolation between B. ferox and B. orientalis clades is ancient, and that the clade including the two Iberian populations of B. ferox is geographically structured. Conversely, Iberian and Hungarian populations of B. orientalis do not show geographical structure for the mitochondrial fragment. Lack of geographic structure coupled with very low genetic distances indicates that current Iberian and Hungarian populations of B. orientalis originated from a common population stock, and that the time elapsed since their separation has not been long enough to render the clades reciprocally monophyletic. We hypothesize that colonization of the Iberian Peninsula by B. orientalis is probably the consequence of a single recent dispersal event, and consequently we confirm the synonymy between B. cervantesi and B. orientalis.  相似文献   

11.
We assessed the effect of long-term (11 years) mowing with a hand scythe on the distributions of plant species and species turnover within meadow communities dominated by Carex acutiformis and C. acuta in a small lowland river valley subjected to annual flooding. We hypothesized that mowing would trigger the process of species exchange toward multispecies communities according to the abiotic environmental gradients, as has been reported for traditionally used wet meadows. We found that mowing had a much greater impact on the increase in plant species abundance in wetter, subjected to deeper and longer flooding, zone of the valley than in its drier part. The treatment and hydrology had no substantial effect on the sedges and cryptogams while the graminoids and the forbs were the least stable components of the plant communities. We found that annual management was conducive to the appearance of numerous seedlings of Alnus glutinosa in the part of wetland situated close to the valley edge. Surface flooding was found to be a driving force modifying the impact of mowing on sedge meadows. This “hydrological resetting impulse” created a specific floristic reset of the community, bringing it to the more simplified forms. Mowing every 4–5 years at the beginning of August is advisable to protect sedge meadows distributed in flooded small lowland river valleys.  相似文献   

12.
Creeping bentgrass (Agrostis stolonifera) and redtop (A. gigantea) are introduced turfgrasses that are naturalized throughout the northern U.S. Interest in creeping bentgrass has risen following the 2003 escape of a genetically modified (GM), herbicide-resistant cultivar near Madras, Oregon. The objectives of this study were to characterize the floristic attributes of the plant communities associated with naturalized Agrostis populations in the Madras area, and to identify plant communities at risk of invasion by transgenic Agrostis. Vegetation data collected from 62 stratified random vegetation plots with and without A. stolonifera and A. gigantea identified 11 distinct plant communities. Community composition was strongly correlated with an indirect soil moisture index based on the wetland status of individual species. Results indicate that wetland plant communities are at the highest risk of invasion by transgenic A. stolonifera. Also, inter-specific gene flow to A. gigantea could affect additional habitats and plant communities where A. stolonifera is not found. Both A. stolonifera and A. gigantea were invasive in wetland and riparian settings in the Madras study area, and introducing glyphosate (e.g., Roundup®, Rodeo®) herbicide tolerance into these populations would eliminate the primary means of control for these species.  相似文献   

13.
The goal of this study is to examine the suitability of three plants, Typha spp., Phragmites spp. and Iris pseudacorus, in a free-water surface constructed wetland created to treat eutrophic water from Lake Albufera (Valencia, Spain), a wetland of international importance. The growth, coverage and nutrient content of the three plants were studied, and chemical analyses were performed according to standard methods. The maximum standing crops measured for each plant were 1.9, 18.2 and 3.3 kg m?2, respectively, and their average nutrient concentrations were 2.1, 1.2 and 1.7 g P kg?1 and 12.1, 11.7 and 10.1 g N kg?1, respectively. A multiple harvest of Iris pseudacorus revealed that the removal of nutrients could be increased up to 50% for N and 100% for P compared with a single harvest. Biomass decomposition assays showed high values for five-day biochemical oxygen demand (115–207 mg O2 g?1, depending on the plant and its age) and a substantial release of phosphorus, up to 100% of that contained in the biomass, highlighting the need to remove the litter fall. This study provides key aspects for vegetation selection and management (planting and harvesting) in a novel application of constructed wetlands to enhance water quality and biodiversity.  相似文献   

14.
There is still not enough palaeoecological data from the southwestern part of the Western Carpathians, where mountain ridges steeply rise from the dry and warm Pannonian basin. The reason is a low availability of sites with sediments harbouring fossil remains. In the Pova?ský Inovec Mts, two small protected calcareous wetlands occur in different geographical position and contain suitable sediments. One represents a foothill site (initiated ca 13,000 cal. BP) whereas the other a low-mountain site (initiated ca 7,400 cal. BP). We investigated fossil pollen, spores, and macroscopic remains of plants and molluscs from their sediments. We further reviewed archaeological data, constructed a macrophysical climate model (MCM) and confronted it with other palaeoclimatic proxies. Temperate deciduous trees (Quercus, Corylus and Ulmus) occurred since the Allerød, but their expansion was blocked by a harsh climate in Younger Dryas, when Larix, Pinus and Betula nana still occurred. The climate firstly moistened at ca 9,500 cal. BP and more distinctly at ca 8,500 cal. BP, which was reflected by a strong calcium carbonate precipitation and expansion of Tilia cordata t., Hedera helix, and Ustulina. Although the MCM predicted a rather stable climate since 8,000 cal. BP, certain changes in aquatic mollusc abundances may indicate hydrological fluctuations, as they are paralleled by changes in climate humidity indicated by other evidence from the Western Carpathians. Younger hydrological fluctuations may be alternatively explained by human activities as they correspond with macro-charcoal abundance and indicators of wetland openness. During their existence, both fens harboured only few fen plant and mollusc species specialized to low-productive sedge-moss fens. In the Middle Holocene both sites were encroached by woody plants (Alnus, Picea and Salix), as most other spring fens in the Western Carpathians. Contrary to some other spring fens with similar site conditions in the Western Carpathians, few fen specialists established in the study sites since deforestation, presumably because of severe disturbances caused by grazing and/or hemp retting instead of the usual mowing.  相似文献   

15.
The aim of this work was to investigate the effect of silicon (Si) on phenolic exudation of plant roots and cadmium (Cd) bioavailability in rhizospheres. For this purpose, pot experiments with two cypress varieties, Juniperus chinensis and Platycladus orientalis, each subjected to 100 mg kg?1 Cd and/or 400 mg kg?1 Si for 220 days, were conducted using a rhizobag technique. The results showed that P. orientalis accumulated a higher amount of Cd, hence caused higher growth inhibition on the leaves compared with J. chinensis. Si alleviated the growth inhibition induced by Cd toxicity on both varieties, but the mechanisms involved were species specific. For J. chinensis, Si did not affect the root exudation but enhanced the Cd retention of the roots by strengthening the exodermis tissues, restraining Cd translocation from the roots to the shoots. For P. orientalis, Si exposure significantly elevated the phenolic exudation (for example, ferulic acid, catechin, and gallic acid) of the roots, which caused greater Cd mobility in the rhizosphere and enhancement of Cd accumulation in the shoots compared with Cd treatment alone. These results suggest that Cd-chelating with the Si-induced phenolics in the rhizosphere is involved in the Cd detoxification in P. orientalis.  相似文献   

16.
Indicator species provide an easy and quick method of evaluating ecosystems. The species comprising the most useful indicators of wetlands should be distributed across a range of water depths and inundation durations, while each species is representative of a specific condition. Hydrophytic vegetation is commonly used to determine the existence and type of wetland; however, such indicator systems often depend on assigning species qualitatively to discrete categories based on assumptions about their distribution along a gradient of conditions. The current study proposes a wetland indicator system based on the quantitative responses of individual vegetation species to a gradient of water depths and periods of inundation. A long-term database was utilized to determine species responses to hydrological alterations in a series of wetlands. The hydrophytic plant species investigated (n = 29) displayed relatively narrow ranges of mean hydrologic values and were distributed linearly along multiple hydrologic gradients (hydroperiod, average water depth, and maximum water depth) ranging from Amphicarpum muhlenbergianum which was observed at the shallowest water depths and shortest hydroperiod to Pontederia cordata and Ludwigia repens which were characteristic of wetlands with the deepest water and longest hydroperiod. The species distribution and means along the hydrologic gradients tested indicates they are prime candidates for inclusion in a quantitative or continuum indicator system. The historical database utilized for this study provided valuable information for numerous species common to the Tampa Bay region for which little or no ecological information was previously available. The methodology utilized in this paper provides a cost and time effective method for obtaining the vast amounts of information required to refine plant indicator systems using a large number of species.  相似文献   

17.

Background

Phylogeographic analyses on the Western Euroasiatic Fagus taxa (F. orientalis, F. sylvatica, F. taurica and F. moesiaca) is available, however, the subdivision of Fagus spp. is unresolved and there is no consensus on the phylogeny and on the identification (both with morphological than molecular markers) of Fagus Eurasiatic taxa.For the first time molecular analyses of ancient pollen, dated at least 45,000 years ago, were used in combination with the phylogeny analysis on current species, to identify the Fagus spp. present during the Last Interglacial period in Italy.In this work we aim at testing if the trn L-trn F chloroplast DNA (cpDNA) region, that has been previously proved efficient in discriminating different Quercus taxa, can be employed in distinguishing the Fagus species and in identifying the ancient pollen.

Results

86 populations from 4 Western Euroasistic taxa were sampled, and sequenced for the trn L-trn F region to verify the efficiency of this cpDNA region in identifying the Fagus spp.. Furthermore, Fagus crenata (2 populations), Fagus grandifolia (2 populations), Fagus japonica, Fagus hayatae, Quercus species and Castanea species were analysed to better resolve the phylogenetic inference.Our results show that this cpDNA region harbour some informative sites that allow to infer relationships among the species within the Fagaceae family. In particular, few specific and fixed mutations were able to discriminate and identify all the different Fagus species.Considering a short fragment of 176 base pairs within the trn L intron, 2 transversions were found able in distinguishing the F. orientalis complex taxa (F. orientalis, F. taurica and F. moesiaca) from the remaining Fagus spp. (F. sylvatica, F. japonica, F. hayataea, F. crenata and F. grandifolia). This permits to analyse this fragment also in ancient samples, where DNA is usually highly degraded.The sequences data indicate that the DNA recovered from ancient pollen belongs to the F. orientalis complex since it displays the informative sites characteristic of this complex.

Conclusion

The ancient DNA sequences demonstrate for the first time that, in contrast to current knowledge based on palynological and macrofossil data, the F. orientalis complex was already present during the Tyrrhenian period in what is now the Venice lagoon (Italy).This is a new and important insight considering that nowadays West Europe is not the natural area of Fagus orientalis complex, and up to now nobody has hypothesized the presence during the Last Interglacial period of F. orientalis complex in Italy.
  相似文献   

18.
Y. Yang  C. Li 《Photosynthetica》2016,54(1):120-129
To uncover adaptation capacities of two flooding-tolerant plant species, Pterocarya stenoptera (a native species) and Pinus elliottii (an exotic species from southeastern USA), to alternating submergence and drought, we investigated their physiological and growth responses to water stress. Water treatments, including control, continuous flooding (CF), and periodic flooding and drought (PF), were applied to seedlings in order to simulate water level fluctuation in the hydrofluctuation zone of the Three Gorges Reservoir Region. Results showed that net photosynthetic rate (PN), stomatal conductance, and intrinsic water-use efficiency of both plant species were negatively affected under CF and PF compared with the corresponding controls. The PN of both species under PF was comparable to that under CF. At the end of the experiment, the ratio of intercellular to ambient CO2 concentration was not statistically different between water treatments, while that of P. elliottii was significantly higher than that of P. stenoptera. Although P. stenoptera formed lenticels under flooding conditions, P. elliottii seedlings allocated more mass to leaves and increased the relative growth rate of height to enhance the photosynthetic efficiency. Our results illustrated that P. stenoptera and P. elliottii seedlings developed different adaptive strategies in response to flooding, both CF and PF. Therefore, both P. stenoptera and P. elliottii are promising candidates for the vegetation reconstruction of the riparian zones in the Three Gorges Reservoir Region.  相似文献   

19.
Invasion biology research, often performed by scientists at relatively small spatial scales, provides experimental precision but may be limited in generalizability. Conversely, large-scale invasive species management represents a largely untapped wealth of information on invasion ecology and management, but such data are difficult to capture and synthesize. We developed a network (“PhragNet”) of individuals managing wetlands occupied by native and non-native lineages of the invasive wetland grass Phragmites australis (common reed). This network collected environmental and genetic samples, habitat data, and management information to identify environmental and plant community associations of Phragmites invasion and patterns of management responses. Fifty managers overseeing 209 Phragmites stands in 16 US states and ON, Canada participated. Participants represented federal agencies (26%), municipalities (20%), NGOs (20%), academia (14%), state agencies (12%), and private landowners (8%). Relative to the native lineage, non-native Phragmites occurred in areas with higher nitrate/nitrite and ammonium than non-native Phragmites. Stand interiors had higher soil electrical conductivity than nearby uninvaded areas, consistent with use of road salt promoting spread of Phragmites. Non-native Phragmites co-occurred with fewer plant species than native Phragmites and was actively targeted for management. Herbicide was applied to 51% of non-native stands; surprisingly, 11% of native stands were also treated with herbicide. This project demonstrates the utility of crowdsourcing standardized data from resource managers. We conclude by describing how this approach could be expanded into an adaptive management framework, strengthening connections between wetland management and research.  相似文献   

20.
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