Assessment of land cover change in western Hungarian landscapes

Transcription

1 Assessment of land cover change in western Hungarian landscapes Éva Konkoly-Gyuró 1 ; Dezső Nagy 1 ; Pál Balázs 1 ; Géza Király 2 University of West Hungary, Faculty of Forestry 1 Department of Landscape Science and Rural Development 2 Department of Surveying and Remote Sensing egyuro@emk.nyme.hu Introduction Landscape historical research has various purposes. Among others it provides valuable information for landscape restoration and nature conservation. This paper refers on land cover change research carried out in the TransEcoNet project ( ) ( With the participation of 15 institutes from 6 Central European countries, this project assess historical landscape changes and elaborates strategies and gives recommendations for developing and managing transnational ecological networks. As it is an important aim to analyse both protected and non protected areas, we have chosen two study areas in Hungary within and around national parks, lying on the Austrian and Slovenian border (Figure 1). The administrative boundaries of the settlements have been used to make the cartographic analysis with statistics comparable. Figure 1: The Hungarian study areas of the TransEcoNet project 75

2 The investigation areas include landscapes with various natural geographical settings, with divers settlement structures and land uses. Therefore the study of their transformation is very instructive in the context of the ecological network. Changes of the extent and the spatial pattern of the natural and semi-natural habitats are the most important, so the GIS analysis of the land cover change is one of the most crucial steps in landscape historical research. We used military surveys from the Habsburg Empire, (published on DVD by Arcanum (2006 1,2, 2007)) and current CORINE land cover maps (FÖMI 2009) to analyze changes of the last two hundred years. The present paper briefly describes the method of land cover change assessment and the first results of 200 years of transformation of the Hungarian investigation areas. It also highlights the inconsistencies of the first analysis due to the contradictions of the different historical sources that need clarification by further research. Study areas The northern study area consists of the region extending from the pre-alpine Sopron Mountains through hills and flatlands of the Fertő - Hanság basin towards the Danube floodplain Szigetköz (Figure 2). This area lying between the Alps and the Carpathians covers 1500 km 2 and includes 47 settlements. The various relief ( m (Magas-bérc) above Baltic Sea Level) and geological settings resulted in a high diversity of landforms: deep lake basin on sediments, wetlands covered with peat, reclaimed marshland, low and elevated terraces, sandstone hills and crystalline low middle ranges. Figure 2: Northern-Hungarian study area 76

3 The region is situated on the frontier of the subalpine and continental climatic zone. Thus it shows significant habitat diversity, preserving several protected species. Not only the natural values but also the cultural heritages are significantly concentrated in this region. The influence of the activities of the Széchenyi and Esterházy families left their imprint on several places in the landscape. The traditions related to reedharvesting, fishing and viticulture are important characteristics of this area. Due to the bio-cultural richness of this landscape, there are nationally and internationally protected areas, including the national parks in Austria and Hungary, Ramsar sites, biosphere reserves and Nature 2000 sites, crowned by the cross-border cultural landscape which UNESCO classified on its World Heritage List. The southern investigation area is situated close to the trilateral border of Austria, Slovenia and Hungary (Figure 3). It is an undulating terrain between 200 and 384 m above Baltic Sea level, with gentle stream valleys and significant forest cover extending on 360 km 2. It consists of characteristic parts of Vendvidék, of Őrség and the Upper-Rába-valley. The relief and the underlying geological setting have been formed by the sediments of the Rába, Zala and Kerka rivers. The area belongs to the pre-alpine zone, rich in precipitation (800 mm/year). Thus it is the most humid area in the continental Hungary. Figure 3: Southern-Hungarian study area 77

4 Due to these natural characteristics, forests have always had an important role in the land cover and land use. Potential forest vegetation consists of hornbeam, alder, oak, ash, elm, and pine forests. The landscape is covered by large forested areas, with scattered grasslands and arable lands, causing its unique mosaic structure. Although the grasslands are threatened today by afforestation and the decrease of livestock, the area preserved a high natural and cultural richness. A predominant feature of its cultural heritage is the dispersed rural settlement structure called szer. This area, was once a defence border zone of Hungary as its name also shows (őr=guard). The groups of houses, and hamlets have been built on the top of the hills and gave warning in case of danger by lighting fires on the higher elevations. This is the only area in Hungary that preserved this ancient settlement structure. The National Park Őrség, founded in 2002, aims to preserve these unique habitats, the traditional landscape management and the characteristic cultural features of the area. Method The historical topographic maps, especially the military surveys of the Habsburg Empire and the Austro-Hungarian Monarchy dating from the th century are highly valuable sources for landscape historical assessment. They provide manifold information and connect several scientific fields, such as history, geography, history and landscape ecology etc. The GIS analysis of the historical maps gives us much more knowledge than the traditional viewing and interpretation. The geometric and thematic harmonisations of these maps are crucial for the GIS analysis and the further evaluation of the results. Geometric harmonisation Geometric harmonisation means that the maps that will be analysed have to be in the same reference systems. The most common way of georeferencing of the archive maps are based on control points, which can be identified on the scanned map, so the pixel coordinates can be precisely defined, and the target coordinates of the same point can also be defined. The sources for the coordinates are usually existing topographic or other maps, but they can also be determined by GNSS measurements. The scanned archive map can be transformed to the reference system of that map when the reference system is known based upon the existing graticules or grids on the map. The four corners of the map sheet can also be applied, when no graticules are available and the map sheet system is known. These maps should be transformed from this older archive reference system to the current target reference system, when these two are diverse. This later transformation can be done using the known projection parameters, when they are available. However, the achievable accuracy is usually limited because of the changes and inaccuracies of these parameters. The most commonly used transformation is a one-step transformation, where we transform the scanned digital image of a historical map to the target projection system. The other commonly used method is the two-step transformation (such as Király et al. 2008). The scanned map sheets have been transformed together in the 78

5 first step, then these connected map sheets are transformed to the target projection system. These kinds of transformations can be done using control points which are known in both coordinate system, in the original and in the target, or based upon the existing graticules on the map. The sources for the coordinates of the control points in the target projection system are usually existing topographic or other maps. A Digital Elevation Model (DEM) can also be used for the target coordinates, as the topography hasn t changed very much during the centuries. Our newly proposed method is based upon the existing topographic information such as valleys on the historical map and the DEM in the case of the Southern Thematic harmonisation Thematic harmonisation means defining the content of the digital maps. First the features that will be digitised on all time layers have to be defined and these should be categorised. In our assessment, 54 land cover categories have been identified in three time layers of historical map series and on the present CORINE land cover (CLC) map, (I. Appendix I). The most important consideration in the identification of the categories has been the comparability of the map series from the different historical periods, with partly different content and accuracy. The preservation of the most possible information of the past land cover was equally taken into account. Obviously not all land cover types occur in all time layers. Recently several new categories appeared on the CLC maps, which did not exist one or two hundred years ago (e.g. airports, leisure facilities). Inversely, we can find land cover types that are not distinguished on the present CLC maps (e.g pasture, meadow, wet grassland). The category system of our research consists of three levels and accordingly codes have three digits. This allows identifying all land cover types in all time layers at the most detailed level of the map. At the first level, six main categories have been defined: 1=; 2=agricultural area; 3= forest and wooded vegetation; 4= grassland; 5=water body and wetland; 6=other surface. The second level consists of the codes, where the third digit is 0, that indicates independent land cover categories, if their subtypes cannot be further differentiated, (e.g. 140=urban green space, 210=arable land or 310=broad leave forest). Since further precision is often possible, a third level has been introduced, (e.g. 141= park, 142 cemetery; 223= intensive large vineyard or fruit tree plantation). Codes ending by 90 always mean others or those patches where the land cover cannot be detected more precisely than the main category. They are mainly for recent CLC categories that can be precisely detected, but had no significance in the past or at the landscape scale, (e.g 190=other urban including construction sites). It is important to note that in our system the CLC50 categories are converted into the historical categories, but the conversion is not irreversible (e.g 2223=hop plantations are converted into 222=fruit or berry plantations, but of course not all fruit and berry plantations are hops). The present system of 60 categories is suitable to assess land cover transformation processes in detail. Nevertheless the overview of the main tendencies is also necessary; therefore s certain amount of aggregation has to be done. One way is to use the 6 main categories or another more detailed version that we have chosen which consists of 9 categories; (see third column of I. Appendix I). 79

6 First results In this chapter we describe the main tendencies of the land cover changes of the two Hungarian study areas. The land cover maps and the graphs show the significant differences in the processes. Main land cover transformation in the Northern-Hungarian study area There is a significant difference in the rate of changes between the hilly and mountainous areas and the lowlands in this region. In the middle range, the closed forest cover has mostly remained and on the hills the various structure of vineyard, orchard, grassland, forest and small built up patches have endured till today. On the contrary, the lowlands transformed significantly. In the Sopron basin, the extending is predominant. Recently these are infiltrating into the forests orchards and vineyards of the hills. Thus the continuity of the land cover in these areas will hardly last in the future. At the deepest elevation of the lowlands, water reclamation effected the transformation. Moderate changes occurred in the Fertő lake basin where the semi-natural habitats still exist, although the open water surface is replaced by the reed covered wetlands due to the constant filling up of the shallow lake. Much significantly changed the Hanság basin and the Szigetköz where only a few patches of the former grassland-forest mosaic survived the reclamations. After the wetlands were dried large arable fields divided by straight tree rows and extensive poplar plantations appeared in the landscape. In the Szigetköz area, the river floodplains bordered by the dams preserve the former semi-natural habitats, which is almost unique. The former connectivity of the wetlands in Hanság and Szigetköz no longer exists, and despite the ecoducts, the remains of the semi-natural habitats are even more isolated by the newly built motorway between Győr and Mosonmagyaróvár ( Table 1, Figure 4). Table 1: Land cover change in the Northern-Hungarian study area ( ) Land cover categories I. Military Survey II. Military Survey III. Military Survey CLC 50 Continuous urban area 0.2% 0.5% 1.6% 2.4% Discontinuous urban area 1.3% 1.2% 1.5% 3.9% Arable lands 29.9% 30.6% 44.9% 53.6% Orchards, Vineyards 1.2% 0.9% 1.5% 2.8% Forests 14.2% 12.6% 10.4% 19.8% Grasslands 28.0% 22.2% 20.5% 10.2% Wetlands 17.7% 25.3% 13.8% 5.4% Open water surfaces 7.5% 6.4% 5.7% 1.9% Bare surfaces 0.0% 0.2% 0.0% 0.0% 80

7 N Land cover change in the Northern-Hungarian study area I. Military Survey 1784 II. Military Survey Continuous built-up area Discontinuous built-up area Arable land Orchard, vineyard and garden Forest Grassland Wetland Open water surface Bare surface III. Military Survey CLC Kilometers This project is implemented through the CENTRAL EUROPE Programme co-financed by the ERDF Figure 4. Land cover change in the Northern-Hungarian study area ( ) Source: Arcanum , 2, 2007; FÖMI 2009

8 Main land cover transformation in the Southern-Hungarian study area In this region the Vendvidék and the Őrség and the higher elevations northwards from the Upper Rába-valley are highly similar. The difference between these landscapes is less in the proportions of arable land, forest and grassland, but more in the settlement structure. The transformation processes show the same characteristics. According to the maps, the extent of arable land has significantly decreased, and has been replaced by forests. The grasslands that are predominantly delineated along the streams at the end of the 18 th century increase constantly till the end of the 19 th century, than they diminish till the present day. The typical mosaic-like pattern of the landscape has partly disappeared. The former open landscape closes with the doubling of the forest area. However, in the Rába Valley, the typical transition can be detected between the grassland and the arable land to the detriment of the grasslands. Dispersed rural settlements on the top of the hills have been typical in the landscape. Most of the belongs to the town Szentgotthárd, in the Rába Valley. Built-up areas have slightly increased during the last two hundred years. The dispersed small settlements have often grown together, approaching the streams and the ancient structure is ever less recognisable. Vegetable gardens, large orchards and vineyards that surrounded the small settlements on the gentle hills during the 19 th century have diminished significantly till today (Table 2, Figure 5). Table 2: Land cover change in the Southern-Hungarian study area ( ) Land cover categories I. Military Survey II. Military Survey III. Military Survey CLC 50 Continuous urban area 0.2% 0.3% 0.8% 0.8% Discontinuous urban area 2.3% 2.1% 3.0% 3.3% Arable lands 50.8% 38.8% 34.4% 21.4% Orchards, Vineyards 1.6% 1.4% 1.1% 1.9% Forests 34.6% 44.8% 42.6% 62.0% Grasslands 9.8% 11.4% 16.3% 9.5% Wetlands 0.1% 0.6% 0.8% 0.3% Open water surfaces 0.5% 0.5% 0.4% 0.8% Bare surfaces 0.1% 0.1% 0.5% 0.0% 82

9 Workshop on Landscape History 22. April 2010 Sopron, Hungary Land cover change in the Southern-Hungarian study area N I. Military Survey II. Military Survey III. Military Survey CLC s r e t e m o l i K Continuous built-up area Discontinuous built-up area Arable land Orchard, vineyard and garden Forest Grassland Wetland and open water surface Bare surface Open water surface This project is implemented through the CENTRAL EUROPE Programme co-financed by the ERDF Figure 5: Land cover change in the Southern-Hungarian study area ( ) Source: Arcanum , 2, 2007; FÖMI

10 Discussion and conclusions The main land cover transformations described above show typical processes that occur in many landscapes in Europe. We can discover some contradictions between the contemporary descriptions and the information of the historic maps. Methodological problems also became relevant. The most important contradiction that has to be resolved is the big proportion of arable land in Őrség and Vendvidék in the southern study area, which is absolutely not justified by the literature. According to contemporary sources (Nemes-Népi Zakál, Gy.1818; Fényes, E. 1851) significant grassland proportion was typical in the landscape. Everywhere in the whole Eörségh, these yellowish clayey fields are very nicely dotted by partly scattered and partly connected pine trees, forests, heaths, pines and bushes, among which there are arable lands; on flatter locations, in valleys and in the vicinity of streams there are meadows. (Nemes-Népi Zakál, Gy.1818) Szalafő:...many forest and grazing-land Őri-Szent-Péter (today: Őriszentpéter): it has plenty of forests and grazing land Dávidháza (today: Bajánsenye): Much grazing land. (Fényes, E. 1851) A solution for this problem could be that on the first and partly on the second military survey, much dry grassland had been mapped as arable land. Further investigation is needed to clarify this contradiction. Another issue is the temporal frequency of the maps. The first three time layers have about 70 and 40 year time spans between them. Then we have more than hundred years between the third military survey and the present day CLC map. The 20th century has been very turbulent and various transformations occurred due to the political changes in Central Europe. It is absolutely necessary to insert one supplementary time layer in the middle of the 20th century. The third topic that has to be raised is the comparability of the historic maps of the scale of and 1:25000 with the CLC map that has the scale of 1: The CLC map is much more detailed thematically but less fine grained geometrically because of the scale. Therefore the refinement of the CLC maps is necessary. 84

11 Appendix I. Appendix: The different land cover (LC) categories in our investigation Historical land cover CORINE 50 land cover Aggregated land cover codes and nomenclature codes and nomenclature codes and nomenclature 1 Urban fabric 110 Continuous 1 Continuous, road and Area of urban centres 1 Continuous, road and Area of ancient cores 1 Continuous, road and Discontinuous built-up area with multiflat houses prevailingly without gardens 120 Discontinuous urban fabric 121 Building and courtyard 1122 Discontinuous built-up area with family houses with gardens 1 Continuous, road and 2 Discontinuous, green 2 Discontinuous, green 122 Sport and leisure facility 1423 Recreation settlement 2 Discontinuous, green Leisure area 2 Discontinuous, green Sport facility 2 Discontinuous, green 130 Farm, hamlet 2 Discontinuous, green Discontinuous built-up area with greenery 2 Discontinuous, green Farmstead 2 Discontinuous, green 140 Green 2 Discontinuous, green 141 Park 1411 Park 2 Discontinuous, green 142 Graveyard 1412 Graveyard 2 Discontinuous, green 143 Garden around building in settlements 2 Discontinuous, green 150 Industrial, commercial and transport unit 1 Continuous, road and 151 Industrial and commercial unit 1212 Area of special installations 1 Continuous, road and Industrial and commercial unit 1 Continuous, road and 152 Road and 1221 Road network and associated 1 Continuous, road and land Rail network and associated land 1 Continuous, road and 153 Port area 1232 River and lake port 1 Continuous, road and Shipyard 1 Continuous, road and Sport and recreation port 1 Continuous, road and 154 Airport 1241 Airport with artificial surfaces of runways 160 Open cast mining or dump site 1 Continuous, road and 1 Continuous, road and 85

12 161 Mineral extraction site 1311 Open cast mine 1 Continuous, road and Quarry 1 Continuous, road and 162 Dump site 1321 Solid waste dump site 1 Continuous, road and Liquid waste dump site 1 Continuous, road and 170 Farmstead, agricultural building 1 Continuous, road and Agro-industry 1 Continuous, road and Greenhouse 1 Continuous, road and 190 Other urban eg. Construction site 1 Continuous, road and Construction site 1 Continuous, road and Education and health facility 1 Continuous, road and 2 Agricultural area 210 Arable land 3 Non-irrigated arable land, permanently irrigated land, rice Arable land with large fields 3 Non-irrigated arable land, permanently irrigated land, rice Arable land with small fields 3 Non-irrigated arable land, permanently irrigated land, rice Permanently irrigated arable 3 Non-irrigated arable land, land Agricultural area with significant share of natural vegetation and with prevalence of arable land permanently irrigated land, rice 3 Non-irrigated arable land, permanently irrigated land, rice 220 Vineyard, orchard 4 Vineyard, orchard, garden 221 Vineyard Vineyard with small fields 4 Vineyard, orchard, garden 222 Fruit tree or berry 2221 Orchard 4 Vineyard, orchard, garden plantation Berry fruit plantation 4 Vineyard, orchard, garden Hop plantation 4 Vineyard, orchard, garden Agricultural area with significant share of permanent crops and with presence of scattered natural vegetation 4 Vineyard, orchard, garden 223 Intensive large vineyard Vineyard with large field 4 Vineyard, orchard, garden or fruit tree plantation 224 Complex cultivation 2421 Complex cultivation pattern 4 Vineyard, orchard, garden pattern without houses Complex cultivation pattern 4 Vineyard, orchard, garden with scattered houses Forest nursery 4 Vineyard, orchard, garden 230 Rice field 3 Non-irrigated arable land, permanently irrigated land, rice Rice field 3 Non-irrigated arable land, permanently irrigated land, rice 290 Other agricultural area 2433 Agricultural area with significant share of natural vegetation and with prevalence of scattered natural vegetation 4 Vineyard, orchard, garden 86

13 Agricultural area with 4 Vineyard, orchard, garden significant share of natural vegetation and with scattered natural vegetation 3 Forest and wooded vegetation 310 Broad leaved forest 5 Forest Broad-leaved forest with 5 Forest continuous canopy in dry area Broad-leaved forest with 5 Forest continuous canopy in wet area Broad-leaved forest with 5 Forest discontinuous canopy in wet area 320 Coniferous forest 5 Forest Coniferous forest with 5 Forest continuous canopy 330 Transitional woodland 5 Forest shrub Broad-leaved forest with 5 Forest discontinuous canopy in dry area Young stand and clear-cut 5 Forest Natural regeneration area 5 Forest 340 Foreign wood plantation 5 Forest Plantation of broad-leaved forest 5 Forest Plantation of coniferous forest 5 Forest Plantation of mixed forest 5 Forest 350 Mixed broad leaved and 5 Forest coniferous forest Mixed forest created by 5 Forest alternation of single trees with continuous canopy Mixed forest created by 5 Forest alternation of stands of trees with continuous permanent crops and with presence of scattered natural vegetation 390 Other wooded area 5 Forest Wild willow plantation 5 Forest Damaged forest 5 Forest 4 Grassland 410 Grassland 6 Grassland Intensive pasture, degraded 6 Grassland grassland without trees and shrubs Intensive pasture, degraded 6 Grassland grassland with trees and shrubs Agricultural area with significant share of natural vegetation and with prevalence of grassland 6 Grassland Natural grassland prevailingly 6 Grassland without trees and shrubs Natural grassland with trees 6 Grassland and shrubs 411 Pasture 6 Grassland 412 Meadow 6 Grassland 87

14 420 Wet grassland 7 Wetland 421 Wet pasture 7 Wetland 422 Wet meadow 7 Wetland 490 Other grassland 6 Grassland 1242 Airport with grass surfaces of 6 Grassland runways 3331 Sparse vegetation on sands or 6 Grassland loess 3332 Sparse vegetation on rocks 6 Grassland 3333 Sparse vegetation on salines 6 Grassland 5 Water body and wetland 510 Inland marsh 7 Wetland Fresh-water marsh 7 Wetland Saline (alkali) inland marsh 7 Wetland 511 Inland marsh with low 7 Wetland vegetation 512 Inland marsh with high 7 Wetland vegetation 520 Peat bog 7 Wetland Explored peat bogs 7 Wetland Natural peat bogs with 7 Wetland scattered trees and shrubs 530 Water courses 5111 Rivers 8 Open-water surface Channels 8 Open-water surface 540 Water body 8 Open-water surface 541 Natural water body with Natural water body with 8 Open-water surface continuous water supply continuous water supply Natural, temporary, salt 8 Open-water surface affected water body 542 Semi-natural artificial Artificial reservoir 8 Open-water surface lake, pond or reservoir 543 Intensively used artificial lake and reservoir Fish pond 8 Open-water surface 590 Other water body and 8 Open-water surface wetland 6 Other surface 610 Bare rock 3321 Bare rock 9 Bare surface, other 620 Beeches, dune or sand 9 Bare surface, other plain Dune River bank 9 Bare surface, other 630 Erosion ditch 9 Bare surface, other 690 Other bare surface 3341 Burnt area 9 Bare surface, other 88

15 References Arcanum, ; The First Military Survey: Kingdom of Hungary ( ) 1:28.800, Arcanum Database Ltd., Budapest Arcanum, ; The Second Military Survey: Kingdom of Hungary ( ) 1:28 800, Arcanum Database Ltd., Budapest Arcanum, 2007; The Third Military Survey ( ) Kingdom of Hungary 1:25.000, Arcanum Database Ltd., Budapest Fényes E. (1851): Magyarország geographiai szótára, Pest. FÖMI, 2009; CORINE 1: land cover database ( ), Institute of Geodesy, Cartography and Remote Sensing (FÖMI), Budapest Király, G.; Walz, U.; Podobnikar, T.; Czimber, K.; Neubert, M.; Kokalj, Ž., 2008: Georeferencing of historical maps methods and experiences. SISTEMaPARC Project Book, Rhombos Verlag Berlin, pp Nemes-Népi Zakál, Gy.,1818; Eőrséghnek leirása ugymint: Annak Természete, Története, Lakosai ezeknek szokásiai, nyelvszokása. A'mellyeket öszve szedegetett Nemes-Népi Zakál György: 1818-dik Esztendőben. Fertő-Hanság Nemzeti Park Igazgatóság. Szombathely