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Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems / Hardo Becker in Silva fennica, vol 52 n° 4 (September 2018)  

Public [article]  inSilva fennica > vol 52 n° 4 (September 2018) Titre : Annual net nitrogen mineralization and litter flux in well-drained downy birch, Norway spruce and Scots pine forest ecosystems Type de document : Article/Communication Auteurs : Hardo Becker, Auteur ; Jürgen Aosaar, Auteur ; Mats Varik, Auteur ; Gunnar Morozov, Auteur ; et al., Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] azote [Termes IGN] betula pubescens [Termes IGN] forêt marécageuse [Termes IGN] nitrification [Termes IGN] Picea abies [Termes IGN] Pinus sylvestris [Termes IGN] sol forestier Résumé : (Auteur) The main aim of the current study was to estimate the annual net nitrogen mineralization (NNM) flux in stands of different tree species growing on drained peatlands, as well as to clarify the effect of tree species, soil properties and litter on annual NNM dynamics. Three study sites were set up in May 2014: a downy birch (Betula pubescens Ehrh.) stand and a Norway spruce (Picea abies (L.) Karst.) stand in Oxalis full-drained swamp (ODS) and a Scots pine (Pinus sylvestris L.) stand in Myrtillus full-drained swamp (MDS). The NNM flux was estimated using the in situ method with incubated polyethylene bags. The highest value of NNM was found in stands that were growing on fertile ODS: 127.5 kg N ha–1 yr–1 and 87.7 kg N ha–1 yr–1, in the downy birch stand and in the Norway spruce stand, respectively. A significantly lower annual NNM flux (11.8 kg N ha–1 yr–1) occurred in the Scots pine stand growing in MDS. Nitrification was highest at fertile ODS sites and ammonification was the highest at the low fertility MDS site. For all study sites, positive correlation was found between soil temperature and NNM intensity. The difference in annual NNM between the downy birch stand and the Norway spruce stand growing on similar drained fertile peatlands was due to litter quality. The annual N input into the soil through leaf litter was the highest at the downy birch site where also the C/N ratio of litter was the lowest. The second highest N input into the soil was found in the spruce stand and the lowest in the pine stand. Numéro de notice : A2018-506 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14214/sf.10013 Date de publication en ligne : 27/09/2018 En ligne : https://doi.org/10.14214/sf.10013 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91192 [article]

Visible + Near Infrared spectroscopy as taxonomic tool for identifying birch species / Mulualem Tigabu in Silva fennica, vol 52 n° 4 (September 2018)  

Public [article]  inSilva fennica > vol 52 n° 4 (September 2018) Titre : Visible + Near Infrared spectroscopy as taxonomic tool for identifying birch species Type de document : Article/Communication Auteurs : Mulualem Tigabu, Auteur ; Mostafa Farhadi, Auteur ; Lars-Göran Stener, Auteur ; Per C. Odén, Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Betula pendula [Termes IGN] betula pubescens [Termes IGN] graine [Termes IGN] rayonnement lumineux [Termes IGN] rayonnement proche infrarouge [Termes IGN] signature spectrale Résumé : (Auteur) The genus Betula L. is composed of several species, which are difficult to distinguish in the field on the basis of morphological traits. The aim of this study was to evaluate the taxonomic importance of using visible + near infrared (Vis + NIR) spectra of single seeds for differentiating Betula pendula Roth and Betula pubescens Ehrh. Seeds from several families (controlled crossings of known parent trees) of each species were used and Vis + NIR reflectance spectra were obtained from single seeds. Multivariate discriminant models were developed by Orthogonal Projections to Latent Structures – Discriminant Analysis (OPLS-DA). The OPLS-DA model fitted on Vis + NIR spectra recognized B. pubescens with 100% classification accuracy while the prediction accuracy of class membership for B. pendula was 99%. However, the discriminant models fitted on NIR spectra alone resulted in 100% classification accuracies for both species. Absorption bands accounted for distinguishing between birch species were attributed to differences in color and chemical composition, presumably polysaccharides, proteins and fatty acids, of the seeds. In conclusion, the results demonstrate the feasibility of NIR spectroscopy as taxonomic tool for classification of species that have morphological resemblance. Numéro de notice : A2018-507 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14214/sf.9996 Date de publication en ligne : 18/10/2018 En ligne : https://doi.org/10.14214/sf.9996 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91193 [article]