Happe A.-K., Alins G., Blüthgen N., Boreux V., Bosch J., García D., Hambäck P.A., Klein A.-M., Martínez-Sastre R., Miñarro M., Müller A.-K., Porcel M., Rodrigo A., Roquer-Beni L., Samnegård U., Tasin M., Mody K. (2019) Predatory arthropods in apple orchards across Europe: Responses to agricultural management, adjacent habitat, landscape composition and country. Agriculture, Ecosystems and Environment. 273: 141-150.LinkDoi: 10.1016/j.agee.2018.12.012
Local agri-environmental schemes, including hedgerows, flowering strips, organic management, and a landscape rich in semi-natural habitat patches, are assumed to enhance the presence of beneficial arthropods and their contribution to biological control in fruit crops. We studied the influence of local factors (orchard management and adjacent habitats) and of landscape composition on the abundance and community composition of predatory arthropods in apple orchards in three European countries. To elucidate how local and landscape factors influence natural enemy effectiveness in apple production systems, we calculated community energy use as a proxy for the communities’ predation potential based on biomass and metabolic rates of predatory arthropods. Predator communities were assessed by standardised beating samples taken from apple trees in 86 orchards in Germany, Spain and Sweden. Orchard management included integrated production (IP; i.e. the reduced and targeted application of synthetic agrochemicals), and organic management practices in all three countries. Predator communities differed between management types and countries. Several groups, including beetles (Coleoptera), predatory bugs (Heteroptera), flies (Diptera) and spiders (Araneae) benefited from organic management depending on country. Woody habitat and IP supported harvestmen (Opiliones). In both IP and organic orchards we detected aversive influences of a high-quality surrounding landscape on some predator groups: for example, high covers of woody habitat reduced earwig abundances in German orchards but enhanced their abundance in Sweden, and high natural plant species richness tended to reduce predatory bug abundance in Sweden and IP orchards in Spain. We conclude that predatory arthropod communities and influences of local and landscape factors are strongly shaped by orchard management, and that the influence of management differs between countries. Our results indicate that organic management improves the living conditions for effective predator communities. © 2018 Elsevier B.V.
Flo, V., Bosch, J., Arnan, X., Primante, C., Martín González, A.M., Barril-Graells, H., Rodrigo, A. (2018) Yearly fluctuations of flower landscape in a Mediterranean scrubland: Consequences for floral resource availability. PLoS ONE. 13: 0-0.LinkDoi: 10.1371/journal.pone.0191268
Doblas-Miranda, E., Alonso, R., Arnan, X., Bermejo, V., Brotons, L., de las Heras, J., Estiarte, M., Hódar, J.A., Llorens, P., Lloret, F., López-Serrano, F.R., Martínez-Vilalta, J., Moya, D., Peñuelas, J., Pino, J., Rodrigo, A., Roura-Pascual, N., Valladares, F., Vilà, M., Zamora, R., Retana, J. (2017) A review of the combination among global change factors in forests, shrublands and pastures of the Mediterranean Region: Beyond drought effects. Global and Planetary Change. 148: 42-54.LinkDoi: 10.1016/j.gloplacha.2016.11.012
Aguillaume L., Rodrigo A., Avila A. (2016) Long-term effects of changing atmospheric pollution on throughfall, bulk deposition and streamwaters in a Mediterranean forest. Science of the Total Environment. 544: 919-928.LinkDoi: 10.1016/j.scitotenv.2015.12.017
The abatement programs implanted in Europe to reduce SO2, NO2 and NH3 emissions are here evaluated by analyzing the relationships between emissions in Spain and neighboring countries and atmospheric deposition in a Mediterranean forest in the Montseny mountains (NE Spain) for the last 3decades. A canopy budget model was applied to throughfall data measured during a period of high emissions (1995-1996) and a period of lower emissions (2011-2013) to estimate the changes in dry deposition over this time span.Emissions of SO2 in Spain strongly decreased (77%) and that was reflected in reductions for nssSO4 2- in precipitation (65% for concentrations and 62% for SO4 2-S deposition). A lower decline was found for dry deposition (29%).Spanish NO2 emissions increased from 1980 to 1991, remained constant until 2005, and decreased thereafter, a pattern that was paralleled by NO3 - concentrations in bulk precipitation at Montseny. This pattern seems to be related to a higher share of renewable energies in electricity generation in Spain in recent years. However, dry deposition increased markedly between 1995 and 2012, from 1.3 to 6.7kgha-1year- 1. Differences in meteorology between periods may have had a role, since the recent period was drier thus probably favoring dry deposition.Spanish NH3 emissions increased by 13% between 1980 and 2012 in Spain but NH4 + concentrations in precipitation and NH4 +-N deposition showed a decreasing trend (15% reduction) at Montseny, probably linked to the reduction ammonium sulfate and nitrate aerosols to be scavenged by rainfall. NH4 +-N dry deposition was similar between the compared periods.The N load at Montseny (15-17kgha-1year-1) was within the critical load range proposed for Mediterranean sclerophyllous forests (15-17.5kgha-1year-1). The onset of N saturation is suggested by the observed increasing N export in streamwaters. © 2015 Elsevier B.V.
Hevia, V., Bosch, J., Azcárate, F.M., Fernández, E., Rodrigo, A., Barril-Graells, H., González, J.A. (2016) Bee diversity and abundance in a livestock drove road and its impact on pollination and seed set in adjacent sunflower fields. Agriculture, Ecosystems and Environment. 232: 336-344.LinkDoi: 10.1016/j.agee.2016.08.021
Osorio-Canadas, S., Arnan, X., Rodrigo, A., Torné-Noguera, A., Molowny, R., Bosch, J. (2016) Body size phenology in a regional bee fauna: A temporal extension of Bergmann's rule. Ecology Letters. : 0-0.LinkDoi: 10.1111/ele.12687
Quevedo L., Arnan X., Rodrigo A. (2015) Post-fire forestry management improves fruit weight and seed set in forest coppices dominated by Arbutus unedo L.. Forest Ecology and Management. 345: 65-72.LinkDoi: 10.1016/j.foreco.2015.02.030
In Mediterranean ecosystems, post-fire forestry management practices are often used to improve forest structure and to reduce the risk of fire in coppices of resprouting species. Such practices enhance tree growth (i.e., height), probably because they release resources. On the one hand, resource release may stimulate reproduction. On the other hand, tree species that are regenerating after a fire may already face a delay in reproduction, and this delay may be lengthened if species mainly invest these additional resources in growth. Within this theoretical framework, it is poorly understood how different forest management practices affect the reproductive abilities of forest species. In this study, we analyzed the effect of two post-fire forestry treatments (selective thinning of resprouts and selective thinning of resprouts plus understory clearing) on a Mediterranean coppice dominated by the resprouter species Arbutus unedo L.; in particular, we examined how the treatments affected this species' reproductive ability (flower and fruit production at the tree and stand level, as well as fruit characteristics). Our results show that the treatments had no effects on the number of flowers and mature fruits per individual. Meanwhile, mature fruit dry mass and seed set were greater in plots that had been both thinned and cleared than in control plots and plots that had only been thinned. This pattern was reversed for seed abortion rate: it was lower in plots that had been thinned and cleared. The dry mass of developed seeds did not differ among treatments. At the stand level, the percentage of strawberry trees that flowered, the percentage of strawberry trees that bore fruit, the dry biomass of mature fruits per hectare, and the number of developed seeds per hectare were not affected by these treatments. Other studies have shown that these two forest management practices can improve the vertical and horizontal structure of A. unedo coppices that are regenerating post fire; this study demonstrates that selective thinning does not modify the species' reproductive success and, such practice when combined with understory clearing might enhance it. Consequently, these forestry practices might ensure the natural regeneration of populations of this species, as well as the availability of food for local fauna. It is thus highly recommended that such practices be used to manage coppices dominated by resprouter species following fire, especially in situations where the growth of the forest canopy has stagnated and/or reproduction of forest species has been delayed. © 2015 Elsevier B.V.
Torné-Noguera A., Rodrigo A., Osorio S., Bosch J. (2015) Collateral effects of beekeeping: Impacts on pollen-nectar resources and wild bee communities. Basic and Applied Ecology. : 0-0.LinkDoi: 10.1016/j.baae.2015.11.004
Due to the contribution of honey bees (Apis mellifera) to wild flower and crop pollination, beekeeping has traditionally been considered a sustainable practice. However, high honey bee densities may have an impact on local pollen and nectar availability, which in turn may negatively affect other pollinators. This is exacerbated by the ability of honey bees to recruit foragers to highly rewarding flower patches. We measured floral resource consumption in rosemary (Rosmarinus officinalis) and thyme (Thymus vulgaris) in 21 plots located at different distances from apiaries in the scrubland of Garraf Natural Park (Barcelona), and related these measures to visitation rates of honey bees, bumblebees (Bombus terrestris) and other pollinators. In the same plots, we measured flower density, and used pan traps to characterize the wild bee community. Flower resource consumption was largely explained by honey bee visitation and marginally by bumblebee visitation. After accounting for flower density, plots close to apiaries had lower wild bee biomass. This was due to a lower abundance of large bee species, those more likely to be affected by honey bee competition. We conclude that honey bees are the main contributors to pollen/nectar consumption of the two main flowering plants in the scrubland, and that at the densities currently occurring in the park (3.5hives/km2) the wild bee community is being affected. Our study supports the hypothesis that high honey bee densities may have an impact on other pollinators via competition for flower resources. Wegen des Beitrages der Honigbiene (Apis mellifera) bei der Bestäubung von Wildblumen und Nutzpflanzen wurde die Bienenhaltung traditionell als eine nachhaltige Aktivität angesehen. Indessen können hohe Honigbienendichten Auswirkungen auf die lokale Verfügbarkeit von Nektar und Pollen haben, was wiederum andere Bestäuber negativ beeinflussen könnte. Dies wird verstärkt durch die Fähigkeit der Honigbiene, Sammlerinnen zu lohnenden Sammelstellen zu dirigieren. Im Buschland des Garraf-Naturparks bei Barcelona maßen wir den Verbrauch von Blütenressourcen an Rosmarin (Rosmarinus officinalis) und Thymian (Thymus vulgaris) an 21 Standorten, die unterschiedlich weit von Bienenständen entfernt lagen, und setzten diese Werte in Bezug zu den Besuchsraten von Honigbienen, Hummeln (Bombus terrestris) und sonstigen Bestäubern. An den gleichen Standorten bestimmten wir die Blütendichte und setzten Farbschalen ein, um die Wildbienengemeinschaft zu erfassen. Die Nutzung der Blüt enressou wurde weitgehend durch die Besuchsraten der Honigbiene erklärt und in geringfügigem Maße durch Hummelbesuch. Nach Berücksichtigung der Blütendichte wiesen Standorte in der Nähe von Bienenständen eine geringere Wildbienen-Biomasse auf. Dies war auf eine geringere Abundanz der großen Wildbienenarten zurückzuführen, also der Arten, die wahrscheinlich durch die Konkurrenz der Honigbiene beeinträchtigt werden. Wir schließen, dass Honigbienen den größten Beitrag zum Pollen- bzw. Nektarverbrauch bei den beiden wichtigsten Blütenpflanzen des Gebietes leisten und dass die Wildbienengemeinschaft bei den gegenwärtigen Honigbienendichten im Park (3.5 Völker/km2) beeinflusst wird. Unsere Untersuchung unterstützt die Hypothese, dass hohe Honigbienendichten durch Konkurrenz um Blütenressourcen einen Einfluss auf andere Bestäuber haben könnten. © 2015 Gesellschaft für Ökologie.
Arnan X., Escola A., Rodrigo A., Bosch J. (2014) Female reproductive success in gynodioecious Thymus vulgaris: Pollen versus nutrient limitation and pollinator foraging behaviour. Botanical Journal of the Linnean Society. 175: 395-408.LinkDoi: 10.1111/boj.12173
Gynodioecy is a dimorphic breeding system in which female individuals coexist with hermaphroditic individuals in the same population. Females only contribute to the next generation via ovules, and many studies have shown that they are usually less attractive than hermaphrodites to pollinators. Several mechanisms have been proposed to explain how females manage to persist in populations despite these disadvantages. The 'resource reallocation hypothesis' (RRH) states that females channel resources not invested in pollen production and floral advertisement towards the production of more and/or larger seeds. We investigated pollination patterns and tested the RRH in a population of Thymus vulgaris. We measured flower display, flower size, nectar production, visitation rates, pollinator constancy and flower lifespan in the two morphs. In addition, we measured experimentally the effects of pollen and resource addition on female reproductive success (fruit set, seed set, seed weight) of the two morphs. Despite lower investment in floral advertisement, female individuals were no less attractive to pollinators than hermaphrodites on a per flower basis. Other measures of pollinator behaviour (number of flowers visited per plant, morph preference and morph constancy) also showed that pollinators did not discriminate against female flowers. In addition, stigma receptivity was longer in female flowers. Accordingly, and contrary to most studies on gynodioecious species, reproductive success of females was not pollen limited. Instead, seed production was pollen limited in hermaphrodites, suggesting low levels of cross-pollination in hermaphrodites. Seed production was resource limited in hermaphrodites, but not in females, thus providing support for the RRH. © 2014 The Linnean Society of London.
Caut S., Jowers M.J., Arnan X., Pearce-Duvet J., Rodrigo A., Cerda X., Boulay R.R. (2014) The effects of fire on ant trophic assemblage and sex allocation. Ecology and Evolution. 4: 35-49.LinkDoi: 10.1002/ece3.714
Fire plays a key role in ecosystem dynamics worldwide, altering energy flows and species community structure and composition. However, the functional mechanisms underlying these effects are not well understood. Many ground-dwelling animal species can shelter themselves from exposure to heat and therefore rarely suffer direct mortality. However, fire-induced alterations to the environment may change a species' relative trophic level within a food web and its mode of foraging. We assessed how fire could affect ant resource utilization at different scales in a Mediterranean forest. First, we conducted isotopic analyses on entire ant species assemblages and their potential food resources, which included plants and other arthropods, in burned and unburned plots 1 year postfire. Second, we measured the production of males and females by nests of a fire-resilient species, Aphaenogaster gibbosa, and analyzed the differences in isotopic values among workers, males, and females to test whether fire constrained resource allocation. We found that, in spite of major modifications in biotic and abiotic conditions, fire had little impact on the relative trophic position of ant species. The studied assemblage was composed of species with a wide array of diets. They ranged from being mostly herbivorous to completely omnivorous, and a given species' trophic level was the same in burned and unburned plots. In A. gibbosa nests, sexuals had greater δ15N values than workers in both burned and unburned plots, which suggests that the former had a more protein-rich diet than the latter. Fire also appeared to have a major effect on A. gibbosa sex allocation: The proportion of nests that produced male brood was greater on burned zones, as was the mean number of males produced per nest with the same reproductive investment. Our results show that generalist ants with relatively broad diets maintained a constant trophic position, even following a major disturbance like fire. However, the dramatically reduced production of females on burned zones compared to unburned zones 1 year postfire may result in considerably reduced recruitment of new colonies in the mid to long term, which could yield genetic bottlenecks and founder effects. Our study paves the way for future functional analyses of fire-induced modifications in ant populations and communities. © 2013 The Authors.
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