Mass‐flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi‐natural habitats (SNHs). Across six European regions and 2 years, we ...assessed how landscape‐scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator‐dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator‐supporting practices in agricultural landscapes.
1. Insectivorous birds are increasingly recognized for the crucial pest control services they provide to agroecosystems. While both the foraging activity and functional diversity of birds are ...enhanced by multiscale habitat heterogeneity, little is known about how these relationships may influence avian top-down control of insects. Specifically, interactive effects of bird community structure and habitat heterogeneity on pest control across spatial scales have rarely been explored. 2. We sampled bird communities and measured avian prédation on plasticine model prey, as a proxy for lepidopteran pest control, in 20 vineyards of south-western France. Vineyards differed both in sward heterogeneity at the local scale and amount of surrounding semi-natural habitats at the landscape scale. Functional diversity metrics and community-weigh ted mean traits were computed for bird communities based on a species-trait table including diet, foraging method, nesting site, migration strategy, laying date, home range size, clutch size and body mass. We used mixed models to test for the interacting effects of habitat heterogeneity and bird functional diversity on avian prédation rates of plasticine prey. 3. Contrary to expectations, bird functional diversity decreased with landscape-scale heterogeneity, but was higher in vineyards managed with heterogeneous sward structures. In contrast, foliage-gleaning insectivores were more abundant in landscapes supporting more semi-natural habitats, suggesting an increase in their contribution to pest control along the landscape heterogeneity gradient. Accordingly, we found that avian prédation on plasticine prey increased with bird functional evenness both in more heterogeneous vineyards at the local scale and in landscape mosaics supporting more semi-natural habitats. 4. Synthesis and applications. Our study demonstrates that habitat heterogeneity at both local and landscape scales influenced avian insectivory in vineyard agroecosystems by interacting with bird community structure. It provides important insights for ecological intensification in vineyards, pointing out that management options need to be adapted to both the functional composition of local bird communities and landscape context. We suggest that both on-field and off-field management can be used to enhance natural pest control services provided by birds in vineyards, especially by favouring sward heterogeneity and patches of semi-natural habitats within large vineyard stands at the landscape scale.
Increasing natural pest control in agricultural fields is an important aim of ecological intensification. Combined effects of landscape context and local placement of agri‐environmental schemes (AES) ...on natural pest control and within‐field distance functions of natural pest control agents have rarely been addressed but might affect the distribution of biocontrol providers. Importantly, it is currently unknown whether ecosystem services provided by adjacent AES are consistent for different crop types during crop rotation.
In this study, we assessed whether crop rotation from oilseed rape to cereals altered within‐field distance functions of ground‐dwelling predators from adjacent agri‐environmental fields along a gradient in landscape context. Additionally, we recorded crop pests, predation rates, parasitoids as well as crop yields on a total of 30 study sites.
Distance functions varied between trophic levels: Carabid richness decreased while densities of carabid beetles, staphylinid beetles as well as crop yields increased towards the field centres. Distance functions of parasitoids and pests were modulated by the amount of semi‐natural habitat in the surrounding landscape, while the effects of adjacent AES were limited.
Distance decay functions found for ground‐dwelling predators in oilseed rape in the previous year were not always present in cereals. Increasing distance to the field edge also increased effects of crop rotation on carabid beetle assemblages, indicating a source habitat function of field edges.
Synthesis and applications. Distance functions of natural pest control are not universal and the effects of agri‐environmental schemes (AES) in different adjacent crops during crop rotation vary and depend on ecological contrasts. A network of semi‐natural habitats and spatially optimized AES habitats can benefit pest control in agricultural landscapes, but constraints as a result of crop type need to be addressed by annually targeted, spatially shifting agri‐environment schemes for different crops.
Distance functions of natural pest control are not universal and the effects of agri‐environmental schemes (AES) in different adjacent crops during crop rotation vary and depend on ecological contrasts. A network of semi‐natural habitats and spatially optimized AES habitats can benefit pest control in agricultural landscapes, but constraints as a result of crop type need to be addressed by annually targeted, spatially shifting agri‐environment schemes for different crops.
Conventional agriculture is frequently associated with large-scale environmental degradation and landscape homogenization. In contrast, ecological intensification incorporates natural habitat ...conservation and landscape complexity to improve important ecosystem services such as pollination and crop yields. In an observational study of 105 fields in the Argentinean Pampas Region, we explored whether sunflower yields were related to landscape composition (percentage of natural habitat) and configuration (field size and edge density), and covariates of agricultural management practices such as nitrogen fertilizer addition, seed density, sowing date and crop cultivar. Our mixed-effects models revealed that field size and edge densities between crop and natural habitat are important predictors of yield. For example, a doubling of edge density from 40 m/ha to 80 m/ha predicted an 11.3% (269 kg/ha) yield increase, while a doubling in the field size from 40 ha to 80 ha predicted a 6.1% (149 kg/ha) yield decrease. We suggest that pollination is an important driver of both effects as higher edge densities and smaller field sizes reduce wild pollinator flight distances to crop flowers and thus increases the chances for effective crop pollination. This study provides key information for sustainable management of sunflower agroecosystems.
1. Semi-natural habitats (SNH) provide essential resources for many organisms in agricultural landscapes and can increase biodiversity at the local and landscape scale. For the management of ...ecosystem services, it is crucial to understand how local characteristics of SNH and the surrounding landscape complexity affect beneficial species. 2. We investigated this for hoverflies (Diptera: Syrphidae)—an important functional group providing both pest control and pollination services—in a total of 138 SNH within 35 agricultural landscapes in Switzerland and Germany. SNH differed in type (woody, herbaceous), shape (areal, linear) and availability of food resources (floral resources and aphids). They were located along a gradient of landscape complexity (1%-75% SNH in a 1 km radius). 3. In total, 9,030 hoverflies belonging to 89 species were collected. In both countries, hoverfly community composition was mainly driven by SNH type and SNH shape, in addition to landscape complexity in Switzerland. Species richness of hoverflies increased with additional SNH at the landscape scale. However, the ubiquitous and dominant aphidophagous species Episyrphus balteatus was indifferent to landscape composition. 4. Species richness of total and aphidophagous hoverflies was higher in woody than in herbaceous SNH. Hoverfly species richness was similar in linear and areal SNH, but non-aphidophagous hoverflies were more vulnerable to landscape simplification in linear than areal SNH. Effects of the SNH type partly differed between the two countries. In Germany, the dominant aphidophagous species E. balteatus preferred woody over herbaceous SNH, while no such difference was found in Switzerland. Overall, local richness and abundance of floral resources were poor predictors for composition. 5. Synthesis and applications. Hoverfly species richness and community composition in semi-natural habitats (SNH) were mainly driven by the SNH type and landscape complexity. Conservation and restoration of complex agricultural landscapes with a high proportion of different SNH types is therefore key for the conservation of hoverfly diversity, and thus likely to promote pest control and pollination services provided by them. Thereby, local improvement of SNH to promote hoverflies has to consider regional differences in habitat characteristics.
The Principles and Standards by Young et al. provide an international framework for ecological restoration of mine sites. Although useful, these Standards are limited as a basis for practice, ...especially in Europe, partly by neglecting the fact that semi‐natural habitats are often desirable restoration targets in anthropogenic cultural landscapes; intermediate and early successional stages are sometimes more ecologically valuable than terminal stages; spontaneous succession can be an effective restoration approach, or it may be combined with assisted restoration; and by a limited number of representative long‐term restoration case studies. Further efforts to create consensual guidelines require a broad discussion across biomes, regions and public and private sectors. Meanwhile, the Standards should be regarded as a tentative academic‐oriented framework with some substantial limitations for practice.
The decline of pollinators is an urgent issue that has gained global attention and many initiatives have been implemented to promote conservation actions. However, interventions aimed at safeguarding ...pollinators can have ripple effects on multiple ecosystem services that are equally important for human well-being. In this work, we investigated whether environmental conditions favouring pollinators are positively associated with the provision of multiple ecosystem services across three different habitats. We selected 96 sites belonging to three habitat types with different roles in supporting pollinators, i.e., crop field margins, semi-natural patches, and urban green areas. We sampled wild pollinators and seven ecosystem services, which included provisioning, cultural, and regulatory services, using which we calculated two ecosystem multi-functionality metrics. Semi-natural patches and crop field margins exhibited both the highest diversity of pollinators and ecosystem multi-functionality, i.e., habitats that supported pollinators also delivered a higher number of environmental co-benefits. However, increasing habitat quality for pollinators did not result in increased multi-functionality, indicating that single ESs exhibited non-linear responses. Therefore, improving local conditions for wild pollinators did not enhance ecosystem multi-functionality, while specific habitat types have been shown to have the potential to improve pollinator diversity while generating multiple environmental co-benefits.
•Interventions supporting pollinators can affect multiple ecosystem services.•Semi-natural patches and field margins enhanced pollinators and multi-functionality.•Increasing flower cover benefitted pollinators, but not multi-functionality.•Promoting pollinators does not always produce environmental co-benefits.
Semi-natural habitats (SNHs) are essential to biodiversity and agroecological conservation. The impact of agricultural policies on the development of SNHs is a matter of substantial importance. This ...study conducted a comparative analysis to examine the variations of SNHs’ quantity, landscape quality, and ecosystem services resulting from the differentiated agricultural policies in China and the EU from 1990 to 2020. The Yangtze River Delta region (YRD) in China and France was selected as the study area. The results revealed that France exhibited a higher proportion of SNHs, along with improved connectivity and diversity in its plains, whereas SNHs in the YRD were limited in quantity and characterized by unstable landscape structure and ecosystem services. Both the YRD and France experienced a shift in the declined SNHs towards higher altitudes. There was noticeable landscape fragmentation and degraded ecosystem services in the hilly areas of YRD and the high plains of France. The agricultural policies of the EU achieved limited success in protecting SNHs, while China's agricultural landscapes were rapidly losing SNHs due to the absence of policy support. Based on these, the paper puts forward some countermeasures and suggestions for developing SNHs in China and the EU. Our study contributes to the global effort for agroecological conservation.
•Comparative analysis of SNHs in China and the EU from 1990 to 2020.•Both YRD and France experienced a shift in declining SNHs towards higher altitudes.•Limited success of EU agricultural policies in SNH protection over three decades.•Rapid loss of SNHs in China's agricultural landscape.
Pesticides, loss of floral resources and parasitism are considered drivers of wild bee decline in agroecosystems, but their interactions are poorly understood under field conditions. Negative impacts ...are predicted to vary across species of distinct crop fidelity because of the associated consequences for pesticide exposure and dependence on wild flowers. We experimentally established populations of two solitary bee species in apple orchards with distinct pesticide hazard and flower availability in surrounding landscapes. The number of nesting females, their reproduction and offspring survival and parasitism rate were tracked throughout apple bloom. We show that in the solitary bee Osmia cornuta, which showed a strong preference to forage in apple orchards, the number of females remaining at nesting sites towards the end of apple bloom and the overall reproductive success of the released bees declined with pesticide hazard. In contrast, the closely related Osmia bicornis, which showed a lower preference for apple, was not affected by pesticide use in orchards. Floral resource distribution furthermore modulated parasitism rates in both species: while large amounts of locally available resources reduced offspring parasitism, it increased with relatively higher food availability in the landscapes surrounding focal orchards, probably due to the bees foraging on a larger scale and thus longer periods during which nests remained unattended. Our findings provide novel insights into the complex interplay of pesticide exposure, flower availability and parasitism risk driving population dynamics of bees in agroecosystems. They show that in particular the most reliable crop pollinator species are especially harmed by high pesticide use in crops. Our study underpins the key role of reducing pesticide risks for pollinators through effective regulation of potentially hazardous agrochemicals and the promotion of alternative pest regulation approaches along with conserving and restoring flower-rich habitats to sustain pollinator populations in agroecosystems.
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•How drivers of bee decline interact is poorly understood under field conditions.•We tracked the fitness of two solitary bee species released in apple orchards.•Pesticide hazard reduced the fitness of the bee with higher crop fidelity.•Floral resource distribution in landscapes modulated larval parasitism rates.•The findings show that drivers of bee decline can act interdependently.
Monitoring grassland plant communities is crucial for understanding and managing biodiversity. Previous studies indicate that mapping these natural habitats from single-date remotely sensed imagery ...remains challenging because some communities have similar physiognomy. The recently launched Sentinel-2 satellites are a promising opportunity for monitoring vegetation. This article assesses the advantages of Sentinel-2 time-series for discriminating plant communities in wet grasslands. An annual Sentinel-2 time-series was compared respectively to single-date and single-band datasets derived from this time-series for mapping grassland plant communities in a temperate floodplain located near Mont-Saint-Michel Bay, which is included in the long-term ecological research network “ZA Armorique” (France). At this 475 ha site, 123 vegetation relevés were collected and assigned to seven plant communities to calibrate and validate the Sentinel-2 data. Satellite images were classified using support vector machine (SVM) and random forest (RF) classifiers. Results show that the SVM classifier performs slightly better than the RF classifier (overall accuracy 0.78 and 0.71, respectively). They highlight that accuracy is lower when using single-date (0.67) or single-band images (0.70). The results also reveal that discrimination of plant communities is more sensitive to temporal resolution (Δ = 0.34 in overall accuracy) than spectral resolution (Δ = 0.12 in overall accuracy).
•Grassland plant communities were accurately classified using Sentinel-2 time-series.•SVM slightly outperforms RF (overall accuracy 0.78 and 0.71, respectively).•Accuracy is lower when using single-date (0.67) or single-band images (0.70).•Spring and early summer are the most discriminating seasons.•Temporal resolution is more important than spectral resolution.
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