Remote Sensing and Geoinformation Lena Halounová, Editor not only for Scientific Cooperation EARSeL, 2011

Land Cover Changes in Using Multi-Temporal Cartographic Data

Mieczysław Kunz and Sylwia Fydrych Nicolaus Copernicus University, Institute of Geography, Department of Cartography, Remote Sensing and GIS, Toruń, ; [email protected]

Abstract. Changes in the land cover/land use are included in many scientific studies, which can be carried out with the use of different source materials, research methods and procedures, and can deal with different time frames. From the ecological perspective, land cover is an important ele- ment differentiating the spatial structure of the landscape. The knowledge about the historical va- riability of the land cover and determination of selected parameters of the spatial landscape struc- ture, enable to understand the relationships occurring between man and the environment, and also is exceptionally valuable when planning different actions in this space. The researches related to determination of land cover/land use changes were carried out in Pomerania. The study area of nearly 50,000 km2 is enclosed within natural boundaries: the Odra River from the western side, the coast of the in the North, the River in the East, and the Warta and Noteć Rivers in the South. As the main material, historical and modern, civil and military topographic maps were used in the scale of 1:100,000 made in the years of 1879-1975, as well as the database CORINE Land Cover of 2000 and 2006. For every temporal state, on the basis of the defined land cover/land use, the landscape structure was calculated using the standard landscape measures. Those were: the number of land cover categories (NumC), the number of patches (NumP), the total length of edges (TE), the shape index (MSI) and the Shannon diversity index (SDI). The research objective was to determine land cover/land use changes in the years 1879-2006, based on the available cartographic materials.

Keywords. land cover, landscape indices, historical maps, CLC 2000 and 2006, Pomerania.

1. Introduction

The sequences of historical and modern topographic maps prepared in a similar scale, together with the analysis of available reference databases, containing spatial and thematic data, are extremely valuable sources of information, which can be used for the determination of structural land cov- er/land use transformations in the studied area. The data coming from different cartographic sources, spatial (georeferencing and thematic) databases, connected in a consistent geographic information system, can constitute the basis for different spatial analyses, including temporal analyses. The research objective was to determine land cover/land use changes in the area of Pomerania between 1879 and 2006, based on available cartographic materials issued in the scale of 1:100,000 or similar. Detailed analysis was carried out on areas in this area. The study was done with the technology of geographical information system (GIS).

2. Study area

The studies considering the definition of changes in land use/cover were conducted in Pomerania (Słowiński and Pomeranian Lake Districts). The range of the analyzed area covers the West Pome- rania province and most of the Pomerania province, part of the Kujawy-Pomerania province, as well as fragments of the Wielkopolska and Lubuskie provinces (Fig.1). The study area of almost

415 Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data

50,000 km2 is enclosed within natural boundaries: the Odra River on the western side, the coast of the Baltic Sea in the North, the Vistula River in the East, and the Warta and Noteć Rivers in the South. According to CORINE Land Cover 2006, agricultural lands (55%), as well as and semi-natural ecosystems (40%) dominate in this area. The relief of this area is characterized by con- siderable spatial heterogeneity, although the whole region was "united" by the homogeneous mor- phogenetic cycle during the Pomeranian stadial of the Baltic glaciation [1]. The delimited area is administered by 96 forest divisions, which are included within five Re- gional Directorates of State Forests – in , Szczecinek, Gdańsk, Toruń and Piła. Despite heavy transformations of forest plant communities and intensification of agricultural economy, the nature of this area is characterized by high qualities, and therefore 4 national parks were delimited (Woliński, Słowiński, Drawieński, Forest) and 15 landscape parks.

Figure 1: Location of the study area (Pomerania) in Poland.

3. The source data and research methods

In the determination of multi-temporal changes occurring in the land cover of Pomerania between the 19th and the 21st century, both historical and modern topographic maps were used, as well as the existing resources of spatial data (Table 1). The former resources comprise three series of topo- graphic maps prepared in the scale of 1:100,000 and the latter ones – the database CORINE Land Cover. The oldest were German black-white topographic maps, so-called Karte des Deutschen Reiches (KdDR), made in 1879-1895. The second state comes from the Review land-use map made in 1930-1939 by Franciszek Uhorczak, based on the map of the Military Institute of Geography. From this resource, only the layer of forests was included in the analysis. Maps of the third state comprise the period of 1968-1975 and they constitute colourful sheets of a civil topographic map published in the coordination system of GUGiK-80.

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Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data

From the existing spatial resources, the database CORINE Land Cover for two periods – 2000 and 2006, was applied. Altogether, this database distinguishes 44 classes of land cover, including 31 classes from the territory of Poland and 29 classes from Pomerania. The database CLC 2000 was compiled on the basis of the interpretation of satellite images Landsat ETM+, whereas CLC 2006 - on the basis of satellite images SPOT-4 HRVIR and IRS P6 LISS III [2][3]. Table 1. A list of cartographic materials used in the study. Century Year Number of sheet maps Description XIX 1879-1895 73 Karte des Deutschen Reiches XX 1930-1939 forest layer Uhorczak review land-use map XX 1968-1975 59 civil topographic map GUGiK-80 XX 2000 digital data CORINE Land Cover XXI 2006 digital data CORINE Land Cover All topographic maps were scanned and calibrated regarding their reference resources in the scale of 1:50,000. This allowed to obtain cartometric topographic base-maps, the content of which was vectorised. PUWG 1992 was accepted as the reference system for the whole study. Based on all available data sources, the process of content standardization was applied, which aimed at preparing the data for multi-temporal analyses. This allowed to determine the surface area covered by particu- lar land cover categories and to compare structural changes in the land cover, which occurred dur- ing the analysed period. Based on the process of data standardization applied to all analysed tem- poral states, altogether 7 categories were identified. The following higher land cover categories were identified: forests, water bodies, built-up areas, meadows, wetlands, arable lands and other ve- getation forms – a short vegetation. The spatial land-cover structure of Pomerania was analysed in historical terms with the use of standard landscape measures [4][5][6]. The following indices describing the landscape structure were calculated and compared: the number of cover classes (NumC), the number of patches (NumP), the total length of edges (TE), the shape index (MSI) and the Shannon diversity index (SDI). The research was conducted with the GIS technology and is a part of a broader project related to analysis of variability and arrangement of the Pomeranian landscape during the last two centuries.

4. Results

Based on the analysis of the collected cartographic resources, the number of land cover classes was determined, as well as the area covered by the identified categories was calculated together with their percentage contribution. Table 2 presents the area of the distinguished land cover categories (after the process of data standardization) in the region of Pomerania between 1879 and 2006. On the German topographic maps (KdDR) from 1879 (Fig. 2), 12 land cover categories were distinguished in Pomerania, with the largest area covered by arable lands (more than 60%) and fo- rests (more than 25%). Meadows constituted over 7% of the total area, and lakes – less than 3.5%. Others land-cover categories covered a small area (each with the contribution of less than 2%). The analysis of the maps from the beginning of the 20th century reveals that in 1930 forests covered less than 29% of the analysed area. On the Polish topographic maps made in the 1970s (Fig. 3), 16 land cover categories were dis- tinguished in Pomerania, with the highest contribution of arable lands (50%) and forests (over 35%).

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Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data

Figure 2: Land cover in Pomerania in 1879.

Figure 3: Land cover of Pomerania in 1968.

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Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data

Meadows covered ca. 4% of the area, lakes 3.5%, waterlogged meadows 3% and young growths 2%. The contribution of other land-cover categories did not exceed 1% each. At the end of the 20th century, based on the resource CLC 2000, 29 land-cover classes were dis- tinguished, with the highest contribution of forests (40%) and arable lands (39%). Meadows cov- ered over 8% of the area, short vegetation 7% and built-up areas 2.4%. Table 2. Changes in the surface area of the distinguished land cover categories in Pomerania in 1879-2006. 1879 1968 2000 2006 Category km2 % km2 % km2 % km2 % forests 12 161 25 18 138 38 19 306 39.93 19 359 40.10 water bodies 1 675 4 1 687 4 1 575 3.27 1 576 3.25 meadows 4 353 9 3 625 7 4 002 8.32 4 062 8.38 wetlands 895 2 66 0.1 154 0.32 154 0.32 arable lands 28 947 60 24 134 50 18 765 38.98 18 970 39.13 built-up areas 66 0,1 376 0,8 1 163 2.42 1 193 2.45 short vegetation 38 0,1 133 0,3 3 176 7.00 3 171 6.54

The analysis of the resource CLC 2006 (Fig. 4) reveals that during the subsequent 6 years, no significant changes in the land cover have been observed in the area of Pomerania. The area cov- ered by forests slightly increased (by 353 km2), as well as the area of meadows (by 60 km2) and built-up areas (by 30 km2).

Figure 4: Land cover in Pomerania in 2006. Fig. 5 presents changes in the forest area, which took place in Pomerania during the last 130 years. During the analysed period, the contribution of forests in the whole analysed area increased 419

Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data from 25% at the end the 19th century to 40% at the end of the 20th century and at the beginning of the 21st century. In 1930, forests covered 13,871 km2, which indicated 28% afforestation rate in this area.

Figure 5: Changes in the forest area in Pomerania in 1879-2006 (A – 1879, B – 1930, C – 1968, D – 2000 and E – 2006).

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Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data

The selected landscape measures were analysed both at the landscape level (Table 3) and at the level of one distinguished category – forests (Table 4). The largest number of categories (29 each) was distinguished for the last two analysed temporal states, but the number of patches distinguished there was the smallest one. This reflects a large area of the selected patches, which is also reflected in the value of the diversity index. Table 3. Selected landscape measures of Pomerania calculated at the landscape level.

Landscape indices Year NumC NumP TE [km] MSI FD SDI

1879 12 32 065 153 427.09 1.52 1.30 1.40

1968 20 36 372 141 977.01 2.07 1.51 1.36

2000 29 17 881 192 623.46 1.98 1.28 1.58

2006 29 1 7884 192 737.12 1.99 1.28 1.58 When analysing the calculated landscape measures, determined at the level of the category - fo- rests (Table 4), one should pay attention to a similar number of patches for the first (1879) and the last two analysed states (2000 and 2006). Despite similar values, these states are heterogeneous in terms of the total number of edges (TE). It means that in 1879, forest complexes with small area dominated, and the subsequent increase in the forest area was related to afforestation of areas adja- cent to already existing forests. Much higher values of all landscape indices were obtained in the analysis of the resources from 1968. This is probably connected with a different instruction for to- pographic maps, valid at that time. All the landscape measures for the last two periods are similar. Table 4. Selected landscape measures of Pomerania calculated for forests.

Landscape indices Year NumP TE [km] MSI FD

1879 6 586 36 925.66 1.54 1.28

1930 4 221 25 801.02 1.30 1.24

1968 14 781 44 199.29 2.09 1.28

2000 6 071 69 451.94 2.00 1.28

2006 6 068 69 469.04 2.00 1.28

5. Conclusions

The performed analysis, the temporal range of which comprises the period of 1879-2006, allowed to determine the changes in the spatial structure of the Pomeranian landscape at the turn of three cen- turies – the 19th, the 20th and the 21st century. During the analysed period, the afforestation rate increased in this area by over 7,000 km2, which resulted in the fact that at present forests are a do- minant element (with the contribution of more than 40%) in the landscape of Pomerania. The most 421

Kunz, M. and Fydrych, S.: Land cover changes in Pomerania using multi-temporal cartographic data significant increase in the forest area took place between 1930 and 1968 (more than 12%). Affore- station of the analysed area was carried out at the expense of the reduced area of wastelands and agricultural lands. Built-up areas increased significantly. Arable lands and wastelands were the main source for these transformations. On the other hand, the area covered by meadows and waters did not change much. The following should be mentioned among the important causes accounting for the changes in the land cover of Pomerania: the historical past, the implementation of the planned forest manage- ment at the turn of the 19th and the 20th century, changes in the agriculture and the progressive process of urbanization. The process of data standardization is an important step in long-term analyses, using different sources of data. Thanks to this process, it is possible to compare the analysed states. This process simplifies, however, the content richness of the collected resources, as well as reduces the analysis and the inference. The collected resources, after completing with the obtained, but not processed, intermediate states, will enable to perform broader analyses on the changes occurring in the spatial structure of the Pomeranian landscape, together with the determination of the influence exerted by these trans- formations on the modern landscape pattern. They will also enable to forecast the future changes.

Acknowledgements

The paper is supported by the Grant of Polish Ministry of Science and Higher Education (MNiSW) No N N304 220835.

References

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