Soil properties under the canopy of four forest tree species 30 years after planting on two different forest sites

The main objective of this study was to demonstrate a relationship between the direction and effectiveness of impact of particular tree species on soil properties and the initial site fertility. The studies were conducted on two neighbouring experimental plots with different forest site types (fresh mixed coniferous forest – BMśw and fresh mixed deciduous forest – LMśw). The analysed species Norway spruce (Picea abies L. Karst.), European larch (Larix deciduas Mill.), Douglas fir (Pseudotsuga menziesii Franco) and penduculate oak (Quercus robur L.) were planted in three replications on 400 m2 plots. It was stated that: 1) the humification processes ongoing under the canopy of the analysed tree species are, to a large degree, determined by the type of forest site; 2) under the same tree species the content of calcium and nitrogen in the nitrate form was found to by markedly lower in the BMśw forest site; 3) in the BMśw forest site, the pH and electrolytic conductivity of the soil under the majority of the analysed tree species were lower; 4) the degrading impact of coniferous species on soil was noticeably stronger on the poorer BMśw forest site

Isozymatic variability in some of the Polish populations of Norway spruce (Picea abies (L.) Karst.) in the IUFRO - 1972 provenance trial

Genetic differentiation of nine Polish Norway spruce populations, expressed by their isozymatic polymorphism, is presented. The results suggest a presence of two gene pools, one in north−eastern, another in southern Poland

Problem of a massive dying-off of Norway spruce stands in the 'Bialowieza Forest' Forest Promotional Complex

The Białowieża Forest (BF) is in many respects an exceptional object, of a great importance for nature protection and forest management, at the international scale. The BF plays also a key role from the point of view of regional development and welfare of local community. In the last period, a big threat for multiple values of the BF has arisen, as a result of enormous bark beetle infestation, which started in 2012 and has killed 1.4 million m3 of spruce trees. In the paper, first, a brief overview of the general history of the BF and an account of long−term human impacts on its functioning and structure is provided. Next, the history of bark beetle infestations in the BF is analysed. It is shown that, in the period 1992−2007, the average volume of spruces killed by bark beetle amounted on average to 20,000 m3 of wood annually. During that period practically all dead trees were removed from the forest by means of salvation cuttings. Starting from 2008, more and more trees infested by European spruce bark beetle were left in the forest, in a result of a pressure exerted by environmental groups. In 2012, Minister of Environment decided to reduce the allowable cut, determined in forest management plans elaborated for the managed part of the BF, from 107,000 to 48,500 m3/year. This decision, along with several other regulations and restrictions, made in practice impossible to stop the development of a current bark beetle infestation, which started in 2011 and intensified during the next 6 years (solely in 2016 bark beetles killed 480,000 m3 of spruce trees). In the paper, the most important implications and consequences of the current situation are briefly summarized and discussed. A special attention is given to the problems concerning: 1) protection of Natura 2000 species and sites (endangered by bark beetle outbreak), 2) a negative influence of large amounts of spruce deadwood on forest soils, 3) threats caused by pathogenic fungi, 4) question of public safety, 5) fire hazard, and 6) economical dimension. The legal and socio−economical foundations of the functioning of Hajnówka, Browsk and Białowieża forest districts comprising the managed part of the BF, as well as their most important environmental and social consequences are discussed too. Among others, it is indicated that, under current conditions of the BF, human intervention plays a key role in maintaining stable and compositionally diverse woodland communities. Finally, several suggestions and recommendations are provided, aimed at, in the short term, breaking off the current bark beetle outbreak, and, in the long term, at maintaining a multifunctional character of the BF and its ability to provide all important ecosystem services on a sustainable basis

Surface physicochemistry and ionic strength affects eDNA's role in bacterial adhesion to abiotic surfaces

Extracellular DNA (eDNA) is an important structural component of biofilms formed by many bacteria, but few reports have focused on its role in initial cell adhesion. The aim of this study was to investigate the role of eDNA in bacterial adhesion to abiotic surfaces, and determine to which extent eDNA-mediated adhesion depends on the physicochemical properties of the surface and surrounding liquid. We investigated eDNA alteration of cell surface hydrophobicity and zeta potential, and subsequently quantified the effect of eDNA on the adhesion of Staphylococcus xylosus to glass surfaces functionalised with different chemistries resulting in variable hydrophobicity and charge. Cell adhesion experiments were carried out at three different ionic strengths. Removal of eDNA from S. xylosus cells by DNase treatment did not alter the zeta potential, but rendered the cells more hydrophilic. DNase treatment impaired adhesion of cells to glass surfaces, but the adhesive properties of S. xylosus were regained within 30 minutes if DNase was not continuously present, implying a continuous release of eDNA in the culture. Removal of eDNA lowered the adhesion of S. xylosus to all surfaces chemistries tested, but not at all ionic strengths. No effect was seen on glass surfaces and carboxyl-functionalised surfaces at high ionic strength, and a reverse effect occurred on amine-functionalised surfaces at low ionic strength. However, eDNA promoted adhesion of cells to hydrophobic surfaces irrespective of the ionic strength. The adhesive properties of eDNA in mediating initial adhesion of S. xylosus is thus highly versatile, but also dependent on the physicochemical properties of the surface and ionic strength of the surrounding medium.Peer reviewe

Effect of DNase on the adhesion of <i>S. xylosus</i> to glass surface in flow cell.

<p>Black bars indicate untreated cells. Crossed bars indicate cells treated with DNase (50 µg/ml), washed and resuspended in PBS. White bars indicate cells resuspended in PBS containing DNase (50 µg/ml). Asterisk indicates statistically significant differences between samples with and without eDNA (t-test, *p<0.05, **p<0.01).</p

Effect of ionic strength and surface chemistries on eDNA mediated adhesion of <i>S. xylosus</i>.

<p>Black bars indicate untreated cells. White bars indicate cells treated with DNase. Experiments were carried out at low (I = 0.015 M), medium (I = 0.19 M) and high (I = 0.70 M) ionic strength. Values are average of 3 replicates (error bars  =  S.D.) Asterisk indicates statistically significant differences between samples with and without eDNA (t-test, *p<0.05, **p<0.01).</p

Cell surface properties with and without eDNA.

<p>Water contact angle and zeta potential measurements of <i>S. xylosus</i> cells with and without eDNA.</p><p>*indicates statistically significant difference (t-test, p<0.05).</p