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Modelowanie rozkładów pierśnic drzew z wykorzystaniem rozkładów mieszanych. II. Aproksymacja rozkładów pierśnic w lasach wielopiętrowych

100%

Podlaski R.

Sylwan

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2011

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tom 155

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nr 05

2

Wykorzystanie dolnych warstw drzewostanu w planowaniu hodowlanym

100%

Zybura H., Pewniak B.

Sylwan

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2016

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tom 160

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nr 10

Currently observed climate change creates favourable conditions for the development of not only deciduous species (oak and beech), but also some coniferous (e.g. fir). In the Scots pine stands growing on fertile forest site types one can observe the dynamic development of the under−canopy layers composed of those species. Oak or beech saplings are often characterized by good silvicultural value. Also silver fir creates a well−developed cover under Scots pine trees. Beech and fir as the most shade−tolerant tree species are able to handle the conditions under Scots pine. They can grow for a long time under the cover without damage to their height or diameter growth. Especially, a dynamic growth of oaks can often be observed on fresh mixed coniferous and fresh mixed broadleaved habitats. Oak layers in Scots pine stands are generally created in the way of natural regeneration with remarkable contribution of the jays, which spread the seeds even at considerable distances from the old trees. The corresponding intensity of thinnings supports to shape the proper silvicultural value of such under−canopy storeys. Observations on growth of such stand layers in the Scots pine stands in eastern and central Poland consider the desirability of including them in the next generation of stands. Their presence contributes to improvement of the biological stability of the stands, and also leads to increased productivity. By implementing to the forest practice the model of semi−natural silviculture, one wants to consider the possibility of using the saplings currently existing under the Scots pine as a component of the future stand. Knowledge about the silvicultural value and the impact on growth of lower layers will enable to develop the principles of proper cultivation of the multi−storey stands.

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Modele struktury grubości w dwu- i wielopiętrowych drzewostanach z udziałem jodły Abies alba Mill. i buka Fagus sylvatica L.

80%

Pach M., Podlaski R.

Sylwan

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2015

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tom 159

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nr 08

The objectives of the study were (1) to determine the models of diameter at breast height (dbh) distributions in two− and multi−storied mixed stands with fir Abies alba Mill. and beech Fagus sylvatica L. as well as (2) to assess the usefulness of single Weibull distribution and two−component mixture of Weibull distribution to approximation of empirical dbh distributions for distinguished models of dbh structures. In the Świętokrzyskie Mountains, 21 sample plots ranging in size from 0.2 to 0.4 ha were established. To identify the models of dbh distributions, in two− and multi−storied stands with similar empirical dbh distributions, the hierarchical cluster analysis (HCA) with the Jaccard's measure and the Ward's minimum variance agglomeration method were used. To approximate dbh distributions, the single Weibull distribution and the two−component mixture of Weibull distribution were employed. In two− and multi−storied mixed stands with fir and beech, with the mean age between 50 and 70 at the dbh, four models of dbh distributions were determined (fig. 1). Two of them were decreasing, strongly asymmetric (OS and OJ models; fig. 2) and the other two were increasing in the initial phase and decreasing in the final, having two maximums (DM1 and DM2 models; fig. 3). In the stands with the complex structure mixed distribution should be used to approximate empirical data. The analysis revealed high suitability and versatility of Weibull distribution both as single form and two−component mixture.

Ograniczanie wyników

3 Sylwan

2 Podlaski R.

1 Pach M.

1 Pewniak B.

1 Zybura H.

1 2016

1 2015

1 2011

Modelowanie rozkładów pierśnic drzew z wykorzystaniem rozkładów mieszanych. II. Aproksymacja rozkładów pierśnic w lasach wielopiętrowych

Wykorzystanie dolnych warstw drzewostanu w planowaniu hodowlanym

Modele struktury grubości w dwu- i wielopiętrowych drzewostanach z udziałem jodły Abies alba Mill. i buka Fagus sylvatica L.