Coppice Management of Iowa Hardwoods, June 1987

Principles and techniques that should be followed to either promote or retard coppice regeneration.

Drivers of increased soil respiration in a poplar coppice exposed to elevated CO2

Background and Aims. The response of soil respiration (SR) to elevated CO2 is driven by a number of processes and feedbacks. This work aims to i) detect the effect of elevated CO2 on soil respiration during the second rotation of a short rotation forest, at two levels of N availability; and ii) identify the main drivers behind any changes in soil respiration. Methods. A poplar plantation (POP-EUROFACE) was grown for two rotations of three years under elevated CO2 maintained by a FACE (Free Air CO2 Enrichment) technique. Root biomass, litter production and soil respiration were followed for two consecutive years after coppice. Results. In the plantation, the stimulation of fine root and litter production under elevated CO2 observed at the beginning of the rotation declined over time. Soil respiration (SR) was continuously stimulated by elevated CO2, with a much larger enhancement during the growing (up to 111 %) than in the dormant season (40 %). The SR increase at first appeared to be due to the increase in fine root biomass, but at the end of the 2nd rotation was supported by litter decomposition and the availability of labile C. Soil respiration increase under elevated CO2 was not affected by N availability. Conclusions. The stimulation of SR by elevated CO2 was sustained by the decomposition of above and belowground litter and by the greater availability of easily decomposable substrates into the soil. C losses through SR were greater in the last year of the plantation due to a lack of effect of elevated CO2 on C allocation to roots, reducing the potential for C accumulation.

Survey of influence of biomass mineral matter in thermochemical conversion of short rotation willow coppice

Short rotation willow coppice (SRC) has been investigated for the influence of K, Ca, Mg, Fe and P on its pyrolysis and combustion behaviours. These metals are the typical components that appear in biomass. The willow sample was pretreated to remove salts and metals by hydrochloric acid, and this demineralised sample was impregnated with each individual metal at the same mol g biomass (2.4 × 10 mol g demineralised willow). Characterisation was performed using thermogravimetric analysis (TGA), and differential thermal analysis (DTA) for combustion. In pyrolysis, volatile fingerprints were measured by means of pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). The yields and distribution of pyrolysis products have been influenced by the presence of the catalysts. Most notably, both potassium and phosphorous strongly catalysed the pyrolysis, modifying both the yield and distribution of reaction products. Temperature programmed combustion TGA indicates that combustion of biomass char is catalysed by all the metals, while phosphorus strongly inhibits the char combustion. In this case, combustion rates follow the order for volatile release/combustion: P>K>Fe>Raw>HCl>Mg>Ca, and for char combustion K>Fe>raw>Ca-Mg>HCl>P. The samples impregnated with phosphorus and potassium were also studied for combustion under flame conditions, and the same trend was observed, i.e. both potassium and phosphorus catalyse the volatile release/combustion, while, in char combustion, potassium is a catalyst and phosphorus a strong inhibitor, i.e. K impregnated>(faster than) raw>demineralised»P impregnated.

Potassium catalysis in the pyrolysis behaviour of short rotation willow coppice

Short rotation willow coppice (SRC) and a synthetic biomass, a mixture of the basic biomass components (cellulose, hemicellulose and lignin), have been investigated for the influence of potassium on their pyrolysis behaviours. The willow sample was pre-treated to remove salts and metals by hydrochloric acid, and this demineralised sample was impregnated with potassium. The same type of pre-treatment was applied to components of the synthetic biomass. Characterisation was performed using thermogravimetric analysis with measurement of products by means of Fourier transform infrared spectroscopy (TGA-FTIR) and pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). A comparison of product distributions and kinetics are reported. While the general features of decomposition of SRC are described well by an additive behaviour of the individual components, there are some differences in the magnitude of the influence of potassium, and on the products produced. For both SRC and the synthetic biomass, TGA traces indicate catalytic promotion of both of the two-stages of biomass decomposition, and potassium can lower the average apparent first-order activation energy for pyrolysis by up to 50 kJ/mol. For both SRC and synthetic biomass the yields and distribution of pyrolysis products have been influenced by the presence of the catalyst. Potassium catalysed pyrolysis increases the char yields markedly and this is more pronounced for synthetic biomass than SRC. Gas evolution profiles during pyrolysis show the same general features for both SRC and synthetic biomass. Relative methane yields increase during the char formation stage of pyrolysis of the potassium doped samples. The evolution profiles of acetic acid and formaldehyde change, and these products are seen in lower relative amounts for both the demineralised samples. A greater variation in pyrolysis products is observed from the treated SRC samples compared to the different synthetic biomass samples. Furthermore, substituted phenols from lignin pyrolysis are more dominant in the pyrolysis profiles of the synthetic biomass than of the SRC, implying that the extracted lignins used in the synthetic biomass yield a greater fraction of monomeric type species than the lignocellulosic cell wall material of SRC. For both types of samples, PY-GS-MS analyses show that potassium has a significant influence on cellulose decomposition markers, not just on the formation of levoglucosan, but also other species from the non-catalysed mechanism, such as 3,4-dihydroxy-3-cyclobutene-1,2-dione. © 2007 Elsevier Ltd. All rights reserved.

Evaluation of the ECOSSE model for simulating soil organic carbon under Miscanthus and short rotation coppice-willow crops in Britain

Acknowledgements This work contributes to the ELUM (Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial) project, which was commissioned and funded by the Energy Technologies Institute (ETI). We acknowledge the E-OBS data set from the EU-FP6 project ENSEMBLES (http://ensembles-eu.metoffice.com) and the data providers in the ECA&D project (http://www.ecad.eu).

Estudo de algumas propriedades mecânicas da madeira de um híbrido clonal de Eucalyptus urophylla X Eucalyptus grandis

A procura por madeiras oriundas de reflorestamentos destinadas à serraria é uma realidade já há muitos anos, principalmente aquelas das espécies do gênero Eucalyptus. Visando buscar novas informações importantes para esse mercado, este trabalho objetivou determinar algumas propriedades mecânicas da madeira de um híbrido clonal de Eucalyptus urophylla x Eucalyptus grandis de duas idades e provenientes de talhadia simples e de reforma. Os resultados indicaram que a madeira desse híbrido apresenta boas características tecnológicas, destacando-se a segunda tora (a partir de 3 m) com as melhores propriedades de flexão estática (Módulo de Elasticidade - MOE e Módulo de Ruptura - MOR) e Compressão Axial das fibras. As árvores de maior idade (166 meses) e que sofreram dois desbastes apresentaram as melhores propriedades de flexão estática e compressão axial.

Autoecología de los hayedos catalanes

Este estudio está basado en el muestreo de campo y posterior análisis de 24 parcelas de hayedo seleccionadas mediante una estratificación de su área de distribución basada en la clasificación CLATERES de la Ecorregión Catalano-Aragonesa. En cada parcela se han evaluado 3 parámetros fisiográficos, 15 climáticos y 18 edáficos, a partir de los cuales se han establecido sus valores paramétricos centrales y marginales que permiten definir los hábitats fisiográfico, climático y edáfico de las masas de Fagus sylvatica L. en Cataluña. Los hayedos catalanes se presentan sobre substratos litológicos muy diversos (plutonitas, vulcanitas, metamorfitas y sedimentitas, tanto ácidas como básicas), con texturas predominantes francas, franco-arenosas o franco-limosas. Los suelos, según FAO, son mayoritariamente cambisoles. A pesar de que la capacidad de retención de agua de sus suelos es escasa, la sequía fisiológica es reducida. Los humus predominantemente pertenecen a los tipos mull forestal y mull cálcico. Además, se presentan una serie de parámetros selvícolas ( Densidad de pies y densidad de chirpiales, Area basimétrica, Altura Total dominante, Índices de Hart-Becking, Índice de Calidad de Estación y Edad de la masa) que al correlacionarlos con los ecológicos nos ha permitido comprobar que los mejores hayedos se encuentran en las localizaciones más térmicas, en las que incluso se podría producir sequía fisiológica si no fuera por que existen suficientes precipitaciones estivales.

Thinning effect on plant growth of pruned eucalypt clone

A pruned stand of eucalypt clone underwent five thinning treatments with the removal of different proportion of the planted trees, at different ages: a) 0% - unthinned, b) 35% at 55 months, c) 35% at 81 months, d) 70% at 81 months, removing sprouts in the thinned plant stumps and, e) 70% at 81 months, without coppice sprouts removal. By the age of 141 months, the Weibull distribution showed higher number of trees in the smallest diameter classes for the unthinned treatment. The 70% thinning, with thinned coppice sprouts removal, presented higher number of individuals in the largest diameter classes. Height and yield were the smallest with the removal of 70% of the trees at 81 months, maintaining coppice sprouts. The afterthinning periodic annual increment was greater by thinning 35% of the trees at 55 months resulting in greater number of trees in the largest diameter classes as compared to the other treatments. Yield was higher for the unthinned treatment. The results of this study indicated that thinning 70% of the trees at the age of 81 months, with coppice sprout removal, could be recommended to obtain trees of larger diameter for multiproduct.

VEGETATIVE RESCUE AND CUTTINGS PROPAGATION OF Araucaria angustifolia (Bertol.) Kuntze

Brazilian pine or araucaria (Araucaria angustifolia) is a coniferous tree with great economic, social and environmental importance in southern Brazil, being exploited for both wood production and for its edible pine nuts. However, no efficient cloning techniques are available and, therefore, the purpose of this study was to evaluate the effectiveness of vegetative rescue methods for cuttings propagation of the species. Shoots/cuttings were generated in two ways: 26 years old trees underwent coppicing and 20 years old trees had the primary branches on the upper third of crown pruned at 2, 20 and 50 cm from the main trunk. Orthotropic shoots were rooted after application of indole-3-butyric acid (IBA) at 0, 2, 4 and 6 g.L-1. Coppicing produced 47 cuttings per plant with 90% orthotropic shoots, while pruning resulted in 182 cuttings per plant with 44% orthotropic shoots. Rooting success indexes were low with no influence of IBA, although they are slightly superior to the ones available in the literature for the species, ranging from 12 to 30% for the coppice shoots and from 0 to 28% for the branches shoots. We conclude that both vegetative rescue techniques are viable and have potentially important applications. Coppicing is recommended for the propagation aiming the production of wood, while shoots derived from the side branches of the crown are more appropriate for seeds orchards formation.

Energiapuun kastelu jätetäytön suotovedellä tuhkasta ja kompostista valmistetussa kasvualustassa

Tässä työssä tutkitaan suotoveden käsittelyä käyttämällä sitä kierrätysmateriaaleista valmistetussa tuhkamullassa loppusijoitusalueen päällä kasvatettavan energiapuukasvuston kasteluun. Kyseisen toimintamallin tarkoituksena on haihduttaa suotovettä energiapuiden avulla sekä sitouttaa ravinteita ja haitta-aineita sekä kasvustoon että kasvualustaan. Tavoitteena on selvittää toimintamallin hyödyntämiskelpoisuus ja tehokkuus suotovesien käsittelymenetelmänä sekä kastelun vaikutukset energiapuun kasvuun. Työssä suoritettiin kesän ja syksyn 2014 aikana energiapuun kastelukoe Mustankorkea Oy:n jätteenkäsittelykeskuksen alueella Jyväskylässä. Kokeessa loppusijoitusalueen päälle istutettuja eri kasvuvaiheissa olevia energiapajukasvustoja sekä hybridihaapakasvustoa kasteltiin jätetäytön suotovedellä. Kokeessa käytettiin kasvualustoina tuhkamultaa, joka oli valmistettu tuhkasta, kompostista ja ylijäämämaa- aineksesta, sekä kompostia. Kasteluveden, valumavesien, kasvualustojen ja pajukasvuston ominaisuuksia seurattiin kokeen aikana analyysien avulla. Lisäksi alueen vesitaseen selvittämiseksi suoritettiin lysimetrikokeet, joissa lysimetreihin istutettuja pajuja kasteltiin suotovedellä sekä hanavedellä. Tulosten perusteella suotovesikastelu lisäsi sekä pajun että haavan kasvua. Kastelu lisäsi pajun ravinnepitoisuuksia. Se myös heikensi hieman pajun poltto-ominaisuuksia. Kasvualustan ominaisuuksiin kastelulla ei havaittu olevan vaikutuksia. Kastelumäärä, jota voidaan käyttää ilman valumia, on kokeen perusteella n. 100–600 mm/kasvukausi käytetyllä kastelujärjestelmällä. Kastelujärjestelmää kehittämällä on kuitenkin luultavasti mahdollista lisätä haihduntaa ja siten kastelumäärää merkittävästi.

Évaluation du potentiel de séquestration de carbone dans le sol de cultures intensives sur courtes rotations de saules dans le sud du Québec

Dans la dernière décennie, plusieurs hectares de terre agricole ont été convertis à la culture intensive sur courtes rotations (CICR) de saules dans le sud du Québec (Canada). Peu d’études ont été réalisées afin de déterminer comment se comporte la dynamique du carbone organique (Corg) dans le sol suivant cette conversion. Nous avons donc comparé la quantité du Corg et de deux pools labiles de carbone (carbone extractible à l’eau chaude et les sucres aminés) entre des CICR en phase initiale d’établissement (1-2 ans) et des parcelles appariées représentant le système de culture qui prévalait avant la transformation en culture de saules (culture fourragère) et d’autres cultures d’intérêt. La même chose a été faite pour une CICR en exploitation (depuis 9 ans) à un autre site. La quantité de Corg du sol n’était pas différente entre les CICR et les parcelles sous culture fourragère. Une plus haute concentration de sucres aminés dans le Corg total des CICR en établissement, par rapport aux autres parcelles sur le même site, permet de soupçonner que les perturbations liées à l’établissement ne mènent pas à une minéralisation accrue du Corg à court terme. La proportion de sucres aminés fongiques, qui diminue théoriquement lors de perturbations, était aussi plus élevée sous la plus jeune culture. Sous la CICR de neuf ans, le Corg était redistribué dans le profil vertical et les pools labiles étaient de plus petite taille (à une profondeur de 20-40 cm) comparativement à une parcelle témoin. La conversion d’une culture fourragère en plantation de saules en CICR n’a pas mené à la formation d’un puits de carbone. L’étude laisse entrevoir qu’un tel puits pourrait être créé si la conversion se faisait à partir d’un aménagement impliquant la culture en rotation de plantes annuelles et des labours.

Séquestration du carbone atmosphérique dans la biomasse racinaire de plantations de saules

Le cycle du carbone (C) est, depuis la révolution industrielle, déstabilisé par l’introduction dans l’atmosphère de C autrefois fossilisé. Certaines mesures de mitigation prometteuses impliquent la séquestration accrue du CO2 atmosphérique dans les sols via le développement du réseau racinaire des arbres. Ce projet de recherche visait à : 1) quantifier la biomasse racinaire ligneuse produite annuellement par unité de surface par le Salix miyabeana cultivé en régie intensive à courtes rotations, 2) doser la concentration en C et en N des racines de saule en fonction de leur profondeur et de leur diamètre et 3) déterminer l’influence des propriétés pédoclimatiques du milieu sur la séquestration du carbone organique (Corg) par les racines. Pour y arriver, six souches de saules ont été excavées à partir de huit sites (n=48) et neuf carottes de recolonisation ont été implantées à cinq sites (n=45) pour évaluer la productivité racinaire fine. Les échantillons séchés ont été pesés pour quantifier la biomasse racinaire produite, et ont été analysés pour le C et le N. La productivité en biomasse racinaire ligneuse du saule en plantation pour tout le réseau d'échantillonnage varie de 0,7 – 1,8 Mg/ha/an. La proportion de C dans la biomasse racinaire s’étend de 31,3% à 50,4% et sa variance dans les tissus est expliquée par le diamètre racinaire et par les conditions environnementales des sites de provenance. Les conditions climatiques constituent la principale influence sur la production de biomasse racinaire. La variance de la biomasse racinaire est significativement contrôlée (p :0,004) par la quantité de précipitation de l’été et de l’année qui contrôlent ensemble 83,4 % du r2 ajusté. La précipitation de l’été est inversement liée à la productivité racinaire puisque les protéines expansines des racines sont stimulées par les carences hydriques du sol. La production de racines fines des plantations (1,2 à 2,4 Mg/ha/an) est, elle, plus fortement contrôlée par les conditions pédologiques du site qui expliquent 36,5% de la variance de productivité des racines fines contre 37,5% de la variance expliquée par les facteurs pédoclimatiques. Le P et le N du sol ont des rôles prépondérants sur la production de racines fines. Une disponibilité en P accrue dans le sol stimule la biomasse racinaire fine alors qu’une quantité supérieure de N dans le sol limite la croissance racinaire tout en favorisant la croissance des parties aériennes de la plante. Ce projet a permis d’améliorer notre compréhension des conditions pédologiques et climatiques qui engendrent, au Québec méridional, une productivité et une séquestration en Corg accrue dans le réseau racinaire du saule.

Effets de facteurs pédoclimatiques sur la composition et l’anatomie du bois de cinq cultivars de saule destinés aux biocarburants

En 2011, cinq (5) cultivars de saules ont été sélectionnés pour leur rendement en biomasse. Ils ont été plantés sur quatre sites de la province du Québec et ont été maintenus selon le protocole de la culture intensive sur courtes rotations (CICR) afin de déterminer leur potentiel pour la bioénergie dans des environnements contrastés. La composition et l’anatomie du bois de ces cultivars ont été caractérisées et comparés en fonction des conditions environnementales caractéristiques de chaque site. La hauteur et le diamètre à la base des plantes diffèrent selon les sites. Ainsi, les cultivars répondent de façon spécifique aux conditions pédoclimatiques dans lesquelles ils sont cultivés. L’effet de l’environnement n’a pas été mis en évidence sur la teneur en lignine des cultivars. Cependant, un effet génotypique a pu être constaté soulignant l’importance de la sélectivité des cultivars. La densité du bois a étonnamment conservé la même hiérarchie génotypique entre les sites. À l’opposé, l’anatomie du bois présente des différences notamment au niveau des caractéristiques des fibres et des vaisseaux. Une forte teneur en polyphénols ainsi que des fibres moins larges et des vaisseaux plus nombreux ont été observés sur le site dont le bois est le plus dense supposant l’effet probable d’un stress abiotique. De plus, deux fois plus de fibres gélatineuses, fibres riches en cellulose, ont été identifiées sur ce site montrant un intérêt pour la production de bioéthanol.

Bio-energy retains its mitigation potential under elevated CO2

Background If biofuels are to be a viable substitute for fossil fuels, it is essential that they retain their potential to mitigate climate change under future atmospheric conditions. Elevated atmospheric CO2 concentration [CO2] stimulates plant biomass production; however, the beneficial effects of increased production may be offset by higher energy costs in crop management. Methodology/Main findings We maintained full size poplar short rotation coppice (SRC) systems under both current ambient and future elevated [CO2] (550 ppm) and estimated their net energy and greenhouse gas balance. We show that a poplar SRC system is energy efficient and produces more energy than required for coppice management. Even more, elevated [CO2] will increase the net energy production and greenhouse gas balance of a SRC system with 18%. Managing the trees in shorter rotation cycles (i.e. 2 year cycles instead of 3 year cycles) will further enhance the benefits from elevated [CO2] on both the net energy and greenhouse gas balance. Conclusions/significance Adapting coppice management to the future atmospheric [CO2] is necessary to fully benefit from the climate mitigation potential of bio-energy systems. Further, a future increase in potential biomass production due to elevated [CO2] outweighs the increased production costs resulting in a northward extension of the area where SRC is greenhouse gas neutral. Currently, the main part of the European terrestrial carbon sink is found in forest biomass and attributed to harvesting less than the annual growth in wood. Because SRC is intensively managed, with a higher turnover in wood production than conventional forest, northward expansion of SRC is likely to erode the European terrestrial carbon sink.

Stomatal conductance and not stomatal density determines the long-term reduction in leaf transpiration of poplar in elevated CO2

Using a free-air CO2 enrichment (FACE) experiment, poplar trees (Populus · euramericana clone I214) were exposed to either ambient or elevated [CO2] from planting, for a 5-year period during canopy development, closure, coppice and re-growth. In each year, measurements were taken of stomatal density (SD, number mm2) and stomatal index (SI, the proportion of epidermal cells forming stomata). In year 5, measurements were also taken of leaf stomatal conductance (gs, lmol m2 s1), photosynthetic CO2 fixation (A, mmol m2 s1), instantaneous water-use efficiency (A/E) and the ratio of intercellular to atmospheric CO2 (Ci:Ca). Elevated [CO2] caused reductions in SI in the first year, and in SD in the first 2 years, when the canopy was largely open. In following years, when the canopy had closed, elevated [CO2] had no detectable effects on stomatal numbers or index. In contrast, even after 5 years of exposure to elevated [CO2], gs was reduced, A/E was stimulated, and Ci:Ca was reduced relative to ambient [CO2]. These outcomes from the long-term realistic field conditions of this forest FACE experiment suggest that stomatal numbers (SD and SI) had no role in determining the improved instantaneous leaf-level efficiency of water use under elevated [CO2]. We propose that altered cuticular development during canopy closure may partially explain the changing response of stomata to elevated [CO2], although the mechanism for this remains obscure.