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PubMedDate not supplied

[The simulation of 137Cs distribution in forest ecosystems and prediction of its accumulation by forest products].

A mathematical model of 137Cs migration in forest ecosystem is presented, which describes the behaviour of this radionuclide in the forest litter-soil system, trees, understory and forest animals. The model's parameters for different types of forest ecosystems are estimated and model's adequacy is tested through the use of independent experimental data. The sensitivity of the model's output variables is analyzed to variations in the most significant parameters. The differences in the seasonal and mean annual dynamics of 137Cs concentration in muscles of roe deers and mooses are shown to be defined by specific features of the diets of these animals and variations in 137Cs content in the main diet components.

Cesium Radioisotopes↗

PubMed2001

The state of the ecosystem on Anticosti Island, Québec.

The state of the ecosystem of Anticosti Island, Québec, was studied by veterinary students (n = 17) and faculty (n = 4) in the summer of 1999. The field of ecosystem health is an integrative science requiring the expertise of professionals in several disciplines, including socioeconomic, ecological, biophysical, human health, and animal health (1).

Animal Diseases↗

PubMed1999

Small artificial ecosystems: response to variation of environmental factors (CO2 enrichment).

Response of "wheat plants--rhizospheric microorganisms--artificial soil"--a simple terrestrial ecosystem--to carbon dioxide increased in its atmosphere to 0.06% has been studied. It has been experimentally demonstrated that a simple ecosystem develops and functions different from its individual elements (components), in this case "plants-artificial soil" without microorganisms. With mineral nutrition unlimited and CO2 enrichment the system is capable of binding (involving into turnover) 40% more carbon than the system without microorganisms. With material balance as the basis, this article evaluates the contribution of a system's elements into its development, namely, the contribution of the photosynthesizing component and the contribution of microorganisms.

Biomass↗

PubMed2000

[Wetland ecosystems formation and its protection in Yellow River Delta].

Site investigation, satellite photo analysis and historic material analysis show that the vast neonatal wetlands in Yellow River Delta were created by high concentration sediment of the river and the land-sea evolution. Affected by the regional climate, landform, geological deposition, soil, vegetation and their interactions, the wetlands covered 4.5 x 10(5) hm2, 6.84 x 10(4) hm2 of which were artificial wetlands. The wetland ecosystems changed with the waving of the Yellow River Mouth and the land development in the Delta area. From ocean to land, the sublittoral aquatic wetland, eulittoral wetland, eplittoral salt wetland, bulrush-quitch wetland, meadow wetland and land agroecosystem were developed. The wetland ecosystems had abundant biological resources, including 1524 wild animals, 300 birds and 1040 fishes, which were changed recently by the oil development and affected by the interruption of Yellow River. Wetland protection should be strengthened in resources utilization.

Conservation of Natural Resources↗

PubMed2000

[Forest ecosystem services and their ecological valuation--a case study of tropical forest in Jianfengling of Hainan Island].

This paper attempts to present forest ecosystem services and their indirect economic value of Jianfengling tropical forest in Hainan Island. The results show that average annual integrated ecosystem service value of Jianfengling tropical forest, which covers 44667.00 hm2, adds up to 664.38 million yuan(Chinese RMB), of which, about 71.64 million yuan is of the output of standing trees and other forest products, about 394.29 million yuan of water-holding, about 2.47 million yuan of soil conservation against erosion, about 13.16 million yuan of carbon fixation for reducing green house effect, about 4.29 million yuan of nutrient retention for N, P, K, Ca and Mg, about 178.53 million yuan of air purification.

Air↗

PubMed2001

Fundamental processes within natural and constructed wetland ecosystems: short-term versus long-term objectives.

Use of wetland ecosystems for water pollution control consists essentially of sustained induced disturbances as pollutants are loaded to complex biological communities. Objectives are to maximize pollutant loading, incorporation, and retention while maintaining highest levels of community metabolism and minimal alteration of community structure. Several basic processes are emphasized: (a) macrophyte productivity in relation to shoot:root ratios, and nutrient availability; (b) macrophyte life history strategies, succession, and biodiversity under constant pollutant stress; (c) importance of standing dead and particulate detritus; (d) functions and controlling mechanisms of heterotrophic and autotrophic periphyton in pollutant retention and recycling; (e) coupling of microbial metabolism to macrophyte retention of pollutants; (f) gaseous losses to the atmosphere; (g) losses of dissolved organic matter and its utilization; and (h) water losses by evapotranspiration and effects on wetland efficacy. Short-term wetland removal efficiencies are confounded by massive variations in retentive capacities diurnally, seasonally, and spatially, in exceeding physiological tolerance levels, and in species succession. Problems of channelization, altered microhydrology, and assimilation/retention are major in natural and non-engineered ecosystems. Wetlands are highly ephemeral and variable in their capabilities for sequestering and retention of nutrients and other pollutants.

Ecosystem↗

PubMed2001

[Vegetation carbon storage and density of forest ecosystems in China].

To improve the estimation of carbon pool of forest ecosystems is very important in studying their CO2 emission and uptake. The estimation of vegetation carbon pool in China has just begun. There is a significant difference among estimates from different methods applied. Based on forest inventory recorded by age class, the vegetation carbon storage of forest ecosystems in China was estimated to be 3.26-3.73 Pg, accounting for 0.6-0.7% of the global pool. The carbon densities were difference among forest types and provinces, in range of 6.47-118.14 Mg.hm-2. There is an incremental tendency from southeast to north and west. This trend is negatively related with the change in population density in logarithmic mode, which indicates that the actual forest carbon density is prominently determined by human activities.

Age Factors↗

PubMed2002

[How can we prevent alveolar echinococcosis? Ecosystem and risk management viewpoints].

PURPOSE: This article focuses on understanding epidemiological features of alveolar echinococcosis and discussing its prevention and control, especially from a viewpoint of the ecosystem and risk management. METHOD: Publications on alveolar echinococcosis throughout the world were systematically reviewed with special reference to ecology, epidemiology and countermeasures. RESULTS: Alveolar echinococcosis, caused by accidental infection with larva of the parasite Echinococcus multilocularis is fatal to humans unless diagnosed at an early stage. No effective control measures have been identified so far because it is difficult to fully understand the ecology of the parasite and its intermediate and definitive hosts. It is also not easy to determine the precise infection route to humans mainly because of the long latent period. In Hokkaido, infection rates among red foxes have recently risen even in low endemic districts. Not only stray and domestic dogs but also some pigs in Hokkaido have been found to be infected. While the number of reported human cases is still small, around 10 cases per year, local residents seem to be threatened with the risk of infection. DISCUSSION AND CONCLUSIONS: We predict that the incidence of alveolar echinococcosis among humans in Japan will increase in the near future if no effective preventive measures are conducted. In addition, Echinococcus multilocularis infection has the potential to affect the economy of Hokkaido because of its impact on the agricultural and tourist industries. Well-designed epidemiological surveys are therefore urgently required, in the context of ecosystem and risk management prior to large outbreaks. International collaboration is also desired.

Animals↗

PubMed2002

[Dynamics of accumulation and disappearance of Zirconium-95 in the maize/soil and soybean/soil ecosystem].

The dynamics of accumulation and disappearance of 95Zr in two kinds crop-soil ecosystem was studied by using isotope-tracer techniques for simulated pollutants, and the fitting equation was confirmed by application of the closed tow-compartment model and nonlinear regression method. The results showed: 1. The Zirconium-95 absorbed from soil main retention in root of the maize and soybean, and the specific activity of 95Zr in root increased with time slowly, then tended dynamics balance gradually after a period of time. The specific activity of rest parts was lower, and biggish parts were background activity level, which indicated that the 95Zr absorbed by roots was difficult of transference and transportation in the maize and soybean. 2. The 95Zr in soil main retention in surface layer soil(0-8 cm), and the rate of it's activity and total activity > 97.5%, which indicated that the 95Zr absorbed by surface soil could not readily move downwards with percolating water. 3. The regression equation of accumulation and disappearance of 95Zr in the maize and soybean were Cm(t) = 3.2067(1 - e-0.1582t) and Cb(t) = 3.0925(1- e -0.1363t) by analyzing the experiment data with exponential regression method. The results of squared deviations analyzing indicated that each regression equation could describe the dynamics of accumulation and disappearance of 95Zr in the maize-soil and soybean-soil ecosystems preferably.

Ecosystem↗

PubMed2002

[Tick-borne diseases and changes in the ecosystem in Lorraine].

The number of persons suffering from tick-borne diseases has notably increased in the French region of Lorraine since the mid 1990s. Greater awareness of the pathology is insufficient to explain such an increase in incidence. Instead, the proliferation of ticks is a major factor in the increased incidence of cases, and is mainly due to a modification of the ecosystem. Prophylaxis is based upon appropriate information for persons concerned and requires a sound understanding of the biology and habits of the vector ticks. Numerous factors--anthropogenic, natural, social--may contribute to the destabilisation of a well-balanced ecosystem, but all are more or less the direct result of human activity. The geographic specificities of this region may be an additional factor in the emergence of tick-borne diseases.

Adaptation, Physiological↗

PubMed2002

[Variation of bacteria numbers in fish-shrimp mix-culturing ecosystem].

The study on variation of bacteria numbers in Penaeus chinensis-fish mix-culturing ecosystem in 1997. Indicated that at the beginning of culturing season, total number of heterotrophic bacteria and that of nitrate-reducing bacteria in mix-culturing ponds was low, but it was higher than that in mono-culturing shrimp pond. With time going on, the number of bacteria in mono-culturing pond increased rapidly and remained at a high level in August and September, an that in mix-culturing ponds also increased. But the latter increased slowly, and it was never over 10(4) cells.ml-1 and dropped in September. Number of bacteria in bottom of the ponds varied with the similar regulation, but the numbers was 10-100 times higher. The numbers of vibrio in mix-culturing ponds was always lower than that in contrastive pond at the same time. So, in fish-shrimp mix-culturing ponds, the contents of organic matter were lower and the total amount and variability of phytoplankton were higher than corresponding items in mono-culturing pond. It was concluded that mix-culture could stimulate and control the growth of heterotrophic bacteria, accelerate the degradation of organic pollutants, consequently fasten and stabilize the circulation of mater in ecosystem of ponds in culturing season.

Animals↗

PubMed2002

[Complexity of land ecosystem].

In recent years, complexity studies has become a new research region and been widely applied in engineering, biology, economy, management, military, police and sociology. In this paper, from the view of complex science, the main complexity characteristics of land ecosystem were described, furthermore, the application of fractal, chaos, and artificial neural network on the complexity of land ecosystem were also discussed.

Conservation of Natural Resources↗

PubMed2002

[Landscape ecological mechanism on system coupling of the meta-ecosystem consisted of mountain, desert and oasis in Hexi corridor, Gansu, China].

The fundament of system coupling is heterogeneity, and the basic prerequisite is that there are connective corridors in the same type between ecosystems. The landscape ecological mechanism of system coupling is the spatial difference of non-biotic environment and the heterogeneity caused by disturbances. The force or energy of system coupling is disturbances. From in the view of landscape ecology, system coupling is the merging process of different landscape elements between different landscape ecosystems followed by the process of character changing of landscape elements with scale changing. Based on the essence of disturbances, system coupling can be divided into two types as natural system coupling and artificial system coupling. Natural system coupling is the base of artificial system coupling, and hence, the enhance of eco-productivity of coupling system is based on the optimization of artificial system coupling.

China↗

PubMed2002

[Effects of elevated atmospheric CO2 on the exchange of trace gases between ecosystems and the atmosphere].

The latest researches on the effects of elevated atmospheric CO2 on the exchanges of trace gases (e.g., CO2, CH4 and N2O) between the atmosphere and ecosystems were reviewed. The techniques and methods involved in the researches were introduced firstly. Then the review mainly focused upon the results from those studies using the open-top-chamber (OTC) methods and the free-air carbon dioxide enrichment (FACE) system. Generally, elevated atmospheric CO2 may stimulate biomass accumulation, and enlarge C/N ratio in plant tissue so as to reduce the decomposition of organic matter. This action could increase CO2 sequestration in terrestrial ecosystems. Elevated atmospheric CO2 could impact on methanogenic bacteria and CH4 emissions. An increase in CH4 emissions from wetland may appear. The argument among the responses of N2O emissions to elevated CO2, however, was inconsistent. So far, no study on other trace gases was reported. More efforts should be taken in the research on the effects of elevated atmospheric CO2 on the exchange of trace gases.

Atmosphere↗

PubMed2003

[Cycling and balance of copper in farmland ecosystem of Jianghan plain in Hubei Province].

The cycling and balance of copper in 8 cropping systems, i.e., wheat-rice, rice-rice, rape-soybean, rape-peanut, wheat-sesame, wheat-cotton, pepper-cabbage and radish-eggplant in Jianghan plain of Hubei Province were studied. The results showed that the main output of copper was crop harvesting, up to 85.9%-95.1% of total output, and the output of copper by field runoff and soil leaching was low. The main inputs of copper were organic fertilizer, rainfall, falldrop, and natural return. The inputs of copper from inorganic fertilizer and seeds (seedlings) were low. The balance analysis pointed out that copper had an accumulative trend in two patterns of rice and commercial vegetable ecosystem, and was in balance in upland field ecosystem.

Agriculture↗

PubMed2003

Environmental effect of vegetation restoration on degraded ecosystem in low subtropical China.

The environmental effect of degraded ecosystem's vegetation restoration in low subtropical China was studied. Results indicated that the vegetation recovery on degraded lands significantly ameliorates surrounding environment, increases species diversity, improves soil structure, raises soil fertility, enhances productivity, and promotes regional agricultural production and social economic development dramatically. Through the combining engineering and biological measures, the restoration of degraded ecosystem in low subtropical area is possible and economical. The restoration experience in Xiaoliang, Wuhua and other sites are valuable for other degraded subtropical area was introduced.

China↗

PubMed2003

[Spatial heterogeneity of Ulmus pumila open forest ecosystem in Otindag sandy land].

Ulmus pumila open forest ecosystem plays an important role in Otindag Sandy Land. Using biostatistics (U test and Pearson correlation analysis) and geostatistics (Semivariogram analysis and Kriging interpolation), the spatial heterogeneity of soil organic matter (SOM), soil total nitrogen (STN), soil pH (SpH), soil water content (SWC), and the correlations between them, as well as their relationships with herbaceous coverage (HC) and Ulmus pumila were studied. The results showed that spatial heterogeneity and spatial dependence were apparent in SOM, STN, SpH, SWC and HC. With Kriging interpolation in the sampling area, the contour maps for these properties were drawn. Using the contour maps, the relationship between Ulmus pumila and spatial heterogeneity of the studied properties was investigated. The possible reason for the formation of fertility island under the Ulmus pumila trees in the ecosystem was discussed.

Ecosystem↗

PubMed2003

[Small rodents in the forest ecosystem as infectious disease reservoirs].

Due to numerousness of populations and width of ecologic valence, small rodents are important parts of almost any forest ecosystem. The represent an important animal group, which connects primary makers with higher trophic levels. They transmit various infectious diseases dangerous for the health of people and domestic and wild animals (trichinosis, leptospirosis, tick encephalitis, Lyme disease, hemorrhagic fever with renal syndrome, etc.). The following species of small rodents live in forest ecosystems of Croatia: Chletrionomys glareolus Schreib., Arvicola terrestris L, M. subterraneus de Sel., M. arvalis Pall., M. agrestis L, M. multiplex Fat., Apodemus agrarius Pall., A. sylvaticus L. and A. flavicollis Melch. Small rodents transmit causative agents of diseases in active (excretion products) of passive (ectoparasites and endoparasites) ways. Their multiplication potential is quite high. Transmission of certain disease sometimes takes place extremely fast due to the high number of rodents, their high movability and distribution, and the fact that they easily get in touch with men and domestic and wild animals. The number of population of each species is directly influenced by abiotic and biotic factors and changes during one year and in a several year period. In a year when the influence of ecologic factors is favorable, it is presumed that the number of these rodents will significantly increase, by which the danger of their damaging effect also increases. The following factors influence the increase of a small rodent population: number and physiologic condition of the population, meteorologic conditions, habitat, food sources, natural enemies, and diseases. The occurrence of an epidemic is closely connected to the number and infectivity of causative agents. Regular control of the number of rodent population and their infectivity can help in planning preventive epidemiologic and sanitary measures to preclude the occurrence of epidemics and individual cases of disease among animals and humans who come in contact with forest (forest workers, holiday makers, hikers, soldiers, tourists, etc.).

Animals↗