The Level II aggregated forest soil condition database links soil physicochemical and hydraulic properties with long-term observations of forest condition in Europe

Key message

Aggregated, consolidated, and derived soil physicochemical data of 286 ICP Forests Level II plots were completed with soil hydraulic properties for integrated use with forest monitoring data. Database access should be requested at http://icp-forests.net . Metadata associated available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=153e599e-6624-4e2b-b862-8124386ea9cd&hl=eng

Context

The ICP Forests database is one of the most comprehensive forest ecosystem datasets in Europe and contains the accumulated results of more than two decades of harmonised forest monitoring all over Europe.

Aims

The aim of this paper is to share knowledge on the ICP Forests Level II soil data for broader use among forest scientists.

Methods

After standard analysis, quality checks, aggregation, and calculation of derived variables (e.g. nutrient stocks, base saturation, C:N ratio, and water retention parameters), data have been gathered into a static database (AFSCDB.LII.2.2), which will be updated to new versions as soon as new measurements become available.

Results

The database provides a basis for the combined evaluation of up to 130 unique soil variables of 286 plots with dynamic data on tree growth, ground vegetation, foliar chemistry, crown condition, tree phenology, leaf area index, ozone injury, litterfall, soil solution chemistry, deposition, ambient air quality, and meteorological data assessed on the same plots.

Conclusion

The unprecedented comprehensiveness and level of detail in this newly aggregated database may overcome existing restrictions so far impeding the realisation of large-scale forest ecosystem studies in Europe.

     

Relation between oak tree phenology and the secretion of organic matter degrading enzymes by Lactarius quietus ectomycorrhizas before and during bud break

The ectomycorrhizas (ECM) formed by Lactarius quietus, an ECM fungus specifically associated with Quercus spp., are abundant all the year long. Root and stem growth, beginning before bud break in oak, are strong carbon sinks partially fulfilled with carbohydrate reserves. We hypothesized that L. quietus contributes to providing trees with carbon at bud break through enzymatic activities before photosynthesis begins. Activities of eight secreted enzymes (xylosidase, glucuronidase, cellobiohydrolase, β-glucosidase, N-acetyl-glucosamine, leucine aminopeptidase, acid phosphatase and laccase) relevant to carbon cycling and the release of phophorus and nitrogen from soil organic matter were measured on L. quietus ECMs before, during and after the bud break. Phenological, climatic and pedoclimatic parameters were also measured. Laccase, glucuronidase, cellobiohydrolase and β-glucosidase activities proved to be significantly related to tree reactivation and climate. All these activities can help the formation of new tissues by supplying carbon. L. quietus can behave saprotrophically, using soil organic matter as substrate. This is consistent with the hypothesis that it provides the oak trees with carbon when demand is high and photoassimilates are not yet available.     

Hydrolysis of whey protein isolate with Bacillus licheniformis protease: fractionation and identification of aggregating peptides

The objective of this work was to identify the dominant aggregating peptides from a whey protein hydrolysate (degree of hydrolysis of 6.8%) obtained with Bacillus licheniformis protease. The aggregating peptides were fractionated with preparative reversed-phase chromatography and identified with liquid chromatography-mass spectrometry. The results showed that the dominant aggregating peptide, at pH 7.0, was beta-lg AB [f1-45]. In addition, the peptides beta-lg AB [f90-108]-S-S-alpha-la [f50-113], alpha-la [f12-49]-S-S-alpha-la [f50-113], beta-lg AB [f90-108]-S-S-beta-lg AB [f90-108], beta-lg A [f90-157], and beta-lg AB [f135-157/158] were also identified as main aggregating peptides. The results further showed that aggregation, via hydrophobic interactions, prevented further digestion (at pH 8.0), thereby explaining the large size of the aggregating peptides. It is hypothesized that B. licheniformis protease breaks down hydrophilic segments in the substrate and, therefore, preserves hydrophobic segments that aggregate once exposed to the solvent.     

Do railway edges provide functional connectivity for plant communities in an urban context?

Functional connectivity is essential to maintaining biodiversity in fragmented landscapes but little attention has been given to structures that can provide it in an urban context. Using both the taxonomic and functional diversity of semi-natural grassland plant communities, we assessed the functional connectivity of linear transportation infrastructures in urban landscape. We sampled the vegetation at 71 study sites located along the edges of two railway lines. We hypothesised that if railways favour functional connectivity, then spatially connected communities should be more similar than disconnected communities. Therefore, we compared floristic dissimilarities between site pairs that were either connected or separated by a railway spatial break (overpass or station). As a further approach, we supposed that functional connectivity may attenuate the effect of urbanisation filters on plant communities. Thus we examined whether and how edges’ plant communities were influenced by urbanisation and compared our results to the patterns described in the literature. Functional connectivity was mainly maintained at railway stations, contrary to overpasses, which seemed to interrupt dispersal, demonstrating that railway edges provide connectivity for some but not all functional groups: this was only true for moderately mobile species. Surprisingly, railway edges did not seem to play an additional connective function for invasive species, the presence of which being strongly related to the urbanisation intensity and not influenced by spatial breaks along railways. Our study thus highlights the potential function of railway edges as corridors for common grassland plants. Landscape managers should include railways in green networks to improve connectivity in urban landscapes.     

用基因组原位杂交方法分析甘蔗-斑茅杂种及回交后代的染色体组成

斑茅(Erianthus arundinaceus Retz)是甘蔗的近缘属植物,具有多种优良特性,是甘蔗育种的重要种质资源之一。本实验使用基因组原位杂交(GISH)技术分析了甘蔗-斑茅杂种及回交后代F1、BC1和BC2的染色体构成与传递行为。结果表明:在F1代,来自斑茅HN92-77的染色体数目介于28～30条,来自热带种Badila的染色体数目介于38～40条,体细胞染色体数为2n=68～70,基本符合n+n的染色体传递方式;在BC1和BC2代,来自斑茅的染色体数分别为22～28条和13～15条,来自甘蔗的染色体数分别是87～94条和98～101条,其体细胞染色体数2n分别为110～121条和112～115条,基本上分别符合2n+n和n+n的染色体传递方式。在所观察的渐渗系中,均存在有染色体丢失的现象,但未观察到染色体发生交换与重组。     

Cold acclimation of winter and spring peas: carbon partitioning as affected by light intensity

Like most plants, pea (Pisum sativum L.) becomes tolerant to frost if it is first exposed to low non-freezing temperatures, a process known as cold acclimation. Cold acclimation is a complex process involving many physiological and metabolic changes. Two spring dry peas, two winter dry peas and one winter forage line were exposed to cold temperature in a controlled environment in two experiments, one using low light intensity and the other regular light intensity. Plants were harvested throughout the experiment and dry matter accumulation, water content, soluble and insoluble sugar concentrations were determined from shoot and root samples. Cold acclimation did not occur when temperatures were low if light intensity was low, even in winter peas. In contrast, with regular light intensity, the winter peas acquired more freezing tolerance than spring peas and a close relationship was found between the soluble sugar concentration of leaves just before the frost and the degree of freezing tolerance obtained by the different genotypes. Relationships between freezing tolerance and carbon partitioning between shoot and roots are discussed.     

Variability of the polyphenolic composition of cider apple (Malus domestica) fruits and juices

Five French cider apple varieties were compared on the basis of their detailed polyphenol profile in the cortex and in the juices. Among the factors studied, variety was the most important variability factor in fruits, whereas polyphenol profiles showed an overall stability from one year to another, and a limited decrease of polyphenol concentration was observed during the starch regression period of fruit maturation. In juices, procyanidins remained the preponderant polyphenol class with concentrations up to 2.4 g/L even in centrifuged juices. Compared to the fruits, the average degree of polymerization of procyanidins was significantly reduced in the juice. Centrifugation of the crude juice had only minor effects on the polyphenol composition. For one variety, highly polymerized procyanidins with average degrees of polymerization of 25 were shown to be soluble in the centrifuged juice at a concentration of close to 1.2 g/L. Oxygenation of the juices during processing resulted in a significant decrease of all classes of native polyphenols. Catechins and procyanidins were particularly affected by oxidation, whereas caffeoylquinic acid was partly preserved. The transfer of polyphenols after pressing was maximal for dihydrochalcones and minimal for procyanidins with extraction yield values close to 80 and 30%, respectively.     

Plant and spider communities benefit differently from the presence of planted hedgerows in highway verges

Road verges should play a crucial role as a refuge for native flora and fauna in human dominated landscapes. However, the influence of construction choices, such as plantation of woody species, on the biodiversity supported by roadsides has received little attention, although the presence of hedgerows in roadsides is likely to enhance their role as a refuge, notably for woodland species. Using standardised methods, we assessed the impact of planted hedgerows on two taxonomic groups (plants and spiders) inhabiting highway verges within an intensive agricultural landscape. We examined community richness, taxonomic and functional composition in sites with and without planted hedgerows. At the site level, the response of plant and spider communities to the presence of planted hedgerows differed markedly: hedgerows were associated with significantly higher plant richness (higher α-diversity), but similar spider richness. Plant communities in sites without hedgerows appeared as a subset of communities in sites with hedgerows, whereas spider communities in non-planted sites were complementary to that of planted sites (increased β-diversity). The presence of planted hedgerows was also associated with increased taxonomic and functional trait diversity at the landscape level (γ-diversity), through an increased β-diversity in both plants and spiders. Our results thus suggest that a mosaic of planted hedgerows and grassland habitats is crucial for the maintenance of biodiversity at a landscape scale. By providing information for road practitioners and policy makers regarding their potential impact on biodiversity, these results have important direct implications for the management of road networks.