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1.
The structure of the ichthyofauna in water bodies of Kaluga oblast has undergone significant rearrangements over the past 20 years. The abundance of some species has increased, while that of other species has decreased; spontaneous dispersal of some fishes is underway. Synchronous fluctuations of fish abundance (“waves of life”) take place simultaneously in the Western Dvina, Dnieper, and Volga basins. These processes differ in intensity depending on fish species and are conditioned by a number of factors, including changes in hydrological regimes of rivers, improvement of the ecological state of small rivers, and increased poaching pressure. The results of monitoring the ichthyofauna fauna of small rivers are used as an example to trace the routes of fish dispersal and discuss changes in the composition of fish communities.  相似文献   

2.
To better understand how Batrachupems tibetanus responds to different temperature regimes in the blood parameters and to estimate the change in plasma cortisol level in this species exposed to different temperatures, the animals were stochastically divided into three groups and exposed respectively to 4.6°C, 14.6°C and 19.6°C for 12 days. The concentrations of glucose, total protein, albumin, triacylglycerol, Ca2+, K+, Na+, Cl, and plasma cortisol level were measured respectively. There was no significant difference between the plasma cortisol level of the control group and the experiment groups. Glucose level at 4.6°C and 19.6°C was significantly lower than glucose level at 14.6°C. The plasma triacylglycerol level was significantly influenced by acclimation temperature. The concentration of total protein, albumin, globulin and the ratio between albumin and globulin were not significantly influenced by temperature when compared with control group. There was no significant change in concentration of Ca2+ at different temperatures. The concentration of K+ was significantly influenced by temperature. Plasma K+ level significantly increased at 19.6°C. The plasma Na+ level and Cl were significantly influenced by temperature. Na+: Cl ratio was significantly influenced by temperature. Therefore, glucose, triacylglycerol, Na+ and Cl levels could be considered as indicators of thermal stress in B. tibetanus; plasma cortisol, albumin, globulin levels, and albumin/globulin ratio are not influenced by temperature.  相似文献   

3.
Some specific features of the distribution of resident Chiroptera (10 forms) in the eastern East European Plain and adjacent areas (44°–65° N, 40°–60° E) are described. It is noted that in different seasons of the year,Myotis dasycneme, M. daubentonii, M. nattereri, M. mystacinus, M. brandtii, Plecotus auritus, Eptesicus nilssoni, andE. serotinus serotinus are found more often in upland areas with karst and other erosional forms of relief, whereasE. serotinus turcomanus andPipistrellus kuhlii display no preference for these types of relief.  相似文献   

4.
We compared differences in plant species diversity between conifer (Pinus tabulaeformis) plantations and natural secondary forests in the middle of the Loess plateau. The goal of the study was to examine the differences in the effect of stand development on species diversity and in species responses to changes between forest types and between forest layers. To clarify the effects of differences in forest management, we emphasized the functional types of plant species occurring in each forest type. The result as follow: (1) The H′ and S of tree layer were significantly lower in natural conifer forest than old conifer and secondary forest, but were not different compared with mid aged conifer forest. The H′ and S of shrub layer were significantly lower in mid aged conifer forest compared with other forest types. The H′ of herb layer showed no significant differences in the four forest types. The evenness index (J′) of tree layer of mid aged conifer forest was lower than other forest communities and its J′ of shrub layer was highest although its richness of shrub layer was lower than in the other forest types. (2) The analysis of β diversity index also indicated large differences between conifer plantations and natural forests. Although the tree layer species were similar in old plantation and natural conifer forests, they differed greatly between the natural conifer and secondary forests. The natural conifer and secondary forest species composition in shrub layer differed significantly from those in plantation and secondary plots. Tree species were significantly less common in plantations than in abandoned coppice forests. Species composition in the herb layer of different forest types was similar. (3) The management of P. tabulaeformis plantations alters plant species composition considerably; the number of sub tall-tree species is increased in old aged conifer forest, especially species dispersed by animals. Plantation management appears to affect ecological processes through seed dispersal. From the perspective of management, the change in the structure and composition of the canopy in plantations could affect the behavior of dispersers and regeneration.  相似文献   

5.
This study presents a reconstruction of the fire activity of the last ~14,200 cal. years BP (before AD 1950) from Gooches Crater Right, located on the Newnes Plateau, approximately 150 km to the west of Sydney (~33°27′S, 150°16′E) within the Blue Mountains National Park. Charcoal analysis and palynology were undertaken with the aim of untangling any inter-relationship between climate, humans and fire. A chronology of the site was provided by radiocarbon dating. The dominant control on fire in this environment during the Holocene appears to be climate. Periods of climate change, identified in previous studies, are associated with higher levels of fire activity. Fire was less ubiquitous between ~9,000 and 6,000 years BP, a period normally described as having a higher effective moisture in south-eastern Australia. The mid-Holocene fluctuations in charcoal may reflect anthropogenic fire, climate forcing or alternatively human responses to any climate change. Coeval changes in palaeoclimatic sequences elsewhere and palynology at the site support a climatic explanation or that Aboriginal people used fire within a climatic framework.  相似文献   

6.
Comparative allozyme analysis of 26 marginal island populations of Pinus sylvestris L. and 20 populations from the center of the species range has confirmed, at the species level, the Wright-Dubinin “island model” of automatic genetic processes and Mayr’s hypothesis about homozygotization of small isolated populations at range boundaries. It has been shown that the polymorphism of isolated populations sharply decreases when their area is reduced below 15–20 km2 and increases to the level observed in the center of the range when the population area exceeds 50–100 km2. A chorogenetic classification of marginal P. sylvestris populations is proposed.  相似文献   

7.
The structure of the long-eared owl (Asio otus L.) settlements in anthropogenic landscapes has been studied in the Zhuravlinaya Rodina protected territory in the northern Moscow region in 2001–2005. The possible factors that cause the formation of such settlements have been analyzed. The differences in the breeding success between owls nesting near and away from human settlements have been estimated. Aggregated nesting of owls is assumed to be mainly related to a lower predator pressure in the vicinity of human dwellings in the incubation period. Aggregated nesting is regarded as an expression of synanthropization of the species.  相似文献   

8.
9.
Objectives and methods of mapping the ecological state of the plant cover at different spatial levels—federal, regional, and local—are analyzed. The maps used as examples are as follows: at the federal level, “Ecological State of Rangelands in Russia” (1:10 000 000); at the regional level, “Vegetation of Moscow Oblast” (1:200 000); and at the local level, “Vegetation of Narofominskii Raion” and “Current State of the Plant Cover in Narofominskii Raion” (1:50 000).  相似文献   

10.
Possible climate change will modify snow-cover depth and change the characteristics of winter tourism and skiing districts. Our model describes seasonal snow-cover depth related to altitude in six Alpine climate regions as the best fit of all snow stations. Data cover 30 winter seasons (November to April values) from 1965 to 1995. We modified the data according to a scenario of temperature and precipitation change (2 °C warming, no precipitation change) and achieve a new simulated snow-cover depth. The indicators MARP (mean altitude of resident population) and MASPSL (mean altitude of starting point of ski lifts) serve as references for “critical altitudes” of Austrian districts. A warming implies a reduction of snow in all districts, but the loss is overproportional in lower altitudes. The direction of economic impacts is clear – income losses and adaptation costs – but magnitude and time frames remain uncertain. Received: 24 February 1999 · Accepted: 15 May 1999  相似文献   

11.
Analysis of organic contaminants is reported for the Oluyoro stream located in the South-Western Nigeria. Using gas chromatography methods with flame ionization, electron capture and mass spectrometer detectors, alarming levels of organic pollutants including alkanes, alkenes, alcohols and alkyl halides were detected. Remarkably, toxic halogenated organic substances such as 4,4′-dichlorodiphenyltrichloroethane (4,4′-DDT), 4,4′-dichlorodiphenyldichloroethane (4,4′-DDD), beta-benzenehexachloride (beta-BHC), heptachlor epoxide, endrin aldehyde and endrin ketone are found to be at 15,820, 6,176, 1,155, 336, 24 and 13 times, respectively, more than the permitted levels of the United States Environmental Protection Agency (US-EPA). Furthermore, 4,4′-DDD, a probable human carcinogen, and methoxychlor are detected for the first time when compared to the last report published in 1992. Activities such as high influx of domestic and industrial wastes to the stream have drastically increased the concentrations of these halogenated contaminants. Results presented in this article provide important information for potential future effects of these contaminants on human health and the integrated environment in the region.  相似文献   

12.
Study of ecological adaptations, including torpor, related to survival through the adverse conditions of the autumn-winter season is important for both the estimation of the body reserves in mammals in general and the search for the ways to increase the cold-stress resistance in humans. The changes in the body temperature during the period from October to May were studied in hamsters of six species under the natural photoperiod and temperature conditions. Incidental winter torpor (a drastically decreased physiological activity) was detected in all species except Cricetulus griseus; in three of them, it had not been observed before. No specific combination of conditions causing torpor was identified. Apparently, it is determined by individual characteristics of the animal. Torpors were the most frequent in January, at temperatures from −15 to −5°C; their depth was positively correlated with the ambient temperature. Since torpor is a rare event, it is assumed to be a stored resource of the body allowing animal to save energy and occurring only in extreme situations.  相似文献   

13.
VALUING ECOSYSTEM SERVICES OF CHILEAN TEMPERATE RAINFORESTS   总被引:1,自引:0,他引:1  
The Valdivian Rainforest Ecoregion (35°–48° S) in southern South America is among the ecosystems with highest conservation priority worldwide due to its rich diversity, degree of endemism, and critical conservation status. Temperate rainforests in this vast area are essential as source of biological resources and to maintain different ecosystem services which remain largely unmeasured and unvalued. Consequently, the benefits they provide are not reflected in decision-making regarding forest management and conservation. Based on existing studies and results from ongoing research we describe selected ecosystem services and provide estimates of their economic value. Timber benefits for secondary forests expressed as net present stumpage values were US$ 3742 ha−1 and US$ 3093 ha−1 for sustainable forest management (SFM) and unsustainable harvesting, respectively. Timber benefits for old growth forests␣equaled US$ 4546 ha−1 and US$ 5718 ha−1, for SFM and unsustainable harvesting, respectively, using an 8% discount rate. Annual benefits from recreation were US$ 1.6 ha−1 and US$ 6.3 ha−1 for the two most important national parks located in the study area. The annual value of maintaining soil fertility was US$ 26.3 ha−1 using the replacement cost of nutrient losses due to soil erosion. The annual economic value of water supply for human consumption using the production function method was US$ 235 ha−1. These results provide valuable information on the kind and magnitude of values that could be relevant in decision-making concerning conservation and management of native forests in the Valdivian Rainforest Ecoregion.  相似文献   

14.
The alpine ecosystems in permafrost regions are extremely sensitive to climate change. The headwater regions of Yangtze River and Yellow River of the Qinghai-Tibet Plateau are on the permafrost area. Aerial photos of the Source Regions of the Yangtze and Yellow River taken in 1968 and three phases of TM images acquired from 1986, 2000, and 2008 were used to analyze the spatial alterations of the land cover and corresponding effects on the environment guided by landscape ecology theory. Firstly, land cover types were divided into three classes and 11 subclasses. Analysis results revealed the trends and magnitude of the eco-environmental changes in the regions over the past four decades and showed a continuous degradation of grasslands and the extension of desertification and salinization. Secondly, five landscape pattern indices (i.e., NP, MPS, PR, SHEI, CONTAG) commonly used in landscape ecological studies were calculated, and results showed that this region had become more centralized and diversified. Finally, the factors causing the degradation of alpine grasslands were analyzed. The regional climate exhibited a tendency toward significant warming and desiccation with the air temperature increased by 0.03 °C per year and relative stable precipitation over the last 40 years. And the temperature of permafrost in 0–20 cm soil layer obviously raised by 0.2–0.3 °C in the last 40 years. The combined effects of climate warming and permafrost variation were the major drivers for the changes of landscape in alpine ecosystems.  相似文献   

15.
Climate change projections have drawn attention to the risks of extreme heat and the importance of public health interventions to minimise the impact. The city of Perth, Western Australia, frequently experiences hot summer conditions, with recent summers showing above average temperatures. Daily maximum and minimum temperatures, mortality, emergency department (ED) presentations and hospital admissions data were acquired for Perth for the period 1994 to 2008. Using an observed/expected analysis, the temperature thresholds for mortality were estimated at 34–36 °C (maximum) and 20 °C (minimum). Generalised estimating equations (GEEs) were used to estimate the percentage increase in mortality and morbidity outcomes with a 10 °C increment in temperature, with adjustment for air pollutants. Effect estimates are reported as incidence rate ratios (IRRs). The health impact of heatwave days (three or more days of ≥ 35 °C) was also investigated. A 9.8% increase in daily mortality (IRR 1.098; 95%CI: 1.007–1.196) was associated with a 10 °C increase in maximum temperature above threshold. Total ED presentations increased by 4.4% (IRR 1.044; 95%CI: 1.033–1.054) and renal-related ED presentations by 10.2% (IRR 1.102; 95%CI: 1.071–1.135) per 10 °C increase in maximum temperature. Heatwave days were associated with increases in daily mortality and ED presentations, while total hospital admissions were decreased on heatwave days. Public health interventions will be increasingly important to minimise the adverse health impacts of hot weather in Perth, particularly if the recent trend of rising average temperatures and more hot days continues as projected.  相似文献   

16.
Badger setts in two model areas located in the middle taiga zone of Western Siberia have been studied in order to estimate the density of their distribution and the proportions of large, medium, and small setts. A comparative geographic analysis of the structure of setts within the badger geographic range has been performed. The results show that in the study area, regardless of its peripheral location, the density of setts is similar to that in the central parts of the range.  相似文献   

17.
Regional Siberian studies have already registered climate warming over the last several decades. We evaluated ongoing climate change in central Siberia between 1991 and 2010 and a baseline period, 1961–1990, and between 1991 and 2010 and Hadley 2020 climate change projections, represented by the moderate B1 and severe A2 scenarios. Our analysis showed that winters are already 2–3°C warmer in the north and 1–2°C warmer in the south by 2010. Summer temperatures increased by 1°C in the north and by 1–2°C in the south. Change in precipitation is more complicated, increasing on average 10% in middle latitudes and decreasing 10–20% in the south, promoting local drying in already dry landscapes. Hot spots of possible forest shifts are modeled using our Siberian bioclimatic vegetation model and mountain vegetation model with respect to climate anomalies observed pre-2010 and predicted 2020 Hadley scenarios. Forests are predicted to shift northwards along the central Siberian Plateau and upslope in both the northern and southern mountains. South of the central Siberian Plateau, steppe advancement is predicted that was previously non-existent north of 56°N latitude. South of 56°N, steppe expansion is predicted in the dry environments of Khakasiya and Tyva. In the southern mountains, it is predicted that the lower tree line will migrate upslope due to increased dryness in the intermontane Tyvan basins. The hot spots of vegetation change that are predicted by our models are confirmed by regional literature data.  相似文献   

18.
Chennai city the capital of Tamil Nadu is located in southeastern India. Its average population growth rate is 25% per decade, which recurrently alters the city’s land-cover particularly the receding green-cover distressed the city’s self-renewal capacity, in terms of groundwater recharge, pollution sequestration and microclimatic amelioration. This has been appraised by means of a GIS model. This model was developed using three sets of green-cover associated parameters, namely air quality amelioration, hydrological process regulation and microclimatic amelioration. The outcome confirms the difference in the city’s environmental performance between the 1997 and 2001. At some parts of the city, due to the green-cover change, the extent of modification was 38%, in terms of mean percent change in all three sets of parameters mentioned earlier. Through coefficient of correlation (r) method, relationship between green-cover change and environmental performance change are checked. It confirms positive relationship (r = 1) in all parts, except at few places.  相似文献   

19.

Even if climate change mitigation is successful, sea levels will keep rising. With subsidence, relative sea-level rise represents a long-term threat to low-lying deltas. A large part of coastal Bangladesh was analysed using the Delta Dynamic Integrated Emulator Model to determine changes in flood depth, area and population affected given sea-level rise equivalent to global mean temperature rises of 1.5, 2.0 and 3.0 °C with respect to pre-industrial for three ensemble members of a modified A1B scenario. Annual climate variability today (with approximately 1.0 °C of warming) is potentially more important, in terms of coastal impacts, than an additional 0.5 °C warming. In coastal Bangladesh, the average depth of flooding in protected areas is projected to double to between 0.07 and 0.09 m when temperatures are projected at 3.0 °C compared with 1.5 °C. In unprotected areas, the depth of flooding is projected to increase by approximately 50% to 0.21–0.27 m, whilst the average area inundated increases 2.5 times (from 5 to 13% of the region) in the same temperature frame. The greatest area of land flooded is projected in the central and north-east regions. In contrast, lower flood depths, less land area flooded and fewer people are projected in the poldered west of the region. Over multi-centennial timescales, climate change mitigation and controlled sedimentation to maintain relative delta height are key to a delta’s survival. With slow rates of sea-level rise, adaptation remains possible, but further support is required. Monitoring of sea-level rise and subsidence in deltas is recommended, together with improved datasets of elevation.

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20.
We tested separately the effect of two taxonomically related rotifers (B. patulus and B. macracanthus) on the population dynamics of another species (A. fissa) at low (0.5 ×10 6) and high food levels (1.5 × 106 cells/ml of Chlorella vulgaris) using different inoculation densities (0–100%). We also quantified the impact of A. fissa on the two brachionid species. Regardless of the presence of the competing species, an increase in the availability of food led to increase in the abundances of the three rotifers. The population growth of B. patulus, B. macracanthus, or A. fissa was affected negatively when cultured together with another species. An increase in the initial density of any one of the competing species became advantageous to maintain a certain population size. At a low algal food level, B. patulus was able to suppress A. fissa more strongly than B. macracanthus. On the other hand, at a high food level, B. macracanthus suppressed the population of A. fissa more strongly than B. patulus. Peak population densities for A. fissa varied from about 150 to 1000 ind./ml, depending on food density and the presence of competitors. The rate of population increase (r) of A. fissa, B. patulus, and B. macracanthus increased with an increase in food availability but decreased with increasing initial density of the competitor. Both Brachionus spp. experienced negative growth rates in the presence of A. fissa, especially at a high initial density of the latter. Published in Russian in Ekologiya, 2007, Vol. 38, No. 5, pp. 381–390. The article was submitted by the authors in English.  相似文献   

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