One Ecosystem :
Research Article
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Corresponding author: Stoyan Nedkov (snedkov@abv.bg)
Academic editor: Benjamin Burkhard
Received: 13 Jun 2017 | Accepted: 27 Nov 2017 | Published: 04 Dec 2017
© 2017 Stoyan Nedkov, Miglena Zhiyanski, Stelian Dimitrov, Bilyana Borisova, Anton Popov, Ivo Ihtimanski, Rositsa Yaneva, Petar Nikolov, Svetla Bratanova-Doncheva
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Nedkov S, Zhiyanski M, Dimitrov S, Borisova B, Popov A, Ihtimanski I, Yaneva R, Nikolov P, Bratanova-Doncheva S (2017) Mapping and assessment of urban ecosystem condition and services using integrated index of spatial structure. One Ecosystem 2: e14499. https://doi.org/10.3897/oneeco.2.e14499
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Urban ecosystems are the areas where built infrastructure covers a large proportion of the land surface but the main source of ecosystem services provision is the green infrastructure. This provision is very much dependent on the particular combination of green spaces such as parks or vegetation belts and paved areas such as buildings and streets. The spatial arrangement of these elements is an important parameter which could be used for the assessment of the ecosystem condition in the urban areas. An integrated index of spatial structure is proposed which incorporates built types and land cover from the Local Climate Zones (LCZ) concept with urban ecosystems' classes developed on the basis of MAES typology. An algorithm has been developed for index generation using an urban ecosystems' database and remote sensing data. The index is used to define vegetation cover in urban ecosystems and assess their condition as a part of the assessment framework. It is also applied in the assessment of several ecosystem services through quantification of ecosystem services' indicators or as an indicator in a complex assessment. The results show that, although most urban ecosystems in Bulgaria are assessed as moderate and good condition, very few of them have very good condition and about 3.5% have very bad condition. The highest scores are defined for urban green areas while the lowest are for transport networks. The use of an integrated index in urban ecosystem services' assessment is represented by examples for global and local climate regulation. The results are used to develop maps of ecosystem services supply capacity for selected cities. The overall analysis indicates that the urban ecosystems in Bulgaria have a moderate to good capacity for local climate regulation and moderate to low capacity for global climate regulation. The integrated index of spatial structure provides an appropriate basis for characterisation and assessment of the urban ecosystems condition and ecosystem services following the requirements of the EU Biodiversity Strategy and the MAES process. The proposed approach enables the internal heterogeneity of the urban ecosystems at national level to be defined, this being one of the main challenges in studying urban ecological systems.
Urban ecosystems, MAES, green infrastructure, land cover, built type, carbon storage, climate regulation
Ecosystem services (ES) are defined as “the contributions of ecosystem structure and functions, in combination with other inputs, to human well-being” (
Following the MAES framework, a methodology for mapping and assessment of urban ecosystems and their services in Bulgaria was developed (
However, the implementation of the methodology in practice encounters particular problems related to the identification of vegetation cover and the availability of spatial data. Firstly, the applied ecosystem classification does not reveal some important spatial aspects of the urban ecosystems. For instance, the class "urban green areas" covers all urban green spaces larger than 0.25ha, but they can be urban tree park, grass field or a meadow in the suburban area. These three kinds of green area are characterised by different structures and functions as well as by the services they provide which could not be differentiated using the existing classification. Secondly, most spatial data sources for the assessment of ecosystem condition and services are referred to small scale which could not reveal the heterogeneity of the urban ecosystems. Furthermore, the vegetation cover indicator could not be calculated as there are tens of thousands of individual polygons in the database.
One possible solution for solving these problems is to include an additional spatial index which is based on urban morphology and can reveal the internal heterogeneity of the urban ecosystems. Urban morphology is the application of a diverse range of scientific approaches, aimed at creation of a particular thematic land cover classification and providing specific spatial information in support of urban management and planning.
The spatial heterogeneity in urban systems is an important issue as the urban land cover is clearly heterogeneous and the heterogeneity itself is a core ecological concept and plays a role in the functioning of the systems (
In this context, the following main objectives were defined for this paper:
- to present a new indicator for urban ecosystem assessment – integrated index of spatial structure
- to assess the condition of urban ecosystems in Bulgaria using this index
- to test its application in urban ecosystem services' assessment
The methodology for mapping and assessment of urban ecosystems is part of the national methodological framework which aims to streamline the national ecosystems and ecosystem mapping and biophysical assessment processes in Bulgaria (
Level 1 |
Terrestrial |
Level 2 (Type) |
Urban |
Level 3 (subtype) |
J1. Residential and public areas of cities and towns |
J2. Suburban areas |
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J3. Residential and public low density areas |
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J4. Recreation area outside cities and towns |
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J5. Urban green areas (incl. sport and leisure facilities) |
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J6. Industrial sites (incl. commercial sites) |
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J7. Transport networks and other constructed hard surfaced sites |
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J8. Extractive industrial sites (incl. active underground mines and active opencast mineral extraction sites and quarries) |
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J9. Waste deposits |
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J10. Highly artificial man made waters and associated structures |
The assessment of an ecosystem condition is measured by a set of indicators which are organised in a system based on the concept of ecosystem integrity. It is defined as “supporting and maintaining a balanced, integrated adaptive community of organisms having a species composition, diversity and functional organisation comparable to that of a natural habitat of the region” (
The final step of the whole process is the assessment of ecosystem services in urban areas. The identification of ecosystem services is based on CICES classification (
The assessment of ecosystems in Bulgaria under the Biodiversity Strategy and MAES process is implemented through a funding scheme with two main lines, one of them being directed to NATURA 2000 zones and the other for the rest of the country. As the current study is part of the mapping and assessment activities outside NATURA 2000 zones, the mapping is performed in all urban ecosystems outside protected areas. The delineation of urban ecosystems was performed in two steps. Firstly, the extent of urban ecosystems, corresponding to level 2 of the typology, was outlined and then the resulting polygons were divided into ecosystem subtypes corresponding to the more detailed level 3 of the classification. This process necessitates detailed spatial data which is not available as one single database; therefore different data sources were used. The restored property plan database was used as a main source for delineation of ecosystems at level 2. This is the most precise spatial database for the land use types in urban areas available for the whole country, therefore it was used as a reference layer to delineate the extent of urban ecosystems in Bulgaria. Then, the NATURA 2000 areas were excluded from the database. Thus, the area for the current study was defined to 5301.7km2, which is about 94% of all urban areas in the country. It includes 235 cities and towns, 4555 villages and 59 other places such as resorts, holiday villages, open-pit mines etc. For delineation of the ecosystems at level 3, a flexible spatial approach was developed (
As mentioned above, the assessment of the urban ecosystems' condition is based on a set of indicators which represent different aspects of the ecosystem integrity. Ecosystem structure indicators are divided into biotic and abiotic. The latter consists of several groups including soil heterogeneity, hydrological heterogeneity, air heterogeneity, geomorphological heterogeneity, disturbance regime and other abiotic heterogeneity indicators (
LCZ is based on the assumption that each city is unique with respect to its geographical location and setting, cultural history and architectural expression (
Built types and land cover types (after
Built Types |
Definition |
Land cover types |
Definition |
1. Compact high-rise |
Dense mix of tall buildings to tens of storeys. |
A. Dense trees |
Heavily wooded landscape of deciduous and/or evergreen trees. |
2. Compact mid- rise |
Dense mix of mid-rise buildings (3–9 storeys). |
B. Scattered trees |
Lightly wooded landscape of deciduous and/or evergreen trees. |
3. Compact low-rise |
Dense mix of low-rise buildings (1–3 storeys). |
C. Bush, shrub |
Open arrangement of bushes, shrubs and short, woody trees. |
4. Open high-rise |
Open arrangement of tall buildings to tens of storeys. |
D. Low plants |
Featureless landscape of grass or herbaceous plants/crops. |
5. Open mid-rise |
Open arrangement of midrise buildings (3–9 storeys). |
E. Bare rock or paved |
Featureless landscape of rock or paved cover. |
6. Open low-rise |
Open arrangement of low-rise buildings (1–3 storeys). |
F. Bare soil or sand |
Featureless landscape of soil or sand cover. |
7. Lightweight low-rise |
Dense mix of single-storey buildings. |
G. Water |
Large, open water bodies such as seas and lakes, or small bodies such as rivers, reservoirs and lagoons. |
8. Large low-rise |
Open arrangement of large low-rise buildings (1–3 storeys). |
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9. Sparsely built |
Sparse arrangement of small or medium-sized buildings in a natural setting. |
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10. Heavy industry |
Low-rise and mid-rise industrial structures (towers, tanks, stacks). |
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11. No buildings |
Open areas with no built structures |
The application of the integrated index of spatial structure in mapping and assessment of urban ecosystems necessitates generation of the index for each polygon of the database i.e. for each single urban ecosystem in Bulgaria. The generation of the spatial index is a result of several repetitive procedures including GIS-based analyses and visual interpretation of orthophoto images (Fig.
The process of land cover and built types identification was performed using ArcGIS software and the ecosystems database. The codes of built and land cover types were stored in separate columns in the attribute table. Thus, the three elements of the integrated index (ecosystem sub-type, built type and land cover type) were recorded in the database and then it was generated using a Python string script. This structure enables easy and repetitive verification of the index’s elements which is very important for such extensive databases. The data verification was performed by a field study in representative sites where all three elements were checked. As a result of these procedures, 532 different combinations of the index were identified. As some of them were represented in a single or limited number of polygons with limited area, a generalisation procedure was performed. All indices found in less than 5 polygons and with an area less than 5ha were selected and analysed. Most of them were transformed to indices with similar structure and only combinations that represent specific urban ecosystems were left. For instance, the indices of waste deposits (J9) were left because they were represented in limited areas and most of them had unique land cover which could not be easily attributed to another index.
The urban ecosystem condition is assessed by a set of indicators whose parameters should be measured by particular quantitative units. As some of these indicators have not been supplied by an appropriate dataset at national level, other approaches were needed. The integrated index of spatial structure could be used as an appropriate tool for generation of the necessary data. The vegetation cover is one of the most important ecosystem condition indicators representing the plant diversity group of the biotic heterogeneity. It is measured as the percentage of green areas (green infrastructure) within the urban ecosystems which means that it should be defined for each polygon of the database (
The integrated index of spatial structure, as a part of the ecosystem condition assessment framework, is an indicator that represents the abiotic heterogeneity of the urban ecosystems. The indicators of ecosystem condition should illustrate the cumulative effect of pressures on ecosystems over time (
Expert assessment scores of the urban ecosystem condition as a combination of built types and urban land cover (built type and land cover codes are given in Table
Built types |
Urban land cover |
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A |
B |
C |
D |
E |
F |
G |
|
2 |
3 |
2 |
2 |
1 |
1 |
2 |
|
3 |
3 |
2 |
2 |
1 |
1 |
2 |
|
4 |
4 |
3 |
2 |
2 |
1 |
1 |
2 |
5 |
4 |
3 |
2 |
2 |
1 |
1 |
2 |
6 |
4 |
3 |
2 |
2 |
1 |
1 |
3 |
7 |
3 |
2 |
2 |
1 |
1 |
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8 |
3 |
3 |
2 |
2 |
1 |
1 |
2 |
9 |
3 |
2 |
2 |
1 |
1 |
3 |
|
10 |
3 |
2 |
2 |
1 |
1 |
3 |
|
11 |
5 |
4 |
3 |
3 |
1 |
2 |
4 |
The impact of different funtional aspects of the ecosystem sub-types was added through weighted coefficients which range from 1 for J5 (green areas functioning as closest to natural) to 0.6 for J6 (functioning industrial areas generate highest pressure). Furthermore, weighted coefficients were assigned to different land cover combinations in order to reflect different proportions of green and paved areas. Thus, combination EBD gets a lower weighting than BDE because the share of green areas in the first is lower. The final assessment of each index is calculated through the formula:
\(Asp= ((∑a,b,c…n/n*WLc))We\) (1)
where: Asp - ecosystem condition assessment; a, b, c - urban land cover types for particular build type from Table 3; n – number of land cover types; Wlc – weighted coefficient of land cover combination; We – weighted coefficient of ecosystem sub-type.
The condition of ecosystems is a key component for their potential to deliver economic benefits to people. However, the regions for which ecosystems provide benefit for both biodiversity and ecosystem services cannot be identified unless the ecosystem condition and services can be quantified and their areas of production mapped (
Ecosystem services' provision depends on the physical, chemical and biological condition of an ecosystem and one of the important further steps in the MAES framework is to devise a method for linking the condition of the ecosystem types to the supply of ecosystem services (
Quantification of ES indicators |
Indicator in complex assessments |
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Ecosystem services |
Indicators |
Ecosystem services |
Indicators for complex assessment |
Fibres and other materials |
Above-ground biomass |
Cultivated crops |
Soil productivity, environmental condition, integrated index of spatial structure |
Air quality regulation |
Air pollutants capture |
Surface water for non-drinking purposes |
Precipitation, potential evapotranspiration, integrated index of spatial structure |
Global climate regulation |
Above ground carbon storage |
Erosion regulation |
Vegetation cover, soil sealing, integrated index of spatial structure |
Flood regulation |
Vegetation cover, urban runoff index, soil moisture, integrated index of spatial structure |
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Pest and disease control |
Vegetation cover, integrated index of spatial structure, risk to atmospheric drought |
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Local climate regulation |
integrated index of spatial structure, vegetation cover, water bodies |
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Soil formation and composition |
integrated index of spatial structure, climate, topography, vegetation cover, organic matter etc. |
Although global climate regulation can be assessed using different indicators, the common indicators are carbon storage and carbon sequestration (
Another application of the proposed index is in the complex ecosystem services assessment (Table
Maps of ecosystem services were produced using the same general approach presented in the previous section. The capacities of the ecosystems to deliver ecosystem services were assessed on a relative scale ranging from 0 to 5 (after
The application of the proposed approach for the urban ecosystems outside NATURA 2000 zones in Bulgaria resulted in identification of the spatial index for each single polygon in the database. The results show that there are 364 unique combinations of the index (see appendix 2), which are not equally distributed amongst different ecosystem subtypes (Table
Ecosystem sub-types |
Number of combinations |
% |
Number of polygons |
% |
Area (ha) |
% |
J1 |
41 |
11.3% |
1684 |
2.1% |
27796.4 |
5.2% |
J2 |
16 |
4.4% |
376 |
0.5% |
8486.5 |
1.6% |
J3 |
60 |
16.5% |
28326 |
35.6% |
311697.0 |
58.8% |
J4 |
22 |
6.0% |
460 |
0.6% |
3276.7 |
0.6% |
J5 |
57 |
15.7% |
17059 |
21.4% |
50113.0 |
9.5% |
J6 |
89 |
24.5% |
14007 |
17.6% |
82761.8 |
15.6% |
J7 |
13 |
3.6% |
8511 |
10.7% |
22548.6 |
4.3% |
J8 |
25 |
6.9% |
304 |
0.4% |
20127.1 |
3.8% |
J9 |
27 |
7.4% |
247 |
0.3% |
2163.2 |
0.4% |
J10 |
14 |
3.8% |
451 |
0.6% |
1199.7 |
0.2% |
The most common index combination by far is J36BDE (Table
Index |
Number of polygons |
Area (ha) |
Average area of polygon (ha) |
Percent |
J36BDE |
13861 |
233386.29 |
16.84 |
44.02% |
J68BDE |
5264 |
39801.85 |
7.56 |
7.51% |
J39BDE |
3693 |
23276.43 |
6.30 |
4.39% |
J36BD |
3307 |
22335.06 |
6.75 |
4.21% |
J711E |
7366 |
16029.30 |
2.18 |
3.02% |
J68DE |
3238 |
13722.85 |
4.24 |
2.59% |
J15BDE |
544 |
12794.87 |
23.52 |
2.41% |
J511BD |
5530 |
12706.89 |
2.30 |
2.40% |
J811DF |
49 |
12089.57 |
246.73 |
2.28% |
J511BDE |
4037 |
11152.94 |
2.76 |
2.10% |
J39BD |
3951 |
9513.28 |
2.41 |
1.79% |
J610BDE |
246 |
6894.74 |
28.03 |
1.30% |
J26BDE |
228 |
6816.01 |
29.89 |
1.29% |
J16BDE |
401 |
5547.18 |
13.83 |
1.05% |
The generation of the index of spatial structure and the identification of green areas for each index combination enable the vegetation cover for each polygon of the database to be defined. The results showed that most of the urban ecosystems in Bulgaria have vegetation cover above 50% (Table
Vegetation cover (%) |
Number of polygons |
Area (ha) |
Percent |
0 |
8073 |
20041.1 |
3.7% |
1 - 25 |
1567 |
21273.7 |
4.0% |
25-50 |
5350 |
45782.7 |
8.6% |
51-75 |
21840 |
315210.2 |
59.4% |
76-100 |
34595 |
127861.9 |
24.1% |
The condition of urban ecosystems measured by the integrated index of spatial structure represents a complex assessment of an ecosystem’s characteristics related to the spatial arrangements of built and land cover types in combination with particular ecosystem sub-type. The calculation of formula 1 in GIS resulted in generation of an assessment score for each polygon in the database. The results show that most urban ecosystems in the country are assessed as moderate (score 3) and good (score 4) condition (Table
Urban ecosystems condition based on the integrated index of spatial structure.
Condition |
Area (ha) |
Percent |
1 – very bad |
18071,7 |
3,4% |
2 – bad |
46133,7 |
8,7% |
3 - moderate |
398330,4 |
75,1% |
4 – good |
60245,8 |
11,3% |
5 – very good |
7388,0 |
1,3% |
The condition of the ecosystem subtypes is calculated as the average score of all polygons from their respective subtypes and the results are presented in Table
Condition of urban ecosystem subtypes based on the integrated index of spatial structure.
Ecosystem sub-type |
J1 |
J2 |
J3 |
J4 |
J5 |
J6 |
J7 |
J8 |
J9 |
J10 |
Condition |
Moderate |
Moderate |
Moderate |
Good |
Good |
Moderate |
Very bad |
Bad |
Bad |
Good |
2.5 |
3.4 |
3.2 |
3.6 |
3.9 |
2.8 |
1.2 |
2.1 |
1,6 |
3,8 |
Maps of the urban ecosystem condition at scale 1:125 000 have been prepared for the whole country using the GIS database of the ecosystem subtypes and assessment results (Fig.
The maps in Fig.
The application of the proposed approach for the urban ecosystems outside NATURA 2000 zones in Bulgaria resulted in identification of the spatial index for each single polygon in the database. The results showed that there were 364 unique combinations of the index (see Suppl. material
The most common index combination by far was J36BDE (Table
The urban ecosystem services assessment framework in Bulgaria developed by
The global climate regulation ecosystem service is represented by the carbon storage capacity of urban ecosystems. The overall analysis at national level indicates an even distribution of the areas with low, moderate and high capacities which cover respectively 25%, 28% and 31% of whole urban ecosystems area. Only 5% have no capacity, 2% have very low cpacity and 9% have very high capacity. Urban green areas (J5) have the highest capacity of 4.0, followed by low density residential areas (J3) with 3.3 and recreation areas outside cities (J4) with 2.9. The lowest average score (0.2) is for transport networks (J7). Extractive sites and waste deposits have very low capacity of 1.4 and 1.3 respectively. The selected cities (Fig.
The overall analysis of the results indicated that the Bulgarian urban ecosystems had a moderate to good capacity for local and regional climate regulation. The spatial distribution of this ecosystem service showed that the most widespread urban ecosystem subtype in Bulgaria - J3 (Residential and public low density areas), was characterised by a high capacity (60% of cases). J1 was rated with moderate capacity (over 70%) and, only in district centres, the number of polygons with score “low” increased. Subtypes J2 and J4 were rated with high capacity (over 80%). As expected, the greatest effect was obtained within the range of polygons of Urban green areas (J5 – “very good”). These results were due to natural factors (geographic conditions - heterogeneous landscapes, favourable climate balances and significant presence of deciduous vegetation) as well as anthropogenic factors - historical traditions in the establishment and enlargement of settlements and the character of building process with significant participation of yards, gardens and other green areas in the landscape pattern. The results for J6 (industrial sites, including commercial sites) indicated that under 20% of the polygons were of low capacity and over 50% were of moderate capacity. These outcomes can be explained by the depopulation trend which leads to reduction of economic activity and occurrence of self-restoration processes in the landscapes. The distribution of local climate regulation capacity in the selected cities is given in Fig.
The proposed approach gives an opportunity to reveal some important aspects of the spatial structure of urban ecosystems at national level. In this study, data sources were used that are specific for Bulgaria such as restored property plans or the city cadastre which are not available for other European cities. However, it is possible to use alternative sources in other countries and furthermore the delineation of ecosystem subtypes is possible also by using only satellite or orthophoto images. They can be used as a source for visual interpretation and identification of built and land cover types within predefined urban ecosystems in a vector polygon format. The approach is useful for a national ecosystem assessment which necessitates identification and evaluation of great numbers of spatial units in large areas. The visual interpretation is a time- and labour-consuming method but enables identification of site specific features which are very important for correct definition of the built and land cover types. Thus, it can be used as an effective tool in meeting the requirements of the EU Biodiversity Strategy to 2020 and the implementation of MAES urban ecosystem assessment framework (
As urban condition is dependent on many factors, the combination of built types and land cover types in urban territories is an informative complex indicator for assessing the condition of specific subtypes of urban ecosystems. The integrated index of spatial structure can be used as an indicator for the ecosystem condition as well as to support the quantification of other important indicators such as vegetation cover, soil sealing and fragmentation of green infrastructure. It can also be used effectively in ecosystem services' assessment. The results obtained for local climate regulation has the potential to meet the important issues in relation to landscape and urban planning and management by providing answers to the following questions: (i) where are the hotspots of the analysed ES in the current configuration and the composition of the Green Infrastructure (GI); (ii) what is the potential of GI to influence local climate in particular locations of importance to the development of the town – e.g. trade centres, transport hubs, social institutions, densely populated residential areas etc. and (iii) where should further improvement of GI be targeted to strengthen the supply of analysed ES? The resulting maps will increase public understanding and enables greater participation in public hearings and discussions.
In the process of implementation of the proposed index in the national assessment and mapping, some limitations were observed. The identification of the index was performed on the basis of preliminary delineated polygons representing urban ecosystems. This predefined dominance of mixed land cover types as the polygons delineation did not take into account the character of the vegetation. The identification of built types, based on the principle of dominance, ignored the existence of some built types which led to another source of uncertainty. For large scale urban ecosystems mapping, it is better to perform ecosystems delineation and index identification in parallel, thus providing more precise results. A comparison of these results, with much more detailed mapping, will provide sufficient data for uncertainty analysis and further improvement of the approach.
The scores of ecosystem services were relevant only for urban ecosystems in Bulgaria. For instance, very high capacity of carbon storage supply was assigned to ecosystems which have from 123 to 266tC/ha. Although the latter figure was the highest amount calculated for the urban ecosystems in Bulgaria, in forest ecosystems, this figure could be higher and the scoring scheme would be different. The same problem could arise at sub-national, continental or global scale.
For territorial and urban planning purposes (especially from national to regional scale of analysis), it is highly recommended to combine the spatial index with the indicator for population density. Such an approach would significantly optimise the results from the assessment of urban ecosystem condition and the assessment of the potential for particular ESs (mainly of regulation services). Integration of the demographic information in integrated assessment would support the analysis of the balances “potential-flows", "demand-consumption” and "supply-demand”. The results of such an expanded version of the assessment approach are expected to be a highly informative for ES economic valuation.
The integrated index of spatial structure revealed the spatial arrangements of land cover and built types in combination with functional characteristics of the urban ecosystems. It provided an appropriate basis for characterisation and assessment of the urban ecosystems' condition and ecosystem services following the requirements of the European Biodiversity Strategy and the MAES process. The proposed approach enabled the definition of the internal heterogeneity of the urban ecosystems at national level which is one of the main challenges in studying urban ecological systems (
The index can be used in assessment and mapping of several ecosystem services especially when there is a lack of appropriate spatial data. It contains valuable information on the green infrastructure which enabled calculation of important indicators such as above-ground biomass and carbon storage. The assessment and mapping of ecosystem services based on integrated approaches, including the presented spatial indicator, provided significant spatial information in support of decision-making and planning activities for sustaining the actual flows of local and regional climate regulation service.
This study is supported by the project “Toward better understanding of ecosystem services in urban environments through mapping and assessment" (TUNESinURB), funded by the FM of EEA 2009-2014 (www.tunesinurb.org) and the project "Enhancing ecoSysteM sERvices mApping for poLicy and Decision mAking" (ESMERALDA) funded by the EU HORIZON 2020 programme (http://www.esmeralda-project.eu).
Figure representing examples of catalogues used during the identification built and land cover types.
Table representing all combinations of the integrated index of spatial structute in urban ecosystems in Bulgaria
Map of urban ecosystem condition representing an example of map sheets that cover the whole country
Contains descriptions of urban ecosystem subtypes and their relation to EUNIS habitat classess