Filters
The effect of herbicides on morphological features of pollen grains in Prunus serotina Ehrh. in the context of elimination of this invasive species from European forests
AbstractPrunus serotinaEhrh. is an alien invasive neophyte widespread in European forests. So far, no effective methods of its elimination have been developed. For this reason, the aim of our study was to determine how herbicides affect the morphological characteristics of pollen grains. This knowledge may be crucial to control this invasive species. The current study was carried out in a research area of 2.7 ha located in the Zielonka Forest near Poznań, Poland (N 52°31′58.016″, E 17°05′55.588″). We tested morphological differences among ten features ofP. serotinapollen, based on the samples collected from 15 control trees compared to the 50 trees treated with five different herbicides. In total 1950 pollen grains were measured. We confirmed the adopted hypotheses of long-term herbicide influence onP. serotinapollen. Pollen grains from the control trees had a longer equatorial axis, were more elongated in shape and had the largest range of exine thickness compared to the pollen from the herbicide-treated samples. Exine thickness in the control sample was on average 0.74 µm, ranging from 0.42 to 1.19 µm. The average values and the ranges of this trait in the samples treated with herbicides were larger (e.g. average exine thickness was from 0.90 to 0.95 µm). There were differences in the P/E ranges of variability between the control and herbicide-treated samples. In the control sample the P/E ratio was 1.32–2.04 and elongated forms of pollen shapes prevailed, while in the herbicide-treated samples it ranged from 1.03 to 1.47. The share of deformed pollen grains in the herbicide-treated samples was lower than expected, ranging from 8.7 to 25.3%, while in the control samples it was 6%. Logo and Mustang turned out to be the most effective among the herbicides used in the described research. The two used application methods were found to have an effect on pollen quality.
Effect of sowing density on performance and biometric features of pedunculate oak
Sowing density is one of the most important factors influencing seedling quality. In forest nurseries, to ensure full seeding, it is recommended to obtain approximately 200 seedlings from 1 m2 (ZHL 2012). The aim of the study was to assess the effect of sowing density on sowing efficiency and the morphological features of pedunculate oak seedlings. Acorns were sown directly by broadcast seeding on 20 test plots, each 4 m in length, in four replications. The following variants were used:- 250acorns capable of germination totaling 341 acorns per 1 linear meter (0.9 m2);- 300 acorns capable of germination totaling 410 acorns per 1 linear meter (0.9 m2);- 350 acorns capable of germination totaling 478 acorns per 1 linear meter (0.9 m2);- 400 acorns capable of germination totaling 546 acorns per 1 linear meter (0.9 m2);- 450 acorns capable of germination totaling 614 acorns per 1 linear meter (0.9 m2). At the end of the growing season, seedlings were counted per 1 m (0.9 m2) in the central part of each plot. Sowing efficiency was determined as a percentage of seedling yield from the sown seeds. For laboratory analysis, 30 seedlings from each plot (600 in total) were collected. Based on biometric features like shoot height, root collar diameter, and dry weights of shoots, roots, and leaves, quality indicators such as the sturdiness quotient (SQ) and the Dickson quality index (DQI) were calculated. Sowing efficiency at the end of the vegetation season ranged between 39.68% and 50.12% and was not statistically significant. The research revealed that sowing density influenced seedling biometric characteristics. Pearson’s correlation coefficients showed significant negative correlations between the number of seedlings obtained in an experimental plot and the dry weight of the root, number and dry mass of leaves, as well as the DQI. The seedlings from all sowing variants complied with the binding Polish standard, outlined in the Regulation of the Minister for the Environment of 18 February 2004 (Ministerstwo Środowiska 2004) by over 96%. Keywords: seeding density, sowing rate, seedling quality, sowing performance, sturdiness quotient (SQ), Dickson quality index (DQI), Quercus robur L.
Climate warming, ecological dynamics and nature conservation drive tree diversity in Wigierski National Park, Poland
In response to ongoing climate warming, tree species adapted to colder climates are expected to shift their geographic ranges northward. Within the framework of long-term ecological monitoring in Wigry National Park (northeastern Poland), observed changes in forest biocenoses reflect the combined influence of climate change and natural ecological dynamics. This study compares dendroflora composition and diversity between two monitoring periods, 2011 and 2024, as part of an ongoing effort to track climate-related ecological shifts. Tree observations and measurements were carried out using concentric circular plots. In the largest plots, all trees with a diameter at breast height (d.b.h.) ≥ 12 cm were recorded by species, and their d.b.h. was measured. In the smaller plots, all trees with a d.b.h. ≥ 2 cm and < 2 cm but taller than 30 cm were similarly identified and measured. Data were recorded with Field-Map software integrated with an electronic calliper. The species-level taxonomic data, individual counts and basal area per species and plot were used to calculate biodiversity indices. Over the 13-year interval, a marked increase in overall dendroflora diversity was observed. Notably, the dominance of canopy-forming conifers – Pinus sylvestris and, to a lesser extent, Picea abies – measured as the proportion of individuals or stem density, has declined. This decline of coniferous species has been accompanied by an increase in the abundance and diversity of broadleaved deciduous species, including Tilia cordata, Quercus robur, Betula pendula, and Acer platanoides. Other thermophilous deciduous taxa also exhibited upward trends in both presence and abundance. Furthermore, the exponential of Shannon entropy, reached the highest value when evergreen conifers comprised 35% of the stand composition in 2011 and 18% in 2024. This finding suggests that maximum dendroflora diversity reaches its highest level at an intermediate proportion of conifers presence, rather than under conifers dominance or absence. Collectively, the processes occurring in Wigierski National Park illustrate the gradual shift in ecotonal forest ecosystems from cold-adapted coniferous species to broadleaved deciduous taxa due to ongoing climate change.
Shields against pollution: phytoremediation and impact of particulate matter on trees at Wigry National Park, Poland
Variability of Functional Groups of Rhizosphere Fungi of Norway Spruce (Picea abies (L.) H.Karst.) in the Boreal Range: The Wigry National Park, Poland
Rhizosphere microbial communities can influence plant growth and development. Natural regeneration processes take place in the tree stands of protected areas, which makes it possible to observe the natural changes taking place in the rhizosphere along with the development of the plants. This study aimed to determine the diversity (taxonomic and functional) of the rhizosphere fungal communities of Norway spruce growing in one of four developmental stages. Our research was based on the ITS region using Illumina system sequencing. Saprotrophs dominated in the studied rhizospheres, but their percentage share decreased with the age of the development group (for 51.91 from 43.13%). However, in the case of mycorrhizal fungi, an opposite trend was observed (16.96–26.75%). The most numerous genera were: saprotrophic Aspergillus (2.54–3.83%), Penicillium (6.47–12.86%), Pyrenochaeta (1.39–11.78%), pathogenic Curvularia (0.53–4.39%), and mycorrhizal Cortinarius (1.80–5.46%), Pseudotomentella (2.94–5.64%) and Tomentella (4.54–15.94%). The species composition of rhizosphere fungal communities was favorable for the regeneration of natural spruce and the development of multi-generational Norway spruce stands. The ratio of the abundance of saprotrophic and mycorrhizal fungi to the abundance of pathogens was high and promising for the durability of the large proportion of spruce in the Wigry National Park and for forest ecosystems in general.
Cherry spruce rust in the Wigry National Park and Suwałki Forest District: cone infestation and its implications
Abstract Thekopsora areolata and Chrysomyxa pirolata are pathogens preferentially infesting Norway spruce cones and lead to the complete failure of spruce seed yield. Thus, the presence of seed-injuring pathogens may be a crucial factor driving close association between cherry spruce rust occurrence on trees and limited natural regeneration of the preferred host. However, a major uncertainty remains as to which pathogens are responsible for cone infection and reduced seed viability, resulting in impeded renewal of young trees. Our study aims to investigate whether T. areolata or C. pirolata presence on the Norway spruce cones was responsible for cherry spruce rust in three sites within the Wigry National Park (one site) and the Suwałki Forest District (two sites) in North-Eastern Poland. We harvested randomly five infested Norway spruce cones from each location and analysed them to verify specific pathogen occurrence. We analysed rDNA fragments such as ITS regions and 28S to precisely identify the disease causal agent on the cones and estimate the potential of genetic diversity of the analysed fungus species. Thekopsora areolata was identified as the main fungus promoting cherry spruce rust, suggesting that host species regeneration is constrained by this pathogen’s distribution. We assumed that the apparent cherry spruce rust presence and lack of Norway spruce natural regeneration likely result from cone infection and the availability of healthy, high-quality seeds. Moreover, the occurrence of cherry spruce rust may explain the challenges associated with the deficit of seeds used for the artificial regeneration of spruce stands.
Regenerating oak trees with different techniques has long-lasting legacy effects on root development, stem growth and plant physiology
Abstract Regeneration methods can have legacy effects on tree physiology and growth via differential root development and affect forest climate sensitivity. However, there are few studies providing a long-term perspective on how forest regeneration techniques affect root development and physiology of established seedlings that have grown into trees. This study investigates leaf carbon (C), oxygen (O) and nitrogen (N) isotope composition (δ13C, δ18O, δ15N) and stem growth in ⁓20-year-old oak (Quercus robur L.) trees regenerated in two stands by three methods: direct acorn sowing in the field, bare-root planting preceded by root pruning and containerized planting with the root plug intact. Leaf isotopic values were measured three times during summer, together with tree-ring δ13C. Ground penetrating radar analyses indicated that acorn sowing resulted in deep root systems compared shallower root systems of bare-root and containerized trees. Higher annual basal area increment was observed in acorn-sown oaks than in bare-root or containerized oaks. Leaf δ13C, δ18O and δ15N values varied among regeneration origins. Trees with deeper root systems consistently showed lower leaf δ18O values, regardless of the season, which suggests higher uptake of water from deep soil horizons and better leaf hydration. In contrast, oaks with shallower root systems exhibited higher leaf δ18O values, which were positively related with δ13C. More negative leaf δ15N values in shallow-rooted oaks pointed to higher water stress. A lack of correlation between N concentration and intrinsic water-use efficiency (iWUE) for containerized trees suggests that variability in stomatal conductance rates governed iWUE in these shallow-rooted oaks. The lack of correlation between leaf and tree-ring δ13C supports that leaf physiological processes do not necessarily explain latewood isotopic composition. We conclude that regeneration techniques have long-lasting, carry-over effects on root development, plant physiology and tree growth. The findings underscore the importance of considering tree regeneration origin and root distribution when assessing the impact of climate change on tree performance and forest vigor.