The Effects of Ash and Black Carbon (Biochar) on Germination of Different Tree Species

Forest fires generate large amounts of ash and biochar, or black carbon (BC), that cover the soil surface, interacting with the soil’s constituents and its seedbank. This study concerns reproductive ecology assessments supported by molecular characterisation to improve our understanding of the effects of fire and fire residues on the germination behaviour of 12 arboreal species with a wide geographic distribution. For this purpose, we analysed the effects of three ash and one BC concentration on the germination of Acacia dealbata Link, A. longifolia (Andrews) Willd., A. mearnsii De Wild., A. melanoxylon R. Br., Pinus nigra Arnold, P. pinaster Aiton, P. radiata D. Don, P. sylvestris L., Quercus ilex L., Q. pyrenaica Willd., Q. robur L., and Q. rubra L. Each tree species was exposed to ash and BC created from its foliage or twigs (except for Q. rubra, which was exposed to ash and BC of Ulex europaeus L.). We monitored germination percentage, the T50 parameter, and tracked the development of germination over time (up to 1 yr). The BC of A. dealbata, P. pinaster, and Q. robur was analysed by pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS) to assess the molecular composition. In six species, ash inhibited the germination, while in another five species, germination was not affected by ash or by BC. In Q. rubra, ash and BC stimulated its germination. This stimulating effect of the BC on Q. rubra is likely to be related to the chemical composition of the ash and BC obtained from Ulex feedstock. The BC of U. europaeus has a very different molecular composition than the other BC samples analysed, which, together with other factors, probably allowed for its germination stimulating effects.This study was carried out within the Project 10MDS200007PR, financed by the Xunta de Galicia; the Project AGL2013-48189-C2-2-R, financed by the Ministerio de Economía y Competitividad, Spain; and FEDERS

The first widespread solar energetic particle event observed by Solar Orbiter on 2020 November 29

Context. On 2020 November 29, the first widespread solar energetic particle (SEP) event of solar cycle 25 was observed at four widely separated locations in the inner (less than or similar to 1AU) heliosphere. Relativistic electrons as well as protons with energies >50MeV were observed by Solar Orbiter (SolO), Parker Solar Probe, the Solar Terrestrial Relations Observatory (STEREO)-A and multiple near-Earth spacecraft. The SEP event was associated with an M4.4 class X-ray flare and accompanied by a coronal mass ejection and an extreme ultraviolet (EUV) wave as well as a type II radio burst and multiple type III radio bursts.Aims. We present multi-spacecraft particle observations and place them in context with source observations from remote sensing instruments and discuss how such observations may further our understanding of particle acceleration and transport in this widespread event.Methods. Velocity dispersion analysis (VDA) and time shift analysis (TSA) were used to infer the particle release times at the Sun. Solar wind plasma and magnetic field measurements were examined to identify structures that influence the properties of the energetic particles such as their intensity. Pitch angle distributions and first-order anisotropies were analyzed in order to characterize the particle propagation in the interplanetary medium.Results. We find that during the 2020 November 29 SEP event, particles spread over more than 230 degrees in longitude close to 1AU. The particle onset delays observed at the different spacecraft are larger as the flare-footpoint angle increases and are consistent with those from previous STEREO observations. Comparing the timing when the EUV wave intersects the estimated magnetic footpoints of each spacecraft with particle release times from TSA and VDA, we conclude that a simple scenario where the particle release is only determined by the EUV wave propagation is unlikely for this event. Observations of anisotropic particle distributions at SolO, Wind, and STEREO-A do not rule out that particles are injected over a wide longitudinal range close to the Sun. However, the low values of the first-order anisotropy observed by near-Earth spacecraft suggest that di ffusive propagation processes are likely involved.</p

The effects of ash and black carbon (biochar) on germination of different tree species

Forest fires generate large amounts of ash and biochar, or black carbon (BC), that cover the soil surface, interacting with the soil’s constituents and its seedbank. This study concerns reproductive ecology assessments supported by molecular characterisation to improve our understanding of the effects of fire and fire residues on the germination behaviour of 12 arboreal species with a wide geographic distribution. For this purpose, we analysed the effects of three ash and one BC concentration on the germination of Acacia dealbata Link, A. longifolia (Andrews) Willd., A. mearnsii De Wild., A. melanoxylon R. Br., Pinus nigra Arnold, P. pinaster Aiton, P. radiata D. Don, P. sylvestris L., Quercus ilex L., Q. pyrenaica Willd., Q. robur L., and Q. rubra L. Each tree species was exposed to ash and BC created from its foliage or twigs (except for Q. rubra, which was exposed to ash and BC of Ulex europaeus L.). We monitored germination percentage, the T50 parameter, and tracked the development of germination over time (up to 1 yr). The BC of A. dealbata, P. pinaster, and Q. robur was analysed by pyrolysis-gas chromatography-mass spectrome try (PY-GC-MS) to assess the molecular composition. In six species, ash inhibited the germination, while in another five species, germination was not affected by ash or by BC. In Q. rubra, ash and BC stimulated its germination. This stimulating effect of the BC on Q. rubra is likely to be related to the chemical composition of the ash and BC obtained from Ulex feedstock. The BC of U. europaeus has a very different molecular composition than the other BC samples analysed, which, together with other factors, probably allowed for its germination stimulating effects. © 2015, Association for Fire Ecology. All rights reserved.This study was carried out within the Project 10MDS200007PR, financed by the Xunta de Galicia; the Project AGL2013-48189-C2-2-R, financed by the Ministerio de Economía y Competitividad, Spain; and FEDER.Peer Reviewe