Ulla Mörtberg

A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers.

Urbanization contributes to the loss of the worlds biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the worlds cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

Red-listed forest bird species in an urban environment — assessment of green space corridors

The aim of this work was to investigate if the forest remnants of the city and the system of green space corridors could support target species for conservation, in the form of red-listed forest bird species, to show through the presence of the target species what habitat qualities are still possible near cities, and to reveal those features and properties of the landscape structure that were important in this sense. The findings could be used for developing guidelines for design of urban green space corridors. A spatial analysis was performed, covering the landscape in the study area and 67 sample sites with natural vegetation, within and outside of the green space corridors. Breeding forest birds were recorded and breeding of target species in the sample sites as functions of landscape descriptors was tested using logistic regression. Seven red-listed forest bird species were found breeding in the sample sites. Considering them as indicators of habitat qualities, the results would imply that the qualities of the urban and suburban forests were due to a vast range of deciduous forest, especially broad-leaved, and possibly also to a lower intensity of forestry than in rural areas, resulting in a sufficient number of mature and decaying trees. The logistic regression models showed that important properties of remnants of natural vegetation were large areas of forest on rich soils, together with connectivity in the form of amounts of this habitat in the landscape. These properties were associated with the green space corridors. Implications for the design of urban green space corridors would be to treat mature and decaying trees and patches of moist deciduous forest as a resource for vulnerable species, and to conserve large areas of natural vegetation together with a network of important habitats in the whole landscape, in this case forest on rich soils, also in built-up areas.

Governance of Water Resources in the Phase of Change : A Case Study of the Implementation of the EU Water Framework Directive in Sweden

In this article, focusing on the ongoing implementation of the EU Water Framework Directive, we analyze some of the opportunities and challenges for a sustainable governance of water resources from an ecosystem management perspective. In the face of uncertainty and change, the ecosystem approach as a holistic and integrated management framework is increasingly recognized. The ongoing implementation of the Water Framework Directive (WFD) could be viewed as a reorganization phase in the process of change in institutional arrangements and ecosystems. In this case study from the Northern Baltic Sea River Basin District, Sweden, we focus in particular on data and information management from a multi-level governance perspective from the local stakeholder to the River Basin level. We apply a document analysis, hydrological mapping, and GIS models to analyze some of the institutional framework created for the implementation of the WFD. The study underlines the importance of institutional arrangements that can handle variability of local situations and trade-offs between solutions and priorities on different hierarchical levels.

Urban ecosystems and sustainable urban development-analysing and assessing interacting systems in the Stockholm region

In order to build competence for sustainability analysis and assessment of urban systems, it is seen as essential to build on models representing urban form, landuse and transportation, urban metabolism, as well as ecological processes. This type of analysis of interacting sub-systems requires an advanced model integration platform, yet open for learning and for further development. Moreover, since the aim is to increase urban experience with ecosystem management in the wide sense, the platform needs to be open and easily available, with high visualisation capacity. For this purpose, the LEAM model was applied to the Stockholm Region and two potential future scenarios were developed, resulting from alternative policies. The scenarios differed widely and the dense urban development of Scenario Compact could be visualised, destroying much of the Greenstructure of Stockholm, while Scenario Urban Nature steered the development more to outer suburbs and some sprawl. For demonstration of the need for further development of biodiversity assessment models, a network model tied to a prioritised ecological profile was applied and altered by the scenarios. It could be shown that the Greenstructure did not support this profile very well. Thus, there is a need for dynamic models for negotiations, finding alternative solutions and interacting with other models. The LEAM Stockholm case study is planned to be further developed, to interact with more advanced transport and land use models, as well as analysing energy systems and urban water issues. This will enable integrated sustainability analysis and assessment of complex urban systems, for integration in the planning process in Stockholm as well as for comparative sustainability studies between different cities, with the goal to build more sustainable urban systems and to increase urban experiences in ecosystem management.

IMPACTS OF REGION-WIDE URBAN DEVELOPMENT ON BIODIVERSITY IN STRATEGIC ENVIRONMENTAL ASSESSMENT

In urbanising regions, urban sprawl and infrastructure cause profound alterations of natural habitats. Initial decisions on urban expansion and major infrastructure investments are often made on a strategic level where the long-term development of a region is determined. For these types of decisions a strategic environmental assessment can be prepared. However, the lack of an adequate conceptual and methodological framework can pose a major problem for the prediction of impacts, not least concerning biodiversity. This paper will highlight the need for effective methods for biodiversity analysis at landscape and regional levels, with reference to the long-term urban development of the Stockholm and Malaren regions. Problems of habitat loss, fragmentation and other impacts related to large-scale urbanisation and infrastructure developments will be addressed. GIS-based methods focusing on predictive ecological modelling will be discussed in a scenario context. The implementation of such methodologies in the strategic environmental assessment process would allow a better integration of biodiversity in planning and decision-making, further promoting a sustainable planning system.

Distinction, quantification and mapping of potential and realized supply-demand of flow-dependent ecosystem services

This study addresses and conceptualizes the possible dependence of ecosystem services on prevailing air and/or water flow processes and conditions, and particularly on the trajectories and associated spatial reach of these flows in carrying services from supply to demand areas in the landscape. The present conceptualization considers and accounts for such flow-dependence in terms of potential and actually realized service supply and demand, which may generally differ and must therefore be distinguished due to and accounting for the prevailing conditions of service carrier flows. We here concretize and quantify such flow-dependence for a specific landscape case (the Stockholm region, Sweden) and for two examples of regulating ecosystem services: local climate regulation and storm water regulation. For these service and landscape examples, we identify, quantify and map key areas of potential and realized service supply and demand, based for the former (potential) on prevailing relatively static types of landscape conditions (such as land-cover/use, soil type and demographics), and for the latter (realized) on relevant carrier air and water flows. These first-order quantification examples constitute first steps towards further development of generally needed such flow-dependence assessments for various types of ecosystem services in different landscapes over the world.

Effects of Different Retention Parameter Estimation Methods on the Prediction of Surface Runoff Using the SCS Curve Number Method

Quantifying different hydrological components is an initial step for sustainable water resources planning and management. One rising concern is the conflict between the environment, hydropower and agriculture mainly in lowland areas where a large share of the base flows need to be abstracted. The Soil and Water Assessment Tool (SWAT) model was used to understand the hydrological processes of the Upper Awash River Basin with the emphasis on analyzing the different options for surface runoff generation using the Soil Conservation Service (SCS) Curve Number (CN) method. In this study, SWAT was applied incorporating two methods for estimating the retention parameter (S) for the SCS-CN method. The first allowed S to vary with soil profile moisture content (SM method) and the second allowed S to vary with accumulated plant evapotranspiration (PT method). Hydrograph comparison indicated that the PT method was better in simulating peak flows while the SM method was better in simulating the low flows. While the predicted stream flow hydrographs showed an agreement between the two methods, the simulated annual water balance indicated a disagreement in quantifying the different hydrological components. After evapotranspiration, base flow was the dominant component simulated in the SM method whereas surface runoff was the foremost in the PT method simulation. The analysis indicated that care must be taken when selecting an appropriate tool for quantifying hydrologic system to be used for decision making especially for un-gauged catchments where validation of model results is not possible.

URBAN LANDSCAPES IN TRANSITION, LESSONS FROM INTEGRATING BIODIVERSITY AND HABITAT MODELLING IN PLANNING

Sustainable urban development has been widely recognized as requiring energy and transport efficient urban growth, while ecological issues are often not well integrated in sustainability assessments and Strategic Environmental Assessment (SEA). In order to achieve such integration, methods and tools based on Geographic Information Systems (GIS) in a Landscape Ecological Assessment (LEA) framework were developed and integrated in planning in four case studies in and around the city of Stockholm, Sweden. This involved the application of recently developed methods for impact prediction and for integration into the planning processes. The aim of the study was to compare the case studies concerning strengths and weaknesses of LEA and its GIS-based components. The methodology enabled identification of important structures in the landscape to support biodiversity, across administrative borders. The LEA facilitated discussions on consequences of alternatives for localisation of built-up areas, infrastructure and other developments as well as management. The GIS-based LEA approach could thus contribute to a sustainable urban development with consideration of the landscape-level biodiversity values integrated with energy-efficient urban growth trajectories.

Prevalence of microbiological contaminants in groundwater sources and risk factor assessment in Juba, South Sudan

In low-income regions, drinking water is often derived from groundwater sources, which might spread diarrheal disease if they are microbiologically polluted. This study aimed to investigate the occurrence of fecal contamination in 147 improved groundwater sources in Juba, South Sudan and to assess potential contributing risk factors, based on bivariate statistical analysis. Thermotolerant coliforms (TTCs) were detected in 66% of the investigated sources, including 95 boreholes, breaching the health-based recommendations for drinking water. A significant association (p<0.05) was determined between the presence of TTCs and the depth of cumulative, long-term prior precipitation (both within the previous five days and within the past month). No such link was found to short-term rainfall, the presence of latrines or damages in the borehole apron. However, the risk factor analysis further suggested, to a lesser degree, that the local topography and on-site hygiene were additionally significant. In summary, the analysis indicated that an important contamination mechanism was fecal pollution of the contributing groundwater, which was unlikely due to the presence of latrines; instead, infiltration from contaminated surface water was more probable. The reduction in fecal sources in the environment in Juba is thus recommended, for example, through constructing latrines or designating protection areas near water sources. The study results contribute to the understanding of microbiological contamination of groundwater sources in areas with low incomes and high population densities, tropical climates and weathered basement complex environments, which are common in urban sub-Saharan Africa.

Locating suitable sites for the construction of subsurface dams using GIS

Subsurface dams constitute an affordable and effective method for the sustainable development and management of groundwater resources when constructed on suitable sites. Such dams have rarely been constructed in crystalline rock areas and to best of our knowledge, geographic information system (GIS) has never been used in any methodology for locating suitable sites for constructing these dams. This paper presents a new methodology to locate suitable sites for the construction of subsurface dams using GIS software supported by groundwater balance modelling in a study area Boda-Kalvsvik, Sweden. Groundwater resources were calculated based on digitized geological data and assumptions regarding stratigraphic layering taken from well archive data and geological maps. These estimates were then compared with future extractions for domestic water supply using a temporally dynamic water balance model. Suitability analyses for subsurface dams were based on calculated topographic wetness index (TWI) values and geological data, including stratigraphic information. Groundwater balance calculations indicated that many of the most populated areas were susceptible to frequent water supply shortages. Of the 34 sub-catchments within the study area: ten were over-extracted, nine did not have any water supply demand at all, one was self-sufficient and the remaining 14 were able to meet the water supply demand with surplus storage capacity. Six suitable sites for the construction of subsurface dams were suggested in the vicinity of the over-extracted sites based on suitability analysis and groundwater balance estimates. The new methodology shows encouraging results for regions with humid climate but having limited natural water storage capacities. The developed methodology can be used as a preliminary planning step for subsurface dam construction, establishing a base for more detailed field investigations.