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EN
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 was 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.
EN
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.
EN
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.
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