Poden conviure el bosc i el foc? : nous avenços de la recerca en ecologia del foc

El foc és un factor ecològic natural en nombrosos ecosistemes, però la seva freqüència i extensió han estat modificades per l'home. Actualment el règim d'incendis en moltes zones de clima mediterrani es caracteritza per un augment en el nombre d'incendis, en la seva reiteració i en la seva grandària. Aquest fet, unit a l'augment de la temperatura i dels episodis de sequera induïts pel canvi climàtic en aquesta àrea, genera incerteses sobre quina pot ser la resposta funcional dels ecosistemes i quins canvis es poden produir en la distribució d'espècies i l'estructura de les comunitats. Malgrat la reconeguda resiliència de les comunitats mediterrànies al foc, estudis recents demostren que aquesta resposta no és extensiva a tot tipus de sistemes i que fins i tot aquelles espècies que presenten mecanismes que els permeten regenerar-se eficaçment davant aquesta pertorbació, com la rebrotada o el manteniment de bancs de llavors protegits, poden veure's greument afectades per un augment en la freqüència, intensitat o grandària dels incendis o la seva combinació amb altres pertorbacions (p. ex., sequera). Fins a quin punt aquests efectes poden ser mitigats mitjançant diferents estratègies de gestió requereix un considerable esforç d'investigació.Fire is a natural ecological factor, but fire frequency and fire expansion have been modified by human activities. The present wildfire regime in most Mediterranean-type climate areas is characterized by an increase in the number, recurrence and size of fires. Moreover, increasing warming and drought episodes due to climate change in this ecological scenario may challenge the functional response of ecosystems and induce changes in the structure and species composition of Mediterranean communities. In spite of the well known resilience of Mediterranean-type ecosystems to fire, recent studies have demonstrated that this response is not applicable to all communities and that, even species with a successful regeneration after fire, due to resprouting or the presence of seed banks, may be threatened by an increase in the frequency, intensity and size of fires and/or the occurrence of other disturbances (e.g. drought). To what extent these effects could be modified by different management strategies remains to be further investigated

Diagnóstico molecular de plagas de la dehesa y protocolos de gestión para facilitar su control biológico por el ganado

Póster presentado al I Congreso Ibérico de la Dehesa y el Montado, celebrado en Badajoz del 6 al 7 de noviembre de 2013.La investigación sobre las plagas y patógenos que reducen la producción de bellotas plantea aún numerosos retos. Presentamos los resultados de nuestros estudios con los gorgojos (coleópteros) parásitos de las bellotas. Las técnicas moleculares nos permitieron identificar larvas para las que no existen claves; a partir ahí pudimos conocer con detalle los ciclos vitales de las diferentes especies. Comprobamos que los ciervos y jabalíes depredan intensamente sobre las larvas (especialmente de las especies tempranas), pudiendo llegar a reducir las tasas de infestación de bellotas. Ahora pretendemos perfeccionar el diagnóstico molecular de plagas y patógenos aumentando la base de datos con secuencias de ADN de más especies. También investigaremos el papel del ganado como depredador de insectos plaga y dispersante de patógenos, para así desarrollar pautas de manejo ganadero que maximicen el vigor del arboladoPeer Reviewe

El arquitecto viajero

[ES] Sin resumenBosch Espelta, J. (2003). El arquitecto viajero. EGA. Revista de Expresión Gráfica Arquitectónica. (8):66-69. https://doi.org/10.4995/ega.2003.10351SWORD6669

Masting plants: Why combine abstinence and lust in reproduction?

La majoria de plantes perennes produeixen llavors cada any, però n’hi ha algunes que mostren un comportament reproductiu estrany: les seves poblacions produeixen extraordinàries collites de manera erràtica i sincrònica, però passen alguns anys pràcticament sense reproduir-se. Són les espècies anyívoles i el motiu d’aquest comportament sexual, com es produeix, i les conseqüències que té per a les xarxes tròfiques ha intrigat els ecòlegs. En aquest treball presentem un resum del coneixement actual sobre les causes evolutives i ecològiques que promourien aquest comportament. Les dues hipòtesis més versemblants de la seva evolució serien els avantatges de controlar les poblacions de depredadors de llavors i afavorir que algunes escapin (saciat dels depredadors) i/o una millor eficàcia en la pol·linització de plantes pol·linitzades pel vent (eficiència en la pol·linització). La variabilitat entre anys en la mida de les collites seria el resultat de la possibilitat que les plantes puguin dedicar més o menys recursos a la reproducció a partir de les condicions ambientals (p. ex. meteorològiques, de mobilització de nutrients) mentre que la sincronia entre individus, fins i tot a grans escales espacials, seria el resultat de l’anomenat Efecte Moran, és a dir, la resposta a una condició ambiental amb àmplia sincronia espacial com és la meteorologia i els seus efectes en la floració o la maduració dels fruits. Finalment, es presenta el coneixement més recent sobre les causes que determinen que una espècie com l’alzina (Quercus ilex), tan important i abundant al nostre país, sigui anyívola i les seves conseqüències.Most perennial plants produce seeds every year, but some species show a bizarre reproductive behaviour: they produce bumper crops randomly and synchronously in some years, while in other years they produce virtually no seeds. These are known as masting species and the benefits of this behaviour, how it occurs, and the consequences for trophic networks have long intrigued ecologists. Here we present a summary of current knowledge about the evolutionary and ecological causes that promote masting. The two most likely hypotheses for its evolution are the advantages of controlling seed predator populations and encouraging some seeds to escape (predator satiation) and/or better efficiency in the pollination of wind-pollinated plants (pollination efficiency). The variability between years in the size of crops results from the fact that plants devote more or fewer resources to reproduction depending on the environmental conditions (e.g. meteorological conditions and nutrient mobilization). In addition, the synchrony between individuals, even at large spatial scales, is the result of the so-called Moran Effect: i.e. the response to an environmental condition with a broad spatial synchronization such as meteorology and its effects on the flowering or maturation of the fruits. Finally, we present the most recent knowledge on the reasons why the holm oak (Quercus ilex), so important and abundant in Catalonia, exhibits masting behaviour, and its consequences

Contrasting effects of fire severity on the regeneration of Pinus halepensis Mill. and resprouter species in recently thinned thickets

Many studies have outlined the benefits for growth and reproduction resulting from thinning extremely crowded young forests regenerating after stand replacing wildfires ("thickets"). However, scarce information is available on how thinning may influence fire severity and vegetation regeneration in case a new fire occurs. We investigated the relationship between thinning and fire severity in P. halepensis thickets, and the effects on the establishment of pine seedlings and resprouting vigour in resprouter species the year after the fire. Our results show a positive relationship between forest basal area and fire severity, and thus reserved pines in thinned stands suffered less fire damage than those in un-thinned sites (respectively, 2.02 ± 0.13 vs. 2.93 ± 0.15 in a scale from 0 to 4). Ultimately, differences in fire severity influenced post-fire regeneration. Resprouting vigour varied depending on the species and the size of individuals but it was consistently higher in thinned stands. Concerning P. halepensis, the proportion of cones surviving the fire decreased with fire severity. However, this could not compensate the much lower pine density in thinned stands and thus the overall seed crop was higher in un-thinned areas. Establishment of pine seedlings was negatively affected by the slope and positively driven by the number of cones and thus it was higher in un-thinned than in thinned stands (respectively, 2581 ± 649 vs. 898 ± 325 seedlings∙ha-1). Thinning decreases fire intensity, and thus it may facilitate fire suppression tasks, but retaining a higher density of pines would be necessary to ensure P. halepensis regeneration after a new fire even

"New Forests" from the Twentieth Century are a Relevant Contribution for C Storage in the Iberian Peninsula

Land-use changes are one of the major drivers of global change. In many developed countries socioeconomic changes have induced forest expansion during the last centuries, with still seldom explored implications for ecosystem services. We assessed the growth rate and the contribution of these “new forests” on C storage under the imprint of land-use history from Mediterranean to temperate forests in two biogeographical regions in the Iberian Peninsula, using data from 6422 plots of the Spanish National Forest Inventory (1986–2007) and the land-cover map of 1956 to distinguish among pre-existing and new forests (appeared after 1956). Almost a quarter of current forests were new forests and they represented 22% of the total C pool. New forests maintained similar C stocks than pre-existing ones (~45Mgha−1), but they are growing at rates 25% faster. Considering the whole Spanish forested territory, the new forest growth rate would offset around 9% of the rate of total C emitted in Spain between 1986 and 2007. The effects of land-use history on forest growth and C stocks varied with environmental conditions (for example, growth of new forests in areas with less water availability was higher than in pre-existing ones), supporting the idea that agricultural legacies may prevail in the long term. In a time when European forests exhibit the first signs of carbon sink saturation, our study endows a relevant ecological role to new forests appearing in the second half of the twentieth century

Assessing intraspecific trait variability during seedling establishment to improve restoration of tropical dry forests

Forest restoration is an effective tool to mitigate climate change, but its implementation in highly diverse and threatened tropical dry forests (TDFs) is particularly challenging due to the hostile environment. Intraspecific trait variability (ITV) in response to these constraints may be very informative for predicting the potential for species acclimation and therefore for improving trait-based species screenings that best match each particular scenario of forest restoration. We analyzed ITV during seedling establishment of three widely distributed and ecologically contrasting TDF species in a greenhouse multifactorial experiment crossing levels of resource availability (nutrients and water) and herbivory to assess the capacity of ITV to discern strategies of seedling establishment and to predict species' growth rates and acclimation potential. The three species studied had contrasting responses to the experimental treatments, suggesting different strategies of seedling establishment. The species with the most plastic pattern of growth performed the best, especially due to its ability to modulate the trade-off of root-to-shoot allocation of biomass depending on nutrient availability. Almost 50% of the variation in the root mass ratio was within species, half of which was a direct response of the treatments, indicating a strong acclimation potential. Individual-level trait measurements, however, were poor predictors of seedling growth rates. ITV, particularly the ability to adapt the pattern of biomass allocation, can be critical during seedling establishment. We propose incorporating information about ITV and the ability of species to modulate their phenotypic expression to cope with environmental variability into programs of forest restoration. Easily implemented and standardized greenhouse experiments are an inexpensive way to obtain high-quality data on the plasticity of forest species, which can be very valuable for predicting the potential of species acclimation and thus improving the selection of species that better match each particular scenario of restoration