The Mediterranean evergreen vegetation of Sicily, comprised in the belt of the Quercetea ilicis, occupies a large part of the island. Human intervention (cutting, fire, pasture) has brought about a degradation of the natural vegetation. This study is based on our phytosociological research of the Quercetea ilicis belt on Sicily.
With the ‘habitat comparison’ method, the dynamical relations between the different vegetation units have been defined.
We distinguish the following stages, with reference to their vegetation structure:
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a herbaceous stage formed by steppic vegetation, preceded by various types of nitrophilous-ruderal vegetation on abandoned fields;
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a garrigue stage dominated by half-shrubs;
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a macquis stage with various distinct plant communities, four communities being important in regressive successions, and three in progressive ones;
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a woodland and shrub-woodland stage with three different substages: pre-existent forests, present woodlands, and woodlands which tend towards the final, stable stage of vegetation (potential natural vegetation).
The dynamic relationships both in progressive and regressive successions have been synthesized in a scheme. In this scheme we have shown the main stages of the vegetation in their dynamics and we have constructed different series of vegetation types in two altitudinal belts, which are determined by varying environmental conditions of today.
The results also show that in some cases the progressive series follow different pathways than the regressive series, and the final stage of the progressive series is different from the original vegetation.
相似文献In recent years the ichthyofauna of Lake Victoria, the world's largest tropical lake, has gone through dramatic changes. The population of Nile perch, a large predator which has been introduced into the lake by man, increased explosively at the expense of many haplochromine cichlid species. At the same time, numbers of a small cyprinid (dagaa) rose sharply.
Previously Pied Kingfishers on Lake Victoria fed mainly on haplochromines. Only the youngest nestlings depended on dagaa as primary food. The current diet of adult birds clearly reflects the changes which have occurred in the fish community. Pellet analysis reveals a shift towards a diet composed of almost 100% dagaa.
The change in prey species composition has increased the number of fish a kingfisher needs to catch daily in order to meet its energetic demands, because:
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(1)
the mean size of haplochromines is larger than that of dagaa;
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(2)
(2) the mean size of dagaa has decreased since the increase in Nile perch;
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(3)
(3) the weight of dagaa is lower than that of haplochromines of equal size;
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(4)
(4) mainly juvenile dagaa and adults in poor condition are accessible to kingfishers.
Increasing numbers of elective surgical procedures are performed as day-cases. The impact of ambulatory surgery on health-related quality of life in the recovery period has seldom been described.
MethodsWe assessed health-related quality of life in 143 adult outpatients scheduled for arthroscopic procedures of the knee and shoulder joints, laparoscopic cholecystectomy and inguinal hernia repair using the RAND 36-Item Health Survey preoperatively and one week after patients had returned to work or comparable normal daily routines.
ResultsPostoperatively all patient groups reported significant improvements in bodily pain and vitality. Physical functioning improved significantly in orthopedic and inguinal hernia patients. However, in the orthopedic groups, postoperative scores for physical health were still relatively lower compared to the general population reference values.
ConclusionsAmbulatory surgery has a positive impact on health-related quality of life. Assessment of the recovery process is necessary for recognition of potential areas of improvement in care and postoperative rehabilitation.
相似文献P32 was, in most part, actively accumulated into leaf disks with time and was incorporated into ATP and other organic phosphates. DNBP inhibited both P32 accumulation and ATP generation. The amount of inhibition increased with time of incubation.
It is concluded that P32 accumulation is related to ATP generation. Even though DNBP greatly inhibits phosphorus accumulation, there is little or no effect on its retention.
DNBP has the ability to uncouple oxidative phosphorylation. Therefore, it is assumed that its inhibitory effect on phosphate accumulation and generation of high-energy phosphorus esters is related to its inhibition of oxidative phosphorylation.
A method is described which appears to be satisfactory to determine the relative amounts of ATP and ADP in leaf disks labeled with P32.
相似文献The paper presents results from plot experiments aimed at the development of an ecological strategy for soil contaminated with mercury. Meadow grass (Poa pratensis) was tested on mercury contaminated soil in a former chlor-alkali plant (CAP) in southern Poland for its phytoremediation potential.
MethodsThe stabilisation potential of the plants was investigated on plots without additives and after the addition of granular sulphur. Biomass production, uptake and distribution of mercury by plants, as well as leachates and rhizosphere microorganisms were investigated, along with the growth and vitality of plants during one growing season.
ResultsThe analysed plants grew easily on mercury contaminated soil, accumulating lower amounts of mercury, especially in the roots, from soil with additive of granular sulphur (0.5 % w/w) and sustained a rich microbial population in the rhizosphere. After amendment application the reduction of Hg evaporation was observed.
ConclusionsThe obtained results demonstrate the potential of using Poa pratensis and sulphur for remediation of mercury contaminated soil and reduction of the Hg evaporation from soil. In the presented study, methods of Hg reduction on “hot spots” were proposed, with a special focus on environmental protection. This approach provides a simple remediation tool for large areas heavily contaminated with mercury.
相似文献Galectins—galactose-specific lectins are involved in various types of cell activities, including apoptosis, cell cycle regulation, inflammation and cell transformation. Galectins are implicated in prostate malignat transformation. It is not known yet if prostate glands with different grade of pathologies are expressing different galectins and if these galectins express different effects on the cell viability.
MethodsCytosolic galactose-spesific lectin fractions from prostate tissue with different diagnosis were purified by affinity chromatography and analyzed by electrophoresis in polyacrylamide gel electrophoresis with sodium dodecyl sulphate. The lectin effects in a source-dependent maner were studied on cell viability on peripheral lymphocytes by MTT reduction method and on apoptosis by flow cytometry method.
ResultsAffinity purified galactose-specific lectins fractions from normal and pathological tissue samples are characterized with different protein composition and they express different effects on cell viability and apoptosis.
ConclusionThe effects of cytosolic galactose-specific lectins depend on the source of lectin fraction (glandular tissue disease). We suppose that the released cytosolic galectins from prostatic high grade intraepithelial neoplasia and adenocarcinoma tissue could suppress the immune status of the host patients.
相似文献Since the 1970s, extensive croplands were converted to forest and pasture lands to control severe soil erosion on the Loess Plateau of China. We quantify the direct and indirect effects of vegetation restoration on runoff and sediment yield on hillslopes in the field to improve environmental governance.
MethodsAn artificial rainfall experiment at a rainfall intensity of 120 mm h−1 and a slope gradient of 22° were used to distinguish the effects of vegetation restoration on runoff and sediment yield.
ResultsCompared to the farmland slopes, vegetation restoration directly prolonged the time-to-runoff by 140%, reduced the runoff rate by 20%, and increased the soil infiltration capacity by 15%. Vegetation restoration indirectly delayed the time-to-runoff by 120%, reduced the runoff rate and sediment yield rate by 50% and 94%, respectively, and increased the soil infiltration capacity by 58% on the hillslopes with vegetation restoration.
ConclusionsThe direct effects of vegetation restoration on runoff and sediment yield were lower than its indirect impacts. Vegetation cover, decreases in soil bulk density, and increases in belowground root biomasses and > 0.25 mm aggregate stability were the primary causes of runoff and sediment yield reduction on the slopes with vegetation restoration.
相似文献
Invertase activity per epicotyl increases relatively more rapidly than does length, reaches a maximum during most active elongation, and declines upon cessation of growth.
GA3 enhances both growth and increase in invertase activity, without altering the kinetics of the 2 processes. If GA3 is added during incubation invertase activity increases more rapidly than does elongation rate.
Incubation of the seedlings in solutions of polyethyleneglycol inhibits the increase of both growth and invertase activity, the latter actually undergoing a decline, but causes no great change in the relative effect of GA3. In presence of polyethyleneglycol GA3 has however a relatively greater effect on invertase activity than on growth.
Sugars in the incubation medium have no significant effect on growth and invertase activity in the epicotyl, except inhibition at relatively high concentrations.
Cycloheximide, actinomycin D, and 5-fluorodeoxyuridine (FUDR) inhibit both growth and the increase in invertase activity. Added during incubation cycloheximide causes complete inhibition of growth and a decrease in invertase activity with no appreciable lag phase. With actinomycin D and FUDR the inhibition occurs after lag periods of 2 to 3 and of at least 10 hours, respectively. Thus the increase in enzyme activity is very probably based on de-novo synthesis, and the enzyme is in a state of turnover during growth.
The enzyme is present in soluble form in the cytoplasm, not firmly bound to any cell structures.
相似文献Data on the variability of hyperaccumulation potential of the facultative serpentinophytes Noccaea kovatsii and N. praecox on different geological substrates are scarce. The aim of this study was to assess the accumulation potential of these two species from ultramafic and non-ultramafic substrates, with special emphasis on the hyperaccumulation of Ni, Zn and Cd.
MethodsSamples of plants and corresponding soils were collected from 16 sites covering a wide range of geochemistry. Elemental concentrations were determined in the roots, shoots and the rhizosphere soils. The pH, particle size distribution and content of organic matter were also determined in the soil samples.
ResultsAll ultramafic accessions of both species hyperaccumulated Ni with high intraspecific variability. Only one accession of N. kovatsii from a schist soil hyperaccumulated Zn, with also a high Cd accumulation. Accumulation and translocation of Ni in both species were much higher in the ultramafic accessions, whereas Zn accumulation and translocation was found in both ultramafic and non-ultramafic accessions.
ConclusionsNi accumulation and translocation was restricted to ultramafic populations of both species, whereas it is a species-wide trait for Zn. This study provides new and comprehensive information on the natural variation of hyperaccumulation of Ni, Zn and Cd in N. kovatsii and N. praecox.
相似文献Integrating aspects of larval lepidopteran behavior that enhance survival into conservation plans could increase the overall impact of the efforts. We previously recommended that where possible, maintaining 2–4 ramets of closely-spaced common milkweed would support the development of at least one monarch through pupation, based on a seemingly innate behavior in which monarch larvae (Danaus plexippus) abandon their natal milkweed ramet (Asclepias sp.). Here, we explored the impact of intraspecific competition on larval ramet abandonment behavior and fitness of monarch larvae in small artificial milkweed patches.
We observed larvae reared under direct and indirect intraspecific competition, and larvae reared alone.
We found no influence of intraspecific competition; however, our study provides further support that milkweed ramet abandonment is a seemingly innate behavior. This behavior occurs before all of the available leaf biomass on a ramet is consumed and prior to the pre-pupal wandering stage.
Implications for insect conservation: Results from our study suggest that in the absence of predation, parasitism, and interspecific competition, and when sufficient plant biomass is present to support larval development, the presence of an intraspecific competitor does not influence larval behavior or fitness. Based on milkweed ramet abandonment behavior, we continue to suggest maintaining small patches of 2–4 milkweed ramets when possible.
相似文献Dietary sugar and starch affect plasma glucose and insulin concentrations. Little information is available about the effect of dietary fibre on plasma glucose and insulin concentration. It is hypothesized that different dietary fibre compositions will alter post-prandial glycaemic- and insulinemic index of test meals. The objective was to measure postprandial glucose and insulin concentrations in horses fed meals of different fibre compositions.
MethodsBlood was drawn via jugular vein puncture and the glycaemic and insulinemic index were calculated.
ResultsThe meal effect on glycaemic and insulinemic response followed the expected pattern, where plasma concentrations increased after feeding and declined after peak concentration. Glycaemic index was 100 (H), 102 (OB), 102 (BB) and 106 (M) and did not differ significantly between meals. Insulinemic index was 100 (H), 140 (OB), 121 (BB) and 125 (M) and did not differ significantly between meals.
ConclusionsIn conclusion, meals containing different fibre compositions did not affect the glycaemic- and insulinemic index in horses.
相似文献Morphological and biochemical traits of four halophytes of the genus Limonium were analysed in plants sampled from salt marshes in SE Spain. This work aimed to explore the mechanism(s) behind the adaptation of these species to stressful habitats, with particular emphasis on responses to drought.
MethodsPlants of each species together with soil samples were collected in summer, which is the most stressful season in the Mediterranean. Soil parameters and plant morphological traits were determined, and the levels of several biochemical stress markers in plants were measured using spectrophotometric assays. A multivariate analysis was performed to correlate soil and plant data.
ResultsMorphological characteristics regarding the underground system topology and several biochemical traits (higher foliar Ca2+, sucrose and glucose, and lower proline, glycine-betaine and fructose) clearly separate L. santapolense individuals from plants of the other three species.
ConclusionsDrought tolerance of L. santapolense in the field is mostly dependent on morphological adaptations: when growing in an arid location, plants of this species develop long taproots that can extract water from the deep, moist layers of the soil.
相似文献Considering the general agreement in the literature that environmental labelling should be based on consequential modelling, while all actually implemented environmental labelling schemes are based on attributional modelling, we investigate the arguments for this situation as provided in the literature, and whether a dual label, representing on the same label the attributional and consequential results for the same product, can be a relevant solution or at least contribute to a more informed discussion.
MethodsWe developed a dual label for three hypothetical, comparable products and presented this for a small test audience, asking three questions, namely “Which product would you choose?”, “Was the attributional information useful?” and “Would you accept to have only the attributional information?”
Results and discussionFrom this small pilot exercise, it appears that informed consumers may have a strong preference for consequential information and that the main problem in communicating consequential results is that they are perceived as less trustworthy and more uncertain due to the fact that the consequences are located in the future. It thus appears important to build into a consequential label some increased level of guarantee of future good behaviour.
ConclusionsWe propose to apply the above questions to a more statistically representative audience to confirm or refute the findings of this little test exercise.
相似文献The biosphere is progressively subjected to a variety of pressures resulting from anthropogenic activities. Habitat conversion, resulting from anthropogenic land use, is considered the dominant factor driving terrestrial biodiversity loss. Hence, adequate modelling of land use impacts on biodiversity in decision-support tools, like life cycle assessment (LCA), is a priority. State-of-the-art life cycle impact assessment (LCIA) characterisation models for land use impacts on biodiversity translate natural habitat transformation and occupation into biodiversity impacts. However, the currently available models predominantly focus on total habitat loss and ignore the spatial configuration of the landscape. That is, habitat fragmentation effects are ignored in current LCIAs with the exception of one recently developed method.
MethodsHere, we review how habitat fragmentation may affect biodiversity. In addition, we investigate how land use impacts on biodiversity are currently modelled in LCIA and how missing fragmentation impacts can influence the LCIA model results. Finally, we discuss fragmentation literature to evaluate possible methods to include habitat fragmentation into advanced characterisation models.
Results and discussionWe found support in available ecological literature for the notion that habitat fragmentation is a relevant factor when assessing biodiversity loss. Moreover, there are models that capture fragmentation effects on biodiversity that have the potential to be incorporated into current LCIA characterisation models.
Conclusions and recommendationsTo enhance the credibility of LCA biodiversity assessments, we suggest that available fragmentation models are adapted, expanded and subsequently incorporated into advanced LCIA characterisation models and promote further efforts to capture the remaining fragmentation effects in LCIA characterisation models.
相似文献