Microhabitat heterogeneity promotes soil fertility and ground-dwelling arthropod diversity in Mediterranean wood-pastures

P. 192-201Mediterranean wood-pastures are extensive agroforestry systems that hold great ecological, social and cultural values, which consist of mixtures of grassland, scattered trees and shrubs, primarily used for livestock grazing. For centuries, low-intensity management in these landscapes has resulted in multiple microhabitats that favour biodiversity and are considered key elements for the long-term persistence of wood-pastures. However, the relative contribution of each microhabitat type to wood-pasture biodiversity and functioning remains poorly studied. We investigated the impact that different wood-pasture microhabitats have on soil chemical fertility and the decomposition food web. We analysed the two main microhabitats that make wood-pastures up – open grasslands and isolated trees – and three additional “litter-trapping” microhabitats – shrubs scattered in the grassland matrix, canopied shrubs and piles of pruning debris—in terms of soil chemical properties (organic matter content, total N, C:N ratio, available P, and exchangeable base cations), collembolan and dipteran (mostly detritivores) abundance, and carabid (seed-eaters and predators) and staphylinid (mostly predators) beetle abundance, body size, biomass, species richness and composition. Grasslands were the most different microhabitats, with the lowest soil nutrient content and particular carabid and staphylinid species composition. Trees had the highest soil fertility levels and abundance of Diptera and staphylinids, and held unique staphylinid assemblages. “Litter-trapping” microhabitats had medium to high soil nutrient values and shared a distinct staphylinid assemblage compared to grasslands and trees. Besides, scattered shrubs provided shelter for large-sized carabid and staphylinid predators, while canopied shrubs held the highest carabid abundance and biomass. “Litter-trapping” microhabitats retained tree leaves that would otherwise be lost to the wood-pasture, recovering nutrients to the system, and provided new habitat, shelter and food for detritivores and unique predator assemblages. “Litter-trapping” microhabitats thus enhanced soil fertility and the decomposition process, at the same time as increased the abundance and diversity of the communities of ground-dwelling detritivores and predators inhabiting wood-pastures. These findings confirmed that microhabitat heterogeneity resulting from low-intensity management is essential to maintain both the primary production and the biodiversity conservation value of wood-pastures.S

Integrating life stages into ecological niche models: a case study on tiger beetles

[EN] Detailed understanding of a species’ natural history and environmental needs across spatial scales is a primary requisite for effective conservation planning, particularly for species with complex life cycles in which different life stages occupy different niches and respond to the environment at different scales. However, niche models applied to conservation often neglect early life stages and are mostly performed at broad spatial scales. Using the endangered heath tiger beetle (Cicindela sylvatica) as a model species, we relate presence/absence and abundance data of locally dispersing adults and sedentary larvae to abiotic and biotic variables measured in a multiscale approach within the geographic extent relevant to active conservation management. At the scale of hundreds of meters, fine-grained abiotic conditions (i.e., vegetation structure) are fundamental determinants of the occurrence of both life stages, whereas the effect of biotic factors is mostly contained in the abiotic signature. The combination of dense heath vegetation and bare ground areas is thus the first requirement for the species’ preservation, provided that accessibility to the suitable habitat is ensured. At a smaller scale (centimetres), the influence of abiotic factors on larval occurrence becomes negligible, suggesting the existence of important additional variables acting within larval proximity. Sustained significant correlations between neighbouring larvae in the models provide an indication of the potential impact of neighbourhood crowding on the larval niche within a few centimetres. Since the species spends the majority of its life cycle in the larval stage, it is essential to consider the hierarchical abiotic and biotic processes affecting the larvae when designing practical conservation guidelines for the species. This underlines the necessity for a more critical evaluation of the consequences of disregarding niche variation between life stages when estimating niches and addressing effective conservation measures for species with complex life cyclesSIAT is funded by Ministerio de Educación, Cultura y Deporte, Spain (Postdoctoral Fellowship EX2009-0989

Carabid beetle occurrence at the edges of oak and beech forests in NW Spain

[EN] We examined the occurrence of carabid beetles (Coleoptera, Carabidae) at the edges of oak (Quercus pyrenaica) and beech (Fagus sylvatica) forests in León, NW Spain. Pitfall traps were used to collect beetles from April to October 2002, and leaf litter cover and depth were measured. Traps were placed at three distances (0, 50 and 100 m) from the edges of eight forest patches. A total of 5436 carabids belonging to 43 species were collected. We found no statistically significant edge effect at the carabid assemblage level, i.e. the number of species and individuals was not higher at the edge compared to the forest interior. However, individual species were affected by distance from the edge. Five of the 14 species analysed responded predictably to the edge, three of them statistically significantly so. Four species did not respond in the predicted direction, two of them statistically significantly so. We found a considerable difference between forest types in terms of carabid assemblage composition and response to the edge. Oak forests were species richer and beech forests had a higher number of individuals. These differences were probably due to small-scale habitat heterogeneity in the oak forest patches, caused by man, and the homogeneous structure of beech forests. Leaf litter appeared to be one possible factor influencing the distribution of some species from the interior to the edge of forestsSIThe study was supported by the Junta de Castilla y León (project 2003/25, reference LE031/03). A. Taboada was financed by the Universidad de León and the Junta de Castilla y Leó

Disruption of trophic interactions involving the heather beetle by atmospheric nitrogen deposition

P. 436-445Elevated nitrogen (N) deposition impacts the structure and functioning of heathland ecosystems across Europe. Calluna plants under high N-inputs are very sensitive to secondary stress factors, including defoliation attacks by the heather beetle. These attacks result in serious damage or death of Calluna, its rapid replacement by grasses, and the subsequent loss of heathland. We know very little about the mechanisms that control the populations and trigger outbreaks of the heather beetle, impeding proper management measures to mitigate the damage. We investigated the effects of N deposition on the relationships between the heather beetle, its host plant, and two arthropod predators at building (rejuvenated through fire) and mature heathlands. The study combines field manipulation experiments simulating a range of N deposition rates (0, 1, 2, 5 g N m−2 year−1 for 2 years, and 5.6 g N m−2 year−1 for 10 years), and food-choice laboratory experiments testing the preferences of adults and larvae of the heather beetle for N-treated Calluna plants, and the preferences of predators for larvae grown on plants with different N-content. The larvae of the heather beetle achieved the highest abundances after the long-term (10-year) addition of N at mature Calluna plots in the field. Contrary to the adults, the larvae foraged preferentially on the most N-rich Calluna shoots under laboratory conditions. Predators showed no aggregative numerical responses to the accumulation of heather beetle larvae at high N-input experimental plots. During the feeding trials, predators consumed a small number of larvae, both in total and per individual, and systematically avoided eating the larvae reared on high-N Calluna shoots. Our study showed that the most severe defoliation damage by the heather beetle is inflicted at the larval stage under prolonged availability of high-N inputs, and that arthropod predators might not act as effective regulators of the beetle's populations.S

Soil-plant relationship in Calluna heathlands after experimental burning and nitrogen fertilization, studies from NW Spain

[EN] We studied changes in the relationship between soil nutrient content and plant species richness in Calluna heathlands after seven years of experimental burning (B) and nitrogen fertilization (NF). Our results indicate that both the treatments (B, NF, B+NF) and modification of several soil characteristics (total N, available Na, and C:N ratio) reflected in a significant increase in plant species richnessS

Provenance and seed mass determine seed tolerance 5 to high temperatures associated to forest fires in Pinus pinaster

P. 381-391We show that Pinus pinaster provenance affects both seed germination and seedling recruitment after fire. This information is crucial for managers to select the best seed-provisioning populations when implementing reforestation programs to assist the natural post-fire regeneration of the speciesS

Large wildfires alter the potential capacity of fire-prone Mediterranean pine forests to provide wild edible mushrooms over the long term

[EN] Projected trends of intensified wildfires due to climate warming and fuel-load accumulation are expected to significantly alter fungal diversity, but we know little about how these changes will impact ecosystem services. We aimed to analyze how large wildfires alter the capacity of fire-prone Mediterranean ecosystems dominated by Pinus pinaster Ait. to deliver the provisioning ecosystem service of mushroom production throughout the post-fire succession. We assessed this at early (20 years) stages after fire, compared to an unburned forest. Our results evidenced that large wildfires significantly reduced the capacity of these forests to provide mushroom harvesting opportunities. This adverse effect was most pronounced in the first few years after wildfire but persisted even after 20 years of post-fire succession. The total fungal species richness, abundance, diversity, and productivity at the post-fire successional stages remained lower than in the unburned forest, failing to reach their pre-fire levels even after two decades. However, the presence of commercially valuable edible fungal species, along with their species richness and productivity, began to recover in the medium and late stages after fire. In the immediate aftermath of the fire, saprotrophic fungal species dominated, while mycorrhizal species became more prevalent during the medium and late stages of secondary succession. Additionally, the abundance and productivity of mycorrhizal species in the late succession stage approached those found in the unburned forest. Soil pH and biochemical variables (microbial biomass C and β-glucosidase enzymatic activity) were key drivers of changes in species composition along the successional stages. This knowledge is essential to guide management solutions aimed at reducing ecosystem service loss and increasing resilience to the new scenario of extreme large wildfire events at shorter fire-free intervals, especially in southern EuropeSINext-Generation Funds of the European Union in the framework of the FIREMAP project (TED2021-130925B-I00), and by the Regional Government of Castile and Le´on, Spain in the framework of the IA-FIREXTCyL project (LE081P23) and the WUIFIRECYL project (LE005P20). Sara Turiel-Santos was supported by a predoctoral fellowship from the Department of Education by the Regional Government of Castilla y Le´on, Spain co-financed by the European Social Fund (EDU/601/2020

Materialidad pictórica. Estudio y percepción de la pintura tardogótica en la actualidad

Estudio con carácter científico e interdisciplinar de los estudios físicos, químicos y visuales de los aspectos materiales e históricos de las pinturas tardogóticas en Castilla, y su difusión a través de las redes sociales de forma visual y didáctica

Plant and vegetation functional responses to cumulative high nitrogen deposition in rear-edge heathlands

P. 980-990Elevated atmospheric nitrogen (N) deposition is a major driver of change, altering the structure/functioning of nutrient-poor Calluna vulgaris-heathlands over Europe. These effects amply proven for north-western/central heathlands may, however, vary across the ecosystem's distribution, especially at the range limits, as heathlands are highly vulnerable to land-use changes combined with present climate change. This is an often overlooked and greatly understudied aspect of the ecology of heathlands facing global change. We investigated the effects of five N-fertilisation treatments simulating a range of N deposition rates (0, 10, 20, and 50 kg N ha−1 yr−1 for 1 year; and 56 kg N ha−1 yr−1 for 9 years) on the Calluna-plants, the plant functional groups, species composition and richness of two life-cycle stages (building/young- and mature-phase) of Calluna-heathlands at their rear-edge limit. Our findings revealed a dose-related response of the shoot length and number of flowers of young and mature Calluna-plants to the addition of N, adhering to the findings from other heathland locations. However, cumulative high-N loading reduced the annual growth and flowering of young plants, showing early signs of N saturation. The different plant functional groups showed contrasting responses to the cumulative addition of N: annual/perennial forbs and annual graminoids increased with quite low values; perennial graminoids were rather abundant in young heathlands but only slightly augmented in mature ones; while bryophytes and lichens strongly declined at the two heathland life-cycle stages. Meanwhile there were no significant N-driven changes in plant species composition and richness. Our results demonstrated that Calluna-heathlands at their low-latitude distribution limit are moderately resistant to cumulative high-N loading. As north-western/central European heathlands under high-N inputs broadly experienced the loss of plant diversity and pronounced changes in plant species dominance, rear-edge locations may be of critical importance to unravel the mechanisms of heathland resilience to future global change.S

Interactions between large high-severity fires and salvage logging on a short return interval reduce the regrowth of fire-prone serotinous forests

P. 54-63New fire disturbance regimes under accelerating global environmental change can have unprecedented consequences for ecosystem resilience, lessening ecosystem natural regeneration. In the Mediterranean Basin, fire-dependent obligate seeder forests that are prone to increasingly frequent stand-replacing fires and then salvaged logged repeatedly can be vulnerable to additional disturbances for decades. In this study, we investigated, for the first time, the cumulative and interactive effects of two large high-severity fires at a short (<15-year) return interval and the subsequent burned timber harvesting with biomass removal on the post-disturbance recovery of such forests. We further assessed the type and amount of the material legacies (deadwood) that persisted through the different post-disturbance successional trajectories, as well as the influence of these legacies on forest regeneration. The early recovery of the studied forests after two consecutive large fires and post-fire logging was, in the first place, driven by fire repetition, which led to reduced seedling recruitment and enhanced regrowth of resprouter shrubs. Despite no interactive effects between fire and logging were detected after a single large fire event, two repeated fires followed by salvage harvesting had a greater negative impact than two fires alone (synergistic effects) on seedling establishment; while a lower positive impact (subadditive effects) on the recovery of resprouter shrubs. There was also an interaction modification effect in which fire repetition worsened the per-unit impact of salvage logging on forest regeneration. Nonetheless, the residual legacies, i.e., fine and coarse woody debris (unburned needles, downed branches, pieces of deadwood, and burned pine cones) that remained after the manual harvesting of the burned trees, aided seedling re-establishment and hindered the regrowth of the shrubby understorey. These findings indicate that high-intensity salvage logging after two large high-severity fires at a short return interval is inadvisable in fire-prone serotinous pine forests, unless it explicitly retains the key material legacies that help tree natural regeneration and enhance ecosystem resilience to the next disturbance.S