Grzegorz Iszkuło

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• Professor
• Professor at Institute of Dendrology, Polish Academy of Sciences

This account presents information on all aspects of the biology of Cytisus scoparius (L.) Link (Broom or Scotch Broom) (Sarothamnus scoparius (L.) W.D.J. Koch) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: dis...

This is a review of the literature on genetics, physiology, and ecology, which concerns Juniperus phoenicea, J. turbinata, and J. canariensis, forming together the complex J. phoenicea. Despite the numerous and varied studies, many gaps and deficiences have been identified in these fields. Further research is particularly needed on the genetic dive...

The horse-chestnut (Aesculus hippocastanum L.), a popular ornamental tree widely cultivated throughout Europe since the 16th century, has a very limited natural range. The work presented was intended to shed light on the human-mediated spread of this species from natural Balkan populations to artificial sites. For this purpose, chloroplast DNA (cpD...

Leaves are crucial organs for plants, and their morphology is highly diverse. This article discusses various hypotheses concerning the serration of leaf margins, including the insect deterrence hypothesis, root pressure hypothesis, bud packing hypothesis, support-supply hypothesis, and early season gas-exchange hypothesis. Each of these hypotheses...

The Juniperus phoenicea complex consists of three taxa: J. phoenicea sensu stricto (s.s.), J. turbinata, and J. canariensis. A review of the literature on the biology of these taxa was conducted, focusing on taxono-my with paleo-data, structure, and geographical distribution to present current knowledge on these topics. Information on ecology, dise...

Aim: The well-proven positive correlation between the increased proportion ofentire-leaved woody dicotyledonous species and increased mean annual temperaturehas been commonly used to estimate temperature in the past. However, in regions ofcolder climates, this relationship is not straightforward, questioning the accuracy oftemperature estimation....

This literature review focuses on the biology and ecology of Juniperus drupacea. Within the context of the series ‘Our Forest Trees’ by the Institute of Dendrology PAS at Kórnik, the following key topics are discussed: taxonomy with paleo-records, morphology, anatomy, geographical distribution, ecology (including habitat, communities, response to b...

This account presents information on all aspects of the biology of Viscum album L. (Mistletoe) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland: distribution, habitat, communities, responses to biotic factors, r...

Dioecious species differ in the pattern and intensity of male and female reproductive investments. We aimed to determine whether female shoots deprived of generative buds show biochemical features, indicating their less-pronounced reproductive effort. For this purpose, the same branches of mature Taxus baccata females were deprived of generative or...

Viscum album L. is a plant of great importance due to its influence on the host trees and, by extension, entire ecosystems. The species is also significant to humans—on the one hand, because of its use in medicine, and on the other, because of the growing threat it poses to the stability of conifer stands. Therefore, it is important to recognize th...

Predicting species-level effects of climatic changes requires unraveling the factors affecting the spatial genetic composition. However, disentangling the relative contribution of historical and contemporary drivers is challenging. By applying landscape genetics and species distribution modeling, we investigated processes that shaped the neutral ge...

Rhododendron ferrugineum occurs in the mountains of the Central Europe with large disjunction in geographic range between Pyrenees and Alps and between Alps and Sudetes. We expect that these discon­tinuities in the species occurrence should involved their phenotypic differentiation, similar as described on the studies of molecular markers. The aim...

The Mediterranean Basin is one of the 36 global hotspots of biodiversity and it is rich in endemic tree species. The complex geological history of the region throughout the Neogene and Quaternary periods that were marked with several palaeoclimatic transformations was a major factor triggering the genetic divergence of lineages in tree species in t...

The possibility of mistletoe growth on our native oaks is often questioned. There is a hypothesis that the reports of mistletoe on oak, existing both in scientific literature and in culture, are a mistake and concern another semi-parasite: European loranth, which is hosted by both our oaks: the common and the sessile oaks. The article briefly revie...

Scots pine is one of the most widely occurring pines, but future projections suggest a large reduction in its range, mostly at the southern European limits. A significant part of its range is located in the Caucasus, a global hot-spot of diversity. Pine forests are an important reservoir of biodiversity and endemism in this region. We explored demo...

Key message: Taxus baccata remnants established recently tend to contribute less to the species' overall genetic variation than historical populations because they are subjected to a greater impact of the founder effect and genetic isolation. As tree trunk perimeter is a rough indicator of genetic variation in a population, this measure should be c...

Female individuals of dioecious plants invest their resources more in storage and defence, and the males have higher nitrogen content invested in the production of pollen grains. An unresolved problem is whether this strategy occurs only in sexually mature plants or can also occur in juvenile plants. To answer this, Taxus baccata (L.) needles from...

Causes of secondary sexual dimorphism (SSD) in dioecious plants are very poorly understood, especially in woody plants. SSD is shown mainly in mature plants, but little is known about whether secondary sexual dimorphism can occur in juveniles. It is also assumed that stress conditions intensify differences between the sexes due to the uneven reprod...

Key message Juniperus communis males are better adapted than females to changing, seasonal environmental conditions due to their higher photosynthetic capacity and the higher concentration of photosynthetic pigments in their needles. Males cope with ROS more efficiently than females having greater carotenoids concentration in needles. AbstractIn di...

This account presents information on all aspects of the biology of Crataegus laevigata (Poir.) DC (Midland hawthorn) (C. oxyacanthoides Thuill.) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habi...

New nuclear microsatellite markers (SSRs) were developed for Aesculus hippocastanum, a relict tree species from the Balkan Peninsula. The development of microsatellites was done using the Illumina MiSeq PE300 platform. Out of a set of 500 SSRs designed, a subset of 13 loci was tested using 290 individuals from seven natural populations. Twelve spec...

Aims Leaf size and shape as objects of natural selection can play adaptive roles, and can change with the age of leaves. They can differ between sexes in dioecious species, and in most cases, females have larger leaves. Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing. In this study we investigated whether ther...

We hypothesized that female and male individuals of the dioecious tree species, Juniperus communis, exhibit different strategies of resource allocation when growing under stress conditions. To test this hypothesis, we performed a two-year pot experiment on plants exposed to different levels of nutrient availability. Analysis of the plants revealed...

Iszkuło G., Armatys L., Dering M., Ksepko M., Tomaszewski D., Ważna A., Giertych M. J. 2020. Jemioła jako zagrożenie dla zdrowotności drzewostanów iglastych. Sylwan 164 (3): 226−236. DOI: https://doi.org/ 10.26202/sylwan.2019121. The forest area infected by mistletoe (Viscum album L.) in Europe has been increasing in recent years. The highest poten...

Horse-chestnut (Aesculus hippocastanum L.) is an endemic and relict species from the Mediterranean biodiversity hotspot and a popular ornamental tree. Knowledge about the evolutionary history of this species remains scarce. Here, we ask what historical and ecological factors shaped the pattern of genetic diversity and differentiation of this specie...

The mating system is a central parameter of plant biology because it shapes their ecological and evolutionary properties. Therefore, determining ecological variables that influence the mating system is important for a deeper understanding of the functioning of plant populations. Here, using old concepts and recent statistical developments, we propo...

Limited pollen availability contributes to lower seed production, especially in dioecious species. It can result from a lower quantity and/or a lower quality of pollen grains. Since the environment can impact pollen development, the effect of long-term nutritional availability on the male parameters of the dioecious, long-lived plant, Taxus baccata...

This account presents information on all aspects of the biology of Aesculus hippocastanum L. (horse‐chestnut) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biot...

Defoliation caused annually by Cameraria ohridella has a considerable impact on the general condition of horse chestnut trees. We investigated the consequences of tree endotherapy against this insect. Wood samples, leaves and insect specimens were collected ten years after the treatment (injection) with pesticides. Insect invasion was manifested in...

Potted T. baccata female and male individuals were grown with or without fertilization. During the three-year experiment, pulse-modulated chlorophyll a fluorescencence and antioxidative enzymes were monitored. Effects of the sexe and fertilization treatment on key photochemical parameters and antioxidative enzymes were investigated.

In dioecious woody plants, females often make a greater reproductive effort than male individuals at the cost of lower growth rate. We hypothesized that a greater reproductive effort of female compared with male Taxus baccata individuals would be associated with lower female photochemical capacity and higher activity of antioxidant enzymes. Differe...

The aim of this study was to update figures for the presence of dioecy among the gymnosperms and investigate its correlation with climate, growth form, pollination and seed dispersal syndromes, and risk of extinction. Dioecy was found in almost 65% of contemporary gymnosperm species, a higher percentage than previous estimates. It dominates in 8 of...

Aesculus hippocastanum is a well-known species, which is popular because of its ornamental value. However, data on the demographic structure and potential distribution of A. hippocastanum are limited. The invasion of Cameraria ohridella into Europe has harmed those trees growing in artificial sites, but the presence of this insect in natural stands...

Damage by herbivore grazing negatively influences the development of subsequent forest generations. Little is known about the long-term impacts of grazing and interactions between grazing and light conditions on sapling growth after the cessation of herbivory impact. In this study, Taxus baccata saplings were grown over a period of four years in ar...

European mistletoe (Viscum album L.) is a semi−parasitic plant attacking selected tree species. It adversely affects the functioning of its hosts especially at water management level. Scots pine infestation by mistletoe subspecies Viscum album ssp. austriacum becomes more and more common. Mistletoe has been proven to have a negative impact on Scots...

Prunus serotina Ehrh. (black cherry) is one of the most important invaders in the European forests, but existing studies have given limited insight into demo-genetic factors underpinning the process of species invasion. Fine-scale genetic structure (FSGS) may deliver important knowledge on genetics of invasion contributing to efficient management o...

Genders of dioecious species often show secondary sexual dimorphisms (not directly related to the sex organs), which may be related to reproductive demand for resources during the year. Our working hypothesis stated that phenology influences yearly sex-specific pattern of foliar nitrogen concentration in dioecious species. The concentration of carb...

The knowledge on chorology of species is basic for biogeographic and ecological studies and for conservation actions. The data on the chorology of Taxus baccata in Morocco have not been studied. The bibliographic resources, herbarium material, unpublished data of several botanists and the authors’ field notes have been reviewed. Two yew populatio...

Taxus baccata L. has a scattered distribution and the decline of yew woodlands is observed across the entire species range. Passively protected populations in the central and northern part of their distribution are declining without human intervention. However, the establishment of new yew populations is observed in habitats that have been signific...

Introduction: Dioecy ensures outcrossing in some plant species. It is posited that this adaptation has to be paid at different extent by male and female individuals with resources allocation to reproduction. We hypothesize that a greater female effort for reproduction than that of male will be reflected with their lower photosynthetic capacity. The...

In plants, the spatial genetic structure (SGS) is shaped mainly by gene dispersal and effective population density. Among additional factors, the mode of DNA inheritance and dioecy influence SGS. However, their joint impact on SGS remains unclear, especially in the case of paternally inherited DNA. Using theoretical approximations and computer simu...

Clathrus archeri is a saprotrophic fungus native to Australia and New Zealand and known in Europe since the beginning of the 20th century. In Poland, C. archeri was recorded for the first time in 1973 and since then basidiomata of this fungus have been recorded almost 90 times, mostly in the southern part of the country. In the present study, we up...

Three populations of Abies cilicica subsp. isaurica and four of A. cilicica subsp. cilicica were analyzed using 35 morphological and anatomical needle characters with the implementation of multivariate statistical methods to verify the differences between subspecies. Moreover, the possible geographic differentiation of A. cilicica subsp. cilicica p...

English yew (Taxus baccata L.) is a strictly outcrossing and dioecious species whose populations are small and isolated. It is known that sex ratios may vary in natural populations due to local environmental conditions or stochastic events. However, unbalanced sex ratios may have negative impacts on genetic diversity through enhanced genetic drift...

The percentage of dicotyledonous species with untoothed leaf margins is positively correlated with mean annual temperature across different continents and biomes. Paleobotanists commonly use this relationship as an index for inferring temperature in the past. However, leaf margin analysis often estimates cooler temperatures than alternative methods...

In the present study, a genetic analysis of nuclear microsatellites was conducted in Abies cilicica populations growing in West Taurus, East Taurus, and Lebanon mountains to obtain evidence for significant genetic differentiation. Despite range fragmentation, all examined populations tended to maintain a relatively high level of genetic diversity (...

European yew (Taxus baccata L.) is a rare species, but is the focus of great interest because of the species recovery attempts and its use in medicine. The aim of this study was to determine the optimum conditions for the development of the young generation of this species. Four-year old yew seedlings were grown under artificial light reduction: 2,...

The aim of this study was the biometrical comparison of Abies pinsapo Boiss., Abies maroccana Trab. and Abies tazaotana Côzar ex Villar from Spain and Morocco. The morphological and anatomical analysis of the needle characters of these firs revealed significant taxonomic differences. The results showed considerable distances between regions and ver...

Juniperus thurifera is an important component of woodland communities of dry sites within the West Mediterranean region and is characterised by a strongly disjunctive geographic range. Two subspecies were recognised, subsp. thurifera in Europe and subsp. africana in Africa. The aim of the study was the comparison of phenetic diversity to the patter...

Like other species of the genus Taxus, European yew trees contain taxanes, including paclitaxel (T) and its precursor 10-deacetylbaccatin III (10-DAB). Taxanes are one of the most effective anticancer drugs. This study was undertaken to describe the levels and patterns of taxane variation in the Sudetian region (SW Poland). Paclitaxel (T) and 10-de...

This paper provides a detailed description of eleven nature reserves located on the Międzychodzko-Sierakowskie Lakeland. Comparison and a list of natural, cultural and tourist attractions of nature reserves were prepared. An impact of tourism on reserves was also studied. It was found that the reserves showed a large cultural and natural diversity....

Context Taxus woodlands suffer from a lack of natural regeneration across its whole distribution range. Aims In Knyazhdvir Reserve in Ukraine Taxus baccata primarily competes with Abies alba. It has been assumed that in the conditions of deep shade, yews have a greater competitive advantage than firs. Methods To verify this hypothesis, a plot with...

Basing on repeated analyses of vegetation of the ‘Cisy Staropolskie im. Leona Wyczółkowskiego’ reserve near Wierzchlas (N Poland) it was found that frequency of species characteristic for Querco−Fagetea association increased at the expense of species typical for acidophilous and wet sites (Vaccinio−Piceetea, Quercetea robori− −petraeae and Alnetea...

W dziejach ludzkości cis pospolity zajmował szczególne miejsce. Ludzie wykonywali łuki cisowe już 15 000 lat p.n.e. Mimo, że wykorzystywanie łuków zakończyło się wraz z rozpowszechnieniem broni palnej, to presja człowieka trwała nadal. Drewno cisa było szczególnie cenne i wykorzystywane, między innymi, do produkcji mebli. Zainteresowanie cisem jesz...

Cis pospolity jest gatunkiem rzadkim w całym swoim zasięgu geograficznym. Często obserwowane liczne młode pokolenie w naturalnych lokalizacjach najczęściej zamiera nie zapewniając ciągłości nielicznych populacji. W publikacji dokonano próby analizy, na podstawie dostępnej literatury, najważniejszych czynników wpływających na brak sukcesu reprodukcy...

Dioecious species are a very interesting object of study because of predicted differences between male and female individuals. Most dioecious species have a higher reproductive effort in female individuals in comparison with males. The object of this study was common juniper (Juniperus communis subsp. communis), dioecious shrubs or small trees. Thi...

The main aim of our study was to verify the influence of climatic factors on the formation of abnormal 3-needle dwarf shoots in the two-needle Pinus mugo. Twenty individuals of the species, which had at least one abnormal brachyblast in 2002, have been studied in the Tatra Mountains (Carpathians) and an additional 20 in the Giant Mountains (Sudetes...

Dioecy is a mating system in which a greater reproductive effort has been observed in one sex than the other. This is expressed in differences between the sexes in growth rate and spatial segregation. The spatial structure of Juniperus thurifera subsp. thurifera and Juniperus communis subsp. communis and growth rate of tree-ring width of J. thurife...

Female and male plants often differ in reproductive effort and habitat requirements. The aim of this study was to analyze these differences between the sexes and the effect of climate on tree-ring width in European yew (Taxus baccata). The study was conducted in five yew populations in western Poland. Wood samples were taken from 196 trees (98 fema...

Taxus baccata L. is a rare and endangered dioecious species in Europe. Species of this mating system are considered to be the most vulnerable to extinction. It is believed that one reason for this state may be the uneven reproductive effort and different habitat requirements of the two sexes. Silver fir and European yew have very similar ecological...

Short title: Influence of biotic and abiotic factors on natural regeneration of European yew This study examines the factors affecting the lack of success in regeneration of natural populations of European yew. Among the numerous local factors that can be important in the existing populations, the lack of reproductive success is most probably due p...

European yew (Taxus baccata) is a rare and endangered species in many European countries. Observations of high levels of T. baccata seedling mortality under the canopy of mature trees suggest that mortality due to low irradiance may contribute to the decreasing population size of this species. The primary goal of my work was to determine if light a...

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...

Sex ratio and sexual dimorphism were studied in the dioecious tree Taxus baccata. We examined five populations of T. baccata in Poland and Ukraine to identify the differences between male and female individuals. The sex of all individuals, height and diameter, needle length and area, specific leaf area (SLA), the number of stomata rows, stomatal de...

The needle life span of evergreen coniferous trees is a species-specific trait but can be also affected and modified 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 f...

The characters of Quercus robur and Q. petraea leaves are of main taxonomic value and the adult trees of both species can be distinguished on them. However, young individuals, mostly seedlings but also saplings, are told to be undistinguishable or only partly distinguishable on the leaf morphology. The aim of the study was to verify this hypothesis...

Taxus baccata L. is a rare and endangered species with restricted occurrence. One or two-year-old yew seedlings occur quite frequently in natural stands of the species, but older seedlings are rarely observed. Therefore we investigated the relationship between light intensity and the growth rate of ten-year-old seedlings of the European yew Taxus b...

The aim of the present work was to analyse the relationship of seedlings and saplings of Taxus baccata to the photosynthetic photon flux density (PPFD) reaching the forest floor under natural conditions. Two permanent plots, subdivided into 1 × 1 m square plots, were established in a naturally regenerating population of T. baccata formed during las...

The aim of the present work was a comparison of the age and spatial structure of two populations of Taxus baccata in the Kórnik Arboretum, formed spontaneously under different initial conditions. The first of them (plot one) comes from at least 11, while the second (plot two) from only two, potential mother tress at a distance up to about 100m. The...

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 occurred during 25 years. We found the tendency towards population ageing but with relatively numerous young individuals and seedlings. Surprisingly, specime...

The relations between Photosynthetic photon flux density (PPFD) and both the number of silver fir (Abies alba) seedlings per unit area and their height growth were investigated. The study was carried out in the Sudety Mts (SW Poland, 50°28'N, 16°19'E), in a forest stand dominated by spruce (Picea abies), growing on site of mixed broad-leaved mounta...

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 Arboretum (W Poland) during last decades was the field of investigations. All ye...

The aim of the present study was to analyse the occurrence of monoecious individuals in selected populations of Taxus baccata in Poland and Ukraine. The investigation showed the monoecy in Taxus baccata to be extremely rare phenomenon. Only four cosexual individuals were found in three by seven populations examines and the frequency of monoecy was...

Research were conducted on the area with forest decline in the Izery Mountains. The transect method of experimental plots, established at the different altitude and in different conditions, was applied. The following characteristics were analyzed: time of coming into being of natural regenerations of silver birch (Bettthi pendula Roth.), their dens...