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PubMed2004

Water environments: anthropogenic pressures and ecosystem changes in the Atlantic drainage basins of Brazil.

Densely occupied drainage basins and coastal zones in developing countries that are facing economic growth are likely to suffer from moderate to severe environmental impacts regarding different issues. The catchment basins draining towards the Atlantic coast from northeastern to southern Brazil include a wide range of climatic zones and diverse ecosystems. Within its borders lies the Atlantic rain forest, significant extensions of semiarid thorn forests (caatinga), vast tree and scrub woodlands (cerrado) and most of the 6670 km of the Brazilian coast and its marine ecosystems. In recent decades, human activities have increasingly advanced over these natural resources. Littoralization has imposed a burden on coastal habitats and communities. Most of the native vegetation of the cerrado and caatinga was removed and only 7% of the original Atlantic rainforest still exists. Estuaries, bays and coastal lagoons have been irreversibly damaged. Land uses, damming and water diversion have become the major driving forces for habitat loss and aquatic ecosystem modification. Regardless of the contrast between the drought-affected northeastern Brazil and the much more prosperous and industrialized southeastern/southern Brazil, the impacts on habitat and communities were found equally severe in both cases. Attempts to halt environmental degradation have not been effective. Instead of focusing on natural resources separately, it is suggested that more integrated environmental policies that focus on aquatic ecosystems integrity are introduced.

Brazil↗

PubMed2004

[Changes of carbon storage and carbon sequestration in plantation ecosystems on purple soil].

This paper studied the carbon storages and carbon sequestration capacities of degraded plantation ecosystems in purple soil area. Using space-time replacement method, four ecological restoration treatments (I, II, III and IV) were selected on the basis of erosion intensions from high to low in Ninghua, Fujian. Treatment I was not treated with any other measures after afforestation. Treatment II adopted engineering soil and water conservation measure after afforestation. In treatment III, the engineering measure associated biological measure was taken after afforestation. As for treatment IV, enclosure was adopted to protect against anthropogenic disturbances after afforestation. We observed that the carbon sequestration potential was increased with weakening erosion degree, i.e., I < II < III < IV. The carbon storage of 4 treatments was 1.4, 8.5, 25.6 and 37.6 t x hm(-2), and the annual assimilation of CO2 was 712.87, 1458.01, 9718.10 and 11,109.56 kg x hm(-2), respectively. It was suggested that the restored forest ecosystem was one of the important carbon sinks in this area. Engineering soil and water conservation measure associated biological measure would be the main means of restoring degraded ecosystem. But presently, the reasonable strategy was to decrease human's disturbances, and hence, the enclosure for reforestation could be used to transform forest ecosystem into carbon sink.

Carbon↗

PubMed2004

[Ecological function of wood-inhabiting fungi in forest ecosystem].

Wood-inhabiting fungi are one of the most important parts of forest ecosystem, and play an important role in degrading the wood in forest ecosystem. The major species of these fungi include the groups of Aphyllophorales (Basidiomycota), Discomycetes (Ascomycota) and some imperfect fungi. They have the ability to degrade cellulose, hemicelluloses and lignin of wood. Three type of wood decaying have been found, i.e., white rot, brown rot and soft rot. Many other organisms of forest ecosystem have symbiosis relationship with wood-decaying fungi. Wood-inhabiting fungi could offer the nutrition for many insects and birds, and spores of many wood-rotting species are spread by some insects. The high biodiversity of wood-decaying fungi is one of the important factors for the health of forest ecosystem.

Ascomycota↗

PubMed2004

[Advances in study of factors affecting soil N mineralization in grassland ecosystems].

The biological and non-biological factors affecting soil N availability in grassland ecosystems were reviewed in this paper. Nitrogen cycling in grassland ecosystems is one of the focuses widely concerned. Nitrogen mineralization is affected by many factors in grassland ecosystem, which can be classified into biological and non-biological ones. Biological factors include soil animals, soil microorganisms and plants. Soil animals could accelerate the organic matter to degrade. The species, structure and function of soil microorganisms correlate significantly with N degradation and mineralization. Different vegetation has different effects on soil nitrogen mineralization. The non-biological factors include environmental factors and anthropogenic disturbance, which have direct and obvious effects on N mineralization. The effects of soil temperature and moisture on N mineralization are given more attention, but many phenomena, such as the effects of soil type, soil structure and vegetation type on N mineralization still could not be explained clearly, and no general agreements were reached. Anthropogenic disturbance such as grazing, firing and fertilization influence N mineralization evidently. It is of great significance to understand the N cycling pattern and N availability in different grassland ecosystems all around the world.

Animals↗

PubMedDate not supplied

[The study of the multifactorial anthropogenic effect on the ecosystems of the industrial reservoirs of "Maiak" industrial complex].

The analysis of the ecological situation of the Southern Urals industrial water reservoirs of the nuclear fuel cycle enterprise, "Mayak" PA is represented. The study was held in the 80s - early 90s. The subjects of the study were: a cooling water reservoir--Kysyl-Tash Lake (R-2) as well as a radioactive waste storage reservoir (R-10). Irtyash Lake, which is a drinking water reservoir for the city of Ozyorsk and Alabuga and Kazhakul Lakes, located on the boundary of the Eastern Urals Radioactive Trace (EURT), were taken as control ones. Such water reservoirs as Irtyash, Kysyl-Tash and the waste storage reservoir (R-10) are incorporated into the Techa River basin; while Alabuga and Kazhakul Lakes are related to the interfluve between the Techa River and the Sinara River. The complex effect from such man--caused factors as radiation, chemical and thermal to water reservoirs' ecosystems was studied. Radionuclide specific activities of the major reservoir components (water, bottom sediments, and biological objects), cumulative stock and radiation doses to the biota were determined. Assessment of the condition of biological structures of individual reservoirs was performed. It was found that the long-term complex influence of radiation, thermal and chemical factors resulted in the formation of the unique technology-induced ecosystems being a part of "Mayak" PA process cycle. Radiation doses to the fish of the cooling water reservoir and the radioactive waste storage reservoir were experimentally estimated. These doses from the incorporated beta-emitters were not less then 2-3 Gy/year. The long-term complex influence of radiation and chemical factors didn't cause any irreversible changes either in the fish population or in the ecosystem. Water purity indicators like crayfish (Astacus leptodactilus Esch) and mollusk (Anodonta cygnea L.) were found in the cooling water reservoir. The comparative analysis of the ecological situation of the reservoirs carried out on the basis of several qualitative indicators and with the help of the formalized scoring system allowed determining that the optimum ecological conditions can be observed in Irtyash Lake. The quality of the environment of Alabuga Lake is slightly lower. The ecological conditions in Kysyl-Tash Lake are up to the standard, while in Kazhakul Lake they are lower than the standard. This is the result of the natural salinization of the ecosystem. The lowest indicator was obtained for the radioactive waste storage reservoir.

Animals↗

PubMed2006

[Ecological control effects of Litchi chinensis-Desmodium intortum complex plant ecosystem on litchi pests].

An investigation on the community structure and dynamics of litchi pests and their natural enemies in constructed Litchi chinensis-Desmodium intortum complex plant ecosystem and single L. chinensis ecosystem showed that the total amount of litchi pests in the complex plant ecosystem was 61.27% of that in the single ecosystem in whole year, and only 50.45% in May, the key time for fruit development, which suggested that there was an interaction between D. intortum and L. chinensis. D. intortum and L. chinensis had a few common pests, but many common natural enemies. D. intortum florescence in winter provided shelter and substitutive food for the natural enemies of pests to survive in the extreme environmental conditions in winter. L. chinensis florescence was on the heel of D. intortum florescence, which provided better conditions for the natural enemies to survive and multiply. During florescence and fruit development stages of L. chinensis (from March to June), the predator/prey ratio in complex plant system was 4.22, 2.34, 2.2 and 20.63 times of that in single plant system in March, April, May and June, respectively, indicating the good control effect on pests of L. chinensis.

Animals↗

PubMed2006

[Eco-value level classification model of forest ecosystem based on modified projection pursuit technique].

To optimize the projection function and direction of projection pursuit technique, predigest its realization process, and overcome the shortcomings in long time calculation and in the difficulty of optimizing projection direction and computer programming, this paper presented a modified simplex method (MSM), and based on it, brought forward the eco-value level classification model (EVLCM) of forest ecosystem, which could integrate the multidimensional classification index into one-dimensional projection value, with high projection value denoting high ecosystem services value. Examples of forest ecosystem could be reasonably classified by the new model according to their projection value, suggesting that EVLCM driven directly by samples data of forest ecosystem was simple and feasible, applicable, and maneuverable. The calculating time and value of projection function were 34% and 143% of those with the traditional projection pursuit technique, respectively. This model could be applied extensively to classify and estimate all kinds of non-linear and multidimensional data in ecology, biology, and regional sustainable development.

Ecosystem↗

PubMed2006

[Mass-balance ecopath model of Belbu Gulf ecosystem].

Based on the investigation of fishery resources and eco-environment in the Beibu Gulf of northern South China Sea from October 1997 to May 1999, and with EwE software, a mass-balance ecopath model of Beibu Gulf ecosystem was constructed, which consisted of 16 functional groups (boxes) including marine mammals and seabirds, each representing the organisms with similar roles in the food web, and covered the main trophic flow in Beibu Gulf ecosystem. The food web in Beibu Gulf ecosystem was dominated by detrital path, and benthic invertebrate played a significant role in transferring energy from detritus to higher trophic levels. Phytoplankton was the primary producer, and the fractional trophic levels ranged from 1.00 to 4.04, with marine mammals occupying the highest trophic level. By using network analysis, the system network was mapped into a linear food chain, and six discrete trophic levels were found, with a mean transfer efficiency of 12.3% from detritus, and 12.2% from primary producer within the ecosystem. The biomass density of commercially utilized species estimated by the model was 8.7 t x km(-2), and the bioproduction only accounted for 1.81% of the net primary production, which indicated that the system was still in developing status and instable.

Animals↗

PubMed2006

[Comprehensive assessment of urban ecosystem health].

Ecosystem health is one of the research hotspots in ecology. This paper discussed the concept of urban ecosystem health, and from the viewpoint of complex ecosystem, presented a new method and a calculation model for the comprehensive assessment of urban ecosystem health to overcome the current researches shortcomings. The application of the method and model in Foshan City of Guangdong Province showed that the assessment results could reflect not only the overall health status of the city, but also the relative health level of the city's sub-systems.

China↗

PubMed1998

Biological filtering and ecological machinery for self-purification and bioremediation in aquatic ecosystems: towards a holistic view.

According to one of the approaches to the definition of criteria for the phenomenon of life, the key attribute is the ability of the system for some self-regulating and self-supporting. Part of such holistic functions of aquatic ecosystems as self-regulating and self-supporting is their cleaning the water via a multitude of various mechanisms. The goal of this paper is to present some fundamental elements of the theory of ecosystem self-purification which emphasizes the importance of the four functional biological filters that are instrumental in purification and upgrading the quality of water in aquatic ecosystems. These functional filters are: (1) direct water filtering by aquatic organisms that are filter-feeders; (2) the filter (represented mainly by communities of aquatic plants/periphyton) which prevents input of pollutants and biogenic elements (N, P) from land into water bodies; (3) the filter (represented by benthic organisms) which prevents re-entry of pollutants and biogenic elements from the bottom sediments into the water; (4) the filter (represented by microorganisms attached to particles which are suspended in the water) that provides microbiological treatment of water column. New experimental data by the author reveal the role of man-made effects on the ecological machinery which purifies water. The analysis and discussion lead to the holistic theory of the natural process of bioremediation of aquatic ecosystems.

Animals↗

PubMedDate not supplied

Phosphorus cycles of forest and upland grassland ecosystems and some effects of land management practices.

The distribution of phosphorus capital and net annual transfers of phosphorus between the major components of two unfertilized phosphorus-deficient UK ecosystems, an oak--ash woodland in the Lake District and an Agrostis-Festuca grassland in Snowdonia (both on acid brown-earth soils), have been estimted in terms of kg P ha--1. In both ecosystems less than 3% of the phosphorus, totalling 1890 kg P ha--1 and 3040 kg P ha--1 for the woodland and grassland, respectively, is contained in the living biomass and half that is below ground level. Nearly all the phosphorus is in the soil matrix. Although the biomass phosphorus is mostly in the vegetation, the soil fauna and vegetation is slower (25%) than in the grassland vegetatation (208%). More than 85% of the net annual vegetation uptake of phosphorus from the soil is returned to the soil, mainly in organic debris, which in the grassland ecosystem is more than twice as rich in phosphorus (0.125% P) as in the woodland ecosystem (0.053% P). These concentrations are related to the rates of turnover (input/P content) of phosphorus in the litter layer on the soil surface; it is faster in the grassland (460%) than in the woodland (144%). In both cycles plant uptake of phosphorus largely depends on the release of phosphorus through decomposition of the organic matter returned to soil. In both the woodland and the grassland, the amount of cycling phosphorus is potentially reduced by its immobilization in tree and sheep production and in undecomposed organic matter accumulating in soil. It is assumed that the reductions are counterbalanced by the replenishment of cycling phosphorus by (i) some mineralization of organically bound phosphorus in the mineral soil, (ii) the income in rainfall and aerosols not being effectively lost in soil drainage waters and (iii) rock weathering. The effects of the growth of conifers and sheep grazing on the balance between decomposition and accumulation of organic matter returned to soil are considered in relation to the rate of phosphorus cycling and the pedogenetic changes in soil phosphorus condition leading to reduced fertility. Although controlled sheep grazing speeds up phosphorus cycling and may reverse the pedogenetic trend in favour of soil improvement, conifers may slow down phosphorus cycling and promote the pedogenetic trend towards infertility.

Agriculture↗

PubMed1999

Environmental conditions and pesticide pollution of two coastal ecosystems in the Gulf of California, Mexico.

In December 1997 and April and September 1998, water temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and pesticide residues were determined in two coastal ecosystems of Sinaloa, NW Mexico: Ensenada del Pabellón and Bahía de Santa María. These two are considered to be among the greatest shrimp producers in the region. Temperature, salinity, and dissolved oxygen were similar to those of other ecosystems of this region: high temperatures and salinity in spring and summer (dry season) and lower in winter and the rainy season. Levels of nitrites and phosphates and chlorophyll concentration were relatively higher than those of other ecosystems nearby, probably due to fertilizers used in the agricultural lands surrounding the water bodies studied. The pesticides more frequently detected were BHCalpha, aldrin, endosulfan and parathion. In some cases, pesticides forbidden by Mexican regulations were detected. These results indicate that the ecosystems studied are in a warning condition, because severe biochemical and physiological alterations have been reported in crustaceans exposed to pesticides. Therefore these pesticides could be one cause of the slow growth, diverse pathologies, and mortality in shrimp that have been reported in recent years.

Animals↗

PubMed1992

Fate and effects of the insecticide Dursban 4E in indoor Elodea-dominated and macrophyte-free freshwater model ecosystems: I. Fate and primary effects of the active ingredient chlorpyrifos.

The fate of the insecticide Dursban 4E (active ingredient chlorpyrifos) and its effect on crustaceans and insects was studied in indoor experimental freshwater ecosystems that intended to mimick drainage ditches. A single dose (simulating aerial drift) was applied to achieve nominal chlorpyrifos concentrations of 5 or 35 micrograms/L. Two experiments were performed, one in which all model ecosystems were dominated by the macrophyte Elodea nuttallii, and one using systems devoid of macrophytes. In macrophyte-dominated systems, Elodea vegetation adsorbed a large proportion of the dose applied and hampered the mixing of the insecticide in the water (at least up till day 8). Only a small proportion became incorporated in the sediment. In open water systems the insecticide was rapidly mixed in the water, and the sediment played a very significant role as sink for chlorpyrifos. In both Elodea-dominated and open water systems 50% of the dose applied had disappeared on day 8 post-treatment. The rate of disappearance of chlorpyrifos was relatively rapid in water and macrophytes, and relatively slow in the sediment. Of the arthropods in the zooplankton Cladocera were more susceptible than Copepoda. Significant effects (p less than or equal to 0.05) on Cladocera occurred relatively late in Elodea-dominated systems (in week 4 post-application) in contrast to open water systems (week 1), which is in accordance with the observed differences in the fate of chlorpyrifos. Daphnia pulex, D. longispina and Simocephalus vetulus recovered in the model ecosystems when chlorpyrifos concentrations were lower than 0.1-0.2 micrograms/L, which is in agreement with results of laboratory protocol tests performed with these cladocerans. Among the macroscopic Arthropoda the apparent order of susceptibility was amphipods greater than insects greater than isopods. The isopod Asellus aquaticus was more sensitive to the application of the insecticide than the closely related species Proasellus coxalis. In treated open water systems the latter even increased significantly in numbers. Cage experiments in the model ecosystems performed with several species of Arthropoda indicate that laboratory protocol tests may give a reasonable prediction of short-term direct effects of chlorpyrifos for the same species inhabiting more complex aquatic systems.

Animals↗

PubMed1977

Local consideration of polymorphisms for populations coexisting in stable ecosystems.

The stability problem for multiallelic genetic polymorphisms for n populations coexisting in stable ecosystems is considered. Taking into account only density-dependent interactions a generalization of Fisher's theorem is obtained. Specifically, the average fitness of a population must be locally maximized subject to the constraint that the equilibrium population sizes are fixed if the polymorphism is stable. Further, the quasi-equilibrium population sizes Ni corresponding to fixing the genetic structure of all populations in the ecosystem at various values have extrema at the equilibrium point. Such an equilibrium can be a maximum, minimum or saddle point depending upon the type of ecosystem under consideration. A simple test separating these cases on the basis of the so-called ecosystem matrix is suggested. The general equilibrium problem is reformulated as a maximization problem under some restrictions. Conditions under which the maximized function can be expressed as sigma ni=1 Ni are formulated.

Alleles↗

PubMed1996

Why Ecosystem Management Can't Work Without Social Science: An Example from the California Northern Spotted Owl Controversy

It is increasingly obvious that social science, while not a sufficient condition for making ecosystem management effective, is a necessary condition. A social science typology of ecosystems is developed, applied, and shown to have substantial and unexpected implications for the practice of ecosystem management. Ecologists and environmental scientists, in particular, will find some conclusions uncomfortable. The application involves a case material from the California northern spotted owl controversy.KEY WORDS: Ecosystem management; Social science; Adaptive management; Top-down versus bottom-up planning; Outside-in versus inside-out planning

Journal Article↗

PubMed1996

Adaptive Management for Sound Ecosystem Management

/ Sound ecosystem management meshes socioeconomic attitudes and values with sustainable natural resource practices. Adaptive management is a model for guiding natural resource managers in this process. Ecosystems and the societies that use them are continually evolving. Therefore, managers must be flexible and adaptable in the face of uncertainty and lack of knowledge. To couple good science to management, it is important to develop goals, models, and hypotheses that allow us to systematically learn as we manage. Goals and models guide the development and implementation of management practices. The need to evaluate models and test hypotheses mandates monitoring, which feeds into a continuous cycle of goal and model reformulation. This paper reviews the process of adaptive management and describes how it is being applied to oak/pine savanna restoration at Necedah National Wildlife Refuge as an illustration. Our aim is to help managers design their own adaptive management models for successful ecosystem management.KEY WORDS: Adaptive management; Ecosystem management; Monitoring; Restoration; Savanna

Journal Article↗

PubMed1976

Biophysical questions in ecology and environmental research. Part 2: The extremes of an ecosystem (author's transl).

Some basic differences and developmental aspects of ecosystems are demonstrated. Maximum "energy conductivity" and the pathways of energy flow through ecosystems are discussed as the force, potential, or principle to drive the evolution of the system. A working hypothesis is offered: Ecosystems maximize the total energy flow to optimize temperature stability. The paper stresses in general the need and search for new approaches to analyze the evolution of ecosystems. The hypothesis presented in this paper should be regarded as stimulation for further research.

Ecology↗

PubMed2005

Can ecology help genomics: the genome as ecosystem?

Ecologists study the rules that govern processes influencing the distribution and abundance of organisms, particularly with respect to the interactions of organisms with their biotic and abiotic environments. Over the past decades, using a combination of sophisticated mathematical models and rigorous experiments, ecologists have made considerable progress in understanding the complex web of interactions that constitute an ecosystem. The field of genomics runs on a path parallel to ecology. Like ecology, genomicists seek to understand how each gene in the genome interacts with every other gene and how each gene interacts with multiple, environmental factors. Gene networks connect genes as complex as the 'webs' that connect the species in an ecosystem. In fact, genes exist in an ecosystem we call the genome. The genome as ecosystem is more than a metaphor--it serves as the conceptual foundation for an interdisciplinary approach to the study of complex systems characteristic of both genomics and ecology. Through the infusion of genomics into ecology and ecology into genomics both fields will gain fresh insight into the outstanding major questions of their disciplines.

Ecology↗