Biomass Yield and Economic, Energy and Carbon Balances of Ulmus pumila L., Robinia pseudoacacia L. and Populus × euroamericana (Dode) Guinier Short-Rotation Coppices on Degraded Lands under Mediterranean Climate

The steadily increasing demand for energy and concerns about climate change have prompted countries to promote the use of renewable energy sources, including lignocellulosic biomass. In this context, this work aims to assess the biomass production for energy purposes in crops with short rotation, as well as its effect on soil properties. Deciduous tree species were used, mainly Siberian elm (Ulmus pumila L.), black locust (Robinia pseudoacacia L.) and a hybrid poplar clone (Populus × euroamericana (Dode) Guinier, clone ‘AF2’). Four field trials were implemented, under two different types of Mediterranean climate, where highly productive taxa were tested, in addition to the mixed planting of a nitrogen-fixing species with a non-fixing one. Short-rotation coppices (SRCs) of these taxa yield about 12–14 t ha−1 year−1 of high-quality dry woody biomass, when fertilizers and irrigation water are supplied; generate 205–237 GJ ha−1 year−1 net and earnings of about EUR 1.5 per EUR 1 invested; and sequester into the soil 0.36–0.83 t ha−1 year−1 of C and 57 kg ha−1 year−1 of N. Therefore, these species raised as SRCs could improve degraded soils if the crop is properly managed, resulting in favorable economic, energy and CO2 emission balances. The use of mixed plantations can bring economic and environmental gains, and the biomass transformation into high-quality chips or pellets gives it added valueThis research was funded by the Science and Innovation Ministry (ref. AGL2010-16575) and the Economy and Competitiveness Ministry of Spain (ref. CTQ2013-46804-C2-1-R and CTQ2017- 85251-C2-2-R), by FEDER funds of the EU, and by the company ENCE, energía y celulosa S.A. (8%, 6%, 6%, 70%, 10%, respectively). The authors want to thank the Diputación de Granada (Spain) for the donation of farmland for the establishment of the experimental plots in Los Morales, and for the help in the cultivation works; the company Tubocás S.L. for its contribution to the sampling and transport of biomass, as well as to the harvest at the end of each crop rotation; and Biopoplar Ibérica S.L. for the provision of some plant tax

Quality of the Pellets Obtained with Wood and Cutting Residues of Stone Pine (Pinus pinea L.)

The use of wood and residual biomass from forestry works is a CO2 emission-neutral source of energy that also contributes to reducing the risk of spreading forest fires, especially under Mediterranean climate. The forest stands of stone pine (Pinus pinea L.) occupies about 0.7 million hectares in the Mediterranean basin. In this study, the commercial quality of the pellets manufactured from different types of cutting residues (needles and thin branches, medium branches and bark), as well as wood from trunks and thick branches, was assessed. It was concluded that with the exclusive use of residual biomass it is not possible to obtain pellets of high commercial quality, useful for residential or industrial use. However, the highest quality pellets could be obtained by combining them with stone pine debarked wood, but in a certain proportion that differs depending on the type of residue (around 15% for bark, 30% for medium branches and less than 15% for needles and thin branches). It is recommended to take advantage of both the thick wood (trunk + thick branches) and a proportion of medium branches and bark, while in the case of needles and thinnest branches it would be more convenient to leave them in the forest for their incorporation into the soil, given their high nutrients concentration and their low quality for energetic use. The results found support a greater valorization of the biomass obtained in the stone pine fellings. In the future it will be necessary to study which is the most appropriate logistics of the silvicultural works to be able to conveniently apply the results of this study.This study was financed by Projects: “Iberian Center for Research and Forest Firefighting”, CILIFO (0753_CILIFO_5_E) and “Strengthening of cross-border systems for the prevention and extinction of forest fires and improvement of resources for rural employment generation post COVID- 19”, FIREPOCTEP (0756_FIREPOCTEP_6_E). Both are Projects co-financed by the European Regional Development Fund (ERDF), within the framework of the Interreg V A Spain—Portugal Program (POCTEP) 2014–2020

Influencia de la poda en la producción de la bellota y el crecimiento en dehesas de la provincia de Huelva

Las dehesas son sistemas agrosilvopastorales de gran importancia económica ecológica y social en la provincia de Huelva. Su gestión debe considerarse de forma integral sin olvidar las buenas prácticas selvícolas, en un momento en que muchas de estas formaciones están sufriendo la influencia del fenómeno de la “seca”, que afecta de forma dramática al estado sanitario de estas formaciones y a su supervivencia. En este trabajo se evalúa la influencia de las podas, uno de los tratamientos más frecuentes en las dehesas, en la producción de bellota y en el crecimiento diamétrico de los pies. De acuerdo con los resultados obtenidos se realizan recomendaciones de gestión referentes a este tratamiento._________________________________The “dehesas” are agro-silvicultural systems with a huge economical, ecological and social interest for the province of Huelva. Its management must be considered in a global way without forgetting the good silvicultural practices, specially when this forests are dramatically affected by the oak decline. In this paper the influence of pruning on acorn production and diametric growing is evaluated, and starting from the obtained results, management options in relation with pruning are discussed

Leguminosas leñosas de rápido crecimiento como cultivos energéticos en el Suroeste de la Península Ibérica

Este estudio pretende evaluar las posibilidades del empleo de leguminosas leñosas de rápido crecimiento como cultivos destinados a la producción de biomasa como fuente de energía. El ensayo consistió en el cultivo de 14 especies / procedencias de los géneros Leucaena (L. leucocephala, L. salvadorensis, L. diversifolia, L. collinsi), Prosopis (P. alba y P. julyflora), Sesbania (S. sesban), Chamaecytisus (C. proliferus var palmensis) y Retama (R. monosperma). Las plantas fueron producidas a partir de semillas e inoculadas con bacterias del género Rhizobium. Tras una fase de vivero fueron transplantadas en dos parcelas de ensayo sometidas a dos regímenes de riego. Durante el cultivo se monitorizó el crecimiento (altura, diámetro y peso). La producción anual de biomasa se evaluó durante 3 años consecutivos bajo tres sistemas de aprovechamiento: cortas anuales o a los 2, y 3 años. Todas las especies y variedades salvo Leucaena salvadorensis y Sesbania sesban mostraron una buena adaptación edafo-climática a las características de la zona de estudio (Huelva). La variación en las tasas de crecimiento entre especies fue muy grande desde las 0.3 toneladas de materia seca leñosa por hectárea y año (Retama monosperma, Prosopis julyflora) hasta las 25-35 t/ha y año (Luecaena leucocephala). Todas las especies soportaron bien las cortas anuales menos Chamaecytisus proliferus que se mostró muy sensible a la corta del primer año sobretodo en la parcela más regada._____________________________________We cultivate 14 species / provenances of genera Leucaena (L. leucocephala, L. salvadorensis, L. diversifolia, L. collinsi), Prosopis (P. alba and P. julyflora), Sesbania (S. sesban), Chamaecytisus (C. proliferus var palmensis) and Retama (R. monosperma). The plants were produced from seeds and inoculated with specific bacteria of the genus Rhizobium. After a nursery phase, seedling were planted in two experimental plots subjected to two water regimes. Annual biomass production was evaluated under three management systems: annual biannual and three annual clear-cutting All the species and varieties except Leucaena salvadorensis and Sesbania sesban showed a good edafo-climatic adaptation to the characteristics of the study area (Huelva). Variation in growth rates among species was high, from the 0.3 t of woody dry matter per hectare and year (Retama monosperma, Prosopis juliflora) until 25-35 t ha-1 year-1 (Leucaena leucocephala). All the species supported annual cutting with a vigorous re-sprouts except Chamaecytisus proliferus that was very susceptible especially in the most irrigated plots

Obtención de pasta celulósica a partir de madera procedente de la poda de encina (Quercus ilex L.)

En el trabajo se plantean la utilización de los residuos procedentes de podas de encina para la obtención de pasta celulósica y hojas de papel mediante los procesos a la sosa con antraquinona, kraft y organosolv utilizando el etilenglicol como disolvente. Dentro de la memoria se incluye una exhaustiva revisión s de los materiales no madereros utilizados hasta la fecha con la obtención de pasta celulósica. En cada uno de los métodos de obtención de pasta celulósica ensayados se aplica un diseño de composición central, a partir del cual se determina los rangos de las variables del proceso de cocción (temperatura, tiempo y concentración de álcali o disolvente) con los que se obtienen los valores óptimos de las propiedades de las pastas celulósicas y de las hojas de papel. Se realizan asimismo diversos ensayos de blanqueo obteniéndose grados de blancura similares a los de pastas comerciales de otros materiales madereros.---------------------------------The thesis proposes the use of holm oak trimmings to obtain cellulose pulp and paper processes throuhg the soda with anthraquinone, kraft and organosolv using ethylene glycol as solvent. Within the memory includes an exhaustive review of non-wood materials used so far to obtain cellulose pulp. In each of the methods tested is applied a central composition design from which we determine the ranges of cooking processing variables (temperature, time and concentration of alkali or solvent). From them we obtain the optimal values of the properties of the pulp and paper sheets. Several bleaching tests were also made. In the same were obtained degrees of brightness similar to those of commercial pastes of other timber materials

Biomass Yield and Economic, Energy and Carbon Balances of Ulmus pumila L., Robinia pseudoacacia L. and Populus × euroamericana (Dode) Guinier Short-Rotation Coppices on Degraded Lands under Mediterranean Climate

The steadily increasing demand for energy and concerns about climate change have prompted countries to promote the use of renewable energy sources, including lignocellulosic biomass. In this context, this work aims to assess the biomass production for energy purposes in crops with short rotation, as well as its effect on soil properties. Deciduous tree species were used, mainly Siberian elm (Ulmus pumila L.), black locust (Robinia pseudoacacia L.) and a hybrid poplar clone (Populus × euroamericana (Dode) Guinier, clone ‘AF2’). Four field trials were implemented, under two different types of Mediterranean climate, where highly productive taxa were tested, in addition to the mixed planting of a nitrogen-fixing species with a non-fixing one. Short-rotation coppices (SRCs) of these taxa yield about 12–14 t ha−1 year−1 of high-quality dry woody biomass, when fertilizers and irrigation water are supplied; generate 205–237 GJ ha−1 year−1 net and earnings of about EUR 1.5 per EUR 1 invested; and sequester into the soil 0.36–0.83 t ha−1 year−1 of C and 57 kg ha−1 year−1 of N. Therefore, these species raised as SRCs could improve degraded soils if the crop is properly managed, resulting in favorable economic, energy and CO2 emission balances. The use of mixed plantations can bring economic and environmental gains, and the biomass transformation into high-quality chips or pellets gives it added value

Hacia la modelización de la producción de bellota en encinares ("Quercus ilex Ballota")

La producción de bellota en encinares (Quercus ilex ballota) supone una importante fuente de alimento para el ganado doméstico y la fauna cinegética. Por otro lado, de la producción de bellotas depende la propia persistencia del encinar, ya sea a través de semillas para repoblación artificial o mediante regeneración natural. La modelización de la producción de bellota puede contribuir a un mejor conocimiento de la misma. En la primera parte de este trabajo se pasa revista a los distintos modelos forestales de simulación que tienen en cuenta la producción de bellotas en diferentes especies de Quercus, fundamentalmente de especies americanas. La segunda parte del trabajo se basa en los datos obtenidos en dos parcelas experimentales localizadas en dehesas de encina de la provincia de Huelva, en donde se está cuantificando la producción de bellota mediante varios métodos: trampas o contenedores, muestreo de sectores de copa, rangos y conteo total. A partir de dichos datos experimentales se deduce que un modelo de producción de bellota en encinares debe tener en cuenta los siguientes factores: características de la estación (clima y suelo), estructura del arbolado (dimensiones y competencia), tratamientos selvícolas (podas y laboreos), variabilidad individual (diferencias genéticas entre individuos) y vecería (variabilidad interanual de la producción). Los datos obtenidos durante los tres primeros años de toma de datos ponen de manifiesto la especial importancia de la vecería y la variabilidad individual, por encima del efecto de los tratamientos selvícolas

Biomass Production and Quality of Twelve Fast-Growing Tree Taxa in Short Rotation under Mediterranean Climate

Sustainable production of lignocellulosic biomass for energy use can contribute to climate change mitigation. This work aims to compare the biomass production of twelve fast-growing woody taxa belonging to the Eucalyptus, Casuarina, Populus and Paulownia genera, the quality of their biomass for energy use and its valorizing through transformation into pellets, as well as the effect of the crop on the soil. Over the course of two rotations, plant growth and biomass production were assessed. The yield of aboveground dry biomass ranged from 9 to 61 Mg ha−1 year−1 (equivalent to 137–867 GJ ha−1 year−1). The highest yields were obtained for Eucalyptus clones (51–61 Mg ha−1 year−1). The N-fixing species Casuarina equisetifolia and two Populus × euramericana clones (‘Adige’ and ‘AF2’) also achieved high yields (28–33 Mg ha−1 year−1), though significantly smaller than those of the eucalypts. Due to its low wood density, Paulownia fortunei was not very productive in terms of biomass (18 Mg ha−1 year−1), despite its good growth in diameter and height. However, some management practices, such as not removing nutrient-rich and poor-quality biomass fractions for energy use (leaves and thin branches) from the harvested crop, as well as the use of N-fixing species and by taking into account all nutrient inputs and outputs, can ensure the sustainability of the cultivation systems and improve degraded soils