Littérature scientifique sur le sujet « Services Habitats seminaturels »

Large-scale infrastructure development projects can have devastating impacts upon biodiversity. We investigated the impacts of roads on land-use change in a coastal area of South-east Asia, an area of high biodiversity subject to intense human pressure. The objectives of this study were (1) to examine impacts of major roads on rates of land-use change and habitat conversion in and around the Inner Gulf of Thailand, a large wetland of international importance; and (2) to evaluate the conversion rate of salt-pans (a critical habitat for several species of threatened shorebirds) between 1990 and 2011. Nine land-use types were categorised into two groups: seminatural and human-dominated. Proportions of each land-use type at different distances from major roads were determined using GIS data. More than 40% of the area was used for aquaculture during the entire study period. The amount of seminatural habitats was positively correlated with distance from major roads. Agriculture and urban areas showed the greatest changes in area (decreasing and increasing, respectively). Habitats that changed from seminatural to human-dominated were negatively correlated with distance from major roads. Most of the converted salt-pans were lost to aquaculture. To protect important wetlands from further biodiversity loss: (1) new major road construction should be avoided or minimised; and (2) land-use strategies that both satisfy short-term human needs and maintain ecosystem capacity to provide services in the long term should be adopted.

Invertebrates perform many vital functions in agricultural production, but many taxa are in decline, including pest natural enemies. Action is needed to increase their abundance if more sustainable agricultural systems are to be achieved. Conservation biological control (CBC) is a key component of integrated pest management yet has failed to be widely adopted in mainstream agriculture. Approaches to improving conservation biological control have been largely ad hoc. Two approaches are described to improve this process, one based upon pest natural enemy ecology and resource provision while the other focusses on the ecosystem service delivery using the QuESSA (Quantification of Ecological Services for Sustainable Agriculture) project as an example. In this project, a predictive scoring system was developed to show the potential of five seminatural habitat categories to provide biological control, from which predictive maps were generated for Europe. Actual biological control was measured in a series of case studies using sentinel systems (insect or seed prey), trade-offs between ecosystem services were explored, and heatmaps of biological control were generated. The overall conclusion from the QuESSA project was that results were context specific, indicating that more targeted approaches to CBC are needed. This may include designing new habitats or modifying existing habitats to support the types of natural enemies required for specific crops or pests.

Agri-environmental schemes (AES) aim to restore biodiversity and biodiversity-mediated ecosystem services in landscapes impoverished by modern agriculture. However, a systematic, empirical evaluation of different AES types across multiple taxa and functional groups is missing. Within one orthogonal design, we studied sown flowering AES types with different temporal continuity, size, and landscape context and used calcareous grasslands as seminatural reference habitat. We measured species richness of 12 taxonomic groups (vascular plants, cicadas, orthopterans, bees, butterflies, moths, hoverflies, flower visiting beetles, parasitoid wasps, carabid beetles, staphylinid beetles, and birds) representing 5 trophic levels. A total of 54,955 specimens were identified using traditional taxonomic methods, and bulk arthropod samples were identified through DNA metabarcoding, resulting in a total of 1,077 and 2,110 taxa, respectively. Species richness of most taxonomic groups, as well as multidiversity and richness of pollinators, increased with temporal continuity of AES types. Some groups responded to size and landscape context, but multidiversity and richness of pollinators and natural enemies were not affected. AES flowering fields supported different species assemblages than calcareous grasslands, but assemblages became more similar to those in seminatural grasslands with increasing temporal continuity. Our results indicate that AES flowering fields and seminatural grasslands function synergistically. Flowering fields support biodiversity even when they are relatively small and in landscapes with few remaining seminatural habitats. We therefore recommend a network of smaller, temporally continuous AES flowering fields of different ages, combined with permanent seminatural grasslands, to maximize benefits for biodiversity conservation and ecosystem service delivery in agricultural landscapes.

On-farm pollination experiments were conducted in 30 different small-scale coffee fields to determine monetary value attributable to pollination services in coffee production and to identify the degree of influences of various socio-ecological drivers in Uganda. Ecological-economic approaches were applied to determine the economic value of pollinating services. Economic value of bees increased significantly with increase in coffee farm size, bee diversity, and cover of seminatural habitats. The value of bees declined sharply (P<0.05) with forest distance and cultivation intensity. Economic values of pollinating services associated with coffee fields established in regions with low intensity were found to be high. Organically managed small-scale coffee fields were 2 times more profitable than commercially managed farms. The annual value of pollinating services delivered by wild bees oscillated between US$67.18 and US$1431.36. Central Uganda produces in total 0.401 million tons of coffee beans for an approximate economic value of US$214 million from which US$149.42 million are attributable to pollination services. Policy makers should strengthen environmental/agricultural extension service systems to better serve farmers. Farmers are recommended to protect/increase the cover of natural and semi-natural habitats in the vicinity of their coffee fields to receive high economic benefits from pollinating services delivered by bees.

Plant diversity often contributes to the shape of arthropod communities, which in turn supply important ecosystem services. However, the current biodiversity loss scenario, particularly worrying for arthropods, constitutes a threat for sustainability. From a trait-based ecology approach, our goal was to evaluate the bottom-up relationships to obtain a better understanding of the conservation of the arthropod function within the ecosystem. Specifically, we aim: (i) to describe the plant taxonomic and functional diversity in spring within relevant habitats of a natural protected area from the Mediterranean basin; and (ii) to evaluate the response of the arthropod functional community to plants. Plants and arthropods were sampled and identified, taxonomic and functional indices calculated, and the plant–arthropod relationships analyzed. Generally, oak forests and scrublands showed a higher plant functional diversity while the plant taxonomic richness was higher in grasslands and chestnut orchards. The abundance of arthropod functional groups increased with the plant taxonomic diversity, functional dispersion, vulnerability and originality, suggesting that single traits (e.g., flower shape or color) may be more relevant for the arthropod function. Results indicate the functional vulnerability of seminatural habitats, the relevance of grasslands and chestnut orchards for arthropod functions and pave the way for further studies about plant–arthropod interactions from a trait-based ecology approach.

Abstract The bertha armyworm (BAW) Mamestra configurata Walker is a significant pest of canola Brassica napus L. (Brassicales: Brassicaceae) in western Canada. Its activity is monitored through a large network of pheromone-baited monitoring traps as a part of the Prairie Pest Monitoring Network across the Canadian Prairies. The unintentional bycatch of bee pollinators in pheromone-baited traps targeting moth pests occurs in many agroecosystems and may have repercussions for biodiversity and pollination services of wild plants and managed crops. We conducted field experiments to determine the abundance and diversity of bees attracted to green-colored BAW pheromone-baited traps across the canola growing regions of Alberta, Canada. A higher species diversity and more bumble bees were captured in BAW pheromone-baited than in unbaited control traps. Bombus rufocinctus Cresson (Hymenoptera: Apidae) was the most commonly captured species. Few other wild bees or honey bees Apis mellifera L. (Hymenoptera: Apidae) were captured during this study. Additionally, we evaluated the influence of local and landscape-level habitat features on bee bycatch. Local flowering plant abundance improved overall model fit but did not directly impact bee bycatch. The proportion of natural and seminatural habitat, and especially forested area, in the area surrounding monitoring traps affected bee bycatch. Both local and landscape-scale factors were important in this study and often have combined effects on bee communities. This study provides recommendations to reduce the bycatch of beneficial bee pollinators in a large-scale pheromone-baited monitoring network.

Decomposition of organic matter supports important soil ecosystem services. The rate of decomposition depends mostly on the type of plant material being decomposed and the abundance and diversity of organisms that process the organic matter. Consequently, any disturbance to the soil ecosystem will affect the decomposition process. Invasive plants, such as Solidago species, pose a serious ecological threat to natural habitats, so effective and environmentally safe methods of controlling their occurrence should be developed. In this study, decomposition rates were used as indicators of soil health during grassland restoration after Solidago invasion. Different seed mixtures (grasses, grasses with legumes, seeds collected from a seminatural meadow; use of fresh hay and no seeds) were sown during a field experiment and different mowing frequencies (1, 2 and 3 times per year) were established. Two hypotheses were tested: (1) plant species composition used in the restoration process affects litter decomposition rates, and (2) mowing regimes affect litter decomposition rates. It was found that decomposition rates were higher in plots with the highest species diversity. This indicates that an increase in species diversity has a positive effect on soil processes. Secondly, mowing two and three times per season has a positive effect on the decomposition process. In conclusion, decomposition rates can be used as a tool to identify adequate grassland management.

Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25–50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.

Changing environmental conditions, disturbances, and escalating demands for forest ecosystem services require foresters to restore present forestlands with new forest generations that will exhibit ecological integrity, diversity, high adaptive capacity, and the ability to provide essential ecosystem services. Establishing such forests requires careful consideration of the forest landscape and site dynamics. In pursuit of these requirements, we developed a novel framework that enables the restoration of forest sites and promotes the desired features of the forest complex at the same time. This framework was designed with the methods of system engineering and was organized in the same way as the forest planning process. It was tested in the habitat type of Illyrian Fagus sylvatica forests belonging to the Natura 2000 network. The environmental, vegetation, and site conditions were investigated via field inspections, available forest management plans, and simple GIS analyses. Additionally, we established a seminatural stand composed of European beech, sessile oak, sycamore maple, silver fir, and some wild fruit tree species. The survival of planted species was assessed using census and simple random sampling, the performance of provenances by the Student’s test, while microhabitat factors were explored by a one-way ANOVA. The survival rate of key species was estimated to be 55.6%, while that of fruit species was estimated to be 94.5%. Our framework demonstrated satisfactory performance and contained sufficient benchmarks to facilitate consistent decision-making. In the discussion, we elucidate the framework’s primary features and attributes of the mixed stand, where we also expose some open issues to be addressed in the future.

Increasing landscape heterogeneity has been suggested to be an important strategy to strengthen natural pest control in crops, especially through enhancing the amount of seminatural habitats. Increasing crop diversity is also a promising strategy to complement or replace seminatural habitat when seminatural habitat is scarce. However, their relative or possibly interactive effects on pest and weed infestation remain poorly investigated, and the role of different types of seminatural habitats has been understudied. Using an extensive sampling effort in 974 arable fields across 7 y, we evaluated the separate and interactive effects of crop diversity (seven arable crop types) and the amount of four types of seminatural habitats (meadows, hay, forests, and hedgerows) in the landscape on pest and weed control. Meadows and crop diversity, respectively, supported insect pest and weed control services in agricultural landscapes through a complementarity effect. Crop diversity increased weed seed predation rate (by 16%) and reduced weed infestation (by 6%), whereas long-term grasslands (to a much higher degree than hay or woody habitats) increased insect pest predation rates (by 23%) and reduced pest infestation (by 19%) in most arable crops. Our results demonstrate that diversification of the agricultural landscape requires long-term grasslands as well as improved crop diversity to ensure the delivery of efficient pest and weed control services.

Le déclin de la biodiversité dans les agroécosystèmes est largement attribué à l'essor de l'agriculture moderne. Les principales causes sont la destruction des structures semi-naturelles, l’extension de la taille des parcelles agricoles et l'utilisation intensive d'intrants. Les arthropodes jouent un rôle important dans l’amélioration de services écosystémiques essentiels tels que la régulation des ravageurs et la pollinisation. Pour favoriser leur présence, la végétation est un facteur primordial. En effet, les plantes fournissent des ressources alimentaires cruciales et permettent la création d’habitats pour les arthropodes. Pour favoriser ces organismes dans les agroécosystèmes et restaurer les fonctions écologiques associées, des pratiques telles que l'introduction de structures semi-naturelles sont pertinentes. Dans des cultures permanentes comme les vignobles, de telles structures peuvent être implantées à l’intérieur des parcelles. En région méditerranéenne, la gestion des inter-rangs de vigne implique souvent l'élimination de la végétation non-cultivée pour des raisons de compétition hydrique et pour contrôler les espèces végétales considérées comme nuisibles. Ces travaux de thèse visent à mieux comprendre comment la végétation des inter-rangs peut favoriser la présence d'arthropodes bénéfiques et la fonction de prédation mais limiter la prolifération des espèces végétales nuisibles en viticulture méditerranéenne (Luberon, France). Trois questions principales de recherche se sont posées : (1) La présence de l’enherbement et sa composition floristique influencent-elles la présence des fourmis, actrices importantes de la fonction de prédation dans les vignes ? (2) Quels groupes fonctionnels de la végétation sont reliés à l’abondance des arthropodes prédateurs et pollinisateurs ainsi que la fonction de prédation ? (3) Est-ce qu’un enherbement diversifié et local augmente la présence d’arthropodes bénéfiques, améliore la fonction de prédation et limite l’installation des espèces végétales problématiques ? Dans un premier chapitre nous avons étudié la réponse des fourmis à l’enherbement dans 23 vignobles. Les fourmis jouent un rôle crucial dans la prédation des vignobles méditerranéens (Luberon, France). Nous avons testé l’effet de trois modes de gestion de la végétation sur la diversité et fréquence des fourmis : des inter-rangs enherbés, partiellement enherbés et non enherbés. Nous avons montré que les vignobles partiellement enherbés présentaient une plus grande richesse de fourmis comparé à ceux non-enherbés. Le recouvrement en graminées et la présence de plantes pérennes ont influencé positivement la richesse de fourmis, suggérant l'importance de prendre en compte ces facteurs dans la gestion de la végétation. Dans le second chapitre, nous avons examiné quelles caractéristiques de la végétation spontanée influencent les arthropodes bénéfiques et la fonction de prédation sur 37 vignobles. Nous avons constaté que le recouvrement en fleurs nectarifères et la richesse en espèces végétales favorisaient la plupart des groupes d'arthropodes bénéfiques, ainsi que la fonction de prédation. Ces résultats soulignent l'importance des ressources florales et de la diversité végétale pour favoriser la présence des arthropodes étudiés. Enfin, le dernier chapitre est consacré à une expérimentation de semis et de son suivi sur deux ans. Trois types d’enherbements sont comparés : un semis haute diversité, la végétation spontanée et des inter-rangs sans végétation. En accord avec le deuxième chapitre, nos résultats soulignent les effets positifs de la richesse végétale et du recouvrement en fleurs sur le contrôle des mauvaises herbes, l'abondance des arthropodes bénéfiques et la fonction de prédation. L’ensemble des résultats de ces travaux de thèse convergent et mettent en lumière l’importance de considérer différents paramètres de la végétation pour favoriser les arthropodes bénéfiques en viticulture
Biodiversity decline within agroecosystems is mainly attributed to modern agriculture. The main causes include the destruction of semi-natural structures, the increase in field size and the high use of agrochemicals for fertilisation and pest control. Arthropods contribute significantly to the key ecosystem services such as pest control and pollination. They largely depend on the vegetation within fields and in the surroundings. Plants provide food resources and other habitat functions that are crucial for the survival and reproduction of arthropods. Semi-natural structures are important to maintain species-rich vegetation, and thus arthropods with associated ecological functions. In permanent crops such as vineyards, semi-natural structures can be established in inter-rows within fields. However, in the French Mediterranean, inter-rows are often tilled to remove non-crop vegetation since winegrowers are afraid of water competition and the spread of undesirable weeds. This thesis aims to better understand how inter-row vegetation promotes beneficial arthropods and predation of pest insects while limiting the spread of undesirable plant species in Mediterranean vineyards of South-Eastern France (Luberon). The present thesis addresses three major research questions: (1) Do inter-row vegetation cover and its floristic composition affect ant species and diversity, that were found to be vineyard predators? (2) Which functional groups of the vegetation are related to the abundance of predators, parasitoids, pollinators and predation sentinel prey? (3) Does species-richinter-row vegetation increase the abundance of such beneficial arthropods, improve predation of sentinel prey and limit the spread of undesirable plant species? In the first chapter, we studied the ant response to inter-row vegetation in 23 vineyards. We tested the effects of three types of inter-row vegetation management on ant diversity and frequency: fully, partially, and non-vegetated vineyards. We showed that partially vegetated vineyards had greater ant species richness compared to non-vegetated ones. Grass and perennial plant cover positively influenced ant species richness, demonstrating the importance of inter-row vegetation and itsmanagement. In the second chapter, we examined which characteristics of spontaneous vegetation affect beneficial arthropods and sentinel prey predation in 37 vineyards. We found that nectariferous flower cover and plant species richness favoured most groups of beneficial arthropods, as well as predation. These results underline the importance of floral resources and plant diversity in promotingthe studied beneficial arthropods. The last chapter focuses on a sowing experiment that was analysed for two years. Three types of inter-row vegetation were compared: high diversity sowing, spontaneous vegetation, and inter-rows without vegetation. In agreement with the second chapter, our results highlight the positive effects of plant species richness and flower cover on weed control, beneficial arthropod abundance, and predation of sentinel prey. The overall results of the different studies conducted in this thesis converge and highlight the importance of considering vegetation characteristics to promote beneficial arthropods in vineyard ecosystems

Grasslands (also known as savanna, prairie, steppe, and pampas) are natural or seminatural areas encompassing vegetation belonging to the family Poaceae as the most dominant vegetation, while, sedges and rushes may also constitute a minor proportion. These provide numerous natural products such as food feed medicinal raw material, and honey along with nonproduct-based ecosystem services. Grasslands in lowlands and mountains either in natural form or developed landscape can provide an added value in terms of ecotourism opportunities owing to having huge esthetic and recreational potential compared to uniform agricultural areas. Grasslands characterized by high species and habitat diversity-based ecotourism are nature-based tourism whereby people visit natural or developed areas for recreation, sight-seeing, permitted and controlled hunting, on-site purchase of organic products, etc., and are usually managed by adopting sustainable practices. Ecotourism generates multifaceted economic advantages for local communities such as direct sale of products to tourists. However, ecotourism may also have a variety of negative impacts when the tourists’ number multiplies which leads to overuse of resources. The most pronounced challenges confronted to the development of grasslands for ecotourism include lack of community cooperation, careless herders, need of hefty investment, and absence of trained human capital along with climate change and loss of biodiversity.