Jean-Pierre Rossi

Bio: Jean-Pierre Rossi is an academic researcher from SupAgro. The author has contributed to research in topics: Population & Soil biology. The author has an hindex of 36, co-authored 117 publications receiving 4241 citations. Previous affiliations of Jean-Pierre Rossi include Institut de recherche pour le développement & Commonwealth Scientific and Industrial Research Organisation.

Range expansion of the invasive brown marmorated stinkbug, Halyomorpha halys: an increasing threat to field, fruit and vegetable crops worldwide

Abstract: The brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), has emerged as a harmful invasive insect pest in North America and Europe in the 1990s and 2000s, respectively. Native to eastern Asia, this highly polyphagous pest (>120 different host plants) is spreading rapidly worldwide, notably through human activities. The increasing global importance of the pest suggests that more coordinated actions are needed to slow its spread and mitigate negative effects in invaded areas. Prevention of large-scale outbreaks will require accurate identification and effective mitigation tools to be rapidly developed and widely implemented. In this short review, we update the current distribution of H. halys, discuss potential geographic range expansion based on passive and active dispersal and provide insight on the economic, environmental and social impact associated with H. halys.

SOM management in the tropics: Why feeding the soil macrofauna?

Abstract: This paper synthesises information on the food requirements of soil macroinvertebrates and some of their effects on soil organic matter dynamics. Some clues to techniques that would optimise their activities through organic matter management are suggested. Soil macroinvertebrates can consume almost any kind of organic residues in mutualistic association with soil microflora. Significant amounts estimated at several T per ha of predominantly easily assimilable C are used yearly in natural ecosystems as energy to sustain these activities. Sources of C used are highly variable depending on the feeding regime. The largest part of the energy assimilated (e.g., 50% by the tropical earthworm Millsonia anomala) is actually spent in burrowing and soil transport and mixing. Bioturbation often affects several thousand tons of soil per hectare per year and several tenth of m3 of voids are created in soil. A great diversity of biogenic structures accumulate and their nature and persistance over time largely controls hydraulic soil properties. The OM integrated into the compact biogenic structures (termite mounds, earthworm globular casts) is often protected from further decomposition. Most management practices have negative effects on the diversity and abundance of macroinvertebrate communities. Structures inherited from faunal activities may persist for some weeks to years and the relationship between their disappearance and soil degradation is rarely acknowledged. When SOM supply is maintained but diversity is not, the accumulation in excess of structures of one single category may have destructive effects on soil. It is therefore essential to design practices that provide the adequate organic sources to sustain the activity and diversity of invertebrates. Special attention should also be paid to the spatial array of plots and rotations in time.

Comparative community ecology studies on old world figs and fig wasps

Abstract: Ficus and their species-specific pollinator wasps (Agaonidae) form a remarkable plant–insect obligate mutualism Each monoecious fig species also shelters a community of nonpollinating chalcids, composed of both gallmakers and parasitoids The few previous studies that took these species into account aimed at determining their potential effect on the mutualism To go further, we argue that the fig wasps represent an interesting model for studies of community ecology Figs and fig wasps of different groups were studied in Cote d'Ivoire to quantify local ecological interactions Regardless of their fig host or taxonomical position, we identified three ecological groups of nonpollinating fig wasps on the basis of their timing of oviposition in the fig and on their oviposition behavior Pollinating and nonpollinating fig wasps were shown to interact intimately, and to have a significant effect on the host plant in at least some cases Each species of the community seems to preferentially oviposit in a part of the female flowers, depending on their depth inside the fig Convergence in fig exploitation thus exists in various chalcid lineages, and the community structure and organization are very similar between fig species Concepts developed in parasitoid community ecology could now be tested on this promising model

Large-scale Effects of Earthworms on Soil Organic Matter and Nutrient Dynamics

Abstract: This chapter synthesizes information on the effects of earthworms on soil systems at scales longer than 1 year, and earthworm behavior that may affect these processes is detailed

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Biochar effects on soil biota – A review

Abstract: Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.

The ecodist Package for Dissimilarity-based Analysis of Ecological Data

Abstract: Ecologists are concerned with the relationships between species composition and environmental framework incorporating space explicitly is an extremely flexible tool for answering these questions. The R package ecodist brings together methods for working with dissimilarities, including some not available in other R packages. We present some of the features of ecodist, particularly simple and partial Mantel tests, and make recommendations for their effective use. Although the partial Mantel test is often used to account for the effects of space, the assumption of linearity greatly reduces its effectiveness for complex spatial patterns. We introduce a modification of the Mantel correlogram designed to overcome this restriction and allow consideration of complex nonlinear structures. This extension of the method allows the use of partial multivariate correlograms and tests of relationship between variables at different spatial scales. Some of the possibilities are demonstrated using both artificial data and data from an ongoing study of plant community composition in grazinglands of the northeastern United States.