Posibilidades de la variabilidad genética de encinas y alcornoques en la conservación y recuperación de bosques amenazados por la "seca"

Phytophthora cinnamomi Rands. (hongo patógeno del suelo) es el principal responsable del decaimiento de encinas y alcornoques en el Suroeste de la Península Ibérica. Este decaimiento es uno de los problemas ambientales más graves que amenaza la supervivencia y sostenibilidad, tanto ecológica como económica, de las formaciones de Quercus del sur peninsular. Este trabajo analiza la posibilidad del empleo de la variabilidad genética de la resistencia o tolerancia de los árboles al patógeno del suelo P. cinnamomi.____________________________________Phytophthora cinnamomi Rands is the main pathogen responsible for the holm and cork oaks decline in south-western Iberian Peninsula. This decay is one of the more serious environmental problems that threatens the survival and both ecological and economic sustainability of Quercus forests in southern Iberian Peninsula. The present work analyses the possibilities of use of genetic variability of resistance or tolerance of trees to the pathogen P. cinnamomi

Seed Dormancy and Seedling Ecophysiology Reveal the Ecological Amplitude of the Threatened Endemism Picris willkommii (Schultz Bip.) Nyman (Asteraceae)

Plant communities can undergo drastic changes in their composition if the ecosystem is severely altered by human actions or climate change. These changes endanger any vulnerable species, mainly if it lives in a small area, as is the case of Picris willkommii (Schultz Bip.) Nyman. Therefore, it is essential to know how an ecosystem alteration could affect the seasonal pattern of the life cycle, seed production, germination time, as well as both plant emergence and development. During three consecutive years, the growth phenology and seed morpho-physiological traits of Picris willkommii were assessed, as well as the environmental factors that affect them (light, temperature, substrate). Under natural conditions, germination is in early autumn (15–25 °C air temperature), flowering is in spring, and seed maturation in late spring. The species produces two types of seeds differentiated in the degree of dormancy and other morpho–physiological traits, which contributes to the dispersal and spreading capacity; it prefers fine-textured limestone substrates with high N and P availability; it does not tolerate frosts below −5 °C; and it is able to acclimatize to changing environmental conditions, but there is a risk of being replaced by other more aggressive species. All of this is useful for species conservation programsThe authors want to thank the support of the Andalusian Government for providing some batches of seeds and allowing the study of this species; and the support of Ricardo Arribas, the company Dintel Domus S.A. and the Ayamonte´s city council for the acquisition of materials for experimentation and for their help in field trip

Adaptación a la sequía y necesidades hídricas de Eucalyptus globulus Labill. en Huelva

Eucalyptus globulus Labill. es una especie ampliamente utilizada en plantaciones para producción de madera. Está adaptada a vivir sobre suelos pobres y bajo clima mediterráneo pero suave y con influencia oceánica. Soporta cierto grado de estrés hídrico pero le van mal temperaturas extremas que sobrepasen 40 ºC ó -5 ºC. Su cultivo en la provincia de Huelva está seriamente limitado por la frugalidad de los suelos y la sequía estival, así como por el ataque de plagas, especialmente virulentas en situaciones de estrés hídrico como en el caso de Phoracantha spp. En este trabajo se muestra una recopilación de varias experiencias, llevadas a cabo en vivero y en parcelas de campo, sobre la reacción de los clones al estrés hídrico y sus necesidades de consumo de agua. Al igual que para otros tipos de estreses biótico o abióticos, la especie manifestó variabilidad genética (a nivel clonal) en su grado de resistencia al estrés hídrico, lo que ofrece la posibilidad de seguir desarrollando programas de selección y mejora de la especie destinada a plantaciones forestales. Dicha resistencia se implementaba al ser expuestos a situaciones de estrés hídrico, poniendo en juego mecanismos de evitación (morfología foliar, cierre estomático, vulnerabilidad a la cavitación del xilema, etc.) y de tolerancia (ajuste osmótico y elástico). No obstante el grado de variación de cada uno de los parámetros medidos difirió entre los clones, manifestando distintas estrategias entre clones, lo que puede ser utilizado a la hora de establecer el criterio de selección en función del objetivo perseguido en cada línea de mejora (resistencia al ataque por Phoracantha spp., producción y eficiencia en el uso del agua, resistencia a valores críticos de estrés hídrico, etc.).___________________________________________Eucalyptus glubulus is a widely used species in forest plantations for wood production. It is adapted to live on poor soils under Mediterranean climate with oceanic influence. It supports some degree of water stress but not extreme temperatures exceeding 40 ºC or -5 ºC. Its cultivation in the province of Huelva is seriously limited by the frugality of the soils and the summer drought, and it is attacked by pests such as Phoracantha spp., particularly virulent under water stress conditions. In this work, we analyzed the results of several experiments, carried out in nurseries and in field plots, regarding to the response of E. globulus clones to water stress and its water consumption needs. As for other biotic or abiotic stresses, the species showed genetic variability (at clonal level) in their resistance to water stress, which offers the possibility to further develop and improve breeding programs. Under water stress conditions, it reacts by coming into play avoidance mechanisms (leaf morphology, stomatal closure, vulnerability to xylem cavitation, etc..) and tolerance mechanisms (osmotic and elastic adjustment). However, the degree of variation of each of the above cited parameters differed between clones, showing different strategies among them. This can be used when establishing the selection criteria in relation to the purpose of each breeding program (resistance to be attacked by Phoracantha spp., production and water use efficiency, resistance to threshold values of water stress, etc.

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

Aclimatación al frío en diferentes clones de Eucalyptus globulus Labill durante el régimen natural de endurecimiento

En la región mediterránea la principal limitación de la expansión del las plantaciones de Eucalyptus es la ocurrencia periódica de temperaturas bajas durante los meses de invierno (-5 a -10 oC). Por esta razón es crucial implementar un programa para mejorar la resistencia al frío en las especies utilizadas de este género. E. globulus, la especie más extendida en la península ibérica es considerada una especie moderadamente susceptible al frío. Se testaron 16 clones a los cuales se les realizó un seguimiento durante el régimen natural de endurecimiento y la salida del mismo para el periodo 2005-2006. La tolerancia al frío fue evaluada en tejido foliar desarrollado, tanto en hojas pecioladas maduras como en hojas sentadas juveniles, simulando condiciones de helada en ambiente controlado. De esta forma se demostró que existe un proceso de aclimatación de las plantas a las bajas temperaturas a medida que se acumulan las horas de frío y una desaclimatación de las mismas a medida que acaba el invierno. En todos los clones se determinó un máximo de tolerancia para la segunda quincena de enero, lo que corresponde con un total acumulado de 415 horas de frío por debajo de los 7 oC (HF7). Por otra parte se observó un cambio significativo en el umbral de temperaturas que causan un daño al 50% de la superficie del tejido foliar (TL50), siendo el valor medio de éstas -4,5 ºC antes de comenzar la temporada de frío y de – 6,5 ºC una vez alcanzado el máximo de endurecimiento.______________________________The greatest constraint on the expansion of Eucalyptus plantations in the Mediterranean region is the periodic occurrence of low temperatures (–5 to –10 oC) during winter. This has raised the need to launch a programme aimed at increasing the tolerance to cold weather of Eucalyptus species in the region. Eucalyptus globulus, which is the most widespread Eucalyptus species in the Iberian peninsula, is moderately vulnerable to cold. In this work, a total of 16 clones of this species were monitored during their natural hardening regime and at its end over the period 2005–06. Tolerance to cold was evaluated in well-developed tissue of both mature petiolate leaves and seated young leaves by mimicking freezing conditions in a controlled environment. The plants were found to gradually acclimate to low temperatures as the number of cold hours increased and to de-acclimate as the winter neared its end. Tolerance in all clones peaked in the second half of January, after an overall 415 could hours at temperatures below 7 oC (HF7). Also, the temperature threshold below which at least 50% of leaf surface tissue was damaged (TL50) varied markedly, from an average –4.5 oC at the beginning of the cold season to an average –6.5 oC at the point of maximum hardening

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

Electroantennographic Responses of Cerambyx welensii Küster to Host-Related Volatiles

Wood-boring insects, such as Cerambyx welensii Küster, are involved in oak decline in Mediterranean areas. To advance our understanding of the olfactory perception of C. welensii, we recorded electroantennographic (EAG) responses from male and female antennae to 32 tree volatile organic compounds typical of emissions from its main Quercus L. hosts, and also analysed the dose-dependent response. Cerambyx welensii antennae responded to 24 chemicals. Eight odorants elicited the highest EAG responses (normalized values of over 98%): 1,8-cineole, limonene-type blend, β-pinene, pinene-type blend, sabinene, α-pinene, turpentine and (E)-2-hexenal. Cerambyx welensii exhibits a broad sensitivity to common tree volatiles. The high EAG responses to both limoneneand pinene-type blends suggest the detection of specific blends of the main foliar monoterpenes emitted by Q. suber L. and Q. ilex L. (limonene, α- and β-pinene, sabinene and myrcene), which could influence the intraspecific host choice by C. welensii, and in particular, females may be able to detect oak trees with a limonene-type chemotype. In addition, C. welensii showed high antennal activity to some odorants that characterize emissions from non-host tree species (1,8-cineole, β-pinene, α-pinene, turpentine, δ 3 -carene and camphene). The results obtained may be applicable to optimize monitoring and mass-trapping programmes in an integrated pest management context: This research was funded primarily by the Andalusian Regional Council of Environment and Spatial Planning and conducted through a collaborative agreement between the University of Huelva and University of Córdoba (Ref.15-2003-UHU) We thank Peter Gordon and Julia G. Fenn for commenting on an earlier version of the manuscrip

La biodiversidad como herramienta en la gestión y certificación forestal : zonas de alto valor de conservación en montes madereros del suroeste peninsular

Este artículo presenta un estudio sobre la biodiversidad y el estado de ocho Zonas de Alto Valor de Conservación en la provincia de Huelva (localizada en el suroeste de la Península Ibérica), colindantes a plantaciones de especies de crecimiento rápido (Eucalyptus globulus). El estudio se incluye en el marco de un proceso de certificación forestal. Se han evaluado algunos parámetros de biodiversidad –riqueza, diversidad alfa, diversidad beta- y estado –regeneración, cobertura, densidaden 143 parcelas de comunidades leñosas. Se han registrado un alto número de taxones animales y vegetales, algunos de los cuales son especies amenazadas o endémicas. El uso de los índices de diversidad ha sido esencial; son simples abstracciones de la estructura altamente compleja de las comunidades, muy útiles para hacer comparaciones. Han mostrado la alta diversidad de las zonas estudiadas mediante datos cuantificables. Este tipo de estudios son muy importantes e útiles para conocer el estado de ecosistemas forestales y abordar su seguimiento, y por lo tanto para la gestión forestal.____________________________________This paper presents a study about the biodiversity and the status of eight Zones of High Conservation Value within the province of Huelva (located in the southwest of the Iberian Peninsula), near plantations of fast growing species (Eucalyptus globulus). The study is in the framework of a forest certification process. Some parameters of biodiversity –species richness, diversity alpha, diversity beta– and status – regeneration, cover, density– have been evaluated in 143 plots of woody communities. A high number of vegetal and animal species have been recorded; some of them are endangered or endemic species. The use of diversity indices has been essential; they are simple abstractions of the highly complex structure of communities, very useful for comparisons. They have shown the high biodiversity of the study areas using quantifiable data. Such studies are very important and useful to know the status of forest ecosystems and to address the monitoring of these ones, and therefore for forest management

Antennal response of "Prinobius myardi" to synthetic tree volatiles

Prinobius myardi Mulsant is a wood borer implicated in the decline of Mediterranean oaks, especially Quercus suber L. and Quercus ilex L. Plant volatiles play an important role in plant-insect interactions, and electroantennography (EAG) is an effective tool for exploring the electrophysiological activity of host plant volatiles on insects. To improve our understanding of the olfactory sensitivity of P. myardi, we recorded EAG responses to 20 tree volatiles, and analyzed the dosedependent response to five doses (10–4:1 to 1:1 v/v) of the three most EAG-active compounds. Antennae of P. myardi responded to 13 chemicals, mainly monoterpenes and green leaf volatiles, with the strongest EAG responses being observed with β-pinene, (+)-α-pinene and 1,8-cineole. Dose–response profiles showed positive dose-dependent responses for all three compounds. Our results suggest a broad sensitivity of P. myardi to common tree volatiles, particularly some hostrelated compounds and volatiles associated with wounded trees; the olfactory recognition of ratios of these compounds could play a role in host selection by P. myardi