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Communication Dans Un Congrès Année : 2011

Intra-annual heterogeneity of the cultivated mosaic: impact on carabid beetle populations

Stéphanie Aviron
Chloé Vasseur
  • Fonction : Auteur
Sophie Puyo
  • Fonction : Auteur
Stéphanie Saussure
  • Fonction : Auteur
Jacques Baudry

Résumé

Spatio-temporal heterogeneity is recognised as a key factor for biodiversity. In agricultural landscapes, landscape heterogeneity is mostly described by the amount of semi-natural elements. In addition, the heterogeneity of cover types in the cultivated matrix might also influence biodiversity (Fahrig et al. 2011). Within a year, this matrix is highly heterogeneous in space and time, due to the diversity of crop covers, to crop phenology and cultural practices. Thus, for species that use crops during their life cycle, the cultivated matrix can be viewed as a mosaic of asynchronous habitats with fast-changing suitability, which is likely to affect species distribution and survival (Vasseur et al. 2008). In this study, we tested whether intra-annual heterogeneity of the cultivated mosaic affects population distribution and dynamics of a beneficial carabid species (Pterostichus melanarius). We hypothesize that distribution of carabid populations is driven in space and time by seasonal changes in habitat suitability in crops, and by insect movements from unsuitable to suitable crops during the season. The study was conducted in a 30ha mosaic of five to six adjacent crop fields (winter cereals, maize) and their boundaries in Western France. Winter cereals and maize exhibit dense vegetation cover at different periods (May-July and July-September respectively) and were supposed to have asynchronous suitability for carabid beetles. From May to September 2009 and 2010, trapping was used to describe: 1) densities of post-emerged adults in crop fields (enclosed emergence arenas), 2) carabid activity-density in crop fields and field boundaries (open pitfall traps) and 3) carabid movements between adjacent crop fields, and between crop fields and their boundaries (directional barrier traps). In the early season (May-July), carabid activity-density was higher in cereals than in maize fields. This was partly explained by lower densities of emergent adults in maize fields due to destructive effects of spring soil tillage on larvae and pupae in maize. On the other hand, suitable vegetation cover and microclimatic conditions in cereals might also have result in higher carabid activity-density. During this period, carabid beetles moved preferentially from maize fields with bare soil, toward cereal fields with dense vegetation cover. Later in the season, cereal harvest and vegetation growth in maize were followed by a drastic increase in carabid activity-density in maize fields due to massive colonization of these crops by insects. The results suggest that the distribution and dynamics of carabid populations is driven by asynchronous suitability of cereals and maize fields, which act as complementary habitats during the season. The spatio-temporal heterogeneity of the cultivated mosaic might therefore play a crucial role for the persistence of beneficial carabid beetles.
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hal-01458577 , version 1 (06-06-2020)

Identifiants

  • HAL Id : hal-01458577 , version 1
  • PRODINRA : 46369

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Stéphanie Aviron, Chloé Vasseur, Sophie Puyo, Stéphanie Saussure, Jacques Baudry. Intra-annual heterogeneity of the cultivated mosaic: impact on carabid beetle populations. Colloque IALE world “landscape ecology for sustainable environment and culture”, Aug 2011, Pekin, China. pp.14. ⟨hal-01458577⟩
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