Abstracts - IALE World Congress

Breuste, J. H.
INVESTIGATING THE ECOLOGICAL STRUCTURE OF URBAN LANDSCAPES - METHODS AND RESULTS OF GERMAN URBAN ECOLOGICAL RESEARCH

The presentation will be an overview and an evaluation of European, especially Central European research lines of the last 20 years of urban structural ecological research. The author will evaluate the theory of urban landscapes and present own results in structuring the urban landscape on examples of German cities in different scales and compare this with other European examples. There will be given outlooks to use this European method under other urban conditions.
One of the first important questions of urban ecology in Europe in the 1970's was the question of spatial distribution of investigated ecological phenomena. It could be showed that there were connections and regularities between single species, plant communities, urban soil conditions, urban climate et cetera and the urban form and inner structure. It was recognized that human impact as land use and land cover are the most important factors influencing the conditions of urban habitats. This lead to the hypothesis of determination of the urban ecological conditions by land use influences and to the theory of urban ecological units.
The investigation of urban ecological structure could be an interesting field of exchange of international experiences. The investigation and classification of the spatial distribution of human impact as most important steering factor of urban ecological conditions is a contribution to modelling the urban ecosystem and allows the comparison of different cities in the same "cultural and natural sphere" as well as of used methods for classification world wide. The European urban ecology has many traditions in urban structural investigations. This was possible by working together of several disciplines as biology, geography and landscape ecology. It could be interesting to compare the results of the experiences of the Central European School of urban ecology with experiences of other regions of the world, to check up and improve the methods in other cultural and landscape contexts.
The German urban ecology school began to develop a theory of "urban ecological units" in 1979, which is sill in widespread use and undergoing further development. It has been used in an excellent procedure of urban biotope mapping for more than hundred German cities and towns. Urban ecological units in different scales of investigation can be a useful tool not only to describe the existing ecological condition of an area but also to connect the scientific results to planning, environmental quality targets and to modern technical methods in analysing the ecological conditions of a whole city or urban landscape.
The development of methods for investigating and to describe the urban ecological structure will be explained. The used methods will be showed and explained on concrete examples of German cities and it will be explained how modern technical methods as remote sensing and Geographical Information Systems can be linked with the analysis.

Making inter-city comparisons of the direction and magnitude of variation in anthropogenic factors that control ecosystem processes can help determine which trends most cities share. Establishing such trends will help predict how remnant natural communities may respond to urban development. An urban-rural gradient approach was used to establish that greater atmospheric nitrogen (N) deposition and greater soil N production occurred in urban oak forests in New York City (population 8 million) compared to rural counterparts. Another urban-rural gradient of oak forests was established in Louisville, Kentucky USA (population 700,000) to determine whether these patterns existed in a smaller city. Similar to trends in New York, net throughfall flux of inorganic N to oak canopies was five times greater in urban than in rural forests from May-October 2002 (7.0 vs. 1.4 mmol N m-2). However, unlike New York, soil N mineralization rates were not highest in the urban forests over a similar period (14% less than rural). This unexpected result suggests that some factors controlling N-mineralization may counteract the expected stimulatory effects on this process of urban heat islands and of greater ammonium deposition. Urban forests may therefore receive proportionately more N from exogenous anthropogenic sources than do nearby rural forests.

Chapman, M.G.
REVIEW OF ENVIRONMENTAL EFFECTS OF URBANIZATION WHEN VIEWED FROM LAND OR WATER
Urbanization has many effects on natural environments. These include fragmentation of habitats into remnants, provision of new and artificial habitats, introduction of feral species, increased pollution of land, air and water and ongoing physical disturbances of large numbers of people interacting with their surroundings. Effects of urbanization have been considered far more widely in terrestrial than in marine habitats, even though many large cities are on the coast or in estuaries and therefore impact adjacent waters. In addition, the relative importance that ecologists place on different "classes" of impacts appears to reflect their background in terrestrial or aquatic ecology. Much research of urbanization in terrestrial habitats has considered isolation and connectedness of habitat fragments, addition of new built structures and introduced species. In adjacent marine waters, most research considers problems of water quality or pollution. This division of interest and emphasis, with little overlap, interaction or quantitative comparison between the two approaches, decreases our understanding of the overall ecological effects of urbanization. Here, I review selected publications in urban ecology in marine and terrestrial habitats to quantify differences in interest, methodology and analyses, to attempt to develop a more holistic approach to the ecology of urbanization.

Urban vegetation studies are useful for management and conservation purposes. Floristic and phytosociological studies were carried out in some South African cities to develop biotope maps and make vegetation information more accessible to planners and managers. Urban open spaces are, however, still over-managed due to a lack of studies focusing on the long-term monitoring of changes to plant communities in reaction to anthropogenic influences. To address this issue, the dynamics of species composition and abundance has been investigated in different anthropogenically disturbed biotopes such as pavements, managed grasslands and specific urban agricultural areas (ecocircles) in which certain management practices were changed. Quantitative studies were conducted in fixed plots over a three year period. Through multivariate data analysis techniques significant trends in vegetation dynamics were identified. These trends include changes in the abundance of certain species due to differences in chemical and physical soil characteristics and management practices such as mowing and irrigation. The results will give managers the opportunity to develop strategies to manipulate species abundances with regard to invasive exotics versus natives. To enhance the understanding of the complex disturbances in urban biotopes this research should be complimented by urbanization gradient studies linked to specific biotopes based on certain land-uses.

Artificial night lighting replacing the natural dark sky is developing more and more as a serious impact factor on nature and ecosystems. The illuminated area is fast growing from urban areas into surrounding landscapes and along coasts. A field study about the attraction of insects to standard street lamp types is presented. Insects are very sensitive to any lighting showing a special flight-to-light behavior. Three main effects have been derived from entomological observations of insect's endless turns around artificial lights: 1) 'Fixation or captivity effect', 2) 'Crash-barrier effect' and 3) 'Vacuum cleaner effect'. Additionally the importance of background illumination for the attraction of insects to lamps is described with the help of three scenarios: dark sky, moonlit sky and urban sky glow. Based on empirical catch rates and known observations about the fate of insects at lamps, insect mortality near street luminaries is estimated: a) for a medium-sized town and b) for the state area of Germany. Some considerations are presented with respect to changes of the German street light pool during the last few years, and also some negative effects of skybeamers on insects and birds are documented. In response to the increasing light pollution there is a need for permanent monitoring of the insect activity along urban gradients to detect long-term changes of the fauna. It is proposed that artificial night lighting should become part of the local Agenda 21 process, which tries to adapt the global aspects of the Rio 1992 convention to the level of municipalities and landscapes. In Germany more than 2000 municipalities take part of this process as yet which has the goal to promote sustainable development on local levels.

Abstract: Remnant vegetation in urban landscapes is often highly fragmented and subject to substantial anthropogenic disturbance. Despite this, the original and unique vegetation remaining in cities may be of high conservation value and remnants are often subjected to intensive management and active restoration efforts. We investigated the ecology of urban fragmentation of woodland habitats in the Sydney Basin bioregion of eastern Australia, focusing on arthropod assemblages and the dominant flora. We used surveys and manipulative experiments to assess how changes in invertebrate assemblages may affect levels of herbivory and seed dispersal in urban fragments. We found that disruptions to fundamental ecological processes associated with the loss of species from higher trophic levels contributed to declines in the quality of vegetation in small remnants, limiting the extent to which pre-disturbance states could be restored. Species loss, and subsequent disruptions to ecological processes, may therefore be indicative of the biotic state and health of these remnants. Our work also suggests that terrestrial invertebrates may be effective indicators of the success of restoration of ecological processes in restored bushland remnants. These findings reflect the need to consider invertebrates and their ecological roles when developing restoration and management strategies for remnant bushland in urban landscapes.

Recent change of the urban forest landscape is significantly related to decrease the area of forested land. Industrialization and urbanization have created man-made barriers such as roads and railroads, which separate ecosystems, thereby threatening habitat richness and biodiversity in the forest patch. According to quantitative landscape analyses of urban landscape change, Seoul during 1983-1996, we clarified that the developed area was extended to inner boundary of forest patches. Land transformation process usually produce source-sink patches according to several land use patters and the various biogeoecological ways. Including some naturalized plants that had been support to artificial landscape restoration, many alien plant species have been invaded to original habitat or ecosystem for native plant. Moreover, fragmented forest patch and extending developed area was source patch or corridor to transfer invaded plant species. Urban forest has multifunctional ecosystems including air, water and human health, therefore, urban forest should be major landscape element in urban landscape. In recent, many joint projects with GO and NGO to increase green-space in the urban landscape according to biotope creation and urban forest management. Especially, useful guidelines for ecological forest creation planning provided the joint projects are applied to landscape planning in many cities in Korea.

Urban planning and landscape architecture have played essential roles in shaping urban ecosystems around the world. English Picturesque and Victorian style (very eclectic in its nature) were the most influential in Europe, and colonial countries such as the United States, Australia, and New Zealand. "Park like landscape" with scattered trees on extended lawns, colorful flowerbeds with exotic plants from over the world, clipped hedges, tidy small private gardens with "emerald green" carpet lawn and street trees resulted in creating a united and homogenous design language. Using similar urban planning structures (downtown and extended suburbs in the USA, Australia and New Zealand; dense Medieval-Renaissance-Baroque-Classic core-downtown and new blocks of houses in Western and Eastern European cities), landscape design fashion, planting design (with the same plants) and similar construction materials (brick, concrete, asphalt) resulted in the appearance of similar urban habitats with similar flora and fauna. Today these modified European prototypes of meadows; woodlands and edges (lawns, parks and hedges), together with modern materials and technology serve as symbolic attributes of Western civilization. Nevertheless there is an awareness, among not only ecologists and environmentalists about losing natural biodiversity in urban landscapes through using primarily introduced plants and landscape modification, but also among landscape architects, architects and even politicians about losing social local identity and urban quality of life. The "Ecopolis" program in Russia, the Plant Signature concept in New Zealand and urban ecological problems in the comprehensive city plans in the USA could be seen as innovative tools in developing sustainable cities. Thee are a series of ecological and ethical constraints and opportunities of these approaches that will be addressed.

Although complex to quantify, urban-rural gradients are intuitively obvious - most people know what is meant by urban, suburban and rural. These gradients have proved useful for comparative studies of the ecological effects in increasing land-use intensity in urban areas. We studied communities of carabid beetles in residual forest patches along urban-suburban-rural gradients in four cities (Helsinki, Finland; Edmonton, Canada; Sofia, Bulgaria and Hiroshima, Japan) to examine their responses to urbanisation. Cluster analyses revealed distinct separation of the carabid communities along the gradient in both Helsinki and Hiroshima, but not in Edmonton and Sofia. Furthermore, our results provide some support for the predictions that species richness will decrease, that opportunistic species will gain dominance, and that small-sized species will become more numerous under disturbance such as that provided by urbanisation. Given these broad generalisations, individual cities did display city-specific carabid beetle community characteristics. For example, Edmonton was characterised by large numbers of exotic carabid species, and Hiroshima by a highly significant change in number of individuals and species across the gradient and by very distinct carabid communities in urban, suburban and rural sites. These city-specific differences are explored with reference to differences in the historical makeup of the cities and in terms of the intensity of the urbanisation gradient.

Comparative research has been an important source of enlightenment and understanding contributing to the development of ecological theory. There has been little attempt to compare the ecology of cities and towns from around the world. We explore the requirements of cross system comparisons and the potential advantages and limitations of conducting comparative analyses on urban environments. The development of comparative studies requires an understanding of the components of the systems, their geographical distribution and the critical processes connecting them in space and time. The wealth of information on the human components and processes of urban environments presents many opportunities for comparative studies. Unfortunately, there is relatively little information on the non-human components of urban environments (i.e. indigenous plant and animal communities). To overcome the lack of detailed knowledge of the plants and animal communities, researchers can utilise the concept of functional classifications of component organisms. Successful cross system comparisons are based on good questions supported by appropriate methodologies. Comparative studies of cities and towns will provide a variety of benefits including new insights into the structure and dynamics of urban ecosystems, the identification of general principles, and opportunities to address questions at the scale of entire cities.

Despite the accelerating pace of global urbanization, there is a lack of even basic data on how urbanization affects many organisms, and even less is known about how similar response patterns are across cities in different biomes. A recent surge in interest in urban ecology, however, has inspired several studies on how urban development impacts the abundance and distribution of organisms like arthropods. Research that we conducted with colleagues in Phoenix, Arizona (USA), on arthropod community composition and dynamics revealed patterns of deterministic species loss and replacement that have also been observed in other urban areas. Although the identities of the arthropod species may differ among cities, patterns of arthropod community simplification and homogenization via declines in richness are consistent and can be attributed primarily to similarities in land use (which translates to similarities in vegetative/habitat composition and structure) among cities regardless of biome. Such similar response patterns may facilitate urban planning for biodiversity conservation.

Urban landscapes are highly impacted mosaics of primary habitat, parkland, gardens, and industry, linked by modified catchment processes. Paradoxically, cities provide refugia and restoration potential for significant elements of regional biodiversity. They frequently straddle biome junctions, national pests may be absent, human and economic resources are abundant, and social impact of conservation successes is high. However, the risks and resource values of urban woodland is poorly known in New Zealand. To quantify treed environments of residential Auckland, we randomly selected 100 250 x 250-m areas, stratified into 5 classes of satellite multispectral "greenness", and subsampled front yards within them. We recorded details of all trees, soil type and pH, topography, rainfall, coastal proximity, neighbourhood and section leafiness, social factors, and toxin parameters as predictors of residential vegetation character. Preliminary results suggest a high incidence of indigenous and fleshy fruit/nectar bearing species, but also biosecurity risks. Knowledge/ interest in biodiversity varies according to location, socio-economic factors and suburb age. Our results will provide city biodiversity planners with spatial data to better target education and design/manage sustainable wildlife habitat patches, corridors and matrices, thereby contributing to urban ecological integrity and sense of place.

This project focuses on the floodplain as a complex socio-environmental system that is central to the function and structure of the Phoenix metropolitan area as an urban ecosystem and landscape. The goal of the project is to develop an integrated land-use decision making model based on systems theory and adaptive management that can be used in floodplain planning, policy, and management processes. The study will have two objectives: (1) the evaluation of the existing floodplain planning, management, and policy processes in the Phoenix metropolitan area and (2) the integration of data from the first objective into a spatially explicit system simulation and GIS model. The study will test hypotheses about a specific type of land transformation, the land-use decision-making that is associated with alternative land development policies, and its past and future effects on the spatial patterns of the floodplain landscape in the Salt River and Gila River watersheds. The emphasis is on how the decision-making of landowners, communities, and governmental agencies can influence the selection of preservation, conservation, and restoration targets as a mosaic sequence of spatial patterns in a floodplain landscape along an urban-rural transect. Three hypotheses will focus on the identification and analysis of changes and thresholds in the mosaic sequences of land use, land cover, and habitat patterns in the floodplains and watersheds from alternative landscape development policies. The findings of this study will have important implications for theory in urban landscape ecological planning and ecosystem management.

Urban gradient provide a useful laboratory for landscape ecology. Along the gradient, not only decrease habitats for animals, but their arrangement changes. We compared the response of various taxonomic groups in a big city of Japan in order to examine relationships between the abundance and arrangement of the habitats, and life history trait of the species. We will present species specific responses to habitat fragmentation. We developed multiple logistic regression models for a suite of species of birds, butterflies and ants. We also built Principal Component Regression Models to predict the species richness. Species richness decreased more rapidly in birds than ants along the urban gradient, and butterflies were intermediate. Birds were influenced by the habitat area and matrix quality. On the other hand, ants were less influenced by the habitat area, but were susceptible to the history and isolation of the habitat. Effects of habitat loss and fragmentation are different characteristics of landscape function for species existence. Simultaneously, variation of the life history influences the distribution of species. For example, Parus major can breed in urban area by using scattered trees in urban matrix; Their home range enlarge in the urban area to secure enough food.

Urban areas are highly modified and complex landscapes, within which green or open areas are seen as valuable for human well-being as well as wildlife. The biological processes of dispersal interact with the landscape structure in determining the distribution of populations of species present. Many cities have a network of habitat fragments or 'urban greenways' comprising areas of semi-natural habitats, secondary succession, ruderal and pioneer environments and open areas. These habitats may be important features for biodiversity both as stable and as transient habitats, and may also be valuable for their possible function as 'corridors' and 'stepping stones' to facilitate species dispersal. In urban landscape planning, urban greenways and wildlife corridors are increasingly advocated to encourage animals and plants to move around urban areas and thus to preserve or enhance urban biodiversity. This research aimed to analyse the extent to which invertebrates utilise the 'urban areas' by undertaking research into the ecological characteristics of the biota of cities, and the effects of habitat fragment size and connectivity upon the ecological diversity and individual species distributions.

The presentation will describe the urban ecological research of the Alterra-team for Urban-Rural Relations. During the past five years the team applied landscape ecological principles on urban ecological topics in a innovative way. This research happens to be successful because a number of basic principles are taken into account: i) It is important to fit a monofunctional view (ecology of plants & animals) in a multifunctional approach, ii) Do not lose sight of reality but also do not let the current views on urban nature interfere too much, iii) It is through unexpected combinations of functions that opportunities are created for nature and iv) Approach the opportunities that nature provides in a specific situation particularly by considering ecological conditions and not so much based on designation, function or current use. This successfull approach will be described on the basis of several case studies and enters in detail into five innovative urban-rural concepts as regards the interaction between man and nature. Perhaps the most surprising of them is the design of multilevel highway wild passage, including several levels of offices and an ecological corridor on the roof.

Zipperer, Wayne
VEGETATION PATTERNS OF UPLAND AND RIPARIAN FOREST PATCHES ALONG URBAN-RURAL GRADIENTS.

Urban-rural gradients have been used to assess the responses of ecosystems to varying degrees of urbanization. I used literature data from Milwaukee, Wisconsin (remnant-upland) and New York, New York (remnant-upland) and unpublished data from Baltimore, Maryland (remnant-upland and riparian) and Syracuse, New York (remnant and reforested-upland) to summarize vegetation patterns of forest patches along urban-rural gradients. Structurally, tree-stem densities increased with urbanization with opportunistic tree-species accounted for the increase in density. For upland forest patches, the largest diameter trees were found in the urban landscape. For riparian landscapes, they occurred in the rural landscape. Non-native species richness and non-native tree, seedling and herbaceous stem densities increased with urbanization. Non-native shrub density varied by patch type. Non-native shrub density in riparian patches decreased from rural to urban. Riparian and reforested patches also showed compositional shifts. In riparian forest patches, species shifted from a wetland to an upland composition with urbanization. In rural reforested patches, native species dominated the canopy, whereas in urban reforested patches, non-native species dominated. Structural and compositional shifts were attributed to patch size, disturbance regime, altered moisture regime, and site legacy, and may indicate that urban forest patches are undergoing major changes.

Back to Abstracts