Pallieter De Smedt

Ecosystem Services from Small Forest Patches in Agricultural Landscapes

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.

Does neighbourhood tree diversity affect the crown arthropod community in saplings

Mixed forest with multiple tree species is expected to create heterogeneous habitat and diverse niches for the canopy arthropod community. We assessed arthropod abundance, order richness, and community composition in the crowns of saplings of nine temperate tree species in two plantations of a recently established tree diversity experiment in Belgium, and looked for relationships with the diversity and structure of the sapling’s local neighbourhood. The crown arthropod community differed between the two study sites, both in terms of abundances and composition. More arthropods were found in the post-agricultural site; the arthropod community was more complex in the formerly forested site. The tree species identity of a sapling, its apparency, and the phylogenetic diversity of its local neighbourhood all affected the crown arthropod community. Our study suggests that mixing phylogenetically distant tree species creates niches for a complex crown arthropod community.

Habitat properties are key drivers of Borrelia burgdorferi ( s.l .) prevalence in Ixodes ricinus populations of deciduous forest fragments

BackgroundThe 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 (sensulato), 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.MethodsWe 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.ResultsDuring 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.ConclusionsDiluting 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.

Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe

PurposeMost 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.MethodsMacrodetritivores 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.ResultsForest 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.ConclusionsLandscape 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.

Vertical stratification of moth communities in a deciduous forest in Belgium

Moths are a diverse and abundant species group, playing important functional roles in many terrestrial ecosystems, as pollinators, herbivores and as bulk food for many other taxa. Forests are complex ecosystems and beside horizontal variation, they exhibit a very diverse vertical structure, creating a matrix of micro‐niches along the vertical gradient. One could expect that this results in varying moth community assemblages, but the vertical distribution and underlying mechanisms have hardly been investigated in temperate forest ecosystems. We sampled macro‐moths on a weekly basis for 14 months on a tower in an ancient deciduous forest in Belgium. Alternatingly light and bait traps were used at ground level and at 7, 14, 21, 28 and 35 m height in the forest. We analysed total moth abundance along the vertical gradient and distribution patterns of individual species and families, using generalised linear mixed‐effects models. We demonstrated a strong vertical stratification, resulting in distinct moth communities in different strata. The observed patterns were non‐random but related to specific response traits of the species. Notably, we found large differences between families; whereas Geometridae‐moths were much more abundant at ground level, Noctuidae showed a preference for both the ground level and the canopy layer. Comparing species‐specific patterns within families revealed strong differences between species. We welcome future research to further document vertical stratification patterns and unravel the different underlying mechanisms.