Rodrigo A, Martínez-Vilalta J, Piñol J, Lloret F, Ribas A, Retana J, Losarcos J (2008) Disseny i aplicació d’una proposta d’aprenentatge cooperatiu dels continguts de l’àrea d’Ecologia mitjançant l’estudi de casos. En “Cap a l’espai europeu d’educació superior. Experiències docents innovadores de la UAB en ciències experimentals i tecnol ogies i en ciències de la salut”. Servei de Publicacions UAB. Bellaterra
Broncano M.J., Rodrigo A., Retana J. (2008) Post-dispersal seed predation in Pinus halepensis and consequences on seedling establishment after fire. International Journal of Wildland Fire. 17: 407-414.LinkDoi: 10.1071/WF07095
In the present study, we analyse the spatiotemporal patterns of seed predation and the consequences of this predation in the establishment of new Pinus halepensis individuals. Rodents were the main predators of P. halepensis seeds in burned areas, while predation by ants was considerably lower. Concerning spatiotemporal patterns of seed predation, the results obtained indicate that, although there were some small differences among distances or among seasons, removal of P. halepensis seeds was consistently very high in all situations, whether close to or far from the unburned margins, in pine or mixed forests, in different sites and in all sampling periods throughout the year. We analysed the role of seed predation on the modulation of post-fire regeneration of P. halepensis. Just after fire, no differences in seedling density were found between plots with or without rodent exclusion, probably owing to the high density of seeds on the ground and the low density of rodents affected by fire. One year after fire, when rodent populations had recovered in burned areas and seeds were much less abundant, the combination of addition of seeds and rodent exclusion led to an increase in pine seedling establishment. © IAWF 2008.
Pausas J.G., Llovet J., Rodrigo A., Vallejo R. (2008) Are wildfires a disaster in the Mediterranean basin? A review. International Journal of Wildland Fire. 17: 713-723.LinkDoi: 10.1071/WF07151
Evolutionary and paleoecological studies suggest that fires are natural in the Mediterranean basin. However, the important increase in the number of fires and area burned during the 20th century has created the perception that fires are disasters. In the present paper, we review to what extent fires are generating ecological disasters in the Mediterranean basin, in view of current fire regimes and the long-term human pressure on the landscapes. Specifically, we review studies on post-fire plant regeneration and soil losses. The review suggests that although many Mediterranean ecosystems are highly resilient to fire (shrublands and oak forest), some are fire-sensitive (e.g. pine woodlands). Observed erosion rates are, in some cases, relatively high, especially in high fire severity conditions. The sensitive ecosystems (in the sense of showing strong post-fire vegetation changes and soil losses) are mostly of human origin (e.g. extensive pine plantations in old fields). Thus, although many Mediterranean basin plants have traits to cope with fire, a large number of the ecosystems currently found in this region are strongly altered, and may suffer disasters. Post-fire disasters are not the rule, but they may be important under conditions of previous human disturbances. © IAWF 2008.
Rodrigo A., Sardà-Palomera F., Bosch J., Retana J. (2008) Changes of dominant ground beetles in black pine forests with fire severity and successional age. Ecoscience. 15: 442-452.LinkDoi: 10.2980/15-4-3117
This study analyzes the effect of fire on the composition and abundance of ground beetles in Pinus nigra forests. We used pitfall traps to sample beetles in burned P. nigra forests in Catalonia (Spain). Since fire dramatically alters forest structure and composition and beetles follow vegetation changes, we expected drastic changes in beetle composition and abundance immediately after fire. Because P. nigra forests do not recover after fire, we also expected beetles in burned and unburned areas to differ along a chronosequence. Beetle abundance per plot increased in canopy-fire-burned areas, but per plot species richness, diversity, and dominance were not affected by fire. Species composition varied depending on fire intensity. Some species were associated with canopy fire and low vegetation cover. Other species were associated with shrub cover and time since fire. Finally, some species were not dependent on fire or vegetation cover. Beetle abundance in burned areas was independent of time since fire. This lack of medium-term convergence between burned and unburned P. nigra forests agrees with our second hypothesis. Given the increase in fire frequency and size in submediterranean areas and the observed slow recovery of beetle species, a decline in beetle diversity at a regional scale is expected.
Rodrigo A (2007) Incendis forestals: com es recupera la vida animal? UAB Divulga 02:2007 (http://www.uab.es/uabdivulga).
Arnan X., Rodrigo A., Retana J. (2007) Post-fire regeneration of Mediterranean plant communities at a regional scale is dependent on vegetation type and dryness. Journal of Vegetation Science. 18: 111-122.LinkDoi: 10.1658/1100-9233(2007)18[111:PROMPC]2.0.CO;2
Question: We tested whether (1) the change in composition and structure of whole plant communities after fire is directly related to regeneration of the dominant tree species in the canopy; (2) the change in structure and composition of plant communities several years after fire decreases with the proportion of obligate seeders and (3) the proportion of obligate seeders in plant communities increases with the dryness gradient. Location: Catalonia (NE Spain). Methods: We measured floristic differences between burned and long-since burned sites in eight vegetation types across a climate gradient. We compared 22 sites burnt in 1994 in paired plots with 22 sites that had not been burnt since the 1940s. In each site we placed plots in burned and long-since burned areas, where we identified the presence and abundance of all plant species. Results: When the tree canopy recovers, structure and composition of the vegetation also return to the long-since burned community; when tree canopy does not recover, composition of the post-fire community varies compared to the long-since burned one. A higher proportion of obligate seeders in the pre-fire community promotes quicker regeneration of the original community. The proportion of obligate seeders increased along the dryness gradient. Conclusions: Regeneration of plant communities after fire depends on the vegetation type before the fire. Regeneration increases when the dominant tree or shrub species persists after fire and with a higher proportion of obligate seeders in the pre-fire community. The proportion of obligate seeders varies along the dryness gradient, which suggests that vegetation in drier areas (when seeders are more abundant) recovers earlier than in moister areas. © IAVS; Opulus Press.
Arnan X., Rodrigo A., Retana J. (2007) Uncoupling the effects of shade and food resources of vegetation on Mediterranean ants: An experimental approach at the community level. Ecography. 30: 161-172.LinkDoi: 10.1111/j.2006.0906-7590.04796.x
Vegetation is one of the main factors affecting the composition and structure of ant communities. The effect of vegetation is both by offering food resources and by modifying the proportion of ground cover exposed to shade conditions. However, it is difficult in field studies to uncouple the effects of food resources and shade on animal communities. The goal of this study was to analyze experimentally the effects of vegetation through food and shade supply on the structure and composition of a Mediterranean ant community. We have crossed these two factors in a factorial design where we have eliminated vegetation in experimental treatments and we have simulated the effects of vegetation by manipulating separately the supply of food resources and shade. The expected decrease in ant abundance and richness in plots without food resources but with shade was only partially confirmed by the results, because there was a decrease in the number of ant species but not a significant decrease in overall ant abundance in plots without food resources. We did not confirm the second hypothesis that the decrease in shade while maintaining food resources resulted in an increase of heat-tolerant, subordinate species and, consequently, ant richness. Species composition differed in the different experimental treatments. Stress-tolerant species were abundant in areas without shade and without food resources. Heat-tolerant species were mainly present in plots without shade but with food resources. Finally, species with high requirements of shade and/or food resources were associated to control plots with both shade and food resources from vegetation. Overall, this study provides an experiment that uncouples experimentally shade and food resources and dissects their effects on the whole ant community, and shows that the effects of the two factors are independent and affect different components of ant community structure and composition. Copyright © Ecography 2007.
Quevedo L., Rodrigo A., Espelta J.M. (2007) Post-fire resprouting ability of 15 non-dominant shrub and tree species in Mediterranean areas of NE Spain. Annals of Forest Science. 64: 883-890.LinkDoi: 10.1051/forest:2007070
Post-fire resprouting ability of the non-dominant tree and shrub species of the Mediterranean Basin has not yet been experimentally tested, although this group contributes to maintain the richness of Mediterranean plant communities. In this study, we have analyzed the post-fire recovery ability of 15 woody species that occur in relatively low abundance in dry and sub humid Mediterranean areas in NE of Spain. The main goals have been: (i) to determine experimentally the post-fire resprouting ability of these species and (ii) to compare the abundance of these species in areas affected by wildland fires and in unburned areas. We have observed a high resprouting ability after prescribed burning of most species except for Juniperus communis and J. phoenicea which showed a null resprouting. As the species with high resprouting ability showed similar presence in burned and unburned areas, we can conclude that wildfires are not a factor that constrains the presence of these species in Mediterranean woodlands. However, we found a reduction in the abundance of J. communis and J. phoenicea at the regional level after wildland fires. © INRA, EDP Sciences, 2007.
Rodrigo A., Quintana V., Retana J. (2007) Fire reduces Pinus pinea distribution in the northeastern Iberian Peninsula. Ecoscience. 14: 23-30.LinkDoi: 10.2980/1195-6860(2007)14[23:FRPPDI]2.0.CO;2
This study analyzes the recovery of Pinus pinea in forested areas that have burned in the last 30 years. The main objectives of the study were (i) to analyze the success of the regeneration of P. pinea in areas with the presence or absence of surviving adult trees and (ii) to investigate whether or not the post-fire response of P. pinea may affect its present distribution. We analyzed the survival of adult P. pinea trees and the regeneration of P. pinea seedlings in 8 areas burned by wildfires in Catalonia (northeast Spain) between 1979 and 2001. This study shows that the inability of seedlings to establish after fire, together with the short seed dispersal distance of this species and the low level of seedling survival, renders the natural regeneration of P. pinea in burned areas difficult. A comparison of the presence of P. pinea in plots located in burned and unburned areas throughout its distribution area in Catalonia indicates that its presence at the regional level is clearly reduced after fire. Moreover, in the areas where it persists, tree density and cover are smaller than in unburned areas. This decrease of P. pinea forests is exacerbated by the increase in surface area burned by forest fires during recent decades in the Mediterranean basin and by decreasing profits associated with this species as a consequence of the falling value of its pine kernel.
Arnan X., Rodrigo A., Retana J. (2006) Post-fire recovery of Mediterranean ground ant communities follows vegetation and dryness gradients. Journal of Biogeography. 33: 1246-1258.LinkDoi: 10.1111/j.1365-2699.2006.01506.x
Aim: In the Mediterranean Basin, the main forest communities vary in their ability to recover after fire. In this study we analyse the effects of fire on ant communities occurring in various vegetation types distributed along a geographical gradient in the western Mediterranean region. Location: The study was carried out in burned and unburned habitats of 22 sites corresponding to eight vegetation types distributed along a gradient of dryness throughout Catalonia (north-east Spain). Methods: We placed five pairs of plots (one plot located in the burned area and the second one placed in the unburned margin) per site. We compared ant communities in these unburned and burned plot types 8 years after fire using pitfall traps. Traps were set out in mid-May and mid-July. We analysed the structure and composition of ant communities in the burned and unburned areas of these vegetation types using anova tests, correspondence analysis (CA) and linear regression. Results: The resilience of ant communities varies with vegetation type. Ant communities in forests with high resilience also recover rapidly after fire, while those in forests that do not recover after fire show the lowest resilience. Species richness does not depend on burning or vegetation type. The resilience of these Mediterranean ant communities to fire is related to the environmental characteristics of the region where they live. Accordingly, differences between burned and unburned habitats are smaller for ant communities in areas with higher water deficit in summer than for those in moister ones. Main conclusions: The structure and composition of ant communities after fire depends on the level of direct mortality caused by the fire. It affects ant species differently, as determined by the habitats used for nesting and foraging. The reestablishment of vegetation cover depends on forest composition before the fire. As vegetation cover determines resource and microhabitat availability and competitive relationships among species, forest composition before the fire also affects post-fire recovery of ant communities to the medium-term. Finally, ant communities living in drier areas recover more quickly after fire than those living in moister ones. This pattern might be because in areas with higher water deficit there are more species characteristic of open environments, which are habitats similar to those generated after fire. © 2006 The Authors.
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