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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 ...

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 ...

Co-occurrence of winter-deciduous and evergreen oaks is common in some Mediterranean-type climate areas. However, whether these species show an overlap in their regeneration niche is still poorly understood. We explored experimentally the changes in survival, growth, biomass partitioning, leaf nitrogen content, and water use efficiency (δ13C) in seedlings of a deciduous oak (Quercus cerrioides) and an evergreen oak (Quercus ilex) in response to co-variation in light and water availability. Quercus cerrioides exhibited higher root length, root area, leaf nitrogen content, and less negative δ13C, but lower leafiness than Q. ilex. The interaction between species and light in specific leaf area and root–shoot ratio indicated different mechanisms to overcome water stress in the two oaks, with Q. ilex relying on leaf hardening and Q. cerrioides relying on a high root–shoot ratio. However, the two species showed similar survival and growth in most of the light–water gradient. Ecological inference of the...

Pinus nigra subsp. salzmannii is a pine species that regenerates quite well under its own canopy but has difficulty regenerating after fire. This study analyzes, by means of greenhouse and field experiments, the pattern of seed germination and seedling establishment of P. nigra in a gradient of post-fire environmental conditions. The results obtained in the controlled conditions experiment of cover effects in the absence of vegetation interference indicate that seed germination and seedling survival and growth of P. nigra attained their maximum values under high cover levels. In the field, seed germination and seedling survival of P. nigra were considerably lower than in the experiment outdoors but also followed to a large extent the cover gradient. However, there were differences among microhabitats depending on the type of vegetation present. In general, the behaviour of P. nigra is more similar to that of shade-tolerant species, such as oaks, than to low-altitude Mediterranean pines, because the establishment of P. nigra seedlings is improved under high cover conditions. As these conditions are usually lacking in recently burned areas, the regeneration of this species is strongly limited after fire. The difficulty in recovering after fire of P. nigra forests confirms that they require specific conservation measures to prevent their disappearance in the short term.

Fire has favored pines throughout their natural range in environments subject to continuous disturbances, such as the Mediterranean Basin. However, recovery of pine species after large fires is not always successful. In this study, we analyze the post-fire regeneration pattern of Pinus halepensis, P. nigra and P. sylvestris three years after fire, in an area affected by a large wildfire in 1994. Moreover, we develop a model of succession to predict medium-term changes in forest composition 30 years after fire from the regeneration monitored during the first years after fire. The results show that, although the three pine species regenerate quite well in the absence of fire, their post-fire regeneration is very different: P. halepensis shows high seedling density after fire, but P. nigra and P. sylvestris almost disappear from burned plots. The model simulations of the future forest composition 30 years after fire indicate that 77-93% of plots dominated by these two pines change after fire to commu...

We investigated the temporal and spatial separation of the activity rhythms of ants in three Mediterranean habitats. The different abilities of ant species to tolerate thermal stress influenced the time of day and year during which they were active. Activity of ants followed environmental fluctuations both seasonally and daily. Two groups of ant species could be distinguished in the communities studied: i) heat-tolerant species that were diurnal and changed little in daily activity rhythms throughout the year; ii) heat-intolerant species that shifted activity rhythms from diurnal to crepuscular-nocturnal at higher temperatures, and had peak activity at temperatures lower than 30°C. The different environmental conditions of each site affected the activity of different ant species and, therefore, community organization. In the forest areas, canopy cover created a heterogeneous environment of sunny and shaded areas throughout the day. Heat-intolerant species benefited from this spatial heterogeneity by lengthening their period of activity on hot days in areas covered by vegetation. This decreased the abundance of heat-tolerant species. Instead, in dry and open environments such as grasslands, the lack of trees caused the daily range of temperature to be sufficient to meet the requirements both of heat-adapted and cold-adapted species. This results in an increased diversity and a reduction in the dominance of heat-intolerant species.