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Interrelations among con-generic and co-occurring tree species : asymmetric hybridization and the high success of Quercus petraea (Matt.) Liebl. regeneration in mixed Q. petraea/Q. robur L. stands

Boratyński A., Jasińska A., Iszkuło G., Marcysiak K., Lewandowska A.

Polish Journal of Ecology

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2010

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Vol. 58, nr 2

273-283

EN

Hybridisation and introgression are expected to be common in plant populations composed of various species of the same genera. These processes, however, frequently have one direction or are asymmetric, when one of hybridising species is a donor and other recipient of pollen. The asymmetric hybridisation may be also an important manner of migration by pollen. According to the theory of asymmetric hybridisation in mixed oak populations of European white oaks (Quercus robur and Q. petraea) the number of hybrid saplings should be higher under a canopy of Q. robur than under Q. petraea trees. The aim of this study was to determine, which of the two species in the mixed populations has a greater degree of success in regeneration and colonization, measured by the proportion and density of saplings and young individuals higher than 0.3 m. The taxonomic composition of saplings under the crown ranges of trees was analyzed on the basis of morphological characters of leaves in two distantly located mixed oak stands in Poland, in Jamy and Legnica Forests, where young generation to about 17-18 years old was observed under canopy of 125-140 years old mother trees. The first population is located about 100 km of Q. petraea geographic range and covers area of 6 km, the second about 500 km of Q. petraea range and covers more than 10 hectares. The density of 60 and 134 adult trees per hectare, were found in analysed populations, respectively. A significantly higher proportions of Q. petraea than Q. robur saplings were found in both compared stands. A hybrid saplings proportion were higher than hybrid adult trees. The hybrid saplings were observed more frequently under canopy of Q. robur only in the stand closer to the range of Q. petrea. Gene flow from Q. petraea to Q. robur by cross-pollination was found to be likely. The number of hybrid saplings found under crown projections of Q. petraea trees in both populations suggested also reverse gene flow, at least in the stand located close to the north-eastern limit of the Q. petraea range. A higher regeneration success of Q. petraea was observed in both stands suggesting expansion of this species.

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Life span of needles of Pinus mugo turra : effect of altitude and species origin

Boratyński A., Jasińska A., Boratyńska K., Iszkuło G., Piórkowska M.

Polish Journal of Ecology

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2009

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Vol. 57, nr 3

567-572

EN

The needle life span of evergreen coniferous trees is a species-specific trait but can be also affected and modifies by environmental conditions. On the basis of field observations of needle life span during three periods in two populations of Pinus mugo in the Tatra Mts (altitude: 1600-1700 m) and Sudety Mts (altitude 830-1420 m), 11 populations from various altitudes we concluded that: 1) within the same population needle life span remained the same over the three periods of observations, 2) needle life span in the Tatra Mts is about 1 year longer than in the Sudety Mts, ranging from 5.5 to 5.9 years and 3) needle life span in the Sudety Mts increases significantly with the altitude of the population. The longer life span of needles in the Tatra Mts may be specific for the population, i.e. it may be due to a different population origin (another Pleistocene centre of the species), and the shorter life span of needles noted in the Sudety Mts may be due to higher soil pollution in this region.

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Changes of population structure of Taxus baccata L. during 25 years in protected area (Carpathians, Western Ukraine)

Iszkuło G., Boratyński A., Didukh Y., Romashenko K., Pryazhko N.

Polish Journal of Ecology

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2005

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Vol. 53, nr 1

13-23

EN

The aim of the study was to assess the present state of the Taxus baccata L. population in the Knyazhdvir Nature Reserve (West Ukraine) and to analyse the population structure changes that had occured during 25 years. We found the tendency towards population ageing but with relatively numerous young individuals and seedlings. Surprisingly, specimens with bi- or trifurcate trunks (polycormic) were significantly thicker than those with single trunks (monocormic). This attest to some kind of dominance of polycormic specimens over monocormic ones.

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Interaction between canopy tree species and European yew Taxus baccata (Taxaceae)

Iszkuło G., Boratyński A.

Polish Journal of Ecology

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2004

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Vol. 52, nr 4

523-531

EN

The aim of the study was an examination of the thesis, that canopy tree genera (species) can have positive or negative influence on the germination of seeds and growth of seedlings and saplings of Taxus baccata. The species population spontaneously formed in the Kórnik Arboreum (W Poland) during last decades was the field of investigations. All yew individuals (including seedlings) were positioned and measured on two plots (area 1900 and 2000 m^2) permanently marked in the field. The crown ranges of canopy trees and tree-like yews were measured and projected on the maps. The numbers of seedlings, saplings and tree-like yews under canopies of particular tree genera were compared. The seeds of T. baccata germinated under canopies of all species, most abundantly under the canopy of Pseudotsuga and Abies, but also under mother trees. Seedlings older than 2 years were also most numerous under the canopy of conifferous trees, while the saplings under the canopy of broadleaved trees. The greatest numbers of tree-like individuals were found under Tilia and Carpinus species.