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Universidad Barcelona (2010)

WEED DIVERSITY OF DRYLAND CEREAL FIELDS : EFFECTS OF AGRICULTURAL INTENSIFICATION

Armengot Martínez, Laura

Titre : LA FLORA ARVENSE DELS CONREUS CEREALÍSTICS DE SECÀ : EFECTES DE LA INTENSIFICACIÓ AGRÍCOLA

WEED DIVERSITY OF DRYLAND CEREAL FIELDS : EFFECTS OF AGRICULTURAL INTENSIFICATION

Auteur : Armengot Martínez, Laura

Université de soutenance : Universidad BARCELONA

Grade : Doctorado 2010

Résumé
Agricultural intensification over the past decades, at both the local (management intensification) and the landscape scale, is the main reason for the current biodiversity decline. The decline of arable weed diversity in agro-ecosystems is a matter of great concern because of its key role in supporting biodiversity at higher trophic levels. This thesis focus on the biotic and abiotic factors that may have an influence on arable weed species, in order to evaluate their effect and develop mechanisms to counteract the increasing loss of weed diversity. To fulfil these objectives, several experiments were performed in central Catalonia, in 18 localities placed along a gradient of landscape complexity. In each locality, an organic and a conventional cereal farm were selected. The results of this thesis show that intensification of management, evaluated by means of (i) the comparison of organic and conventional fields (Chapters 1, 3 and 4), (ii) several management variables (Chapters 2 and 3) and an index of land-use (Chapter 2), negatively affects weed flora. The characterization of farming practices (Chapter 2) indicates that land-use intensity is lower in organic fields but also that there is a gradient of land-use intensity between and within organic and conventional farms. These results suggest that it is an over-simplification to always equate organic farming with low intensive management. This thesis also demonstrates that landscape complexity does not influence weed flora within cereal fields (Chapter 3), although several authors have reported some effects on boundaries and crop edges. Finally, the results also highlight that native invaders, such as Lolium rigidum and Avena sterilis, could have negative effects on diversity of weed communities, as it has been previously proved for alien species (Chapter 4).

Mots clés : BOTANICA, ECOLOGIA VEGETAL ; CULTIVOS EXTENSIVOS

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Page publiée le 18 décembre 2011, mise à jour le 13 février 2019