**1. Introduction**

Urbanization has accompanied humankind since antiquity and is a fundamental feature in every civilization. Urbanization refers both to built-up agglomerations and ways of life and describes the process of rural areas transforming into urban ones [1]. During the period of industrialization in the nineteenth century, urbanization processes began to acquire a fast rate and, since then, have become a common phenomenon in expanding cities [2]. The increase in the number of people living in urban areas means that in some European countries this phenomenon affects almost 80% of the population [3]. In addition, some researchers say that by 2030, 75% of all Europe's landscapes will be urban in nature [4]. The constant growth of urban areas is visible mainly around areas of large agglomerations and is related to the processes of suburbanization and urban sprawl [5,6].

The above processes change the structure of the landscape. In this paper, landscape is understood as a combination of different types of land cover [7]. Thus, along with an increase in the degree of urbanization of the landscape, urban areas increase and natural, rural and/or transitional areas decreases. The processes of landscape urbanization have a fundamental impact on its structure and physiognomy and depend on the intensity of changes and technological progress. Thus, in the cities one can speak of an urban landscape, but is this really evident? An urban landscape is understood to be an existing landscape of urban settlements and their surroundings, but with marked types of use of the city and without administrative restrictions [8]. The authors understand the urbanization of landscape as the process of differentiation and concentration of the internal spatial structure of cities and the quantitative increase in the area of landscapes of urban types. This is a

**Citation:** Myga-Pi ˛atek, U.; Zemła-Siesicka, A.; Pukowiec-Kurda,˙ K.; Sobala, M.; Nita, J. Is There Urban Landscape in Metropolitan Areas? An Unobvious Answer Based on Corine Land Cover Analyses. *Land* **2021**, *10*, 51. https://doi.org/ 10.3390/land10010051

Received: 20 November 2020 Accepted: 5 January 2021 Published: 8 January 2021

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result of spatial expansion (urban sprawl) or the transformation of other types of landscapes (suburban, agricultural, forest, etc.) into an urban one. This process is always associated with an increased human impact (or an increase in the gradient of anthropopressure). One important aspect of the urban landscape is its complexity and multidimensionality, which means the living environment of the societal, cultural, historical and economic contexts and a matrix for further development [9].

At the same time as constant socio-economic development, some cities can gain a special hierarchical position in relation to other cities, transforming into metropolises [10]. Therefore, one of the possible ways for the urban landscape to evolve is through the growth of the metropolitan landscape [11]. Metropolises are a unique type of urban complex. Due to the dynamic processes of not only urbanization but also metropolization, the concept of metropolitan landscape is more often considered in landscape geography and in landscape architecture to be a unique type of urban landscape [12]. The concept of metropolitan landscape is related to the fact that the terms "city" and "urban" landscape are inadequate in describing the fullness and enormity of the roles played by urban networks, spaces, environments and processes. They extend far beyond the city area to the peripheral areas around it, both rural and urban [13]. Beunen [14] believes that metropolitan landscape is like an urban field encompassing built-up and open areas within urban centers.

The urban landscape is characterized by the complexity of its aspects, but also by the dynamics resulting from continuous transformation processes [15]. In Poland, the processes of landscape metropolization are in the initial stages; therefore, it is first necessary to recognize the directions of change and the dynamics of urban landscapes. Taking into account the complexity of the concept of urban landscape, it can be considered from many angles and at many research levels [3]. In terms of geography, it means the spatial organization of its individual elements, which are patches of land cover. Their analysis enables the examination of the landscape structure and its identification.

There are various methods in the literature for determining the degree of landscape urbanization. These are mostly based on land cover analysis and land use change. These methods have been tested in various regions, aspects and spatial relationships by many researchers. In the area of Central Europe, studies on the degree of urbanization were carried out by Inostroza et al. [16]. The aim of their work was to perform a spatially explicit quantification of urbanization degrees across the landscape. Dadashpor et al. [17] analyzed land cover changes in the Tabiz metropolitan area in Azerbaijan using the dispersion of urban lands as the landscape indicator. Changes in land cover due to urbanization were also analyzed by Aguilera et al. [18] and Reis et al. [19] using landscape metrics to analyze urban land cover in expanding cities. Tate et al. [20] assessed the impact of urbanization on the natural environment using the multimetric urban intensity index based on variables related to land cover as well as its managemen<sup>t</sup> and socio-economic status. A similar set of variables was used by McMahon et al. [21] who examined the relationship between the degree of urbanization and the quality of surface waters in areas with high dynamics of urban processes. The relationship between urbanization processes and type of land cover was studied by Li et al. [22] in the Beijing area and Weng [23], who analyzed the urban gradient in Wisconsin. Huang et al. [24] dealt with the problem of converting rural landscapes into urban ones based on land cover analysis using statistical methods—the regression model. Fuzzy set theory was used to identify the transition zone between the urban and rural landscape in Olsztyn and Sieradz (Poland) [25,26]. The types of coverage analyzed on the basis of satellite images allowed trends in the urbanization of Eastern European cities to be identified [27]. The landscape of some metropolitan areas in Poland was assessed, e.g., Trójmiasto (Gda ´nsk-Gdynia-Sopot, Marciniak) and Pozna ´n [28,29].

The latest research by Naranjo Gómez et al. [30] concerned the analysis of land cover types and changes that took place in the Canary Islands. In this work, the CORINE land cover was used as the basic research material. The CLC database consists of an inventory of land cover in 44 classes. It covers 39 countries, comprising the European Environment Agency (EEA) members and cooperating countries, including the members of the European

Union. This fact is crucial if comparing of land cover in different countries is the aim of the study. The CLC database supports broad spatial analyses because the data describing land cover in Europe are characterized by spatial continuity and enable non-ambiguous identification of various land-use types. Cie´slak et al. [31] also used the same database in their analyses to assess the urban sprawl process. Similar research was carried out in by Solecka et al. [32], who assessed this process in the suburban area of Wrocław on the basis of the CORINE database. Benito et al. [33] also based their research on the CORINE model in determining land cover changes in the Mediterranean area. Research on the relationship between urban pattern and land cover was conducted in the Toronto agglomeration. For this purpose, researchers used the NDVI index as well as the urban patterns and socioeconomic variables [34].

The aim of the article is to assess the intensity of the urban landscape on the basis of the CORINE database for seven metropolitan areas in Poland and one in Germany. To this purpose, the Urban Landscape Index (ULII) was introduced according to the formula presented by Matuszewska and B ˛edkowski [26]. This index is based on the classification of land cover types in terms of their urban, transitional and rural character proposed by Biłozor [35]. The analyses were conducted at three levels of research details and comparisons made across the cities. The intensity of the urban landscape was calculated at the level of entire metropolitan areas, for administrative units (municipalities) and basic fields in the form of hexagons with an area of 4 km2.

In this paper, we consider a metropolitan area as an area established based on administrative decisions. Simultaneously, it is an area that aspires to be a metropolis in the future. The pace of development of metropolis depends on many factors, but one of them is the presence of urban landscapes, surrounded by non-urban landscapes. Delineating of metropolitan areas in Poland is based on administrative decisions. These decisions take into account varied criteria, such as functional and economical. Their importance is currently discussed in the scientific literature. Landscape criteria have not been taken into account in these decisions so far. It should be expected that delineating metropolitan areas using landscape criterion would result in a completely different spatial extent of metropolitan areas. Since the administratively established metropolitan areas in Poland are characterized by the presence of urban, rural, and urban–rural municipalities, it can be assumed that non-urban landscapes will also occur within the metropolitan areas. It seems to be a paradox. Hence, the following questions may be posed: how many urban landscapes are in metropolitan areas, and how much city is in a city?

In Poland, only one of metropolitan areas is a polycentric agglomeration (Upper Silesia-Zagł ˛ebie Metropolis—US-ZM), while the rest are monocentric agglomerations. Presumably, the US-ZM should be distinguished in terms of landscape due to both the polycentric form of agglomeration and the matter of its origins, because it is the only metropolitan area in Poland whose formation is associated with the mining industry. For the sake of comparison, the Ruhr Metropolis was analyzed, assuming that due to the same genesis, the area might be similar in terms of landscape to the US-ZM.

The metropolitan areas in Poland were not compared in terms of urban landscape so far, although they were studied in terms of agriculture [36]. Additionally, the topic of theirs administrative and landscape dissociation was not raised. The need for landscape studies assessing the intensity of the urban landscape results from the dynamics of processes related to urbanization (suburbanization, urban sprawl, metropolization). The dynamism of these processes generates the need to monitor the areas subject to them.

#### **2. Materials and Methods**

The research procedure can be divided into several basic stages (Figure 1). The first step of the research was the selection of the metropolitan areas. According to the classification of urban centers in Poland [37], the largest seven metropolitan areas in Poland were chosen based on the criterion of population. The other criterion of comparison was the origins of metropolitan area, thus the Ruhr Metropolis (RM) in Germany was chosen.

**Figure 1.** Schematic diagram of the research procedure. Symbols of the metropolitan areas—see Table 1.

Next, the delimitation and classification of land cover types in terms of their urban character were provided. For each land cover type, a value M (the degree of belonging to the urban landscape) was established, showing the urban–rural character of the type. Next, the urban landscape intensity index (ULII) was calculated on three levels of research (topdown approach): ULII value for each metropolitan area (to compare the degree of urban intensity of all studied areas), for each municipality within metropolitan areas (to shows the spatial differentiation and structure of landscape in each metropolitan area), and for geometric basic units—hexagons (to indicate regularities in the metropolitan areas in more detail). After obtaining the index, all metropolitan areas were compared in terms of the spatial distribution of urban, rural and transitional landscapes.
