Agrocampus Ouest

About: Agrocampus Ouest is a education organization based out in Rennes, France. It is known for research contribution in the topics: Population & Soil water. The organization has 2160 authors who have published 3219 publications receiving 75606 citations. The organization is also known as: Institut supérieur des sciences agronomiques, agroalimentaires, horticoles et du paysage & Higher Institute for agricultural sciences, food industry, horticulture and landscape management.

Global change in the trophic functioning of marine food webs.

Abstract: The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI) measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI) quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950–2010 time-periods. Global trends were identified and cluster analyses were used to characterize the variability of trends between ecosystems. Results showed that the most common pattern over the study period is a global decrease in TCI, while the ECI indicator tends to increase. Thus, changes in species assemblages would induce faster and apparently more efficient biomass transfers in marine food webs. Results also suggested that the main driver of change over that period had been the large increase in fishing pressure. The largest changes occurred in ecosystems where ‘fishing down the marine food web’ are most intensive.

Physical properties of structural soils containing waste materials to achieve urban greening

Abstract: The densification and expansion of urban areas will increase the streams of waste materials such as bricks, concrete and street sweeping waste. In parallel, green areas offer the potential to overcome many challenges that face growing/expanding cities but require the use of large amounts of natural resources such as natural topsoil and aggregates. In this work, various waste materials mixed with organic debris are tested for greening applications in urban environments as an alternative to the consumption of natural resources. Five combinations of artefacts were studied either as “growing material” (i.e. dedicated to plant growth) or “structural material” (as support for traffic). These constructed Technosols were studied in situ in lysimeters under two sets of contrasting climatic conditions at two sites in France (Angers, oceanic climate, and Homecourt semi-continental climate). They were planted with trees (Acer platanoides) and with ryegrass (Lolium perenne L.). Compared to natural soils, the constructed Technosols exhibited high porosities and highly saturated hydraulic conductivities (up to 0.76 m3 m−3, and to 34.74 cm h−1, respectively). The physical properties–i.e. macroporosity and microporosity–of these artificial soils revealed high water supply for plants, with available soil water ranging from 0.5 to 2.9 mm cm−1. Tree and ryegrass roots were able to grow in the entire soil volume available in the lysimeters. Organic matter nature and soil pH conditions appeared to be the main drivers of plant development. Constructed Technosols are suitable for vegetation growth and constitute a valuable alternative to the consumption of natural arable earth for urban greening applications, e.g. gardens, parks, and tree lines. Furthermore, they can provide high levels of relevant ecosystem functions in cities such as water retention and infiltration, plant settlement, carbon sequestration and even biodiversity habitats.