Sept articles, publiés entre 2015 et 2018, exposent des résultats issus du projet smallFOREST :
* Habitat properties are key drivers of Borrelia burgdorferi s.l. prevalence in Ixodes ricinus populations of deciduous forest fragments.
Ehrmann, S., Ruyts, S.C., Scherer-Lorenzen, M., Brunet, J., Cousins, S.A.O., Deconchat, M., Decocq, G., Frenne, P.D., Smedt, P.D., Diekmann, M., Gallet-Moron, E., Gärtner, S., Hansen, K., Kolb, A., Lenoir, J., Lindgren, J., Naaf, T., Paal, T., Panning, M., Prinz, M., Valdés, A., Verheyen, K., Wulf, M., Liira, J.
Parasites & Vectors, 2018 , 11:23/ DOI :10.1186/s13071-017-2590-x
The tick Ixodes ricinus has considerable impact on the health of humans and other terrestrial animals because it transmits several tick-borne pathogens (TBPs) such as B. burgdorferi (sensu lato), which causes Lyme borreliosis (LB). Small forest patches of agricultural landscapes provide many ecosystem services and also the disservice of LB risk. Biotic interactions and environmental filtering shape tick host communities distinctively between specific regions of Europe, which makes evaluating the dilution effect hypothesis and its influence across various scales challenging. Latitude, macroclimate, landscape and habitat properties drive both hosts and ticks and are comparable metrics across Europe. Therefore, we instead assess these environmental drivers as indicators and determine their respective roles for the prevalence of B. burgdorferi in I. ricinus.
We sampled I. ricinus and measured environmental properties of macroclimate, landscape and habitat quality of forest patches in agricultural landscapes along a European macroclimatic gradient. We used linear mixed models to determine significant drivers and their relative importance for nymphal and adult B. burgdorferi prevalence. We suggest a new prevalence index, which is pool-size independent.
During summer months, our prevalence index varied between 0 and 0.4 per forest patch, indicating a low to moderate disservice. Habitat properties exerted a fourfold larger influence on B. burgdorferi prevalence than macroclimate and landscape properties combined. Increasingly available ecotone habitat of focal forest patches diluted and edge density at landscape scale amplified B. burgdorferi prevalence. Indicators of habitat attractiveness for tick hosts (food resources and shelter) were the most important predictors within habitat patches. More diverse and abundant macro- and microhabitat had a diluting effect, as it presumably diversifies the niches for tick-hosts and decreases the probability of contact between ticks and their hosts and hence the transmission likelihood.
Diluting effects of more diverse habitat patches would pose another reason to maintain or restore high biodiversity in forest patches of rural landscapes. We suggest classifying habitat patches by their regulating services as dilution and amplification habitat, which predominantly either decrease or increase B. burgdorferi prevalence at local and landscape scale and hence LB risk. Particular emphasis on promoting LB-diluting properties should be put on the management of those habitats that are frequently used by humans. In the light of these findings, climate change may be of little concern for LB risk at local scales, but this should be evaluated further.
*Desiccation resistance determines distribution of woodlice along forest edge-to-interior gradients.
Pallieter De Smedt, Lander Baeten, Matty P. Berg, Emilie Gallet-Moron, Jörg Brunet, Sara A. O. Cousins, Guillaume Decocq, Martin Diekmann,Brice Giffard, Pieter De Frenne, Martin Hermy, Dries Bonte and Kris Verheyen
European Journal of Soil Biology, Volume 85, 2018, 1-3/ DOI :10.1016/j.ejsobi.2017.12.002
Abstract :Forest edges show strong abiotic and biotic gradients potentially altering community composition and ecosystem processes such as nutrient cycling. While abiotic gradients are well studied, short-scale biotic gradients, like detritivore species composition and their associated trait distribution remains a poorly explored research-field. We sampled woodlicein 160 forest patches across Europe at varying distances from the forest edge and discovered that species desiccation resistance determines distribution along forest edge-to-interior gradients. Forest edges are warmer and dryer compared to interiors and favour drought-tolerant species, while abundance and activity of drought-sensitive species is reduced at the edge. Key ecological factors for litter-dwelling detritivores (i.e. humidity) act as environmental filter, because of species-specific differences in desiccation resistance. Future research should focus on quantifying the consequences of a changing detritivore community and their associated functional traits for nutrient cycling.
*Promoting biodiversity values of small forest patches in agricultural landscapes: Ecological drivers and social demand.
Varela E, Verheyen K, Valdés, A, Soliño, M, Jacobsen, J B, De Smedt, P, Ehrmann, S, Gaertner, S, Górriz, E, Decocq, G.
Science of the Total Environment 2018 ; 619-620 : 1319-1329./ DOI :10.1016/j.scitotenv.2017.11.190
Abstract :Small forest patches embedded in agricultural (and peri-urban) landscapes in Western Europe play a key role for biodiversity conservation with a recognized capacity of delivering a wide suite of ecosystem services. Measures aimed to preserve these patches should be both socially desirable and ecologically effective. This study presents a joint ecologic and economic assessment conducted on small forest patches in Flanders (Belgium) and Picardie (N France). In each study region, two contrasted types of agricultural landscapes were selected. Open field (OF) and Bocage (B) landscapes are distinguished by the intensity of their usage and higher connectivity in the B landscapes. The social demand for enhancing biodiversity and forest structure diversity as well as for increasing the forest area at the expenses of agricultural land is estimated through an economic valuation survey. These results are compared with the outcomes of an ecological survey where the influence of structural features of the forest patches on the associated herbaceous diversity is assessed. The ecological and economic surveys show contrasting results; increasing tree species richness is ecologically more important for herbaceous diversity in the patch, but both tree species richness and herbaceous diversity obtain insignificant willingness to pay estimates. Furthermore, although respondents prefer the proposed changes to take place in the region where they live, we find out that social preferences and ecological effectiveness do differ between landscapes that represent different intensities of land use. Dwellers where the landscape is perceived as more “degraded” attach more value to diversity enhancement, suggesting a prioritization of initiatives in these area. In contrast, the ecological analyses show that prioritizing the protection and enhancement of the relatively better-off areas is more ecologically effective. Our study calls for a balance between ecological effectiveness and welfare benefits, suggesting that cost effectiveness studies should consider these approaches jointly.
* Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe.
Pallieter De Smedt, Lander Baeten, Willem Proesmans, Matty P. Berg, Jörg Brunet, Sara A. O. Cousins, Guillaume Decocq, Marc Deconchat, Martin Diekmann, Emilie Gallet-Moron, Brice Giffard, Jaan Liira, Ludmilla Martin, Astra Ooms, Alicia Valdés, Monika Wulf, Martin Hermy, Dries Bonte, Kris Verheyen.
Landscape ecology, 2018/ DOI :10.1007/s10980-017-0607-7
Most of the agricultural landscape in Europe, and elsewhere, consists of mosaics with scattered fragments of semi-natural habitat like small forest fragments. Mutual interactions between forest fragments and agricultural areas influence ecosystem processes such as nutrient cycling, a process strongly mediated by the macrodetritivore community, which is however, poorly studied. We investigated macrodetritivore distribution patterns at local and landscape-level and used a key functional trait (desiccation resistance) to gain mechanistic insights of the putative drivers.
Macrodetritivores were sampled in forest edges-centres of 224 European forest fragments across 14 landscapes opposing in land use intensity. We used a multilevel analysis of variance to assess the relative contribution of different spatial scales in explaining activity-density and Shannon-diversity of woodlice and millipedes, together with a model-based analysis of the multivariate activity-density data testing the effect on species composition. Secondly, we tested if desiccation resistance of macrodetritivores varied across communities at different spatial scales using linear mixed effect models.
Forest edge-centre and landscape use intensity determined activity-density and community composition of macrodetritivores in forest fragments, while fragment characteristics like size and continuity were relatively unimportant. Forest edges and higher intensity landscapes supported higher activity-density of macrodetritivores and determined species composition. Forest edges sustained woodlouse communities dominated by more drought tolerant species.
Landscape use intensity and forest edges are main drivers in macrodetritivore distribution in forest fragments with desiccation resistance a good predictor of macrodetritivore distribution. Key functional traits can help us to predict changes in community structure in changing landscapes.
* Environmental drivers of Ixodes ricinus abundance in forest fragments of rural European landscapes.
Ehrmann, Steffen; Liira, Jaan; Gärtner, S.; Hansen, K.; Brunet, J.; Cousins, S. A. O.; Deconchat, M.; Decocq, G.; De Frenne, P.; De Smedt, P.; Diekmann, M.; Gallet-Moron, E.; Kolb, A.; Lenoir, J.; Lindgren, J.; Naaf, T.; Paal, Taavi; Valdés, A.; Verheyen, K.; Wulf, M. Scherer-Lorenzen, M.
BMC Ecology, 17 (1), 1−31.10.1186/s12898-017-0141-0. / DOI :10.1186/s12898-017-0141-0
The castor bean tick (Ixodes ricinus) transmits infectious diseases such as Lyme borreliosis, which constitutes an important ecosystem disservice. Despite many local studies, a comprehensive understanding of the key drivers of tick abundance at the continental scale is still lacking. We analyze a large set of environmental factors as potential drivers of I. ricinus abundance. Our multi-scale study was carried out in deciduous forest fragments dispersed within two contrasting rural landscapes of eight regions, along a macroclimatic gradient stretching from southern France to central Sweden and Estonia. We surveyed the abundance of I. ricinus, plant community composition, forest structure and soil properties and compiled data on landscape structure, macroclimate and habitat properties. We used linear mixed models to analyze patterns and derived the relative importance of the significant drivers.
Many drivers had, on their own, either a moderate or small explanatory value for the abundance of I. ricinus, but combined they explained a substantial part of variation. This emphasizes the complex ecology of I. ricinus and the relevance of environmental factors for tick abundance. Macroclimate only explained a small fraction of variation, while properties of macro- and microhabitat, which buffer macroclimate, had a considerable impact on tick abundance. The amount of forest and the composition of the surrounding rural landscape were additionally important drivers of tick abundance. Functional (dispersules) and structural (density of tree and shrub layers) properties of the habitat patch played an important role. Various diversity metrics had only a small relative importance. Ontogenetic tick stages showed pronounced differences in their response. The abundance of nymphs and adults is explained by the preceding stage with a positive relationship, indicating a cumulative effect of drivers.
Our findings suggest that the ecosystem disservices of tick-borne diseases, via the abundance of ticks, strongly depends on habitat properties and thus on how humans manage ecosystems from the scale of the microhabitat to the landscape. This study stresses the need to further evaluate the interaction between climate change and ecosystem management on I. ricinus abundance.
*Ecosystem services from small forest fragments in agricultural landscapes.
Decocq G, Andrieu E, Brunet J, Chabrerie O, De Frenne P, De Smedt P, Deconchat M, Diekmann M, Ehrmann S, Giffard B, Gorriz Mifsud E, Hansen K, Hermy M, Kolb A, Lenoir J, Liira J, Moldan F, Prokofieva I, Rosenqvist L, Varela E, Valdés A, Verheyen K, Wulf M.
Current Forestry Reports 2016 ; 2 : 30-44. / DOI :10.1007/s40725-016-0028-x
Abstract :In Europe, like in many temperate lowlands worldwide, forest has a long history of fragmentation and land use change. In many places, forest landscapes consist of patches of different quality, age, size and isolation, embedded in a more or less intensively managed agricultural matrix. As potential biodiversity islets, small forest patches (SFP) may deliver several crucial ecosystem services to human society, but they receive little attention compared to large, relatively intact forest patches. Beyond their role as a biodiversity reservoir, SFP provide important in situ services such as timber and wild food (game, edible plants and mushrooms) production. At the landscape scale, SFP may enhance the crop production via physical (obstacle against wind and floods) and biological (sources of pollinators and natural enemies) regulation, but may, on the other hand, also be involved in the spread of infectious diseases. Depending on their geographic location, SFP can also greatly influence the water cycle and contribute to supply high-quality water to agriculture and people. Globally, SFP are important carbon sinks and are involved in nutrient cycles, thus play a role in climate change mitigation. Cultural services are more related to landscape values than to SFP per se, but the latter may contribute to the construction of community identity. We conclude that SFP, as local biodiversity hotspots in degraded landscapes, have the potential to deliver a wide range of ecosystem services and may even be crucial for the ecological intensification of agro-ecosystems. There is thus an urgent need to increase our knowledge about the relationships between biodiversity and ecosystem services delivered by these SFP in agricultural landscapes.
*The contribution of patch-scale conditions is greater than that of macroclimate in explaining local plant diversity in fragmented forests across Europe.
Valdés A, Lenoir J, Gallet-Moron E, Andrieu E, Brunet J, Chabrerie O, Closset-Kopp D, Cousins SAO, Deconchat M, De Frenne P, De Smedt P, Diekmann M, Hansen K, Hermy M, Kolb A, Liira J, Lindgren J, Naaf T, Paal T, Prokofieva I, Scherer-Lorenzen M, Wulf M, Verheyen K, Decocq G.
Global Ecology and Biogeography 24: 1094–1105 / DOI :10.1111/geb.12345
Macroclimate is a major determinant of large-scale diversity patterns. However, the influence of smaller-scale factors on local diversity across large spatial extents is not well documented. Here, we quantify the relative importance of local (patch-scale), landscape-scale and macroclimatic drivers of herbaceous species diversity in small forest patches in agricultural landscapes across Europe.
Deciduous forest patches in eight regions along a macroclimatic gradient from southern France to central Sweden and Estonia.
The diversity of forest specialists and generalists at three levels (whole forest patch, sampling plots within patches and between scales) was related to patch-scale (forest area, age, abiotic and biotic heterogeneity), landscape-scale (amount of forest, grasslands and hedgerows around the patch, patch isolation) and macroclimatic variables (temperature and precipitation) using generalized linear mixed models and variation partitioning for each group of variables.
The total amount of explained variation in diversity ranged from 8% for plot-scale diversity of generalists to 54% for patch-scale diversity of forest specialists. Patch-scale variables always explained more than 60% of the explained variation in diversity, mainly due to the positive effect of within-patch heterogeneity on patch-scale and between-scale diversities and to the positive effect of patch age on plot-scale diversity of forest specialists. Landscape-scale variables mainly contributed to the amount of explained variation in plot-scale diversity, being more important for forest specialists (21%) than for generalists (18%). Macroclimatic variables contributed a maximum of 11% to the plot-scale diversity of generalists.
Macroclimate poorly predicts local diversity across Europe, and herbaceous diversity is mainly explained by habitat features, less so by landscape structure. We show the importance of conserving old forest patches as refugia for typical forest species, and of enhancing the landscape context around the patches by reducing the degree of disturbance caused by agriculture.