Oak trees play a significant naturalistic and economic role. Common oaks represent the most valuable forest-creating species in Poland. In the recent years, on the area of the whole country, one can observe a visible deterioration of the health conditions in oak tree stands. It is difficult to indicate the main factor responsible for this phenomenon. Because of the wide range of this observation, it can be assumed that this process is caused by many biotic and abiotic, as well as anthropogenic factors. Studies were out in the Sulęcin Forest District. At the turn of July and August in the years 2009 and 2010, an assessment of the losses in the majority of trees showed a medium degree (49%). Another group of trees showed 36% of leaf loss, while 14% of oak trees did not show any losses at all. A very high degree of defoliation was found only in 1% of trees. The presented data indicate that an average loss in the assimilation apparatus of oak trees amounted to 29.15%.
The paper presents an evaluation of health condition of selected oak stands in the Włoszakowice Forest Division based on a synthetic tree damage index. Field work was conducted in 2007-2008. In order to perform this task seven experimental sites were established, with 25 trees from Kraft’s age classes I-III evaluated in each. It was found that the overall health condition of most stands deteriorated in 2008 in comparison to 2007.
Quercus robur and Q. petraea are important forest-forming species in Europe. Q. robur is believed to require more fertile soils, to be more tolerant to low temperatures and more sensitive to oak decline than Q. petraea. Thus chronologies of the two species from nearby localities were hypothesised to differ more strongly between species than between localities. Wood cores were collected on 23 research plots in 2 national parks and 12 forest districts. In each locality two plots (one with Q. robur and one with Q. petraea) were established in forest stands of similar age at similar site conditions wherever possible. Similarity between chronologies was assessed by the test of parallel agreement (Gleichlaufigkeit), Pearson correlation coefficients, and principal components. The plots were grouped by the Ward clustering method and according to 1st and 2nd principal components. The first 2 methods segregated chronologies nearly ideally into pairs of species from the same forest district, indicating that the chronologies differ between forest districts but not between species. Chronologies clustered in 2 large groups: northern and southern (on the basis of correlation) or northeastern and southwestern (on the basis of parallel agreement). Principal components also distinguished northeastern and southwestern chronologies, but less clearly. The results suggest that differences in climatic and soil requirements between the 2 oak species are generally too small in comparison with the differences caused by climatic factors.
Coppicing is uncommon in Poland; however, some remnants of a previously coppiced oak forest persist in the foothills of the Sudety Mountains (southern Poland). Some of these forests are considered as a kind of thermophilous oak forest, classified as habitat 91I0 in the European programme Natura 2000. As an example of previously coppiced sessile oak (Quercus petraea (Matt.) Liebl.) forest in Poland, the vegetation and environmental factors in the “Wąwoz Lipa” reserve (area 101 ha, altitude ca. 400 m a.s.l.) were surveyed. Canonical correspondence analysis showed a basic compositional gradient of vegetation related to the content of coarse fragments in the soil, light availability and soil pH. The number of species per plot was not correlated with any particular environmental variable; in general, the plant species number and cover decreased in the most exposed sites, where the heat load was highest. We hypothesize that the higher number of species in some plots was the results of an edge effect: this occurred in transitional zones between the most exposed sites, which work as refuges for light-demanding, drought-tolerant species, and less exposed sites, with vegetation typical of acidophilous oak forests. The land relief also allowed the spread of species typical of mesophilous forests, which found refuge in the shaded, wet gorges. Thus, the specific land relief, along with previous coppice management, allowed the coexistence, probably temporally, of species of plants considered typical of different habitats.
Dąb szypułkowy (Quercus robur) to najcenniejszy pod względem gospodarczym gatunek drzewa liściastego lasotwórczego w Polsce. Drzewostany dębowe stanowią ok. 6% ogólnej powierzchni leśnej kraju. W ostatnich latach na terenie całego kraju obserwujemy masowe zamieranie drzewostanów dębowych. Zjawisko zamierania dębów na dużą skalę obserwujemy w Europie od początku lat 80-tych ubiegłego wieku. Zamierają drzewostany o różnym pochodzeniu, w różnych warunkach siedliskowych, w różnym wieku. W pracy oceniono stan zdrowotny drzewostanów dębowych Nadleśnictwa Chojna na podstawie stopnia ubytku aparatu asymilacyjnego. Dla zbadania zdrowotności drzewostanów dębowych wybrano 6 wydzieleń z Obrębu Krzywina Nadleśnictwa Chojna. Na wszystkich powierzchniach wielkość ubytku aparatu asymilacyjnego wahała się od 0 do 95%. Średni stopień defoliacji dla poszczególnych wydzieleń zawierał się w przedziale 12-18%. W świetle uzyskanych wyników badane drzewostany charakteryzuję się bardzo dobrym stanem zdrowotnym.
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