While top-down control plays an important role in shaping both natural and agricultural food webs, we lack insights into how top-down control effects vary across spatial scales. We used a multi-scale ...survey of top-down control of coffee pests and diseases by arboreal ants to examine if colony location creates a small-scale mosaic in top-down control around trees and if the strength of that control varies between sites at the landscape scale. We investigated pest and disease levels on coffee shrubs at different distances from shade trees with and without a Crematogaster spp. ant colony in 59 sites along a coffee management intensity gradient in southwestern Ethiopia. Within sites, ants significantly suppressed herbivory and coffee leaf rust at distances less than 10 m from nesting trees. Top-down control varied between sites, with stronger top-down control of free-feeding herbivory near ant colonies at sites with lower management intensity and stronger top-down control of a skeletonizer at sites with higher canopy cover. We conclude that the strength of top-down control by ants is highly heterogeneous across spatial scales, as a consequence of the biology of the predator at the small scale and herbivore density or changes in herbivore–ant interactions at the landscape scale.
An ongoing decrease in habitat and species diversity is occurring in many areas across Europe, including in grasslands in mountain areas, calling for adapted biodiversity management and measures. In ...this context, we carried out 79 interviews with grassland farmers in five alpine mountain regions in Germany, France, Austria, Italy, and Switzerland. We analyzed farmers’ perceptions about the functions and services of their grasslands, how they qualify “good” grasslands, which grassland management practices have changed over the last 10 years, and proposals to increase species diversity on the farm. They related them primarily to cultural ecosystem services, secondly to provisioning services, and thirdly to regulating and supporting services. Good pastures or meadows were mostly related to composition, quality of forage and productivity, structural criteria, and certain characteristics of soils and topography. The measures for increasing biodiversity that were most frequently proposed were upgrading of forest edges, planting hedges or fruit trees, less or late grassland cutting, reduction or omission of fertilization, and more general extensification of farm productions. Factors hindering the implementation of these measures were mainly increased workload, insufficient time, and a lack of financial means or support to cover additional costs for biodiversity management. These factors have to be taken specifically into account for future policies for enhanced biodiversity management of grasslands, also beyond mountainous areas. Overall, we found that farmers have good but varying knowledge about biodiversity management of their grasslands, but also different perspectives on how to improve it. Here, local initiatives that bring together farmers and flora or fauna specialists to exchange knowledge could be designed and used in participatory pilot schemes to enhance the implementation of improved biodiversity management.
Wild foods constitute an essential component of people's diets around the world, but despite their widespread use and their cultural importance, wild edible plants (WEPs) lack recognition as ...significant contributors to the human diet in developed countries.
We stimulate national and international bodies dealing with food and agriculture, to increase their attention and investments on WEPs, leveraging the results of scientific investigation, enhancing the link between in situ conservation strategies and sustainable use of plant genetic diversity.
WEPs should be reconsidered throughout their value chain, capturing their important socio-cultural, health, and economic benefits to indigenous and local communities and family farmers who are engaged in their production and wild-harvesting.
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•We compare different statistical methods and diversity indices to determine tipping points.•We compare tipping points in different taxonomic groups.•SEGMENTED and Jackknife first order are the most ...adequate method and diversity index to determine tipping points.•Aquatic vascular plants are the best taxonomic group to respond to eutrophic changes.
The management of biodiversity in aquatic ecosystems requires knowing the state of water quality linked to regime shifts in various taxonomic groups. We examine this question by studying the fish ponds in the Dombes region, France. These waterbodies are characterized by a high diversity of species. High levels of nutrients due to certain fish farming practices may cause significant eutrophication leading to loss in biodiversity and a shift from high coverage of aquatic vegetation to phytoplankton dominance may also be observed. The aim of this study is to assess tipping points, thresholds for effect, along a gradient of chlorophyll α in different taxonomic groups: aquatic vascular plants, phytoplankton, dragonflies and aquatic macro-invertebrates. Tipping points are analyzed with three different statistical methods: a method which evaluates tipping points with a difference in the mean (TMEAN), a second method which evaluates tipping point by comparing the mean and linear regressions before and after the tipping point (FSTAT) and third a method which evaluates linear regressions with a pivotal tipping point (SEGMENTED). We also compare tipping points for the different taxonomic groups using five different diversity indices: Observed richness, Jackknife first order, Fisher's alpha, Simpson index and Evenness.
Our results show that there is an important variation in tipping points following the three statistical methods, but the SEGMENTED is the best method for evaluating tipping points. We observe a high difference of tipping point values for the different taxonomic groups depending on the diversity indices used. Jackknife first order has a better performance to evaluate a eutrophic change according to the diversity than the other indices.
In all taxonomic groups, aquatic vascular plants are the most impacted by the chlorophyll α and almost all their tipping points are observed around 60μg/L chlorophyll α concentrations. No significant relationship is found between chlorophyll α and phytoplankton diversity, while the two other groups, dragonflies and macro-invertebrates, are both impacted by the chlorophyll α but their relevant tipping points are situated in higher values than aquatic vascular plants.
Increasing intrafield plant diversity has been shown to regulate pest populations in various agroecosystems. Among the suggested mechanisms for this bottom‐up pest control, the disruptive crop ...hypothesis states that herbivores' abilities to locate and colonize their host plants are reduced by the presence of non‐host plants. Under laboratory conditions, we evaluated how intercropping wheat and legumes modifies the behaviour of apterous cereal aphids, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), in terms of host plant location and population growth. We compared two intercropping systems – soft winter wheat, Triticum aestivum L. (Poaceae), associated with winter pea, Pisum sativum L., or with white clover, Trifolium repens L. (both Fabaceae) – and sole stands of soft winter wheat. Aphids needed more time to locate their wheat host plant and then spent less time on wheat when it was intercropped with clover. At the population level, and accounting for host plant biomass, only intercropping wheat with clover significantly reduced aphid densities on wheat, as this was particularly disruptive to S. avenae behaviour and population growth. Our laboratory study points out that the species used as non‐host plants and their density are important parameters that should be taken into account in field studies on intercropping systems.
Intercropping cereal and legumes has been shown to regulate pest populations in various agroecosystems. Abilities of apterous cereal aphids, Sitobion avenae (Hemiptera: Aphididae), to locate and colonize their wheat host plants are reduced in wheat–clover intercrops, but not in wheat–pea intercrops. At the population level, and accounting for host plant biomass, only intercropping clover with wheat significantly reduced aphid densities.
Summary
1. The way light stress controls the recruitment of aquatic plants (phanerogams and charophytes) is a key process controlling plant biodiversity, although still poorly understood. Our aim was ...to investigate how light stress induced by phytoplankton, that is, independent from the aquatic plants themselves, determines the recruitment and establishment of plant species from the propagule bank. The hypotheses were that an increase in light stress (i) decreases abundance and species richness both of established aquatic plants and of propagules in the bank and (ii) decreases the recruitment success of plants from this bank.
2. These hypotheses were tested in 25 shallow lakes representing a light stress gradient, by sampling propagule banks before the recruitment phase and when the lakes are devoid of actively growing plants (i.e. at the end of winter), established vegetation at the beginning of the summer and phytoplankton biomass (chlorophyll a) during the recruitment and establishment phase.
3. The phytoplankton biomass was negatively correlated with the richness and abundance of established vegetation but was not correlated with the propagule bank (neither species richness nor propagule abundance). The similarity between the propagule bank and established vegetation decreased significantly with increasing phytoplankton biomass.
4. The contrast in species composition between the vegetation and the propagule bank at the highest light stress suggests poor recruitment from the propagule bank but prompts questions about its origin. It could result from dispersal of propagules from neighbouring systems. Propagules could also originate from a persistent propagule bank formerly produced in the lake, suggesting strong year‐to‐year variation in light stress and, as a consequence, in recruitment and reproductive success of plants.
Questions: The highest species richness is usually expected at an intermediate stage of development since the last major disturbance event, but some studies have shown that ecosystem productivity and ...dispersal may modify this pattern, suggesting the need for further studies on the effects of productivity and dispersal on the dynamics of species richness through succession. In this study, we analysed aquatic plant species richness in relation to (1) succession stage, measured as numbers of years since the last disturbance that affected the ecosystems; (2) lake productivity, measured as the chlorophyll a concentration; and (3) connectivity to similar nearby ecosystems, a proxy for the potential input of diaspores. Location: Shallow lakes of the Dombes region, France. Methods: Every 5—7 yr these shallow lakes are emptied and left to dry out for 1 yr. These drought disturbances lead to complete destruction of the submerged aquatic plant communities. Sixty lakes arranged along a gradient of productivity were selected. The probability of diaspore input was considered to increase from upstream to downstream, as lakes are organized in hydrologically connected networks via ditches, through which the downstream lakes receive water from the upstream lakes. For each lake, the aquatic plant species richness (from systematic summer vegetation sampling), time since the last disturbance (last summer drying), productivity (estimated as chlorophyll a concentration) and probability of diaspore input (assessed from position in the network) were recorded. Results: The aquatic plant species richness decreased with the time since the last disturbance for all of the lakes, but there was a significant interaction with the chlorophyll a concentration and position of the lake in the network. At the lowest ecosystem productivities, the relationship between successional stage and species richness was hump-shaped, whereas the species richness decreased with increasing time since the last disturbance when productivity increased. The lake's position in the network did not influence species richness during the first 2 yr after disturbance, but from year 3 and thereafter, lakes connected to high numbers of upstream lakes consistently exhibited decreased richness, contradicting the expected trend of increasing species richness with increasing diaspore inputs. Conclusions: This study indicates that both ecosystem productivity and connectivity strongly affected the relationship between aquatic plant species richness and succession, and that these factors should be taken into account in further developments of the intermediate disturbance hypothesis.
•We interviewed 79 farmers from 5 countries regarding result-oriented measures.•A majority of farmers stated preference for result-oriented measures.•It is seen as easier to implement and providing ...more flexibility for management.•A lot of constraints are also seen by farmers regarding result-oriented measures.•Advice, support, or training is strongly needed for implementation at a wider scale.
Throughout the last decades, both reactive and proactive incentive policies have been developed to support farmers implementing environmental and biodiversity friendly management practices. More recently, however, result-oriented agri-environment measures have also been designed, where farmers are remunerated based on the achievement of certain results (e.g. a specific number of plant species on grasslands) and not solely on the implementation of defined management practices. We analysed this specifically in the context of mountainous farming in different Alpine countries. We carried out 79 interviews with farmers in different case study regions in Germany, France, Austria, Italy, and Switzerland. They included also details regarding farmland and biodiversity management, as well as the farmers’ perceptions of and involvement in result-oriented measures. Lastly, we asked farmers to suggest new future measures.
Many of the farmers interviewed already engaged in agri-environment measures contracts, with a subset using result-oriented contracts. Farmer motivations to become involved with contracts included economic benefits and environmental preservation. Despite perceived constraints in the implementation of result-oriented measures, many farmers would prefer this approach, as it is seen as easier to implement and provides more flexibility to adapt its use to the specific conditions of their farm. In relation to biodiversity management, while many farmers would favour different types of grassland management measures to improve diversity of wild plants and animals (domesticated breeds and wild animals) on the farm, they experienced difficulty in articulating own suggestions for result-oriented measures. Our study shows that the result-oriented approach is an attractive option for many farmers, but a strong need for advice, support, or training would be necessary to implement such measures at a wider scale.
Background:
Agroecology is increasingly seen as an important contribution for the development of more sustainable agriculture and food systems. Research can have a main role to support this path. ...Although it seems that there is a gradual increasing body of agroecology research, it clearly lacks good knowledge about this. The main objective of this study was therefore to map research projects related to agroecology in Europe with the aim to characterize European research in terms of implementation of agroecology elements, identify needs for the future cross collaboration between countries and networks, and support the setting up of appropriate research agendas fostering agroecology research in Europe.
Methods:
A desktop research with different databases related to European and transnational funding programmes was carried out to identify funded research projects involved in agroecology. The obtained projects were used to perform a social network analysis. Furthermore, two surveys were conducted, one with coordinators of identified projects and a second one for researchers engaged in agroecology.
Results:
Our study highlighted a predominant trajectory of agroecology research prone to the transformation of the agri-food system. France, Germany, Italy, Netherlands, Portugal, Spain, and United Kingdom were the most active countries engaged in agroecology research. In all surveys, issues related to efficiency improvement, synergies strengthening, local economy development, and co-creation and sharing of knowledge were the most implemented to support agri-food transformation. Transdisciplinary approaches were mainly addressed by European projects. Surveys reported a limited participation of value chain actors, while researchers, farmers, and their associations were the most involved. Survey respondents suggested to increase project duration and to introduce flexibility methods to modulate research actions according to the dynamic of the contexts.
Conclusion
: On the basis of the results, some policy recommendations were provided to fostering agroecology research in Europe and its contribution for transformation of agri-foods systems.
Background:
Redesigning the agri-food system through agroecology represents a common ambition among practitioners, activists and scholars to achieve environmental and socio-economic sustainability. ...Research can have a main role to support this path. Although it seems that there is a gradual increasing body of agroecology research, it clearly lacks good knowledge about this. The main objective of this study was therefore to map research projects related to agroecology in Europe with the aim to characterize European research in terms of implementation of agroecology elements, identify needs for future cross collaboration between countries and networks, and support the setting up of appropriate research agendas fostering agroecology research in Europe.
Methods:
A desktop research with different databases related to European and transnational funding programmes was carried out to identify funded research projects involved in agroecology. The obtained projects were used to perform a social network analysis. Furthermore, two surveys were conducted, one with coordinators of identified projects and a second one for researchers engaged in agroecology.
Results:
Our study highlighted a predominant trajectory of agroecology research prone to the transformation of the agri-food system. France, Germany, Italy, Netherlands, Portugal, Spain, and United Kingdom were the most active countries engaged in agroecology research. In all surveys, issues related to efficiency improvement, synergies strengthening, local economy development, and co-creation and sharing of knowledge were the most implemented to support agri-food transformation. Transdisciplinary approaches were mainly addressed by European projects. Surveys reported a limited participation of value chain actors, while researchers, farmers, and their associations were the most involved. Survey respondents suggested to increase project duration and introduce flexibility methods to modulate research actions according to dynamic of the contexts.
Conclusion:
On the basis of the results, some policy recommendations were provided to fostering agroecology research in Europe and its contribution for transformation of agri-foods systems.
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