Benoît Ricci

Impact of agricultural practices and environmental variables on plant-parasitic nematode communities in fields at a landscape scale

Agricultural practices shaping plant-parasitic nematode (PPN) assembly are still unclear, and this limits our understanding of the impact of anthropic disturbances on the resilience of PPN communities and the emergence of agronomic problems. Here the abundance and diversity of PPN in France’s oilseed rape production area was determined by sampling 72 fields over two consecutive years. We identified and counted PPN taxa and collected anthropic and environmental variables for the past 5 years. PPN were assigned to seven genera and one family including PPN that have not been identified to genus level. Using multiple correspondence analyses, we selected the main variables and tested their effect on the abundance of each taxon with mixed generalised linear models. We emphasise that at the landscape scale investigated, crop rotations were no longer a major factor impacting the PPN communities. However, we observed that tillage and pesticides had a significant impact on several taxa.

Issues and challenges in landscape models for agriculture: from the representation of agroecosystems to the design of management strategies

ContextAgroecosystems produce food and many other services that are crucial for human well-being. Given the scales at which the processes underlying these services take place, agricultural landscapes appear as appropriate spatial units for their evaluation and management. The design of sustainable agricultural landscapes that value these services has thus become a pressing issue but faces major challenges stemming from the diversity of processes, their interactions and the number of scales at stake. Agricultural landscape modelling can provide a key contribution to this design but must still overcome several difficulties to offer reliable tools for decision makers.ObjectivesOur study aimed at shedding light on the main scientific and technical difficulties that make the building of landscape models that may efficiently inform decision-makers a complex task, as well as translating them in terms of challenges that can be further investigated and discussed.MethodsWe examine current issues and challenges and indicate future research needs to overcome the scientific and technical obstacles in the development of useful agricultural landscape models.ResultsWe highlight research perspectives to better couple landscape patterns and process models and account for feedbacks, integrate the decisions of multiple stakeholders, consider the spatial and temporal heterogeneity of data and processes, explore alternative landscape organisations and assess multiobjective performance.ConclusionCoping with the issues and challenges discussed in this paper should improve our understanding of agroecosystems and give rise to new hypotheses, thereby informing future research.

Annual variation of oilseed rape habitat quality and role of grassy field margins for seed eating carabids in arable mosaics

Promoting the weed seed predation service by carabids requires an understanding of the spatio‐temporal distribution of carabid species during the cropping season. In the present study, we analyzed the spatio‐temporal dynamics of three abundant seed‐eating carabid species in oilseed rape (OSR) and its adjacent habitat (cereal crop or grassy field margin) with four indicators: activity density, nutritional state, the use of the interface with the adjacent habitat, and the proportion of carabids leaving OSR. The activity density and nutritional state of Poecilus cupreus decreased after harvest, comprising a period related to a decrease of resource availability and the end of life cycle. We detected a tendency of movement from OSR to the adjacent habitat after harvest for Amara similata, although this was not as strong as expected. The presence of grassy field margins influenced the spatio‐temporal dynamics of Pseudoophonus rufipes and A. similata, suggesting that spillover processes exist for these two species but not for P. cupreus. Monitoring four complementary indicators gave a more thorough understanding of the perception of local and adjacent habitats by carabids, which is a prerequisite for the identification of landscape configurations that enhance the activity density of these natural enemies within crops.