Effect of agricultural intensification on taxonomic and functional diversity of weed communities in cereal fields

Resumen

Agricultural intensification at field and landscape scales has lead to a dramatic decline of weed diversity in cereal crops during the last few decades across Europe. Intensification at the field scale is related to the increasing of external inputs (e.g. fertilizers and pesticides). At the landscape scale, agricultural intensification is associated to a decrease in landscape complexity, because of the increasing proportion of arable land at the expense of natural or semi-natural habitats. Research on the response of weed diversity to agricultural intensification has been mostly focused on taxonomy (e.g. number of species). However, intensification may also impact the functional diversity of weed communities. Functional traits (e.g. life form, seed mass, pollination type) are key components of diversity that, to date, have received little attention. In this context, the general goal of the present thesis was to study the impact of agriculture intensification at field and at landscape scale on the taxonomic diversity, functional diversity and the distribution of functional traits of weed communities in cereal crops systems under conventional management. The overall structure of this thesis is composed of six chapters; the first, fifth and sixth correspond to the general introduction, general discussion and general conclusions respectively, while chapters II, III and IV correspond to three researching studies. Chapter II is focused on the plant communities inhabiting field margins and attemps to assess the effect of margin width and landscape complexity on plant diversity. Chapter III aims to compare the effects of intensification on weed diversity inside crop fields in climatically and floristically contrasting countries, UK and Spain. Finally, chapter IV is devoted...