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Increased nitrogen (N) and water availability, resulting from global changes or ecosystem management, were predicted to promote plant productivity and change community composition through shifts in competition hierarchies. So far, however, it still remains unclear how competitive interactions respond to N and water additions, which will be important to understand how plant community composition changes. To test plant competition ability in different successional stages under N and water addition treatments, a pot experiment under field conditions was performed. Six dominant plant species, three early-successional species, Artemisia lavandulaefolia, Artemisia capillaris, and Pennisetum centrasiaticum versus three late-successional species, Stipa krylovii, Leymus chinensis, and Artemisia frigida, were grown in monocultures and in two-species mixtures under factorial combinations of N and water addition treatments. We found that (1) there were interactive effects of N addition, water addition and interspecific competition on plant biomass; (2) For a given species, competitive abilities were correlated with biomass difference of neighboring species; (3) N and water additions interactively increased competition intensity and shifted species competitive hierarchies; (4) Late- successional species had stronger competitive abilities in the N addition treatment, whereas early-successional species had stronger competitive abilities after water addition or N + water addition. Our results show that N and water additions increased the intensity and impact of interspecific competition on plant growth, which has great implications for community structures. Since interspecific differences in competitive abilities were not well explained by species biomass, species identity, such as plant functional traits, should be included to predict the impact of increased N and water availability on plant communities and ecosystem functions.
This paper presents the results of studies on cretaceous rendzinas overgrown by the communities that are consecutive stages of xerothermal sward successions. The studies were carried out in the Stawska Góra Nature Reserve close to Chełm. The aim was to trace the directions of the changes in soils physical and chemical properties in the relation to the transformations in the xerothermal phytocenoses. It was stated that content of organic carbon and nitrogen in humic horizons of studied rendzinas as well as hydrolytic acidity and the capillary and maximum water capacity within whole profiles increases with the natural succession of xerothermal sward. Transformations of phytocenoses did not influence soil reaction or the content of carbonates. The succession process in rendzinas with anthropogenically disturbed soil levels goes faster.
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.
The paper presents the characteristics of arborescent vegetation from succession and of tree sites introduced during the process of reclaim in the area of the Szczakowa sand mine excavation. Arborescent communities from succession consisting of Scotch pine (Pinus sylvestris L.) and common birch (Betula pendula Roth) were formed in a biogroup structure which could be used in the reclaim process. The nutrient content and length of Scotch pine needles indicate appropriate site conditions for this species in both area categories in the sand mine excavation. The effect of fertilization, resulting in a higher nutrient supply in Scotch pine needles, is evident only in the youngest group from the reclaimed areas. Heavy metal content in pine needles indicates an industrial impact on the reconstructed ecosystem in this region.
Na podstawie badań przeprowadzonych w 51 pielęgnowanych i niepielęgnowanych parkach wiejskich w stylu krajobrazowym zlokalizowanych w Kotlinie Sandomierskiej określono stopień przekształcenia szaty roślinnej parków. Wykorzystując historyczno-geograficzną klasyfikację gatunków stwierdzono, że gatunki rodzime mają większe pokrycie w poszczególnych warstwach szaty roślinnej (drzew, krzewów i ziół) w parkach niepielęgnowanych, tj, w obiektach z niekoszoną warstwą ziół. Roślinność w parkach niepielęgnowanych jest bardziej zbliżona składem florystycznym do zbiorowisk leśnych grądowych, co stanowi dowód na małe przekształcenie siedliska tych parków. Szata roślinna badanych parków wiejskich, zwłaszcza niepielęgnowanych o dużej powierzchni, odzwierciedla naturalne przemiany sukcesyjne.
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Contemporary changes in vegetation of polar regions

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Rapid climate changes which have been observed over the recent years in both polar regions of the Earth, directly or indirectly affect vegetation dynamics. This article presents the main directions of the changes taking place in the recent years in tundra communities of both polar regions, based on original research carried out in the Arctic in Spitsbergen and in the maritime Antarctic on King George Island.
Plant succession (herb and tree species) in newly planted midfield shelterbelt (0.63 ha of area) was investigated during eight years. Changes of vegetation were found to be similar to the succession on abandoned fields. During first years simple plant communities, consisted by common and very common species, dominated by one species, like: Arthemisia absyntium and Chenopodium album, Conyza canadiensis or Apera spica-venti, substituted year by year. The number of species reached maximal value (48) three years after shelterbelt planting. Among all trees forming the shelterbelt the fastest growing were the species of early succession stages (having light seeds) like: poplar, birch, larch and pine. Those trees form the canopy layer already after four years of succession. That process increased the rate of succession to forest community. Maximum biomass of herb plants (347.84 g dry wt. m⁻²) was noted in fifth year of succession. Litter biomass increased during all study period. Corridor effect of shelterbelt for plants wasn’t evidenced. Introduction of the forest and clear-cutting species is relatively slow and proceeds from the forest adjacent to the shelterbelt.
W pracy przedstawiono wyniki 6-letnich badań, uzyskane w doświadczeniu płodozmianowym, zlokalizowanym na glebie płowej kompleksu pszennego dobrego i żytniego bardzo dobrego. Oceniano plonowanie dwóch odmian grochu siewnego Ergo i Agat, uprawianych w płodozmianie 6-polowym oraz w narastającej 1-6-letniej monokulturze, stosując trzy warianty jego ochrony. Plon nasion grochu w płodozmianie wyniósł średnio 3,99 t·ha⁻¹, zaś w uprawie po sobie był niższy o 47%. W monokulturze nastąpiło zmniejszenie obsady roślin o 12,1%, liczby strąków o 44,2%, a liczby i masy nasion odpowiednio o 48,9 i 21,9%. Odmiany reagowały na zbliżonym poziomie zarówno na rodzaj następstwa (płodozmian, monokultura), jak i na poziom zabiegów plonochronnych (herbicydy, fungicydy). Stosowanie herbicydów i fungicydów w płodozmianie nie jest uzasadnione, natomiast w monokulturze przyczynia się do wzrostu plonu nasion.
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