Growth and Wood Trait Relationships of Alnus glutinosa in Peatland Forest Stands With Contrasting Water Regimes

Human-driven peatland drainage has occurred in Europe for centuries, causing habitat degradation and leading to the emission of greenhouse gases. As such, in the last decades, there has been an increase in policies aiming at restoring these habitats through rewetting. Alder (Alnus glutinosa L.) is a widespread species in temperate forest peatlands with a seemingly high waterlogging tolerance. Yet, little is known about its specific response in growth and wood traits relevant for tree functioning when dealing with changing water table levels. In this study, we investigated the effects of rewetting and extreme flooding on alder growth and wood traits in a peatland forest in northern Germany. We took increment cores from several trees at a drained and a rewetted stand and analyzed changes in ring width, wood density, and xylem anatomical traits related to the hydraulic functioning, growth, and mechanical support for the period 1994–2018. This period included both the rewetting action and an extreme flooding event. We additionally used climate-growth and climate-density correlations to identify the stand-specific responses to climatic conditions. Our results showed that alder growth declined after an extreme flooding in the rewetted stand, whereas the opposite occurred in the drained stand. These changes were accompanied by changes in wood traits related to growth (i.e., number of vessels), but not in wood density and hydraulic-related traits. We found poor climate-growth and climate-density correlations, indicating that water table fluctuations have a stronger effect than climate on alder growth. Our results show detrimental effects on the growth of sudden water table changes leading to permanent waterlogging, but little implications for its wood density and hydraulic architecture. Rewetting actions should thus account for the loss of carbon allocation into wood and ensure suitable conditions for alder growth in temperate peatland forests.

A Descriptive Chemical Composition of Concentrated Bud Macerates through an Optimized SPE-HPLC-UV-MS2 Method—Application to Alnus glutinosa, Ribes nigrum, Rosa canina, Rosmarinus officinalis and Tilia tomentosa

Concentrated bud macerates (CBMs) are obtained from meristematic tissues such as buds and young shoots by maceration in a solvent composed of glycerin, water and ethanol (1/1/1/, v/v). Their traditional utilization in gemmotherapy has gained interest in the past years, and the knowledge of their chemical characterization can provide commercial arguments, particularly to secure their quality control. Therefore, an optimized method for phytochemical analysis including glycerol removal by a preliminary solid phase extraction (SPE) followed by compound identification using high performance liquid chromatography coupled with ultra-violet and tandem mass detectors (HPLC-UV-MS2) was developed. This method was applied on 5 CBMs obtained from Alnus glutinosa, Ribesnigrum, Rosmarinus officinalis, Rosa canina and Tilia tomentosa in order to determinate their chemical composition. Their antioxidant effects were also investigated by radical scavenging activity assays (DPPH and ORAC). Glycerol removal improved the resolution of HPLC chemical profiles and allowed us to perform TLC antioxidant screening. Our approach permitted the identification of 57 compounds distributed in eight major classes, three of them being common to all macerates including nucleosides, phenolic acids and glycosylated flavonoids. Quantification of the later class as a rutin equivalent (RE) showed a great disparity between Rosa canina macerate (809 mg RE/L), and the other ones (from 175 to 470 mg RE/L). DPPH and ORAC assays confirmed the great activity of Rosa canina (4857 and 6479 μmol TE/g of dry matter, respectively). Finally, phytochemical and antioxidant analysis of CBMs strengthened their phytomedicinal interest in the gemmotherapy field.

Mögliche künftige Trends der Lufttemperatur und des Blattaustriebs der Schwarzerle (Alnus glutinosa) in Deutschland

<p>Eine direkte Auswirkung des rezenten Klimawandels auf die Vegetation ist die Verfrühung phänologischer Stadien, besonders im Frühjahr (WALDAU & CHMIELEWSKI, 2018; CHMIELEWSKI et al., 2004; WOLFE et al., 2005). Diese Trends wurden weltweit beobachtet und sind hauptsächlich auf den Anstieg der Lufttemperatur zurückzuführen, was den engen Zusammenhang zwischen Pflanzenentwicklung und Temperatur belegt. Dieser stetige Temperaturanstieg wird sich in Zukunft fortsetzen und zu zeitlichen und räumlichen Verschiebungen in der Vegetationsentwicklung führen. Um diese Veränderungen abschätzen zu können, sind plausible phänologische Modelle erforderlich, wobei das Kältebedürfnis, das für die Überwindung der Dormanz erforderlich ist, hierbei eine der Schlüsselgrößen ist. <br />Ziel dieser Studie war es die zukünftigen Auswirkungen des Klimawandels auf die natürliche Vegetation in Deutschland abzuschätzen. In einer dreijährigen Studie (Winter 2015/16 – 2017/18) wurde der Zeitpunkt der Dormanzbrechung für verschiedene Baumarten experimentell in Klimakammerversuchen bestimmt. Im Rahmen dieses Vortrages sollen die Ergebnisse für die Schwarzerle (Alnus glutinosa) dargestellt werden. Nach der Ermittlung des für den Blattaustrieb der Schwarzerle notwendigen Kältereizes wurde ein Chilling/Forcing Modell parametrisiert und anschließend an den phänologischen Beobachtungdaten des Deutschen Wetterdienstes (1951-2015) validiert. Für die Abschätzung der künftigen klimatischen Entwicklung wurde ein Klimaensemble aus sieben verschieden Klimamodellrechnungen für zwei Klimaszenarien (RCP 2.6 & 8.5) verwendet. Für den Zeitraum 2010-2100 werden neben den zeitlichen Trends der Lufttemperatur und der Phänologie zusätzlich die regionalen Unterschiede in Deutschland (Nord-Ost/Nord-West/Süd-Ost/Süd-West) aufgezeigt.</p> <p> </p> <p>Literatur:</p> <p>CHMIELEWSKI, F. M., MÜLLER, A. & BRUNS, E. (2004): Climate changes and trends in phenology of fruit trees and field crops in Germany, 1961–2000. Agricultural and Forest Meteorology 121 (1), 69-DOI: https://doi.org/10.1016/S0168-1923(03)00161-8.</p> <p>WALDAU, T. & CHMIELEWSKI, F. M. (2018): Spatial and temporal changes of spring temperature, thermal growing season and spring phenology in Germany 1951–2015. Meteorol. Z. 27 (4), 335-342.DOI: https://doi.org/10.1127/metz/2018/0923.</p> <p>WOLFE, D. W., SCHWARTZ, M. D., LAKSO, A. N., OTSUKI, Y., POOL, R. M. & SHAULIS, N. J. (2005): Climate change and shifts in spring phenology of three horticultural woody perennials in northeastern USA. International Journal of Biometeorology 49 (5), 303-309. DOI: https://doi.org/10.1007/s00484-004-0248-9.</p>

Two new species of Diaporthe (Diaporthaceae, Diaporthales) associated with tree cankers in the Netherlands

Diaporthe (Diaporthaceae, Diaporthales) is a common fungal genus inhabiting plant tissues as endophytes, pathogens and saprobes. Some species are reported from tree branches associated with canker diseases. In the present study, Diaporthe samples were collected from Alnus glutinosa, Fraxinus excelsior and Quercus robur in Utrecht, the Netherlands. They were identified to species based on a polyphasic approach including morphology, pure culture characters, and phylogenetic analyses of a combined matrix of partial ITS, cal, his3, tef1 and tub2 gene regions. As a result, four species (viz. Diaporthe pseudoalnea sp. nov. from Alnus glutinosa, Diaporthe silvicola sp. nov. from Fraxinus excelsior, D. foeniculacea and D. rudis from Quercus robur) were revealed from tree branches in the Netherlands. Diaporthe pseudoalnea differs from D. eres (syn. D. alnea) by its longer conidiophores. Diaporthe silvicola is distinguished from D. fraxinicola and D. fraxini-angustifoliae by larger alpha conidia.

Antioxidant Activity of Different Extracts from Black Alder (Alnus glutinosa) Bark with Greener Extraction Alternative

Phenolic compounds isolated from plant biomass consist of bioactive components showing a wide range of benefits for humans, including antioxidant, antimicrobial or anti-inflammatory effects. This paper presents the potential value of black alder (Alnus glutinosa (L.) Gaertn. (Betulaceae)) bark for the production of biologically active substances, despite its current use as a low value fuel source. Most of the extraction methods employ neat organic solvents to obtain extracts with a high antioxidant potential from biomass. The aim of this work is to show the advantages and disadvantages of the extraction process by taking into account the principles of ‘green chemistry’ and replacing the organic solvents with ‘green’ solvent water. Using the advantages of accelerated solvent extraction (ASE), it has been shown that the use of deionized water has the prospect of replacing organic solvents. In the case of the one-step water extraction, the total polyphenol content (TPC) varies from 0.55 to 0.62 Gallic acid equivalent (GAE) g/g in the extracts, depending on the temperature, whereas with the result of the sequential extraction with the organic solvents, the TPC content of the 40% (v:v) ethanol extracts ranges from 0.39 to 0.61 GAE g/g, depending on the temperature. The influence of the total polyphenol content and the total proanthocyanidin content on the antioxidant activity is shown. The antioxidant activity (IC50, mg/L) of the extracts obtained with the organic solvents in the (2,2-diphenyl-1-picrylhydrazyl) DPPH• test varies from 4.05 to 9.58, depending on the temperature in the range of 70–150 °C, respectively, while the results obtained with the deionized water showed promising results in the range of 6.33–7.36 in the temperature range of 70–150 °C, respectively. The extraction with the deionized water showed that approximately 90% of the substances in the extracts obtained with the organic solvents by sequential extraction are possible to obtain as deionized water extracts.

Early transcriptomic response of Alnus glutinosa to Frankia alni symbiont, an upregulated nsLTP (non-specific Lipid Transfer Protein) is implicated in early and late stages of symbiosis

The response of Alnus glutinosa to Frankia alni is complex with several sequential physiological modifications that include calcium spiking, root hair deformation, penetration, induction of primordium, formation and growth of nodule. A transcriptomic study of seedlings in hydroponics after early contact (2.5 days) with Frankia alni, either with a culture supernatant or with living cells separated from the roots by a dialysis membrane, permitted to identify plant genes which expression level was modified upon early contact with Frankia. Forty-two genes were significantly up-regulated in both experiments, most of them encoding biological processes such as oxidative stress or response to stimuli. Among them, the most upregulated gene was a non-specific lipid transfer protein encoding gene with a fold change of 141. This nsLTP was found to increase Frankia nitrogen fixation at sub-lethal concentration. Interestingly, it was immunolocalized to a region of the deformed root hair at an early infection stage and later in nodules, it was localized around bacterial vesicles suggesting a role in early and late stages of symbiosis.

Identification of Alnus glutinosa L. and A. incana (L.) Moench. Hybrids in Natural Forests Using Nuclear DNA Microsatellite and Morphometric Markers

Two alder species (Alnus glutinosa and A. incana) have overlapping distribution, naturally occur in Lithuania, and are considered ecologically and economically important forest tree species. The objective of our study was to estimate the likelihood of spontaneous hybridizations between native alders in natural stands of Lithuania based on leaf morphology and nuclear microsatellite markers. The sampled trees were assigned to the three taxonomic groups of A. glutinosa, A. incana, and potential hybrids based on the leaf and bark morphological traits. The genetic differentiation and potential hybridization between these three groups was tested based on 15 nSSR markers. We identified studied Alnus spp. individuals as pure species and hybrids. Two microsatellite loci were reported as discriminating well between these species. We concluded that our results showed the highest likelihood of two genetic group structures, a clear genetic differentiation between the morphology-based groups of A. glutinosa and A. incana, and rather variable likelihood values in the putative hybrid group. The results provide important implications for genetic conservation and management of Alnus spp.

Investigation of antiparasitic activity of ten European tree bark extracts on Toxoplasma gondii and bioguided identification of triterpenes in Alnus glutinosa barks

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 ( n -heptane, MeOH, MeOH/H 2 O) of ten tree species endemics to temperate regions was investigated against Toxoplasma gondii infection in vitro . Our results showed that the n -heptane extract of the black alder ( Alnus glutinosa ) exhibited a significant antiparasitic activity without any cytotoxicity at the tested concentrations, with an IC 50 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.

Contribution à l'étude des paramètres dendrométriques et à la cartographie des peuplements relictuels d’une espèce septentrionale rare au Maroc : Alnus glutinosa (L.) Gaertn.

Alnus glutinosa (L.) Gaertn. (Betulaceae) est une espèce clé dans certaines formations alluviales et riveraines du continent européen. Au Maroc, elle se trouve en limite méridionale de son aire de distribution où elle est représentée par des formations relictes dans les zones refuges où elle a migré pendant les phases glaciaires du Pléistocène. Malgré sa grande valeur patrimoniale, il y a très peu de données sur son aire de répartition et l’état des peuplements. Ce travail a permis de localiser et cartographier les principaux peuplements dans la zone d’occurrence de cette espèce dans le Rif au nord du Maroc. La typologie des peuplements a été réalisée dans douze sites de référence en déterminant leurs principales caractéristiques telles que la nature du régime forestier, la composition, la taille, le recouvrement et la densité. Les caractéristiques dendrométriques ont permis de renseigner la structure et la dynamique des peuplements. Les résultats obtenus constituent un apport important de données quantitatives géoréférencées sur la répartition actuelle et la dynamique des peuplements d’A. glutinosa au Maroc. Étant donné l’état de conservation des peuplements, la dégradation de l’habitat et la faible régénération, cette espèce peut être considérée comme menacée et doit bénéficier de mesures urgentes de protection.