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Abstract:

Wetlands are usually considered as habitats with high ecological values. Their main landscape properties are surface water cover and water-saturated soils, which are generally regarded as water surplus meaning a natural constraint and an environmental risk for the agriculture and other land uses. According to this, in the traditional Hungarian landscape wetlands were utilized as hay fields, pastures or places of reed harvest, etc., almost without exceptions. Over time, new utilization methods (e.g. arable farming, grape production, construction) occurred on them, despite the improper land suitability originating from the water surplus. From the view point of ecology and traditional landscape, we considered these new utilizations as a land use anomaly, as it could be revealed by GIS methods in the middle part of Duna–Tisza Interfluve, Hungary. The study area with a 25×25 km extent includes a Hungarian big city, Kecskemét, its urban fringe, and the remote rural landscape parts, too. The land cover changes on wetlands, which are ensuing from the land use changes and referring to them, were analyzed by application of historical, recent and cadastral maps, ortophotos and databases originating from the end of 19th century to our days. According to the results, land use anomalies on wetlands were not uncommon already in the historical past and they became more common in parallel to the intensifying anthropogenic transformation of landscape, apart from a special time period in the first half of the 20^th century. It is supposed that at this exceptional time economic (crisis in the world economy and the local economy) and climate change factors (extremely dry, droughty period) combined, and the latter factor led also by itself, and by strengthening the effects of local economic crisis to the large-scale ploughings of water-affected areas. Based on the examination of the land cover changes, ploughings were the most significant from between the different alteration methods in the course of time. Besides, it has caused serious ecological damages of wetlands in several places; it can be regarded also irrational use in the longer term, because of the risk of inland excess water. After ground excavation or landfill, buildings and water facilities often occurred in water-affected areas, as well. Wood plantations and plantation of horticultural products (forming vineyards, orchards and vegetable gardens) affecting wetlands appeared only rarely in the remote and the recent past.