Habitat fragmentation is one of the drivers for amphibian population declines globally. Especially in industrialized countries roads disrupt the seasonal migration of amphibians between hibernation ...and reproduction sites, often ending in roadkills. Thus, a timely installing of temporary mitigation measures is important for amphibian conservation. We wanted to find out if plant phenology can be a proxy in advance to determine the start of amphibian migration, since both phenomena are triggered by temperature. We analysed data of 3751 amphibian and 7818 plant phenology observations from citizen science projects in Austria between 2000 and 2018. Using robust regression modelling we compared the migration of common toads (Bufo bufo) and common frogs (Rana temporaria) with the phenology of five tree, one shrub, and one herb species. Results showed close associations between the migration of common frogs and phenological phases of European larch, goat willow and apricot. Models based on goat willow predict migration of common frog to occur 21 days after flowering, when flowering was observed on 60th day of year; apricot based models predict migration to occur 1 day after flowering, observed on the 75th day of year. Common toads showed weaker associations with plant phenology than common frogs. Our findings suggest that plant phenology can be used to determine the onset of temporary mitigation measures for certain amphibian species to prevent roadkills.
Background and aims Dark septate endophyte (DSE) fungi are the most frequent colonists on the roots of Salix cuprea in highly metal-contaminated soils. The present study was performed to obtain ...insights into the physiology and potential role(s) of DSE fungi for Salix caprea growing in metal-enriched sites. Methods Fungal isolates from S. caprea roots were identified using molecular methods, and tested for their tolerance and metal accumulation in axenic cultures. In addition, an inoculation experiment was performed to monitor the effects of the fungi on the metal uptake by the plant host. Fitness of S. caprea cuttings was assessed by photosynthetic pigment quantification and measurements of transpiration. Results Fungal isolates were identified as members of the Phialophora/Cadophora complex. They showed different levels of metal tolerance and maintained growth on metal-enriched media. In comparison to non-inoculated cuttings, the DSE-inoculated cuttings had lower leaf Cd content, and for isolates DB 146 and DB 148, also lower Zn concentrations. All DSE isolates increased the chlorophyll levels of the cuttings, with isolate DB 146 also positively affecting the transpiration rate of S. caprea. Conclusions Our findings suggest that DSE reduced the metal uptake by the S. caprea cuttings, thus suggesting a beneficial role for S. caprea in metal-enriched soils.
The afforestation of sites disturbed after coal mining has shown to be a favorite technique to restore all ecosystem functions. Leaf traits of trees used in restoration may substantially affect ...nutrient return decomposition rates in soil and thus, ecosystem development. The aim of the study was to compare seasonal changes between the individual tree species at two different sites focussing on seasonal changes of leaf biochemistry, elemental composition, and their role in nutrient return to the forest floor and nutrient cycling. Foliage and litterfall characteristics (specific leaf area (SLA), nutrients, phenolics, lignin, chlorophylls, and cellulose contents) were studied at two sites of the same age (25 years) with different tree species at post-mining sites at the Sokolov area around 50° 14′ 09 N and 12° 39′ 05 E (Czech Republic). The first two sites (unreclaimed) were left to spontaneous succession with a dominance of Betula pendula, Salix caprea, and Populus tremula. The second two sites (reclaimed) was land levelled and afforested by Alders (Alnus glutinosa, Alnus incana). The study showed that foliage quality and composition differed between individual tree species and between sites, especially in the contents of nitrogen (N), calcium (Ca), magnesium (Mg), potassium (K), and lignin concentration. Alder reclamation was most influenced by a symbiotic relationship with bacteria Frankia which support a high concentration of N in foliage and litterfall. However, the highest concentration of basic elements (Ca, Mg, K) was in foliage and litter of unreclaimed sites. A. incana had the highest content of lignin in foliage which increased steeply from August to September. Also, the content of lignin increased slightly in litterfall of unreclaimed sites during the vegetation season thought could have lead to slowing decomposition of litterfall and nutrient cycling in comparison to reclaimed sites.
•Foliage and litter of spontaneous regrowth and restored alder plantation differed.•Both types vegetation had similar content of chlorophyll and seasonal dynamics.•Alder foliage and litter have a higher N content.•Spontaneous regrowth foliage and litter has higher Ca, Mg, K.•Regrowth had a higher lignin content than Alder plantation.
•Difference in tree growth between spontaneous succession and reclaimed sites was studied.•Reclaimed sites however reached higher canopy cover and woody biomass in young sites.•In sites 20 years old ...and older no difference was found.
On an open-cast coal mining heap in the northwestern Czech Republic, development of the canopy cover of woody vegetation was studied using historical aerial photographs of unreclaimed sites overgrown by natural succession and of sites reclaimed by the planting of alder. A comparison of sites by general linear models revealed that canopy cover did not differ significantly between reclaimed sites and unreclaimed sites. Dominant species on unreclaimed sites (Salix caprea and Populus tremula) and reclaimed sites (Alnus glutinosa) sites were destructively sampled to generate site-specific allometric equations. Trees and shrubs were counted and measured on 5-, 19-, 15-, and 45-year-old reclaimed and unreclaimed sites. When sites were 5 years old, tree density was much higher on reclaimed sites (7575trunksha−1) than on unreclaimed sites (1215trunksha−1). On reclaimed sites, tree density gradually decreased with site age and was equivalent to that on unreclaimed sites when sites were 45 years old (1675trunksha−1). Woody biomass did not significantly differ between reclaimed and unreclaimed sites when measured across all ages but did significantly differ when measured at specific ages: thus, woody biomass was greater on reclaimed sites than on unreclaimed sites at age 5 years but was greater on unreclaimed sites than on reclaimed sites at age 25 years.
To characterize bacteria associated with Zn/Cd-accumulating Salix caprea regarding their potential to support heavy metal phytoextraction. Three different media allowed the isolation of 44 ...rhizosphere strains and 44 endophytes, resistant to Zn/Cd and mostly affiliated with Proteobacteria, Actinobacteria and Bacteroidetes/Chlorobi. 1-Aminocyclopropane-1-carboxylic acid deaminase (ACCD), indole acetic acid and siderophore production were detected in 41, 23 and 50% of the rhizosphere isolates and in 9, 55 and 2% of the endophytes, respectively. Fifteen rhizosphere bacteria and five endophytes were further tested for the production of metal-mobilizing metabolites by extracting contaminated soil with filtrates from liquid cultures. Four Actinobacteria mobilized Zn and/or Cd. The other strains immobilized Cd or both metals. An ACCD- and siderophore-producing, Zn/Cd-immobilizing rhizosphere isolate (Burkholderia sp.) and a Zn/Cd-mobilizing Actinobacterium endophyte were inoculated onto S. caprea. The rhizosphere isolate reduced metal uptake in roots, whereas the endophyte enhanced metal accumulation in leaves. Plant growth was not promoted. Metal mobilization experiments predicted bacterial effects on S. caprea more reliably than standard tests for plant growth-promoting activities. Bacteria, particularly Actinobacteria, associated with heavy metal-accumulating Salix have the potential to increase metal uptake, which can be predicted by mobilization experiments and may be applicable in phytoremediation.
Relationships between soil water saturation (SWS) and the accumulation of arsenic (As), cadmium (Cd), and lead (Pb) in soils and aboveground biomass of Populus tremula and Salix caprea were explored. ...SWS was computed with the hydrological model ParFlow/CLM and compared to data from field observations. Plant and soil samples collected at the main pollution sources contained the highest concentrations of As, Cd, and Pb. S. caprea contained higher concentrations of As, Cd, and Pb than P. tremula. In both species, metal(loid) concentrations in leaves were significantly higher than in branches. At strongly mining-affected locations, metalloid concentration in the trees largely reflected the pollution levels in the soil. In remote study locations, the soil-plant transfer of Cd and Pb was affected by water saturation: element accumulation increased significantly with soil moisture. Results demonstrate that coupling field observations with hydrological modelling is a promising approach for estimating element accumulation.
Salix caprea is a cold-tolerant pioneer species that is ecologically important in Europe and western and central Asia. However, little data is available on its population genetic structure and ...molecular ecology. We describe the levels of geographic population genetic structure in natural Irish populations of S. caprea and determine the extent of gene flow and sexual reproduction using both chloroplast and nuclear simple sequence repeats (SSRs).
A total of 183 individuals from 21 semi-natural woodlands were collected and genotyped. Gene diversity across populations was high for the chloroplast SSRs (H T = 0.21-0.58) and 79 different haplotypes were discovered, among them 48% were unique to a single individual. Genetic differentiation of populations was found to be between moderate and high (mean G ST = 0.38). For the nuclear SSRs, G ST was low at 0.07 and observed heterozygosity across populations was high (H O = 0.32-0.51); only 9.8% of the genotypes discovered were present in two or more individuals. For both types of markers, AMOVA showed that most of the variation was within populations. Minor geographic pattern was confirmed by a Bayesian clustering analysis. Gene flow via pollen was found to be approximately 7 times more important than via seeds.
The data are consistent with outbreeding and indicate that there are no significant barriers for gene flow within Ireland over large geographic distances. Both pollen-mediated and seed-mediated gene flow were found to be high, with some of the populations being more than 200 km apart from each other. These findings could simply be due to human intervention through seed trade or accidental transportation of both seeds and pollen. These results are of value to breeders wishing to exploit natural genetic variation and foresters having to choose planting material.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mixed pollination systems have been reported for many angiosperms. Here, we report on a dioecious willow, Salix caprea L., which employs three pollination modes, namely pollination by wind, nocturnal ...moths, and diurnal bees. In four field populations of S. caprea in Germany, we addressed the following questions: (a) How are the pollination modes affected by local mate availability? (b) What is the contribution of each pollination mode to seed set? (c) How does flower opening time affect pollination? We compared seed set among seven pollination treatments (wind pollination, diurnal pollination, nocturnal pollination, natural pollination, apomictic reproduction, daytime/night-time artificial pollination). Pollen limitation was observed across populations. On the other hand, limitations in mate availability affected the pollination modes differently. Insect pollination outperformed wind pollination in situations where nearby males were few or all positioned in the same direction from the females. The contribution of nocturnal moths was lower than that of the other pollen vectors. However, moth pollination worked complementarily with bee pollination in compensating for the lack of wind pollination. Furthermore, we found that the onset of flower anthesis peaked at sunset, and that cold night temperatures had no negative effect on seed set or pollen viability. Thus, nocturnal anthesis and prior pollination by moths may minimize male fitness loss due to pollen collection and grooming by bees. We suggest that S. caprea maximizes its fitness by combining multiple pollination modes that work in different environmental conditions, while optimizing the anthesis so that more pollen would be delivered to stigmas.
In dioecious, zoophilous plants potential pollinators have to be attracted to both sexes and switch between individuals of both sexes for pollination to occur. It often has been suggested that males ...and females require different numbers of visits for maximum reproductive success because male fertility is more likely limited by access to mates, whereas female fertility is rather limited by resource availability. According to sexual selection theory, males therefore should invest more in pollinator attraction (advertisement, reward) than females. However, our knowledge on the sex specific investment in floral rewards and advertisement, and its effects on pollinator behaviour is limited. Here, we use an approach that includes chemical, spectrophotometric, and behavioural studies i) to elucidate differences in floral nectar reward and advertisement (visual, olfactory cues) in dioecious sallow, Salix caprea, ii) to determine the relative importance of visual and olfactory floral cues in attracting honey bee pollinators, and iii) to test for differential attractiveness of female and male inflorescence cues to honey bees. Nectar amount and sugar concentration are comparable, but sugar composition varies between the sexes. Olfactory sallow cues are more attractive to honey bees than visual cues; however, a combination of both cues elicits the strongest behavioural responses in bees. Male flowers are due to the yellow pollen more colourful and emit a higher amount of scent than females. Honey bees prefer the visual but not the olfactory display of males over those of females. In all, the data of our multifaceted study are consistent with the sexual selection theory and provide novel insights on how the model organism honey bee uses visual and olfactory floral cues for locating host plants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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