Biodivers Conserv (2009) 18:3153–3165 DOI 10.1007/s10531-009-9634-2 ORIGINAL PAPER
Recolonization of a burned Mediterranean area by terrestrial gastropods ` ngel Min˜o Xavier Santos Æ Vicenc¸ Bros Æ A
Received: 15 April 2008 / Accepted: 3 April 2009 / Published online: 24 April 2009 Ó Springer Science+Business Media B.V. 2009
Abstract Wildfires are common natural perturbations in Mediterranean ecosystems. Their frequency and extent have changed in recent decades to become one of the main ecological problems for wildlife. The response of fauna to wildfires depends greatly on the life histories and biological traits of each species. Terrestrial gastropods have limited mobility, and their presence is restricted by the vegetal and abiotic characteristics of habitats. For this reason, they are expected to have a low ability to recolonize burned areas. We have explored their survivorship and recolonization patterns according to the crypticrefuge and fire-edge models in a Mediterranean protected area affected by a large fire in August 2003. The low number of species recorded at burned sites demonstrates the negative effects of a wildfire on the richness of gastropod assemblages 4 years after the perturbation. However, the total number of living individuals did not vary between burned and unburned areas, suggesting an after-fire shift in dominant species from woodland to open-space species. Forest species with wide European distributions dominated in unburned sites, whereas open-space species and xerophytic Mediterranean species were present at burned sites. These differences were evident even at the burned sites closest to the unburned forest, suggesting low recolonization rates from the fire edge. By contrast, the abundance of xerophilous species as well as isolated records of mesophilous species in the burned areas suggests the survival of small populations and further recuperation after fire following the cryptic-refuge model. Keywords Wildfires
Biodiversity Burned areas Land snails Recolonization
` . Min˜o X. Santos V. Bros A Parc Natural de Sant Llorenc¸ del Munt i l’Obac, Oficina Te`cnica de Parcs Naturals, Diputacio´ de Barcelona, c/Urgell 187, Edif. Rellotge 3a, 08036 Barcelona, Spain X. Santos (&) Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain e-mail:
[email protected]
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Introduction The Mediterranean Basin is one of the world’s biodiversity hotspots (Myers et al. 2000). Human activities have had an impact on the natural environment since the Neolithic (Bottema et al. 1990), leading to the current Critical/Endangered conservation status of the ‘‘Mediterranean Shrubs’’ ecoregion due mostly to extensive habitat loss, fragmentation, and degradation (Olson et al. 2001). Wildfires are common natural perturbations in Mediterranean ecosystems (Moreno and Oechel 1994; Rundel 1998; Trabaud and Prodon 2002; Lloret 2004), although interactions between human activities and wildfires have increased in number and extent resulting in a political, economic, and environmental problem: each year in the Mediterranean basin, more than 50,000 fires burn between 600,000 and 800,000 ha (Lo´pez-Ornat and Correas 2003). Wildfires impact natural animal communities by causing direct mortality during fire, but mainly by changes in post-fire habitat structure (Whelan 1995; Lyon et al. 2000). Animal responses to fire vary greatly depending on life histories and ecological strategies, with limited mobility being one of the traits that increases vulnerability to fire (Whelan 1995). Terrestrial gastropod communities are an appropriate group in which to evaluate postfire response, as they live on vegetation and litter, have low mobility, and are keenly sensitive to changes in vegetation structure due to their dependence on moisture (Cook 2001). For this reason, we expect low survivorship and recolonization rates after fire. The few studies that have assessed the impact of wildfires on terrestrial gastropods have drawn diverse conclusions, perhaps due to differences in heterogeneity and complexity of habitats: Nekola (2002) and Severs (2005) reported that land-snail communities from American grasslands underwent sharp reductions in prey richness after fire, whereas Kiss and Magnin (2003, 2006) indicated that Mediterranean land-snail communities were particularly resilient to fire on a short-term basis. In the latter region, Kiss et al. (2004) observed that in areas where the fire regime has been maintained over decades or centuries, land snail communities appear to be highly modified and composed mainly of Mediterranean and xerophilous species. Kiss and Magnin (2003, 2006) suggested that the quick recovery of the gastropod communities in low fire regimes is in part influenced by the presence of cryptic refuges that allow initial high land-snail survival. However, at least in some snail species, active dispersal is not as limited as previously thought (Aubry et al. 2006). Hence, we expect that some snail species can recolonize burned areas from the nearby unburned areas. We have explored this hypothesis in burned edges of a Mediterranean protected area in the north-eastern Iberian Peninsula where 4,500 ha burned in August 2003. The aims of this study were to assess differences in a Mediterranean terrestrial snail community between unburned and burned areas, to detect the short-term response of this community to fire, and to analyse whether snail recolonization in burned areas follows the fire-edge or the cryptic-refuge models.
Materials and methods Study site and gastropod sampling The study site is located in St Llorenc¸ del Munt i l’Obac Natural Park, Barcelona province, NE Spain (Fig. 1a). This is a 14,000 ha protected area characterized by a conglomerate landscape with Holm oak forest and Mediterranean shrubs, partially replaced by forest pines in peripheral areas of the park. The natural park has a long history of wildfires, with
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Fig. 1 Location of the study area: a situation in the western Mediterranean; b limits of the Sant Llorenc¸ Natural Park (dashed line) and surface area of the wildfire in August 2003 (grey colour); c sampling design of the three transects (black lines) and the six sampling sites at each transect: site 1 in the unburned area, site 2 in the fire edge and sites 3–6 in the burned area
667 fires recorded between 1965 and 2003. Most fires were quickly extinguished, although in 1985 and 1986 two big fires burned 1,892 and 593 ha, respectively, inside the park perimeter. The latest important fire in the park occurred in August 2003 when 4,443 ha on the eastern border of the park burned, with 1,778 ha of this lying inside the park (Fig 1b). The study area is located on the edge of this burned area in a pine forest not previously burned. Pines are part of the natural regeneration begun 100 years ago. By the beginning of the 20th century, the landscape was dominated by vineyards, and after the devastating Phylloxera plague in this area, the fields were abandoned and naturally replaced by a pine forest. The sampling area was never burned prior to 2003. Sampling of terrestrial gastropods was performed in three replicate transects in June and July 2007. The three transects were randomly selected on the fire edge, in an area with low slope, orientated towards the southeast, and with similar vegetation prior to the fire with dominance of pines and some Holm oaks, hence making the unburned areas reliable control sites. On each transect, we searched for snails at 6 sampling sites, each 100 m apart. The first site of each transect was in an unburned mixed forest with pines and Holm oaks. The second site was at the edge of the burned area. The other four sites in each transect were in the burned area, with each site 100 m farther from the forest (Fig. 1c). At the 18 sampling sites, snails were searched for by two complementary methods: (1) all snails over 5 mm were searched for visually for a period of 30 min in a 10 9 10 m area; (2) snails smaller than 5 mm were collected from four 25 9 25 cm square subsamples of litter and the top 5 cm of soil. The four subsamples were randomly located within the large 10 9 10 square. The subsamples were examined in the laboratory with a
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microscope to count and identify small snails. Specimens were identified to the species level following the nomenclature of Falkner et al. (2002) and Alba et al. (2004). Only fresh shells and living individuals were recorded as representative of current communities. However, we also recorded dead shells when no living specimens were detected for a species. We considered shells as fresh (recently dead) if the periostracum was present and coloured as in the living animal. Other shells were also considered as recently dead depending on their state of preservation in relation to their size and the microhabitat in which they were found, as shell size and direct radiation affect shell degradation in the Mediterranean climate (Me´nez 2002). The combination of living (including recently dead) and dead species at each site reflects the species composition in burned areas prior to the fire. We characterized cover structure of the sampling sites by recording several vegetation and ground-cover variables. Vegetation variables included abundance of several shrub and tree species, as well as extent of grass. Ground-cover variables included abundance of nonvegetation materials such as stones, bare ground, trunks and fallen branches on the ground. At the centre of each sampling site, we recorded vegetation and ground-cover variables at points 50 cm apart along five parallel 10 m transects; thus, we recorded 100 points that characterized the abundance of vegetation and ground-cover types at each site. Statistical analysis We compared cover structure among sampling sites by computing the similarity (Euclidean distance) between pairs of sites from the raw data matrix. From the Euclidean distance matrix of similarities, we performed a multidimensional scaling (MDS) ordination that assumes no shape between variables. We then correlated the two-dimensional configuration scores of the 18 sites and each of the ground-cover variables in order to ascertain which of those variables significantly related to the ordination. The gastropod assemblages were compared among sampling sites following the same statistical procedure. Gastropod species were classified into three categories according to their relative abundance in burned and unburned areas: species only found in burned areas, species only found in unburned areas, and species found in both. We performed a multiple-correspondence analysis (MCA) to assess the association between these three categories and microhabitat, macrohabitat, and the distribution pattern of each species.
Results Vegetation and ground cover The MDS ordination plot of the 18 sites based on the ground-cover variables differentiated the burned sampling sites (numbered 3–6, Fig. 2a) from the unburned (1) and the fire-edge sites (2). The stress value of the MDS ordination was low (0.03). This result clearly shows that 4 years after the fire, unburned and burned sites maintain substantial differences in ground cover and vegetation structure. We correlated scores of the first-dimensional configuration of sites and each of the ground-cover variables. After Bonferroni correction for multiple tests, extent of Holm oak (r = 0.99, P = 0.0001), litter (r = 0.99, P = 0.0001) and ivy (r = 0.84, P = 0.0001) were positively related to the first dimension of the MDS ordination, i.e. more abundant in unburned sites, whereas the extent of bare
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Fig. 2 Plot of MDS ordination of the 18 sampling sites according to ground cover (a) and gastropod species abundance (b). Points numbered 1–6 correspond to sites in the sampling design (see Fig. 1)
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ground (r = -0.68, P = 0.002) and dorycnium (r = -0.71, P = 0.001) were negatively related, i.e. more abundant in burned sites. Terrestrial gastropod assemblage and spatial patterns We recorded 25 species of terrestrial gastropods plus the dead shells of four more species (Table 2). The number of living species was higher in unburned than in burned areas (ANOVA F5,12 = 3.48, P = 0.04), whereas the number of species only found dead showed the opposite pattern (ANOVA F5,12 = 3.15, P = 0.05, Fig. 3a). Combining living and dead species, we found no statistical differences in the number of species at each site (ANOVA F5,12 = 0.38, P = 0.85, Fig. 3a). The total number of living gastropods showed no significant differences among sampling sites (ANOVA F5,12 = 0.94, P = 0.48, Fig. 3b). The MDS ordination plot of the 18 sites based on the living gastropod communities exhibited high variation on the first dimension (Fig. 2b). The communities from the control sites had the lowest values. The stress score of the MDS ordination was low (0.037). After Bonferroni correction for multiple tests, only the abundance of Xerocrassa montserratensis was positively related to the first dimension of the MDS ordination.
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Fig. 3 Mean ± 1 standard error of the total number of gastropod species (triangles), number of species found live (bold circles), and number of species found dead only (open circles) observed (a), and the total number of terrestrial snails recorded (b) in the six sampling sites. Sample sites numbered 1–6 correspond to sites shown in Fig. 1
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Some species occurred only in unburned areas (e.g. Euconulus fulvus, Helicigona lapicida, Paralaoma servilis, Pomatias elegans and Testacella haliotidea) whereas others were found only in burned areas (e.g. Xerocrassa species; see Table 2). The multiple correspondence analysis showed that the species found only in unburned areas have wide distributions, are associated with forest macrohabitats and with humus and fallen-leaf microhabitats (Fig. 4). In contrast, species found in burned areas had Mediterranean distributions, are in open-space macrohabitats and in shrub and herbaceous microhabitats (Fig. 4). Relationships between ground-cover variables and gastropod abundance Only the abundance of fallen branches was correlated to the total number of gastropods (Table 3). The number of living species was positively correlated to vegetation variables characteristic of forest habitats (number of pines and presence of fallen leaves) and negatively correlated to open-area variables [bare ground, stones and herbaceous vegetation; Table 3].
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Fig. 4 Biplot of the Multiple Correspondence analysis showing the association of microhabitat, macrohabitat and distribution categories (see Table 1) with the response of gastropod species to fire: found only at unburned sites (U), found only at burned sites (B) and species found at both unburned and burned sites (A). This classification is based on numbers of Table 2. The macrohabitat symbols are in capital letters, the microhabitat symbols in small letters, the distribution symbols in italics, and symbols of the three gastropod classes in bold and underlined
Discussion This study demonstrates the negative effects of a wildfire on the richness of a Mediterranean gastropod assemblage 4 years after the perturbation. Unburned areas had more species than burned ones. The shells of dead specimens recorded at burned sites indicate that, before the fire, the entire study area had a similar gastropod composition. Pre-burn vegetation, slope, orientation and soil were similar for all the samples. Unburned samples were therefore reliable controls. This study is based on a one-off unreplicated event, with three transects and 18 sites carefully selected to address the questions posed. While our results should be viewed with caution regarding general patterns, this descriptive case study is valuable for improving our general knowledge of the after-fire recolonization dynamics by fauna of limited mobility in Mediterranean ecosystems. Despite the species loss, the total number of individuals did not vary between burned and unburned areas, since fewer although abundant species were recorded at unburned sites. Surprisingly, the commonest species in burned areas (e.g. Xerocrassa sp.; Table 2) were scarce or not detected at unburned sites. This indicates that the wildfire facilitated a shift in favour of open-space species leading to a juxtaposition of two different assemblages in burned and unburned areas. We suspect that the dominant species in burned areas are in general restricted to small open spaces inside the forests. After fire, survival of some of these micropopulations plus an increase in their preferred habitat enhanced their recovery and expansion. The MCA analysis indicated that fire tends to reduce species that live in humus within the forests and have wide European distributions, whereas it promotes open-space species that live in herbaceous and shrub vegetation and have Mediterranean distributions. The negative impact of the wildfire on the gastropod community followed a similar pattern to that observed by Nekola (2002) in North American grasslands, where fire
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Table 1 Predominant macrohabitat and microhabitat, and geographic distribution patterns of terrestrial gastropods recorded in the study area at Sant Llorenc¸ del Munt i l’Obac Natural Park Macrohabitat
Microhabitat
Distribution
Abida polyodon
G
S
M
Acanthinula aculeata
F
H
W
Arion lusitanicus
G
H
E
Cepaea nemoralis
F
H
E
Cernuella virgata
OA
V
E
Clausilia rugosa
F
H
E
Cornu aspersum
G
V
E
Deroceras altimirai
G
H
M
Euconulus fulvus
F
H
W
Granaria braunii
G
S
M
Granopupa granum
OA
S
M
Helicigona lapicida
F
S
E
Jaminia quadridens (dead)
OA
S
E
Lauria cylindracea (dead)
F
S
E
Monacha cartusiana
OA
V
E
Otala punctata
OA
V
M
Oxychilus courquini
F
S
M
Oxychilus draparnaudi
G
H
E
Paralaoma servilis
F
H
W
Pomatias elegans
F
H
E
Pseudotachea splendida
OA
V
M
Pupilla triplicata (dead)
G
S
E
Rumina decollata (dead)
G
H
M
Testacella haliotidea
G
H
E
Vallonia costata
G
S
W
Vitrea sp.
F
H
W
Xerocrassa penchinati
OA
S
M
Xerocrassa montserratensis
OA
S
M
Xerosecta arigonis
OA
V
M
The macrohabitat categories follow the classification of Bros (2000) made in the same area: forests (F), open areas (OA), areas characterized by species occurring in both, i.e. generalists (G). Predominant microhabitat categories follow Bros (2004, 2006) and also new field observations: walls and stones (S), shrub and herbaceous vegetation (V) and humus, fallen leaves and dead trunks (H). The distribution patterns follow Altonaga et al. (1994) and Kerney and Cameron (1999): species with wide distribution (W), central and western European species (E) and Mediterranean species (M)
caused significant population reductions in 44% of the species, although turf-specialist snails underwent the severest reductions due to detritus removal. The increase of Mediterranean and open-space species in burned areas has been reported in other taxa (e.g. Prodon 1988; Athias-Binche et al. 1987; Herrando et al. 2003; Rugiero and Luiselli 2006; Ukmar et al. 2007). The factor that drives shifts in the gastropod assemblage and in epiedaphic fauna after fire in general is the vegetation structure (Stamol 1993; Magnin et al. 1995; Ondina and Mato 2001), as well as several associated abiotic factors such as
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Table 2 Numbers of terrestrial gastropods at the six sampling sites and the three replicate transects: forest (1), the fire edge (2) and burned areas, each site being 100 m away from the fire edge (3–6) Transect 1
Abida polyodon
Transect 2
1
2
3
4
5
6
3
2
1
D D D 2
Acanthinula aculeata
1
1
2
Transect 3
3
4
5
6
1
2
3
4
5
6
D D
D
D D 4
2
D
D
D
D
2
D D 1
D D
D
2
Arion lusitanicus Cepaea nemoralis
1 1
D D 1
D D 2
D 1
Cernuella virgata Clausilia rugosa
4
Cornu aspersum
D D
Deroceras altimirai
3
Euconulus fulvus
4
2
2 D D
Jaminia quadridens
D
D
2
D D
D
D
Lauria cylindracea
6
D
1
D
D
D
D
D
D
D D 1
D
D
D D
D
D
D
D
Monacha cartusiana
1
4
1
1
1
D D
1
Otala punctata Oxychilus courquini
1 4
Paralaoma servilis
D D D 1 1
2
1
D D D D D 2
Pseudotachea splendida
2
1 1
D 1 D
1
D D 1
2
D
D D
D D
Pupilla triplicata
3
D 1
2
D
D D 2
D
1
1
D
D
D
D
D
D
D
D
Rumina decollata
D
D
Testacella haliotidea
2
Vallonia costata
1 3
Xerocrassa montserratensis Xerosecta arigonis
5 4
1 D
Xerocrassa penchinati
D 1
10 D
Helicigona lapicida
Vitrea sp.
D 2
Granopupa granum
Pomatias elegans
3
2
Granaria braunii
Oxychilus draparnaudi
D
12 2
1 D
D 1
3
1
D
8
1
D 1 1
6
5
D D
3
8
7
19 1
1
3
4
2
1 D
D
5
5
D D D 28 26 11 10
‘‘D’’ indicates records of dead specimens at sampling sites where no living specimens or fresh shells were collected
reduced moisture (Cook 2001), greater radiation, and higher fluctuation in daily temperatures (Alcan˜iz et al. 1996), loss of edaphic nutrients (Andreu et al. 1996), and litter and detritus depth (Nekola 2002). Likewise, the selection of food items by gastropods (Speiser 2001) may also influence the marked differences in gastropod assemblages between burned and unburned areas. The finding of shells of several species in burned areas suggests that they died during the fire or from adverse post-fire conditions, as commonly reported in other wildlife studies (Whelan 1995; Monamy and Fox 2000). The dryness of the 2004–2007 post-fire period (mean annual rainfall from 2004 to 2007 was 597 mm, and mean annual rainfall in the 1940–2000 period was 750 mm) could have reduced the ability of gastropods to recolonize
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Table 3 Correlations between number of total terrestrial gastropods and number of living species recorded against abundance of different vegetation variables Number of gastropods
Number of living species -0.50 (P = 0.04)
Herbaceous species
-0.37 (ns)
Italian buckthorn Rhamnus alaternus
-0.04 (ns)
0.41 (ns)
Dorycnium Dorycnium pentaphyllum
-0.12 (ns)
-0.32 (ns)
Blackberry Rubus ulmifolius
-0.19 (ns)
-0.04 (ns)
Grey-leaved cistus Cistus albidus
-0.42 (ns)
-0.44 (ns)
Ivy Hedera helix Redoul Coriaria myrtifolia Rosemary Rosmarinus officinalis Holm oak Quercus ilex Pine trees Pinus sp.
0.36 (ns)
0.45 (ns)
-0.29 (ns)
-0.13 (ns)
0.18 (ns)
-0.18 (ns)
-0.16 (ns) 0.08 (ns)
Moss species
0.23 (ns)
Humus and fallen leaves
0.26 (ns)
0.41 (ns) 0.55 (P = 0.02) -0.14 (ns) 0.72 (P = 0.0008)
Bare ground
-0.44 (ns)
-0.49 (P = 0.04)
Stones
-0.09 (ns)
-0.48 (P = 0.04)
Fallen branches
0.54 (P = 0.02)
0.20 (ns)
Trunks
0.34 (ns)
0.18 (ns)
burned areas. Dryness severely affects the reproductive success of Mediterranean terrestrial gastropods (Arad and Avivi 1998). Two kinds of open-space species were favoured after fire: (1) Xerophilous and rupiculous species such as Xerocrassa penchinati, endemic to the north-eastern Iberian Peninsula and southern France (Clanzing and Bertrand 2000), and Xerocrassa montserratensis, endemic to the Prelitoral Catalan Chain (Bech 1990), both of which live in habitats with high solar radiation and hide under stones; (2) species of ruderal and anthropogenic habitats with high herbaceous and shrub vegetation, such as Cernuella virgata, a species widely distributed in Europe, and Xerosecta arigonis, widely distributed in the Iberian Peninsula (Kerney and Cameron 1999). These results mirror those of Kiss et al. (2004) in southern France, since these authors reported that during the first post-fire years, burned areas were occupied by the most xerophilous species due to the simplification of habitat structure. Terrestrial gastropods have low mobility, which reduces their capability to recolonize new burned areas. Aubry et al. (2006) demonstrated by capture-recapture methods that some species can move up to 42 m in 6 months. However, following large wildfires, which are increasing in Mediterranean habitats due to global climate change (Pin˜ol et al. 1998) and human forest management (Salvador et al. 1997; Lloret 2004), we expect the recolonization of burned areas by gastropods will be slow. Kiss and Magnin (2003, 2006) reported that gastropod assemblages recolonized burned areas in southern France at higher rates than would be expected based on their low mobility. They suggested the existence of cryptic refuges for gastropods within burned areas, which could act as sources to restore surrounding altered lands. Our study was done only 4 years after the fire, a short time for post-fire succession. Considering that the pine and Holm oak forest is the result of more than 50 years of ecological succession, we cannot assess the degree of resilience of the gastropod
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assemblages in the study area. However, the sampling design can evaluate whether the recolonization has followed a cryptic-refuge or forest-edge pattern. Unburned and burned areas, even those nearest the fire edge, had very different gastropod assemblages, suggesting very limited recolonization from the unburned forest 4 years after the fire. Rather than a recolonization from the unburned forest, the results found here suggest the survival and subsequent expansion inside the burned area, of open-ground species previously restricted to small open spaces within the forest. Some data support the existence of refuges within the burned area that were the source of population expansion: (1) several open-ground species (e.g. Granaria braunii, Granopupa granum, Pseudotachea splendida, Xerocrassa montserratensis, Otala punctata) were recorded, only in small numbers, at a restricted number of sampling sites inside the burned area, without connection with the edge, suggesting survival after the fire; (2) there are some mesophilous species (e.g. Cepaea nemoralis, Cornu aspersum, Oxychilus draparnaudi, Vitrea sp.) that were found in the unburned forest as well as at a few places in the burned area. The gastropod assemblages from the unburned forest are rather poor. This result could be due to the landscape history of this area, with severe perturbations due to changes in habitat use (e.g. agricultural activities). However, comparisons with assemblages of other nearby woodland areas indicate that species richness is similar. In Collserola Natural Park (20 km from the study site) Bros (2004) found 5 species per sample on average (n = 57 samples), and in Montserrat Natural Park (8 km from the study site), Bros (2006) found 7 species (n = 13 samples). This relative paucity in the three coastal Mediterranean parks is probably explained by some general but unknown ecological and climatic factors that make this area relatively poor in gastropod species. The fire edge was intermediate in vegetal structure (Fig. 2a) and gastropod species richness (Fig. 3a) between burned and unburned areas, although the total number of gastropods was low (Fig. 3b). Ecotonal habitats have high diversity in general (Odum 1971; Magura et al. 2001). For land snails, Ojea et al. (1987) and Chiba (2007) have reported that high biodiversity in ecotones is related to community overlap in these transitional areas, where faunas with different ecologies can meet at a single site. However, in our study, ecotonal fire edges are dominated by low canopy and low herbaceous cover, with this vegetal structure apparently being unsuitable for many gastropod species. Several studies have reported the importance of post-fire management in wildlife responses (e.g. Beschta et al. 2004; Rodrigo et al. 2004; Herrando et al. 2009). Due to their physiological constraints related to water loss, gastropods possess several characteristics that enhance maintenance of body water content and exhibit various behaviours for avoiding desiccating microhabitats (Cook 2001). The amount of ground water is strongly associated with degree of vegetation cover; thus, post-fire management plans related to vegetation cover can indirectly affect the composition of the mollusc fauna of Mediterranean habitats. Long-term studies are needed to quantify how different malacological communities can be managed according to post-fire criteria, for example by restoring pine forests (the most recent habitat before fire in the study area) or shrub and Holm oak forest (the autochthonous Mediterranean forest). Acknowledgments We thank the people of the Sant Llorenc¸ del Munt i l’Obac Natural Park for collaboration, and Adria` Fabrega, Mari Carmen Ga´miz, Elisabet Ros and Sandra Valentin for logistic support. Two reviewers made valuable suggestions to improve the quality of this work. Marcel Costa provided meteorological data from a station near the study area. Xavier Santos was supported by a Beatriu de Pino´s postdoctoral grant from the Government of Catalonia (BP-B1 10211).
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