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Biodiversity conservation of the vegetation adjacent to watercourses influenced by land reclamation practicies : the floodplain of the Odra River (Silesia, Poland)

Szymura T., Szymura M., Dunajski A.

Polish Journal of Ecology

2011

Vol. 59, nr 4

665-676

The vegetation adjacent to watercourses is an important component of the agricultural landscape due to its influence on water quality, biodiversity and landscape permeability. The structure of the vegetation and the influence of different kinds of usage of adjacent land and watercourse maintenance has been intensively studied in an attempt to establish the most effective management system to maintain biodiversity. In the eastern part of Central Europe however, studies considering those problems are rare. In this research, the vegetation on the banks of ditches in an agricultural landscape in the southwest of Poland was examined, on the floodplain of the Odra River. The land reclamation system consisted of ditches and channels has been neglected since the period of socio-economic transformation in 1990s. The watercourses were divided into homogeneous segments with respect to the adjacent vegetation, watercourse morphology and water depth. Vascular plants species with the cover higher than 5% were noted. A total of 134 km of watercourses were divided into 536 segments, the segments were mapped with GPs receiver. The quantitative participation (QP) of each species was calculated as the sum of percentage cover multiplied by the length of the segment, and was expressed as a percentage of the sum of the QP of all species. The typology of the vegetation was created on the basis of hierarchical clustering method, using TWINSPAN software, the species - environment relations were explored by multivariate statistics (DCA and DCCA). The results showed that a few species, such as Calamagrostis epigejos, Urtica dioica, Quercus robur, Phalaris arundinacea, Prunus spinosa, Phragmites australis, and Alnus glutinosa covered more than 60% of the investigated banks. These species were able to dominate the vegetation and create distinctive assemblages. 8 vegetation types were distinguished: four of them, dominated by grasses, could be connected with the management of ditches, whereas remaining types, consisted woody plants and common reed (Phragmites australis) were results of ditch management cessation. Such cessation leads to widespread of typical forest plants species along watercourses into the areas of open fields, whereas the species typical of open habitats avoid forest neighbourhood. The influence of differed kind of agricultural usage (arable land, grassland, fallow land) was less important than the general difference between watercourses place next to forests and those in the open surrounding. The ditches morphology as well as the presence of water influenced the species composition significantly, nevertheless they were not a crucial factor influencing the surveyed vegetation.

The impact of rectification error on the analysis of landscape transformation based on archival maps

Dunajski A., Sieczka M.

Prace Komisji Krajobrazu Kulturowego

2008

nr 8

164--172

Archival topographic maps are the main source of information about the land cover and land use (LULC) structure, particularly with reference to times before the application of aerial and satellite remote sensing. Maps created in different periods differ substantially in regard to cartographic technique, scale and generalisation level. This brings problems of using them as a data source in landscape transformation analysis. If these problems are not correctly solved in the initial stage of the research, the obtained land use/cover change (LULCC) results may be biased by errors leading to incorrect conclusions. For the interpretation of landscape transformation in the aspect of ecological processes, a simple comparison of proportions of particular LULC classes in certain periods is not sufficient, because a given transformation type in one place might be compensated by an opposite change in another place. Thus, in order to investigate the actual LULCC dynamics, and thereby to get to know its influence on vegetation, biodiversity and other landscape elements, it is necessary to use methods allowing for a detailed analysis of changes between LULC classes in the given period. One of the most straightforward approaches is a transformation matrix. In order to apply a transformation matrix to cartographic materials from different times, they need to be rectified to a common coordinate system. Because of deformations of the topographic map contents due to the map scale, map projection, cartographic and print technique, the possible distortions during storage and utilization, as well as during the digital scanning of the map, different for each map series or even between single sheets of the same map series, a perfect georectification of a scanned topographic map is virtually impossible. Therefore, the transformation matrix contains the information about the factual transitions between LULC categories, as well as about the artificial ones, due to map rectification error. Spatial error assessment procedure is then necessary to extract the information about the real transformation that took place. In this paper a method for reducing the impact of rectification error on the LULCC analysis is presented, based on authors landscape transformation research, conducted in the agricultural landscape of the Odra valley, using digitized maps from 1930's-1940's and 1990's.