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1
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Changes in the structure of tree stands on bog habitats in the Bialowieza forest

100%
Czerepko J.
Folia Forestalia Polonica. Series A . Forestry
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2010
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tom 52
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nr 1
The analyses of 4 permanent study plots located in the Białowieża forest (NE Poland, at 52º43´ N, 23º50´ E) were carried out 4 times, first time in 1973 or 1974 and next in 1985, 1998, 2008. The paper presents the results of a long–term study on natural forest dynamics in two forest communities: raised-bog pine forest of the association Ledo-Sphagnetum magellanici Sukopp 1959 em. Neuhäusl 1969 and transitional bogs represented by the boreal spruce forest Sphagno girgensohnii-Piceetum Polak. 1962. On each measurement date the DBH of all trees were recognized. At the same time, stems of shrub species as well as tree species with the height lower than 1.3 m were counted within the experimental areas. During the study period the structure of stands changed significantly. The major change observed on raised bog sites was an increase in numbers of Betula spp., Picea abies (L.) H. Karst. and Quercus robur L. After 34th-year of observations the boreal spruce forest stand partly passed the terminal phase and regenerated. New species occurred in the stands, especially in their lower layer, are typical for oak-lime-hornbeam forest, such as e.g. Carpinus betulus L., Q. robur, Acer platanoides L. Rapid development of Corylus avellana L. was also observed. During last decades, the decrease in the number of Pinus sylvestris L. trees has been observed. The results of analyses of stand data in four research periods show that the wetland habitat of the Białowieża forest has been a subject to the processes of succession conditioned by environmental changes such as desiccation through lowering of the water table as well as climatic changes entailing inter alia an increase of the air temperature and a decrease of precipitation.
2

Changes in species composition of an abandoned limestone grassland in relation to climatic conditions

100%
Dzwonko Z., Loster S.
Polish Journal of Ecology
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2011
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tom 59
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nr 4
After abandonment many species-rich limestone grasslands have been overgrown by tall grasses and forbs, and often by shrubs and trees. As a result, communities with many regionally rare and endangered species are vanishing. We examined to what extend changes in the cover of sociological species groups and plant functional types in an unmanaged grassland depend on fluctuations in climatic conditions. Vegetation data from permanent plots in an abandoned grassland in southern Poland collected over 12 years were used. Relations between weather variables, time, and the cover of species groups were analysed using multiple linear regression and canonical correspondence analysis (CCA). The climatic data included mean temperatures and precipitation sums for each month from January to December (for the current year from January to July), and for 2, 3 and 4 consecutive months, with time lags of 0, 1, 2 and 3 years. It was found that both inter-annual fluctuation of climatic conditions and successional processes considerably influenced species composition of the study grassland. The fluctuations in precipitation and temperature explained from 0.8% to 27.1% of the variation in the cover of various sociological groups. The greatest effect on the cover dynamics of all species and majority of sociological groups had precipitation in spring and early summer in the current year. Most of species groups were affected also by temperature in spring and/or summer in the previous years, but its effect as lower than precipitation. The obtained results suggest that climatic conditions have also a significant impact on the rate of changes in abandoned limestone grasslands. Higher precipitation in spring and summer favour growth and spread of tall meadow grasses and forbs, accelerating changes from less compact communities dominated by smaller xerothermic species to more compact vegetation with a closed structure. In consequence the role of xerothermic calcareous species decreases and many of them may locally extinct within decades.
3
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Impact of weather on dynamics of plant functional groups in an abandoned limestone grassland

100%
Dzwonko Z., Loster S.
Acta Societatis Botanicorum Poloniae
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2011
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tom 80
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nr 4
We examined to what extend the rate and direction of changes in unmanaged grassland depend on fluctuations in climatic conditions. Vegetation data from permanent plots in a semi-natural grassland in southern Poland collected over 12 years were used. Relations between weather variables, time, and the cover of 41 more frequent species and 14 plant functional groups were analysed. The greatest effect on the dynamics of species and functional groups had precipitation in spring and/or early summer, particularly in the current year. The majority of plant groups were significantly affected also by the temperature in spring and early summer in one of the three previous years. During 12 years, the cover of annuals and biennials, short plants, and plants with small leaves decreased, while the cover of taller plants, plants with larger leaves, and with vegetative spread increased. The analyses suggest that these successional changes were not directly associated with climatic conditions but were affected by them indirectly through interspecific competition. The fluctuations in climatic conditions, chiefly precipitation, had a significant effect on both the composition and the rate of changes in abandoned grassland. The increase in the cover of tall perennial species with broad leaves hindered succession towards woodland despite of the presence of woods in the closed vicinity. It can be expected that during drier periods colonisation of grassland by later successional species could be easier.
4

A 13-year change in ground-layer vegetation of Carpathian beech forests

80%
Lysik M.
Polish Journal of Ecology
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2009
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tom 57
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nr 1
47-61
13 year changes in the ground vegetation of natural beech forest were studied in the Babia Góra National Park (South Poland) and compared with the results of similar study in the Ojców National Park published previously (Łysik 2008). In 1-ha permanent research plot homogeneous vegetation patches of the size at least 1m², that differed from neighbouring patches in species composition and/or species share (patch types) were specified and mapped. After intersecting two (for years 1991 and 2004) numerical maps a synthetic map, used then as a basis for evaluating the ground vegetation changes, was created. Changes in each patch and dynamics of each species were derived using adequate formulas. Shannon-Wiener and evenness indices were measured for both years. Comparison of species composition and structure of the herb layer in 1991 and 2004 gives evidence of a highly dynamic nature of the ground layer. On 27% of investigated area vegetation were totally different than 13 years before, while less than 3% of the study area stayed unchanged. On the rest of the area changes of diverse intensity occurred. However, the mean over-plot intensity of changes was about 65% (calculated according to formula 1). Plant cover decreased by about 20%, but at the same time increases were noticed in species number and patch types. There was a significant increase in the area covered by grasses and ferns at the expense of Rubus idaeus L., which used to be a dominant species in 1991. Moreover, cover share of all species become more evenly distributed in comparison with situation 13 years before (evenness index increased from 0.49 to 0.68). The most dynamic species were those associated with decaying stumps and downed logs. These results suggest that, in natural beech forests, overstory dynamics or other mechanisms (like competition with natural recruitment of trees) make the dominance of any species in ground-layer not longer than a decade.
5

Vegetationsdynamik von Kustenheiden auf Hiddensee nach Brand und Abplaggen

80%
Schubert R.
Fragmenta Floristica et Geobotanica. Supplementum
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1993
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tom 02
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nr 2
6
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Changes in plant species composition in abandoned and restored limestone grasslands - the effects of tree and shrub cutting

80%
Dzwonko Z., Loster S.
Acta Societatis Botanicorum Poloniae
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2008
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tom 77
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nr 1
Abandoned semi-natural limestone grasslands are often overgrown by shrubs and trees. Little is know if and to what extant xerothermic limestone grasslands can be restored by tree cutting. This was tested in a 12-year experiment after the clearing of a 35-year-old secondary pine wood developed on unmanaged grassland in the close proximity of not overgrown old grassland. After 12 years, there were no significant differences in the number of field layer species on the plots in the old and restored grasslands. But over this period the number of meadow species increased in all sites, while the number of xerothermic calcareous species increased significantly only in the old grassland plots. The developing shrub layer negatively influenced the number of nitrophilous and ruderal species in grasslands restored in the former close and open woods, and the number of all species, including the number of non-tufted perennials and perennials with vegetative spread, in the former open wood. The number of meadow species increased in years with higher precipitation in late spring and early summer. The obtained results suggest that in overgrowing grasslands shrubs and trees should be cut every few years, before their covers increase to about 30%. However, this treatment alone will not stop the changes to communities with dominance of tall and vegetatively spreading grasses and forbs. Cutting trees and shrubs in sites where most grassland species have already vanished, without additional managements supporting their dispersal, seedling recruitment and development, is not sufficient to restore limestone grasslands rich in xerothermic species.
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