Ecosystem services and biodiversiy for agricultural landscape sustainability

The aim of this research was to provide a contribution to the study of agricultural landscape sustainability through ecological intensification concept. Ecological intensification advocates to maintain or enhance agricultural production through the promotion of biodiversity and associated ecosystem services. Therefore, we analyzed the sustainability of agricultural landscapes by assessing the impacts of agricultural intensification on (i) biodiversity and (ii) ecosystem services. In particular, after an introduction to the main topic of research (Chapter 1), the thesis is divided into four research papers: the first paper (Chapter 2) focuses on the functional quality of agricultural landscapes as defined by biodiversity and sensitivity to disturbance. Relationships between the structural characteristics and the functional qualities of agricultural landscapes have been explored and insights for their ecological and sustainable management have been obtained. We found landscape functional quality to increase with high percentage of fairly large and not too isolated semi-natural areas and a high level of landscape heterogeneity. In addition, our analysis underlined the importance of specific semi-natural habitat types such as meadows and woods, rather than others (e.g. hedgerows) for improving functional quality of agricultural landscapes. The second paper (Chapter 3) examines how agricultural intensification may affect the spread of exotic plant species (i.e. archaeophytes and neophytes) in different semi-natural habitats. We found differences among habitats on their susceptibility to be invaded by exotic plants changed according to the proximity to the source or amount of disturbance in the landscape. The presence of exotic plant species (both neophytes and archaeophytes) leads to a greater homogenization of the flora in different semi-natural habitats across the landscape. The third paper (Chapter 4) focuses on the effects of conservation tillage, in contrast to conventional tillage, on the supply of multiple ecosystems services supporting cereal production. The ecosystem services considered in the experiment were (i) production, (ii) weed control, (iii) natural aphid pest control and (iv) soil quality (SOM quantity). In addition, we examined whether landscape complexity affects the supply of natural pest control and weed control and whether intensity of fertilization influences production service and weed control. The results showed that tillage system, landscape complexity and fertilization had different influences on ecosystem services. Production did not differ between conservation and conventional tillage, whereas fertilization increased production. Conservation tillage decreased weed control services and favored a greater diversity of weeds. Landscape complexity and fertilization did not show any influence neither on weed control services nor on weed diversity. We found a greater effect of natural pest control by ground predators under conservation tillage. On the other hand, parasitism on aphids was not affected by tillage system, but increased with landscape complexity. Finally conservation tillage positively affected the soil quality. The fourth paper (Chapter 5) focuses on a single ecosystem service: natural aphid pest control. The paper deals with the interactions of soil management (i.e. conservation tillage), landscape complexity and natural enemy communities with the biological control service provided by different guilds of natural enemies in winter cereal crops (birds, flying insects/vegetation-dwelling predators and ground-dwelling predators). We found that conservation tillage supports greater overall BC of aphids in winter cereals than conventional tillage. Primarily this was due to ground-dwelling predators (carabids and arachnoids), whereas some of the other natural enemy guilds studied contributed little to aphid population control. Landscape complexity had a positive effect on parasitism only under conventional tillage but not under conservation tillage, mainly thanks to vegetation-dwelling predators and BC was higher in complex than in simple landscapes. The general conclusion of the research underlines that agricultural landscape management finalized to the improvement of ecological intensification is possible, ensuring production and environmental sustainability. The research highlights the need to join the application of environmentally sustainable cultivation practices combined with a thoughtful landscape planning mindful of semi-natural habitat type and their configuration in the pattern.