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3
86%
Sylwan
|
2003
|
tom 147
|
nr 01
88-95
Studies of moss and soil nematode communities in four age classes of the Scots pine forest In the Białowieża primeval forest demonstrated relatively low number of species. The species diversity and ecological complexity of the communities increases as the shadowing of the forest floor increases. The maturation of the forest is associated with the increase of the proportion of fungivores and decrease of bacteriovores in the soil nematodes communities.
A decrease in the degree of age differentiation of forests stands in Puszcza Białowieska is accompanied by a 50-60% reduction in the number of species of zoophages or sucking and chewing phytophages and a 10-25% reduction in the number of xylo- and cambiophages. The preservation of age differentiation favours the development of useful fauna with an inconsiderable increase in the number of secondary pest species. With the age of the stands becoming uniform (the forest getting older), faunal diversity is usually reduced, while the degree of its utilisation in the organisation of the forest zoocenosis is increased.
In spite of the growing importance of the protective and social functions of forests, their productive function, including production of raw wood with a diversified assortment structure, is still prominent. Changes in the assortment structure depend to a large extent on tree species, habitat conditions and intensity of tending treatments. However, for the temporal organization of forest management, it is essential to recognize the dynamics of these changes in relation to stand age. The paper contains an analysis of quantitative and qualitative changes in the assortment structure of the Ist site index pine stands in the Wilcze Bagno Forest Compartment (Pisz Forest District), depending on the length of the primary production of standing timber. Data from 10 forest stands similar in terms of habitat, stand density and management treatments were taken for analysis. These stands form a homologous series ranging in age between 40 and 130 years.
W pracy przeanalizowano kształtowanie się stanów wód gruntowych w różnowiekowych drzewostanach leśnych siedlisk bagiennych na tle warunków meteorologicznych (temperatury powietrza i opadów atmosferycznych). Badania przeprowadzono w latach hydrologicznych 2002–2005 na 7 powierzchniach doświadczalnych, zlokalizowanych na terenie Puszczy Zielonka oddalonej o około 6 km na północny wschód od granic miasta Poznania. W toku prowadzonych badań stwierdzono, że największą dynamiką zwierciadła wód gruntowych charakteryzują się powierzchnie badawcze z drzewostanami średnich klas wieku, zaś najmniejszą drzewostany najstarsze (V klasy wieku) i w mniejszym zakresie – I klasy wieku. Uzyskane wyniki badań, przez swoją niejednoznaczność, jak również ze względu na krótki ciąg pomiarowy, nie pozwalają przyjąć ani całkowicie odrzucić tezy o istnieniu zależności pomiędzy wiekiem drzewostanu a stanami wód gruntowych w leśnych siedliskach bagiennych.
14
72%
Sylwan
|
2010
|
tom 154
|
nr 07
478-487
According to the current forest management manual, deadwood volume should be evaluated on 10% of sampling plots, located in different species−age layers, which are used for determining stand volume in a given forest unit. Sampling plot size differs depending on tree stand age and ranges from 0.005 to 0.05 ha. The results are reported for the entire forest district and by forest site type. The objective of the study was to analyze the accuracy of deadwood volume estimations in the light of the guidelines stipulated in the forest management manual and to find the ways to improve the obtained results. Deadwood volume was measured on 2752 sample plots used to determine stand volume and the mean value calculated on that basis was 5.4 m³/ha. Subsequently, 30 random draws of sampling plots were performed. Estimates based on randomly selected pools consisting of 10% of sampling plots ranged from 3.5 to 8.6 m³/ha. Subsequently, another 10% of sampling plots were randomly drawn and added to the previous ones. The results for 20% of sampling plots were 4.5−7.0 m³/ha, for 30% – 4.3−6.4 m³/ha, for 40% – 4.6−6.4 m³/ha and for 50% – 4.7−6.0 m³/ha. In the next step, 225 sampling plots located in reserves and special zones around the nests of protected species were discarded. The mean volume of deadwood computed for the managed forest areas alone (2527 sample plots) was 4.7 m³/ha. The random drawing procedure was repeated to give the following results: 3.6−6.8 m³/ha for 10% of sampling plots; 3.8−5.8 m³/ha for 20%; 3.9−5.3 m³/ha for 30%; 4.2−5.3 m³/ha for 40%; and 4.2−5.1 m³/ha for 50% of sampling plots. The categorization of the randomly selected sampling plots by forest site type in most cases yielded results significantly differed from the values computed based on all sampling plots. It was found that estimates based on 10% of sampling plots may diverge considerably from true values due to the uneven distribution of deadwood. In particular, managed and unmanaged forest areas should not be combined due to the high differences in the volume of deadwood between them. If a relatively low number of sampling plots is used, it seems advisable to report results only for the forest division as a whole, without a breakdown into site types. Satisfactory estimates for the different forest sites types would require much more work. The use of a greater number of sampling plots than specified in the forest management manual seems to be a fundamental prerequisite for improving the accuracy of deadwood volume estimates.
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