Summary
The ecological importance of riparian forests is well known. However, these forest habitats have been disturbed by human activities over the past century as a result of the introduction of ...flow regulations. Mortality of the riparian alder population caused by Phytophthora has become an important issue in Europe in the past two decades. The main objective of this study was to examine the pathogenicity of the Phytophthora alni complex (P. xalni, P. uniformis and P. xmultiformis) and P. plurivora in Alnus glutinosa seedlings. Phytophthora alni complex has traditionally been identified as the main causal agent of alder decline; however, in this study, P. plurivora was found to cause as much damage in inoculated seedlings as P. alni complex. In fact, Spanish isolates of P. xalni caused mortality rates of ca. 30%, whereas P. plurivora killed ca. 50% of seedlings. Likewise, there were no differences between P. xalni ‐ and P. plurivora‐inoculated seedlings in either the length of lesion or biomass allocation. The pathogenicity of the species within P. alni complex did not differ significantly. The findings confirm that P. plurivora, which is one of the most common species of Phytophthora found in European nurseries, is highly pathogenic to alder seedlings. Urgent implementation of measures to prevent the risk of spread of the pathogen from nurseries to natural ecosystems is required. Further studies are required to clarify the role that P. plurivora is playing in alder decline both individually and in combination with P. alni complex.
Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on ...germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.
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•δ-HCH influences the germination success rate of Alnus glutinosa seeds.•Germination efficiency changes are progeny-dependent.•Alder seedling uptake of δ-HCH did not exceed 2.52% of the pollutant dose.•Alder seedling’s presence enhanced the effectiveness of δ-HCH removal by 20.85–35.89%.•Alder seedling’s hormones concentrations changed both negatively and positively to some extent during the exposure to δ-HCH.
Inonotus obliquus, a well-known forest fungal pathogen, started gaining attention for its potential medicinal uses. Known as Chaga, the fungus has become prominent due to the bioactive compounds ...present in its conks. Forest owners are cultivating it to produce conks as a source of non-timber profit. However, not much is known about the natural occurrence of this pathogen, its formation of conks, the extent of decay in the infected trees, and the distribution of its basidiospores. Across 80 forest stands in Estonia dominated by Betula pendula, B. pubescens, Alnus incana, and A. glutinosa, the conks of I. obliquus were documented in 17 stands. The conks were more common in continental Estonia compared to the western islands. Among 800 randomly chosen trees, I. obliquus conks were documented on ten trees. Additionally, an asymptomatic I. obliquus infection was detected in one tree. After two years of spore trapping, I. obliquus basidiospores were detected only on four occasions, between the end of July and the beginning of September, and only at night. The proportion of rot damage in the total volume of model tree wood ranged from 8.6% to 58.5%. For fast and reliable detection of I. obliquus, TaqMan species-specific qPCR primers were developed and tested.
•The rot damage caused by I. obliquus ranged from 8.6% to 58.5% of the host tree volume.•obliquus propagates its basidiospores only at night.•The basidiospores were released from the end of July to the beginning of September.•The conks of I. obliquus are equally likely to be found in Betula and Alnus stands.•1.25% of host trees were having I. obliquus conks.
Abstract Plant–microbial interactions in soils are considered to play a central role in regulating biodiversity in many global ecosystems. However, studies on plant–soil feedbacks (PSFs) and how ...these affect forest stand patterns in boreal regions are rare. We conducted a fully reciprocal PSF glasshouse experiment using four boreal tree species. Alnus glutinosa , Betula pendula , Picea abies and Pinus sylvestris seedlings were grown under controlled conditions in sterilised soil with or without soil inoculum collected under mature trees of each of the four species. Bacterial, fungal and oomycete communities in the rhizosphere were investigated using metabarcoding and correlated with differences in plant biomass. Alder grew best in conspecific soil, whereas birch grew equally well in all soil types. Pine and spruce grew best in heterospecific soil, particularly in soil from their successional predecessor. Ectomycorrhizal fungi (EMF) enhanced the growth of most seedlings, and Actinomycetota supported alder and birch growth and fungal plant pathogens hampered pine growth. Increased growth was linked to the ability of trees to recruit specific EMF and root‐associated fungi in heterospecific soils. Synthesis . This study experimentally examines the influence of root‐associated microbiota on the growth of boreal tree species. The observed plant–soil feedbacks mirror the successional patterns found in boreal forests, suggesting a possible contribution of soil microbiota to the successional progression. Species‐specific ectomycorrhizal fungi and a few bacteria rather than fungal plant pathogens or oomycetes seem to drive the feedbacks by promoting seedling growth in heterospecific soils.
Variation in natural susceptibility of the black alder population to Phytophthora ×alni (PA), the oomycete pathogen causing a devastating disease of alder, and its possible relationship to geographic ...origin, was studied in vitro using branch inoculation tests. Ninety black alder genotypes from different regions of the Czech Republic and two isolates of PA were employed. Host susceptibility varied significantly. After 1 week of infection, the lesion surface areas ranged from 254 to 2051 mm² and from 19 to 970 mm² for the two isolates, respectively. The differences were also dependent on the geographical origin and altitude of the sites from which particular host genotypes were taken. These findings have important implications for restoration plantings and for PA resistance breeding programmes, as there is potential to make selections from natural populations.
Rhizosphere and endophytic bacteria are well known producers of siderophores, organic compounds that chelate ferric iron (Fe3+), and therefore play an important role in plant growth promotion in ...metalliferous areas, thereby improving bioremediation processes. However, in addition to their primary function in iron mobilization, siderophores also have the capacity to chelate other heavy metals, such as Al3+, Zn2+, Cu2+, Pb2+ and Cd2+, that can affect homeostasis and the heavy metal tolerance of microorganisms.
The main goal of our study was to select the most efficient siderophore-producing bacterial strains isolated from the roots (endophytes) and rhizosphere of Betula pendula L. and Alnus glutinosa L. growing at two heavy metal contaminated sites in southern Poland. Siderophore biosynthesis of these strains in the presence of increasing concentrations of Cd2+ (0, 0.5, 1, 2 and 3 mM) under iron-deficiency conditions was analysed using spectrophotometric chemical tests for hydroxamates, catecholates and phenolates, as well as the separation of bacterial siderophores by HPLC and characterization of their structure by UHPLC-QTOF/MS.
We proved that (i) siderophore-producing bacterial strains seems to be more abundant in the rhizosphere (47%) than in root endophytes (18%); (ii) the strains most effective at siderophore synthesis belonged to the genus Streptomyces and were able to secrete three types of siderophores under Cd2+ stress: hydroxamates, catecholates and phenolates; (iii) in general, the addition of Cd2+ enhanced siderophore synthesis, particularly ferrioxamine B synthesis, which may indicate that siderophores play a significant role in tolerance to Cd2+ in Streptomyces sp.
•Identification and selection of the most efficient siderophore-producing bacterial strains.•Siderophore biosynthesis in the presence of increasing concentrations of Cd2+.•Analysis of different types of siderophores: hydroxamates, catecholates and phenolates.•Separation of bacterial siderophores by HPLC and characterization of their structure by UHPLC-QTOF/MS.
•The role of black alder in mitigating pine plantation effects on instream ecosystem functioning was assessed at two scales (instream and riparian forest).•Presence of alder stands in riparian zones ...of streams flowing through pine plantations increased stream water N concentrations.•Presence of riparian alder did not affect litter mass loss, but mixtures containing alder litter generally decomposed faster.•Presence of riparian alder promoted microbial nitrogen cycling.•Presence of riparian alder suppressed diversity effects on microbially-mediated litter mass loss.
During the last century, the abandonment of traditional dryland farming and pastures in the Mediterranean basin promoted the development of ambitious afforestation programs causing a drastic transformation of the landscape. Afforestation programs were usually accomplished without considering the potential ecological impacts on the recipient ecosystems. Forest streams rely on terrestrial organic detritus, so their functioning and conservation status can be altered by changes in riparian forest biodiversity and composition. However, the influences of conifer plantations in particular on stream functioning are still unclear, possibly because the presence of multiple species in plantations or the presence of other species in the riparian zones of streams may act as buffers of such effects. Here, by means of a field experiment, we assessed whether the presence of black alder in the riparian zone and/or as leaf litter within the stream may mitigate the impacts exerted by pine plantations on stream ecosystem functioning. We found (i) that streams were functionally similar but differed in water N concentrations; (ii) no differences in litter mas loss between riparian types, but higher total litter mass loss of those mixtures containing alder leaf litter; and (iii) higher N losses (or lower N gains) for all litter types in streams without riparian alder. These results demonstrate that microbial decomposers can use either stream water N or litter N, and that detritivores can feed simultaneously on resources of contrasting quality to balance their diet. Our study underscores the effect of even low-density riparian cover of alder promoting microbial nutrient cycling by moderate increases of water N concentrations. We suggest thinning of pine plantations combined with planting of native deciduous species as alder to alleviate the effects of pine plantations on Mediterranean streams.
•We use Maxent algorithm to hindcast the distributions of two plant species and validate the projections with fossil data.•We study the effects of model complexity on the Maxent's predictive power ...across time.•Maxent default settings can lead to the generation of overly complex models.•Models of intermediate complexity lead to better predictions of past distributions.•Controlling for complexity leads to improved cross-temporal model transferability.
Maximum entropy modeling (Maxent) is a widely used algorithm for predicting species distributions across space and time. Properly assessing the uncertainty in such predictions is non-trivial and requires validation with independent datasets. Notably, model complexity (number of model parameters) remains a major concern in relation to overfitting and, hence, transferability of Maxent models. An emerging approach is to validate the cross-temporal transferability of model predictions using paleoecological data. In this study, we assess the effect of model complexity on the performance of Maxent projections across time using two European plant species (Alnus glutinosa (L.) Gaertn. and Corylus avellana L.) with an extensive late Quaternary fossil record in Spain as a study case. We fit 110 models with different levels of complexity under present time and tested model performance using AUC (area under the receiver operating characteristic curve) and AICc (corrected Akaike Information Criterion) through the standard procedure of randomly partitioning current occurrence data. We then compared these results to an independent validation by projecting the models to mid-Holocene (6000 years before present) climatic conditions in Spain to assess their ability to predict fossil pollen presence–absence and abundance. We find that calibrating Maxent models with default settings result in the generation of overly complex models. While model performance increased with model complexity when predicting current distributions, it was higher with intermediate complexity when predicting mid-Holocene distributions. Hence, models of intermediate complexity resulted in the best trade-off to predict species distributions across time. Reliable temporal model transferability is especially relevant for forecasting species distributions under future climate change. Consequently, species-specific model tuning should be used to find the best modeling settings to control for complexity, notably with paleoecological data to independently validate model projections. For cross-temporal projections of species distributions for which paleoecological data is not available, models of intermediate complexity should be selected.
This paper presents a history of the vegetation in Lake Purwin (NE Poland) and its catchment along with water level changes for the last 8600 cal. BP. The reconstructions are based on a ...high-resolution plant macroremains analysis and the stable isotope record in authigenic carbonates, a fine fraction that is precipitated within the epilimnion of the lake. The stable isotope records suggest that the lake had throughflow during the Holocene and that isotope data can therefore be used in palaeoclimatic reconstructions. The delta super(18)O values record the thermal maximum of the Holocene and the subsequent cooling of the upper Holocene. Water level changes and the history of the lake's productivity are both recorded in the delta super(13)C values. A chronology is established using radiocarbon dating of terrestrial plant macrofossils. The vegetation and water levels in Lake Purwin reflect regional climate changes. The combination of the lithology along the sedimentary sequence, the results of the plant macroremains analysis and the isotope data allowed several alternating periods of high (8600-7300, 6500-5200, 4400-3500, and 3000-950 cal. BP) and low (7300-6500, 5200-4400, 3500-3000 and 950 to -59 cal. BP) water stands to be distinguished in Lake Purwin. Low water levels are indicated by sediments that are enriched in coarse plant detritus, seeds of Rubus ideaus, fruits of Uritca dioica and more macroremains of Alnus glutinosa and rushes.
Toxoplasmosis is a worldwide parasitosis that affects one-third of the population. People at risk, such as immunocompromised patients (AIDS, chemotherapy treatment) or fetuses (maternal-fetal ...transmission) can develop severe forms of the disease. The antiparasitic activity of extracts of different polarities (
-heptane, MeOH, MeOH/H
O) of 10 tree species endemic to temperate regions was investigated against Toxoplasma gondii infection
. Our results showed that the
-heptane extract of the black alder (
) exhibited a significant antiparasitic activity without any cytotoxicity at the tested concentrations, with an IC
of up to 25.08 μg/mL and a selectivity index higher than 3.99. The chemical profiling of this extract revealed triterpenes as major constituents. The ability of commercially available triterpene (betulin, betulinic acid, and betulone) to inhibit the growth of T. gondii was evaluated and showed growth inhibition rates of 44%, 49%, and 99% at 10 μM, respectively.
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