Ecological Issues in a Changing World

Human intrusion is growing at an exponential rate modifying structure and functions of many ecosystems (loss or reduction of habitats for species, loss of biodiversity) and reducing the ecosystem services. Many modifications are not immediately visible creating an ecological debt dangerous for the entire planet (Tilman et al. 1994) and reducing the possibilities for new biological aggregations. Human activity that proceeds at an accelerated rhythm affects several of the environmental constraints that have regulated the biological adaptation) as well as the physical dynamic of the land crust. In particular human activity at difference of other biological processes occupies a system of meta-domains that ranges from the biological realm to the mind realm through a huge possibility to invent new tools that enlarge the sphere of "competencies" touching the functioning of individual organisms, their aggregations (population, communities) and supporting systems (ecosystems, landscape), until the bio-physical processes. Such tools are the result of human capacity to handle things but also to "create" by mental processes new "virtual" conditions that finally are translated in a material domain. The mind domain is largely used to create physical domain by a self-reinforcing closure. Ecology is a relatively young science that enters into the center of the storm of environmental modifications without the necessary tools to face new and unpredictable effects of the thermodynamic disturbance (manipulated by energy), autopoietic processes (sensu Maturana and Varela 1980) complex interactions. The aim of this article is to present new epistemological possibilities for a theory that fill the gap between the separate knowledge that to day reduce the capacity to adapt our life style to ecological processes. The ideas that will be presented are an attempt to create a more general framework in which landscape is considered per se sufficient to justify a separate science.

One of the basic questions in ecology is to understand how the ecological communities and ecosystems are organized. It has gained the greater importance because of the growing concern about the conservation of biodiversity and restoration of damaged ecosystems in a changing world. Species interactions and spatio-temporal variability are the key factors influencing ecological processes. Since many problems interconnect across a range of spatial and temporal scales in the natural world (Levin 1992, Maurer 1999), mathematical modelling is one of the fundamental approaches for untangling the complex networks of interactions in a spatially heterogeneous and temporally varying world. Marked advances in community and ecosystem ecology will be achieved by coordinated development of manipulative experiments on community-wide scales and insightful theoretical investigations. The 8th International Congress of Ecology (INTECOL) was held in Seoul with “Ecology in a Changing World” as the main theme. The symposium “Mathematical View of Community and Ecosystem Processes” was organized to review recent progresses in mathematical theories in community and ecosystem ecology. Our attention was particularly paid to the following aspects; empirical models stemmed from observations of aquatic communities; spatial models for explaining mechanisms which promote coexistence of multiple species; models to access ecosystem health and performance focusing on the matter and energy flow; a model to evaluate efforts to conserve populations; and an evolutionary model for describing self-developing processes of food webs. In this article, we summarize the lectures in the symposium and give a brief review of the background and status of the mathematical view in community and ecosystem ecology. Lawton (2000) wrote that four inter-related challenges confronting community ecology in a rapidly changing world would shape up to this millennium. These are (1) whole system manipulations simulating aspects of global change, (2) approaches in some ways to regional processes, (3) greater collaboration of community ecology and ecosystem ecology, and (4) works with laboratory microcosms and controlled environmental facilities, together with mathematical modelling. This seems a common view to ours, although more mathematical viewpoints were emphasized in our symposium. In the following, we concentrate, first on spatial aspects including regional processes, second on long-term temporal issues, and third on ecosystems and physical processes. Finally we will suggest some future directions that have become clear through recent development in this field and discussions in the symposium.

As any science, ecology is operating within a broad range of objectives, situated between very basic researches on the one hand and applications of the knowledge which has been elaborated throughout these fundamental research activities on the other. But in contrast with most other sciences, ecologists have to bear a certain societal responsibility concerning their contributions to find the best sketch of future developmental directions of the human environment. This “big project” cannot be conducted “in ecological isolation”, because man provides the dominating constraints for ecological dynamics, and thus his and her activities have to be incorporated into the applied research agendas of ecologists. Therefore, it seems to be extremely important to include humanities into ecological research framework, or at least to provide potential levels-of-linkage which could be basic starting points for interdisciplinary environmental analyses. Recent environmental, economic and political demands are also requiring better understanding of the linkage between the ecological and human social systems, especially in the context of the development of management strategies for a sustainable world. We are facing several environment-related threats to human welfare, health and security in the 21st century. The respective questions for a complex system approach to such dynamic human-environmental interactions are extremely important and significant for the scientific progress, as well as for the political decision-making and development processes in the face of inevitable environmental change. We are aware that many different approaches for this “big project” have already been developed, such as ecological economics, ecological engineering, ecotechnology, ecological planning, human ecology, and so on. And we do take into account that these scientific fields have produced many stimulating concepts, methods and results. But, what we are missing in this elaborate group of sub- and inter-disciplines is an approach of systems ecology to cope with issues and problems associated with human-environmental interactions.

Anthropogenic activities have increased the concentration of atmospheric CO₂ from about 280 parts per million (ppm) at the beginning of the industrial revolution to 369 ppm at the present time. Future estimates of atmospheric CO₂ concentration for the year 2050 range between 450 ppm and 600 ppm (Kattenburg et al. 1995). More than two decades of study on the effects of CO₂ enrichment have greatly improved our understanding of plant response such as net primary productivity, species abundance, community composition and soil respiration (root plus microbial respiration) in terrestrial ecosystems (Poorter 1993, Curtis and Wang 1998, Ball and Drake 1998, Mooney et al. 1999, Edwards and Norby 1999, Zak et al. 2000). In addition, the chemical and physical composition of plant material and decomposability of plant litter have drawn much attention (Cotrufo et al. 1994, Cotrufo and Ineson 1995, King et al. 1997) Unlike the terrestrial ecosystem studies, however, relatively less effort has been made to elucidate possible effects of elevated CO₂ on wetland ecosystems. Although wetland ecosystems including peat-forming wetland cover only 2-6 % of global land surface (Gorham 1991), they play a pivotal role in global biogeochemical cycles. Firstly, peat accumulation in peatland ecosystems over thousands of years has resulted in a vast store of carbon of 455 Pg C (Gorham 1991, Van Breemen 1995, Adams and Faure 1998). This represents 20-30% of the world’s pool of soil organic carbon and is comparable to the total carbon in the atmosphere as CO₂ (IPCC 1990). Secondly, wetlands are substantial sources of radiatively active trace gases such as CH₄ and N₂O (Freeman et al. 1993). For example, natural wetlands and rice paddies release about 40-50% of global emissions of CH₄, which is 25 times more radiatively active than CO₂ on a molar basis (Cicerone and Oremland 1988). As such, even small changes in net primary productivity or decomposition of soil organic matter by elevated CO₂ could significantly influence the balance of greenhouse gas flux between the atmosphere and biosphere. This would greatly influence the future trajectory of global warming (Mitchell et al. 2002). However, little is known about how C and N dynamics on wetland ecosystems will respond to elevated CO₂ conditions. In particular, below ground processes in wetland ecosystem are scarcely reported. The aim of this review is to organize existing knowledge about the effects of elevated CO₂ on wetland ecosystems. In particular, we would like to address the issue of how wetland ecosystems will respond to elevated CO₂ conditions and whether these responses may cause feedbacks to further global climate change.

More and More efforts are given to landscape scale models in ecological researches recently, for they are crucial in bridging the gap between broad scale generalization and fine scale measurements in global change studies. Disturbances, such as: fire, wind, drought, insect and disease, are hot topics of landscape scale models, for they are the main agents in creating patchiness to form heterogeneous landscape and shifting mosaics, which are considered to be typical at this scale. Fire, the most common disturbances in most terrestrial ecosystems, and with relative predictable regime (frequency, mean area, return interval) compare to other types of disturbances, is often chosen by researchers as example to show the importance of effects of disturbance on vegetation dynamics. It is now commonly accepted that fire disturbance may plays a major role in shaping and maintaining many terrestrial ecosystems. Models dealing with these ecosystems without considering fire disturbance are thought to be at lest inadequate. Many researchers further point out fire may play a more important role in the responses of vegetation to rapid climate change. Fire regime change may have more drastic effects on vegetation response then the effects of physiological change such as growth rate and mortality during the period of rapid climate change. Many influential research projects, such as IGBP, give high priority in developing an appropriate fire disturbance model. However, it is not a easy task to predict fire effects on vegetation dynamics, because the relationships among weather, fire, and the dynamics of vegetation require an understanding of fine-grained details of fire ignition, fire spread, the patterns of vegetation and their response to fire, and the fast changing weather conditions imbedded in the long term-trends and potential shifts in climate. Additionally, the complexity of human influences and the uncertainty of their trends make the problem more difficult.

Emissions of carbon dioxide (CO₂) from fossil fuel combustion and total anthropogenic emissions have been increasing by around 6.3 and 8.0 Gt C yr-1, respectively (IPCC 1996), of which 3 Gt C year-1 has been explicitly linked to ‘uptake by Northern Hemisphere forest regrowth’ and to additional terrestrial sinks resulting from the combination of CO₂ fertilization, nitrogen deposition, and increasing temperature indirect effects. However, little scientific evidence for the ‘additional terrestrial sinks’ has yet been shown to confirm this, except for relatively short-term results from CO₂ enrichment experiments. The Kyoto Protocol was adopted in 1997, requesting that developed countries reduce their total CO₂ emissions by 2008-2012 to 92-95% of the level in 1990, taking the CO₂ balance of their forest ecosystems into consideration. This has lead to greatly increased attempts to measure directly the fluxes of CO₂ between the atmosphere and forest ecosystems. The main approach has been to use eddy covariance from towers above forest canopies to quantitatively evaluate the net ecosystem exchange of carbon dioxide over short periods (NEE). During the last five years many CO₂ flux towers have been built worldwide (ref. FluxNet: AmeriFlux, CarboEuro, AsiaFlux, etc.). Based on the tower data collected by the CarboEuro program, Valentini et al. (2000) suggested that most of the 30 forest stands monitored to date function as sinks for atmospheric CO₂, with the rate of increase rising from northern (boreal) to southern (warm-temperate) forests. Malhi et al. (1999) indicated that the magnitude of net carbon balance for tropical forest stands depends strongly on their biomass or net primary productivity. However, it is still not clear what suite of mechanisms in forest ecosystems collectively function to create a sink for carbon or where in any particular forest this occurs. Young forest stands generally function as carbon sinks, due to their positive increment in tree and litter biomass, and in some cases soil carbon. In this case, CO₂ fertilization, nitrogen deposition, or human fertilization and other cultivation generally greatly increases the magnitude of the sink. Saigusa et al. (2002) and Goulden et al. (1996) found that variation in weather conditions (precipitation, temperature and radiation) could account for much of the annual fluctuation in annual NEE (or net ecosystem production, NEP), based on long-term tower data over cool-temperate forests in central Japan and the northeastern U.S., respectively. However, few such long-term studies exist in the world. One approach to resolution is to measure simultaneously the component carbon fluxes within ecosystems (e.g., CO₂ fluxes of soil, root or stem respiration and photosynthesis), because the balance of CO₂ fluxes at the tower is the net result of these fluxes (i.e., the balance between net CO₂ assimilation by vegetation and the mineralization of carbon from soil organic matter). For example, Jarvis et al. (1997) attempted to do this beneath a tower at a boreal forest in Canada, although they found that the data could not be scaled up to the stand level.

Increasing productions farmers subsidize energy in order to simplify plant cover structure both within cultivated fields (selection of genetically uniform cultivars and weeds elimination) and within agricultural landscapes (elimination of not productive elements of landscapes like woods, hedges, mid-field small wetlands or ponds and so on being obstacles for work of agromachines). Farmers interfere with natural matter cycles directly by input of fertilizers and pesticides or indirectly by decreasing stocks of organic matter in soils which undermine agroecosystems capacities for chemical storing. These effects of farmers’ activities result in the development of a less complex network of interrelations among the components of agroecosystems. As a consequence of this functional simplification, relationships among agroecosystems components are altered, so that there is less tie-up in local cycles of matter. Hence increased leaching, blowing off, volatilisation and escape of various chemical compounds and materials from agroecosystems are appearing. Intensive application of mineral fertilizers and large inputs of liquid manure have brought threats to environment resulting in deterioration of ground and surface waters. Non-point sources of pollution caused mainly by agricultural activity are recognised as one of the first rank factors decreasing quality of inland water ecosystems (Stanners and Bourdeau 1995, European Environment Agency 1998, COM 1999).

Habitat evaluation at relatively large geographic scales is becoming increasingly more common as biologists confront issues such as biodiversity, fragmentation, and ecosystem management (Roseberry and Hao 1995). This emphasis on larger scales has been made feasible by the availability of remotely sensed data (O’Neill et al. 1999). Satellite imagery can be interpreted for land cover and provides an economical approach to studying large areas (O’Neill et al. 1992). The development of geographical information systems (GIS) software provides the tools for handling the large spatial data sets; the technical capabilities of satellite imagery together with GIS technology offers an ideal combination for analysis of landscape condition (O’Neill et al. 1999). Landscape patterns are of major concern in land management and planning, species conservation, and ecological studies. ‘Landscape pattern’ refers to features associated with the physical distribution or configuration of patches within the landscape (McGarigal and Marks 1995). Some of these features, such as patch isolation or contagion, are measures of the placement of patch types relative to other patch types, the landscape boundary, or other features of interest. Features as patch size and shape are measures of the spatial character of the patches. The spatial relationship of habitat has been important in assessing the status of a variety of organisms (Davidson 1998). Landscape ecology seeks to understand the ecological function of large areas and hypothesizes that the spatial arrangement of ecosystems, habitats, or communities has ecological implications. Therefore, methods to analyze and interpret heterogeneity at broad spatial scales are becoming increasingly important for ecological studies (Ricotta et al. 1997). Changes in the spatial patterns of land use through time are considered to be crucial to the understanding of landscape dynamics and its consequences (Turner and Ruscher 1988). It is important to test a central hypothesis of landscape ecology, i.e. that ecological patterns and processes are linked (Forman and Godron 1986, Turner 1989, Levin 1992).

The great biological richness of the Asian coastal shallow waters including estuaries and intertidal flats seems to be underestimated probably due to its simple and colourless appearance and the delay of the basic studies. Human impacts such as water pollution have damaged the coastal environments. For example, species number and biomass of benthic invertebrates were rapidly decreased in late 1960s or early 1970s in Qingdao in the inner part of Yellow Sea, probably caused by the discharge of pollutants into the bay from many chemical plants (Wu et al. 1992). At the same period, the heavy mercury pollutions causing the severe injury of human health of many local people through food chain occurred in Japanese coasts (i.e., Minamata disease, Ui 1992, Harada 1995). Similarly, in Onsan, South Korean, a disease related with heavy industrial pollution occurred in 1980s (i.e., Onsan disease), and the potential biological effects associated with some organic chemicals seem to be still under exposure in this area (Koh et al. 2002a). Another aspect of recent serious human impacts is the large-scale of reclamation project in shallow coastal zones, especially in intertidal flats of the Asian countries. We feel anxious that the whole original biodiversity and ecological process in these areas might be lost by the serious human impacts in relation to the rapid developments in the Asian countries before we know them. The experiences of ‘Sihwa Project’ in Korea and ‘Isahaya Project’ in Japan would be representative examples. Currently in South Korea, huge reclamation projects such as the ‘Saemangeum Project’ modifying 400 km2 of tidal flat area into farmland are rigidly in progress although their serious impacts are clearly expected.

East Asia has various types of grasslands, such as inland arid and semi-arid natural grasslands in China and Mongolia, and artificially managed semi-natural grasslands in wet monsoon areas like Japan. Diversified utilization and livestock farming are carried out on these grasslands. A variety of grasslands have been maintaining diversified organisms characteristic to grassland ecosystems. However, in those grasslands, irrespective of the types and areas, deterioration of the diversity of grassland organisms is going on. The causes of the decline in biodiversity differ, depending on the particular grassland in question. In the Chinese and Mongolian grasslands, overgrazing associated with retrogression and desertification due to increases in the human population and settlements has resulted in the decline and even extinction of some species of wildlife. In the wet monsoon areas, decreases in grassland area and insufficient management of grasslands due to the decline of livestock farming and the rural lifestyle have led to a deterioration of grassland biodiversity. Accordingly, there is an acute need for conservation and management of grassland biodiversity in these areas. Different grasslands require different strategies for the conservation and management of their biodiversity. This paper summarizes the present conservation issues in the grasslands and presents future prospects for the conservation and management of the grasslands in East Asia.

Invasions of exotic species sometimes cause devastating effects in ecosystems they have invaded. Nowadays worldwide economic activity increases the flow of people and trading materials within and between continents, resulting in increasing occurrence of invasion of exotic species. The invasion process generally involves four phases: arrival, establishment in the new habitat, range expansion, and saturation (Liebhold et al. 1995). The spread pattern of invading organisms has been studied empirically and theoretically by many authors (Andow et al. 1990, Shigesada et al. 1995, Veit and Lewis 1996, Yamamoto et al. 2000). Pinewood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, is the causative agent of pine wilt disease (Kiyohara and Tokushige 1971). The infection of the nematode induces a rapid tree mortality of susceptible pine species such as Pinus densiflora, P. thunbergii, and P. sylvestris (Kiyohara and Tokushige 1971, Kondo et al. 1982). The nematode is inferred to be native to North America and introduced into Japan at the beginning of 20th century (Mamiya 1988). Since then it has spread to Korea, Taiwan, and China and devastated pine forests in East Asia. In Japan, for example, the annual loss of pines reached a maximum value of 2,430,000 m3 in 1979 (Mamiya 1988), and then was held at a level of about 1,000,000 m3 in the early half of 1990’s. It was also found in Portugal in 1999 (Mota et al. 1999). The objective of this article was to determine the spread pattern of pinewood nematode at within-stand, local, and regional levels in Japan. For this purpose, we summarized the biology of the nematode and its vectors first.

Allelopathy is an important mechanism of plant interference mediated by the addition of plant-produced phytotoxins to the plant environment and competitive strategy of plants (Muller 1969, Chou and Lin 1976, Rice 1984, Fischer et al. 1994, Langenheim 1994). Allelochemicals are released from plant tissue in a variety of ways including emission of volatile substances from living plant parts, exudation from roots, or leaching from above ground parts by rain, dew, fog, etc. (Rice 1984). Many researchers have found that inhibitory substances involved in allelopathy are terpenoids, and phenolic substances (Carballeira 1980, Muller 1965, Kil and Yim 1983, Weidenahmer et al. 1994, Seigler 1996). A wide array of biologically active constituents is produced by plants in the genus Artemisia (Marco and Barbera 1990). The volatile essential oil of Artemisia species resulted in reduction in seedling survival (Lydon et al. 1997, Kil et al. 1992). The volatile oil of Artemisia afra has been reported to have several biological activities, notably antibacterial, antifungal and anti-oxidative properties. Monoterpene vapours may cause anatomical and physiological changes in plant seedlings and exposure to volatile terpenes can lead to accumulation of lipid globules in the cytoplasm, reduction in organelles including mitochondria and disruption of membranes surrounding mitochondria and nuclei (Lorber and Muller 1976). The root tip cells subjected to the alkaloids gramine and hordenine caused damages to the cell walls, disorganization of organelles, increase cell vacuoles, and the appearance of lipid and globules, showing food reserves (Liu and Lovett 1993). Large amounts of monoterpene hydrocarbons and/or sesquiterpenes are found to lower the antimicrobial activity of essential oils (Chalchat et al. 1997).

In many developed countries, the enforcement of specific regulations had a significant positive effect on the level of environmental pollution in the last decades, especially through a reduction in point source pollution (e.g. building of sewage treatment plants) and the ban of some persistent chemicals (e.g. DDT, toxaphene). However point source pollution is still a matter of concern in numerous countries and non-point source pollution by organic (e.g. pesticides, dioxins) and inorganic (e.g. heavy metals) compounds is still a matter of concern worldwide. The assessment of environmental quality implies that the biological effects of pollutants could be monitored using adapted tools. Ecotoxicology is a multidisciplinary science which focus on the adverse effects of toxicants at various levels of biological organization and which may provide such tools. Ecotoxicological researches have first been devoted to the study the effects of environmental contaminants at the population, community or ecosystem levels (Forbes and Forbes 1994). However, these traditional approaches are sometimes inefficient, especially to adequately assess the effects of chronic exposure of organisms to low levels of xenobiotics and to detect early biological responses. Therefore, there has been a shift in emphasis towards understanding the sublethal effects of long-term exposure to contaminants at the individual level where exposure can be adequately described and assessed (Newman and Jagoe 1996). It has been necessary to perform studies on individuals at the biochemical and molecular levels where toxicant-induced responses are initiated.

The forest area in Korea occupies 6.3 million ha, about 65% of the total land area as of 2000. The forest can be classified into three groups: coniferous (2.7 million ha), deciduous (1.7 million ha), and mixed (1.9 million ha) forests, and most of the dominant species of deciduous and mixed forests are oak (Quercus) species (Korea Forest Service 2001). Oak species occupy a wide variety of ecological conditions and zones ranging from lowland warm temperate to upper montane conditions, and have been intensively utilized for many different purposes in the country. There is no doubt that oak species play the most important role in ecological aspects and production of wood and by-products of the Korean forests. Six deciduous oak species (Q. aliena, Q. acutissima, Q. dentata, Q. mongolica, Q. serrata, and Q. variabilis), few varieties and hybrids are commonly found throughout the country and five evergreen oak species (Q. acuta, Q. gilva, Q. glauca, Q. myrsinaefolia, and Q. salicina) are scattered along the southern coasts and islands. Many of the previous studies investigated biomass and production, and relatively few studies examined nutrient distribution and cycling of the oak forests. However, most of these studies focused on the deciduous oak forests. The primary object of the current study is to provide an overview of biological productivity and nutrient cycling for natural oak forests in Korea. We collect and compare data sets on biomass and nutrient cycling for the species from the literature, and also include our own data from the on-going research project (“Effects of the changes in local environments on the nutrient cycling of the natural oak stands in Korea” supported by the Korea Science and Engineering Foundation- R01-2000-000-00206-0). As nitrogen (N) and phosphorus (P) are the most common nutrient limiting production in temperate forests, our review focuses on N and P as well as organic matter.

Culex tritaeniorhynchus Dyar and Anopheles sinensis Wiedemann are distributed widely in Korea and are vectors of JE and of both malaria and inland filariasis, respectively. These mosquitoes are particularly abundant in riceland agroecosystems, where they breed in irrigated rice fields and associated lowland areas. Anopheles sinensis and Cx. tritaeniorhynchus are the predominant bloodseeking mosquitoes in July and August, respectively (Shim et al. 1987, 1990, 1997) and, when present in large numbers, these species present a serious threat to human and animal health through annoyance and as vectors of disease. Because of the threat that An. sinensis and Cx. tritaeniorhynchus pose to human and animal health, there is a need to develop management programs that will serve to continually keep populations of these species at acceptably low levels. The development and implementation of such programs require a detailed study of the relationship between environmental factors, including natural enemies and various abiotic factors in ecosystems, and the ecology of these mosquitoes. Traditional mosquito control strategies in conventionally-farmed rice fields used mainly adulticides which include fogging, aerosol sprays and larval control from agro-pesticides in Korea (Ree et al. 1981, Shim et al. 1995a and b). Each of these methods involves the application of relatively large amounts of insecticides into the environment of the rice ecosystems. These methods also may deposit insecticidal residues in rice that can be taken inadvertently by consumers as well as farmers. Therefore, environmental concerns have stimulated other farming methods to reduce the use of insecticides for controlling pests in rice fields. One approach that has recently gained popularity is organic farming. In Korea, 0.08% of farmers cultivate several crops using organic farming, which utilizes organic fertilizers instead of chemical fertilizers and which does not use pesticides (Paek 1992).

Recently net production of salt marsh plants in Eastern Asia, Northern and Eastern Europe and the Middle East has been measured by several authors (Kim 1975, Bjoerk and Graneli 1978, Min and Kim 1983, Oh and Ihm 1983, Allirand and Gosse 1995). These results were obtained from the peak live standing crop by harvest at regular intervals. Such a method had also been applied to estimation of net production in the plant communities along the Atlantic coastal marsh (Udell et al. 1969, Marshall 1970, Jørgenson 1994). The Phragmites communis (common reed) is considered as highly productive, and has a wide global distribution, often present in wet regions as vast homogeneous expanses of reed bads (Pearcy et al. 1974, Bjoerk and Graneli 1978, Allirand and Gosse 1995). P. communis community grows mostly in fresh but also in brackish and saline water (Ondok 1973, Min and Kim 1983, Oh and Ihm 1983, Ihm et al. 2001). They are broadly distributed in the western and southern coast in Korea (Kim et al. 1982, Oh and Ihm 1983, Ihm and Lee 1998). These reeds have been utilized to produce non-food commodities, such as paper pulp, roofing and building materials, and in waste-water treatment plants (Bjoerk and Graneli 1978, Graneli 1984, Bjorndahl 1985, Allirand and Gosse 1995). The stand development and biomass production of P. communis have been studied intensively in the field (Haslam 1969a, 1969b, 1970, Dykyjova et al. 1970, Kvet 1971, Linden 1980, Dykyjova and Pribil 1975, Fiala 1976, Ho 1979). Such characteristics as CO₂ exchange and salt tolerance have been evaluated in the different locations (Purer 1942, Walker and Waygood 1968, Sieghardt 1973, Gloser 1977, Matoh et al. 1988, Cizkova and Bauer 1998, Lissner et al. 1999).

The core change of spatial development planning in 1993 was to introduce the quasi-agricultural zone by use zoning in order to ease the land use regulation (Choi 2001). Designation of quasi-agricultural zone considers development as well as reservation at the same time, but it enables to secure the use that the development is available at any time. For the past 10 years of rampant national land development, it may be attributable to the designation of quasi-agricultural zone that is ambiguous but completely exposed to "development". However, even more troublesome is that the consideration for environment in various spatial development plans was only for the “formality”. Many experts claim that the environment has been destroyed and polluted due to the development without careful planning, but none of the developments has been undertaken without planning in advance. Even the poorest planning presents the plan with much of green area that harmonizes with the surrounding scenery on its plan. However, once developed, we only see the mountains cut open with the clogging of the downstream to show our living environment in worse condition imaginable. The planning report and the policy promotion show the details to reduce the damages to the natural environment caused by development, but the actual enforcement method has yet to be proposed (KRIHS 2001). While the sceneries have been destroyed and the natural environment is damaging from various developments, the environment plan (MOE 2001a) has been making efforts for "Preservation Plan" to protect the species that have the preservation value but under the danger of extinction. And, in order to clean the polluted water and air, it has been strengthen the standard of pertinent laws and expand various environment-based facilities. However, the environment plan does not consider the removal of mountains and disappearance of forests due to the development.

China is experiencing rapid urbanization and industrial transition. The pace, depth, and magnitude of these changes, while bringing about benefits to local people, have exerted severe ecological stresses on both local human living conditions and regional life support ecosystem. Urban sustainability can only be assured with a human ecological understanding of the complex interactions among environmental, economic, political, and social/cultural factors and with careful planning and management grounded in ecological principles. Unlike biological communities, human society is a kind of artificial ecosystem dominated by human behavior, sustained by natural life support system, and vitalized by ecological process. It was named by Shijun Ma a Social-Economic-Natural Complex Ecosystem (Ma and Wang 1984). Its structure is expressed as an eco-complex between human being and its working and living settlement (including geographical, biological and artificial environs), its regional environment (including sources for material and energy, sinks for products and wastes, pools for buffering and maintaining) and its social networks (including culture, institution and technology) and economic networks (the primary, secondary and tertiary industries and infrastructural services). Its natural subsystem consists of the Chinese traditional five elements: metal (minerals), wood (living organism), water (source and sink), fire (energy), soil (nutrients and land). Its function includes production, consumption, supply, assimilation, recycling and buffering, which play a key role in sustaining the city’s complicated human ecological relationships (Fig.1). In recent years, a campaign of Ecopolis development were spontaneously initiated in some Chinese cities and towns. Ecopolis is a kind of administrative unit having economically productive and ecologically efficient industry, systematically responsible and socially harmonious culture, and physically beautiful and functionally vivid landscape. It is aimed at improving its structural coupling, metabolism process and functional sustainability through cultivating an ecologically vivid landscape (ecoscape), totally functioning production (eco-industry) and systematically responsible culture (eco-culture, Fig.2).

Drastic changes have occurred in the Japanese landscape since the Second World War because of urban sprawl, the energy revolution in agricultural communities and modernization of agricultural production systems. In mountainous areas, the national park system has played a major role in protecting natural values. However, a survey of endangered species has revealed the increasing importance of the countryside and the urban fringes. Within urban areas in Kyoto, which is surrounded by mountains, a useful analysis and a planning tool is that of island biogeography, where green areas are considered to be islands in an ‘ocean’ of built-up areas. We are facing a difficult task to maintain biodiversity in rural areas, where the diverse and cultural small ecosystems once associated with traditional land use have been destroyed. Themes of nature restoration in Japan have also changed as a result of the recognition of the biodiversity crisis. Development of adaptive management techniques will be needed both in urban and rural landscapes. Nature restoration in urban areas, where wetlands and forests once existed, is another important task for the ecologically sustainable city. Landscape ecological concepts relevant to landscape analysis, planning and implementations, based on several examples in Japan, are discussed.

Rivers and streams are one of the ecosystems that have been seriously altered by means of human activities, particularly by civil engineering works (e.g. Bravard et al. 1986, Brooks 1988, Décamps et al. 1988). A barrage constructed near river mouth seriously changes estuarine environments (Murakami 2002, Nakamura and Fujino 2002, Yamauchi 2002). Dam construction creates a new lake ecosystem in a river with resultant discontinuity of material transportation and wildlife populations such as migratory fishes (Vannote et al. 1980, Mori 1999). Stabilization of river flow and alteration of sediment transportation by dams affect not only on benthic animals but also on plant species, which depend on hydraulic characteristics and hydro-geomorphic processes in a river (Tanida and Takemon 1999, Jansson et al. 2000, Kamada et al. 2002). Flood frequency and intensity have been reduced by dam operation, and it causes woodland expansion on bars (Harris et al. 1987, Johnson 1994, Woo and Yoon 2002). Channelization changes ecological function due to degeneration of riffle-pool structure of original rivers (Brooks 1988, Nakamura et al. 1997, Nagasaka and Nakamura 1999).

It is not known well when the concept of the “Baekdudaegani” was formed and defined. Other similar concepts could be construed as being used in some old literatures, considering the fact that Koreans have traditionally treated territory configuration very important. We can find one evident record (Lim 1999) in Goryeosaii, which shows that the terrestrial stratum from Baekdu Mountain was then recognized as a kind of “flowing” of national territory. In the Joseon period, Lee Ik(1681-1763) with a literary name of Seongho and Shin Gyeong-jun(1712-1781) with a literary name of Yeoam suggested more concrete conception of the “Baekdudaegan” in Baekdujeonggan and Sansugo and Sangyeongpyoiii, respectively. From the fact that many literatures about the Baekdudaegan have been published after the mid of Joseon period, we find out that people have been interested in national territory and tried to formulate a general system of mountain ranges of the Baekdudaegan since the 18th century. The Baekdudaegan means the contiguous line of terrestrial stratum from Baekdu Mountain to Jiri Mountain without crossing valleys or streams (Yang 2002). It is the central axis of the Korean peninsula, which is connected from Baekdu Mountain, as well as the backbone of mountain ranges. The Baekdudaegan is based on Koreans’ traditional conception of geography, which highlights connected configuration of mountains as shown on the premise of ‘mountain ranges divide streams,’ rather than typical geographical conception of a mountain range. In this regard, regional boundaries and characteristics of the districts on the Baekdudaegan are identical with the mountain ridge. The Baekdudaegan has affected dominantly the formation of common and different features of administrative, cultural and living style between regions. It exits in substance in terms of geography and no doubt in spirit of the Korean people as well.

Landscape change has been largely influenced by human activities, especially in recent days. Population growth and various development activities caused significant change in landcover. Furthermore, industrialization and urbanization have created man-made barriers such as roads and railroads, which fragment ecosystems, thereby threatening biological richness and diversity. Fragmentation is recognized as one of the major anthropogenic changes of landscape. Fragmentation is defined as progressive division of large, comparatively homogeneous tracts of forest into a heterogeneous mixture of much smaller patches (Reed et al. 1996a, b). Consequences of fragmentation include habitat loss for some plant and animal species, habitat creation for others, decreased connectivity of the remaining vegetation, decreased patch size, increased distance between patches, and an increase in edge at the expense of interior habitat (Reed et al. 1996a). Change of landscape structure including fragmentation began to draw attention in ecosystem management because it is recognized that the spatial arrangement of elements in a landcover mosaic controls the ecological process which operate within it (Haines-Young et al. 1996, Ruzicka et al. 1990, Forman 1990, Forman 1995). To achieve the management goals such as conservation of species or natural resources, accurate information characterizing landscape structure and its change is critical prerequisite. However, at the level of landscape, it is very time-consuming and labor-intensive survey that spatially explicit and temporal databases are developed and managed on the basis of traditional technology. The dramatic expansion of spatial and temporal scales at which many environmental problems must be considered has presented another difficult quantitative challenge (Turner et al. 1991). Fortunately, some recent achievements in the field of landscape ecology offer an opportunity on this problem. As one of these achievements, many investigators have been trying to quantify and evaluate the landscape using landscape indices with RS (Remote Sensing) and GIS (Geographic Information System) technology (Haines-Young and Chopping 1996). The major objectives of this study were to quantify forest fragmentation in the Han River Basin, which has been subject to urbanization and road construction during the past years, from 1983 to 1996.

Since the first INTECOL Congress was held in The Hague, The Netherlands, in 1974 with the theme, “Structure, Functions and Management of Ecosystems,” subsequent Congresses have followed: 2nd INTECOL- Jerusalem (Israel) 1978, “The Future of Ecology”; 3rd INTECOL in Warsaw (Poland) was cancelled for political reasons; 4th INTECOL- Syracuse (U.S.A.) 1986, “Global Connections in Ecological Theory and Practice”; 5th INTECOL- Yokohama (Japan) 1990, “Development of Ecological Perspectives for the 21st Century”; 6th INTECOL- Manchester (U.K.) 1994, “Progress to Meet the Challenge of Environmental Change”; 7th INTECOLFlorence (Italy) 1998, “New Tasks for Ecologists after Rio 1992.” At the beginning of the 21st Century, ecological issues have never been more important both at a global scale and at a national level. The International Congresses of Ecology provided important fora to learn more about these issues, to discuss recent advances in ecological science, and to highlight deficiencies in the knowledge, which we urgently need to address. After the VII Congress in Florence, Italy, 1998, the VIII Congress in Seoul, Korea, provided an important opportunity for ecologists to continue the advancement of the science of ecology, and to learn at first hand of the many pressing problems that need to be addressed. The motto of the congress was “Ecology in a Changing World.” This paper was prepared to summarize the activities and to report the progress and achievements of the Congress.