Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 11

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Dentario glandulosae-Fagetum
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
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.
The purpose of this study was to determine the trends and rates of spontaneous changes in the structure and species composition of natural forests which are composed mostly of tree species growing at the limits of their natural range of distribution. We analyzed the demographic processes in populations of woody species in the years 1968‒2005. The investigations were conducted in strictly protected areas in the Roztoczański National Park (The Roztocze Highlands, Eastern Poland) on four 0.5-ha sample plots, established in the 1960s. These plots represented three forest communities: upland fir mixed forest Abietetum polonicum (Ap), Carpathian beech forest Dentario glandulosae–Fagetum (DgF), and pine-oaks mixed forest Querco roboris– Pinetum (QrP)). Measurements were conducted in 1968, 1978 (two sample plots only) and in two study periods (1993‒1995 and 2003‒2005). Measurements in the last two periods included canopy trees (DBH and height) forest regeneration (saplings, seedlings and germinants) as well as dead wood (snags and coarse woody debris). The results revealed significant and dynamic changes in the studied forests. The directions and rates of changes were different among forest communities. Silver fir (Abies alba Mill.) showed continuous decrease in all the forest associations. The highest rates of change were found in the DgF forest association. Data from the last measurement showed, that the rate of fir decline has slowed down, and in some cases even a slight increase of its share was recorded. However, the continuous decrease in abundance of the fir regeneration in all study plots suggests, that fir in the near future can be partly replaced by the broadleaved species. Among them, European beech (Fagus sylvatica L.) revealed the most dynamic species. It showed a systematic increase of it’s share in stand composition, according to the number of trees and basal area in all investigated plots. The largest increase of this species was recorded in the QrP forest association. Untill 1993 hornbeam (Carpinus betulus L.) developed well in the DgF association, and it also increased in abundance in the Ap association. The last measurements confirmed large increase the number of hornbeams in the DgF association, whereas it’s share in stand basal area revealed a weak downward tendency in both associations. After 1993 Norway spruce (Picea abies (L.) H. Karst.) grow only in the Ap forest communities, where its development is rather weak. The share of Norway spruce in forest composition has diminished systematically since 1968. The measurements from 2003 revealed a slight increase of the basal area of spruce and substantial decrease of its regeneration. Other tree species: Scots pine (Pinus sylvestris L.) and pedunculate oak (Quercus robur L.) in the successive measurements showed a systematic decrease of their number, basal area and share in the stand composition. There was also no natural regeneration of these species. Observed changes could be mainly attributed to natural rocesses of forests development (including natural disturbances) in general and to specific mechanisms of competition in forests composed of tree species growing close to the limits of their natural distribution ranges. In some cases the dynamics of researched species (hornbeam, pine and oak) can be explained as the regeneration processes of ecosystems affected previously by human activities.
Celem pracy było określenie zróżnicowania flory wzdłuż wybranych szlaków pieszych zlokalizowanych w zbiorowisku żyznej buczyny karpackiej na terenie Ciężkowicko-Rożnowskiego Parku Krajobrazowego. Badania terenowe i kameralne przeprowadzono w latach 2006–2012. Każdego roku wykonano 700 zdjęć fitosocjologicznych zarówno wzdłuż szlaków turystycznych, jak i wewnątrz zbiorowiska leśnego. Wyniki badań wykazały, iż w obu strefach badawczych dominują gatunki leśne z klasy Querco-Fagetea. Z kolei udział roślin ze zbiorowisk trawiastych z klasy Molinio-Arrhenatheretea oraz synantropijnych z klas Stelarietea mediae i Artemisietea vulgaris był większy wzdłuż szlaków turystycznych niż wewnątrz buczyny karpackiej. Stwierdzono, iż presja turystyczna ma wpływ na kształtowanie się flory wzdłuż wybranych szlaków pieszych.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.