Francesca Di Pietro

Assessing ecologically sustainable agricultural land-use in the Central Pyrénées at the field and landscape level

Abstract Sustainable land use in agricultural systems involves the implementation of agricultural practices at the landscape level instead of at a field level. To test the above hypothesis a case study was conducted in two valleys of the Central Pyrenees (France), with two villages using two contrasting farming patterns: one village used a strong group organisation of agricultural practices at the valley level, while the other used a collection of practices at the field level. Two indicators of landscape organisation were used on both villages. The first indicator was the statistical contribution of the environment to the choice of agricultural practices by farmers, and was calculated at the field level on the overall valley territory. The second indicator was based on relationships between agro-ecological units and farms, measured at the valley level. The comparison between the group practices organised at the valley level and the individual practices organised at the field level showed that the latter system, with fragile and unstable agro-ecological units, had spatially specialised farms, and environmentally independent agricultural practices. Conversely the group practices used at the valley level were linked to stable agro-ecological units, fragmented farms, and environmentally dependent agricultural practices. The ecological sustainability of larger territories seemed to be in opposition with the standard criteria judging economical sustainability of farms. This analysis showed that the dependence of agricultural practices on the environmental features (i.e. the valley level versus the individual farm) secured the sustainability of the resources and landscape, even if it was in contradiction with a farm’s economical criteria. The assessment of agro-environmental practices at a landscape level, intended as a natural level of organisation (such as valleys or watersheds) and larger than the plot level, is necessary, in order to enhance the effectiveness of future agricultural policies.

Functional response of plant assemblages to management practices in road–field boundaries

Questions Management practices implemented on road verges are partly established to preserve biodiversity in agricultural landscapes. Their evaluation was primarily based on the analysis of the taxonomic structure and composition of communities. What is the relationship between management practices and the functional characteristics of road-field plants within elements? Location Western-central France. Methods We sampled the berm, the embankment and the field margin of 40 road-field boundaries located in Western-central France, an area where a delayed mowing of some berms has been practised since 2009 for biodiversity reasons. We characterised management practices implemented on the different elements, i.e. the frequency and timing of mowing (early summer or late summer), the frequency of herbicide treatment in field margins and the nitrogen input rate. We retrieved from databases seven functional traits and types known to be influenced by management practices. To identify relationships between traits and environmental variables we first performed partial RLQ analyses to remove any potential confounding effect of the landscape context studied. We then computed fourth-corner statistics to quantify relationships between traits, environmental variables and partial RLQ axes. Results Late mowing of the berm promoted nitrophilous species within berms and competitive rather than ruderal species within arable field margins. The frequency of herbicide treatment in field margins promoted broadleaf species within this element and, to a lesser extent, within embankments. Finally, the functional characteristics of communities of the three elements were not influenced by the level of nitrogen input in field margins. Conclusions In our environmental context, managing road verges affected the functional structure of plant assemblages both within them and within their adjacent arable field margins. We suggest a single early mowing of berms as a valuable practice for both conservation purposes and weed risk control in adjacent field margins. This article is protected by copyright. All rights reserved.

Community Gardens and Their Potential for Urban Biodiversity

The aim of this research was to explore the potentialities of community gardens—a specific type of urban garden—in terms of urban biodiversity and ecological continuity in the city. We considered the three main scales of organisation of urban ecosystems: local individual habitat, intermediate urban landscape and the larger scale encompassing the entire urban area. The study site within the urban agglomeration of Tours currently contains 29 clusters of community gardens, mainly situated in three central municipalities of the urban area; 12% of the community gardens have disappeared over the last ten years due to residential and industrial urban development. Analysis of land tenure and morphological characteristics of the gardens highlighted that alongside a gradient of very varied gardens, two groups of community gardens can be identified, one more precarious situated on building land, the other established on non-building land in floodable areas, and on road and railway easements. Indeed, at the agglomeration scale half of the community gardens are located in high flood hazard areas and about a third are situated less than 100 m from a railway line or main road network. A measure of the potential ecological continuity of the urban green corridor provided by community gardens compared to urban green spaces shows that the loss of ecological continuity in the event of urbanisation of community gardens would be considerable. Relegated by urban pressure to areas of non-building land, some community gardens could play the role of a discontinuous ecological corridor due to their location along linear axes within the city: water courses, main roads and railway lines. However, the gardening techniques practised there can limit their capacity to contribute to plant diversity in the city.

The contribution of hierarchy theory to environmental assessment: application to water resource management

Environmental assessment methods are generally based on mono-disciplinary approaches drawn from biophysical or social sciences. This paper discusses the use of hierarchy theory to represent ecological systems when building a cross-disciplinary environmental assessment methodology in which a variety of legitimate views are formally taken into account. A hierarchical approach is applied to the study of an environmental problem arising from conflicting water resource allocation requirements among different activities competing for this resource in an eastern Sicilian river basin (Italy). A second case study suggests the usefulness of hierarchy theory in analysing how a community perceives a natural resource and how the concept of natural heritage changes over time.