AgriPop Friday talks

Friday's Agripop Talks

01 March 2013 - 11:30 - Salle Ragondin

Land use influences the ground beetle Poecilus cupreus at different spatial and temporal scales in an agricultural landscape

Ronan Marrec

Certains facteurs peuvent contraindre la distribution et les abondances des espèces. L'abondance d'une population à n'importe quel endroit d'un paysage a été résumée comme fonction des taux de natalité et de mortalité; la capacité intrinsèque de l'espèce à se disperser et se déplacer au sein et entre les sites; et l'accessibilité des sites aux individus dispersant.

Dans les environnements complexes et instables, tels que les agroécosystèmes, l'accessibilité et la favorabilité des habitats pourraient être restreintes, pour deux raisons majeures. Premièrement, la plupart des cultures sont annuelles, et deuxièmement, la plupart des cultures ont des phénologies asynchrones et variant dans le temps. En conséquence, les terres arables ne fournissent pas un habitat constant au cours de l'année et d'une année sur l'autre.
Dans de tels environnements changeants, j'étudie (i) quels types d'éléments paysagers affectent les patrons de distribution et d'abondance chez un Coléoptère carabique très abondant dans les agrosystèmes de l'ouest de la France, Poecilus cupreus (L.), et (ii) à quelle(s) échelle(s) ils influences ces patrons. Je vous présenterai vendredi 1er mars mes résultats sur ce sujet...

Some factors constrain species' distribution and abundances. The population abundance at any location in a landscape has been summarized as a function of local birth and death rates; the intrinsic ability of species to disperse and move within and between areas; and the accessibility of sites to dispersing individuals.

In complex and unstable environments, such as agroecosystems, accessibility and suitability of habitats could be restricted in time and space, for two main reasons. First, much of the fields are annual, and secondly, much crop identities have asynchronous and varying phenologies. As a consequence, arable fields do not provide a constant habitat throughout the year and from one year to another.
In such moving environments, I am studying (i) which kinds of environmental features affect distribution and abundance patterns in a very abundant carabid beetle in our agrosystems in Western France, Poecilus cupreus (L.), and (ii) at which scale(s) they influence these patterns. I will present you on Friday 1st March my results on this subject...

AgriPop Friday talks

Friday's Agripop Talks

  22 February 2013 - 11:30 - Salle Ragondin

Master student project presentations

Do you remember? Just the other day we were discussing that we had never had so many people working on community ecology in our team as this year. Well, here's an example - two M2 project presentations, both on community ecology! Cool, isn't it? And both are really nice and interesting projects, so come along and help the students discuss their project plans!

Relations plantes-criquets en milieu agricole: étude de l'abondance des criquets par une approche "traits fonctionnels"

Gaetane Le Provost

Aspects temporels de la structuration des communautés adventices
Klervi Tocze

So, to start with, where do these figures come from? Yep, that painting included ... come on, it's from some of those so-called 'classics or foundation papers'. There might be some candy for those guessing it (Disclaimer: this promise has the same validity as politicians' promises before elections).

Going back to the upcoming M2 projects - Gaetanne aims to understand what structures grasshopper communities in agricultural landscapes:

Les communautés d’herbivores constituent un maillon essentiel au sein des réseaux trophiques. L’organisation de ces communautés dépend de processus « bottom-up » et « top-down ». Afin de comprendre la structure de ces communautés, il parait donc nécessaire de prendre en compte le réseau trophique dans son ensemble : ressources, prédateurs, mais également les facteurs abiotiques qui vont influencer la qualité de l’habitat. 

Dans un premier temps, les patrons d’abondance de plusieurs espèces de criquet seront analysés en fonction de la qualité et quantité de ressource, de la densité de prédateurs, du microclimat. Or la sensibilité des différentes espèces de criquets à ces facteurs dépend de la variabilité de leurs traits fonctionnels.  

Dans un deuxième temps, une approche fonctionnelle sera donc utilisée pour décrire la niche écologique des différentes espèces et comprendre leurs réponses aux facteurs du milieu, à travers l’étude de leurs traits fonctionnels.

Photo by eliz, downloaded from http://www.fotonatura.ro: http://bit.ly/15wbNsL

 Klervi instead is interested in wild plants which have the unfortunate habit to try to grow on crop fields - often called 'weeds' - and the processes driving temporal variation in community structure:

Comprendre les règles d’assemblage des communautés d’adventices apparait comme essentiel pour gérer à la fois leurs impacts négatifs sur la production agricole et  positifs sur le maintien de la biodiversité (en tant que ressources et habitats). Il existe en écologie des communautés, plusieurs théories sur les patterns observés. En effet, la structure des communautés peut être déterminée par différents facteurs environnementaux, spatiaux ou encore temporels.

On sait que les adventices présentes dans une parcelle sont dépendantes à la fois des pratiques culturales mises en place mais également de la banque de graines présente. Cette dernière étant influencée par les communautés précédentes, sous l’influence des assolements passés. C’est pourquoi, lors de ce stage, je vais étudier l’impact des facteurs temporels à travers l’effet des rotations culturales sur les communautés d’adventices.

 

photo by Jean-François Sérot, downloaded from http://serotjf.com

See you on Friday!

  

 

AgriPop Friday talks

Friday's Agripop Talks

  15 February 2013 - 11:30 - Salle Ragondin

Assessing the effectiveness of different  approaches to species conservation

AndreaSantangeli

Finnish Museum of Natural History, University of Helsinki, Finland

from: Milky Way Scientists facebook page

OK, don't worry, that's not Andrea, it's some other unlucky bloke. And the talk will also not be directly about eagles.

Actually, Andrea's talk will not be taxon specific, as it addresses an important question of general concern, i.e. how to assess the effectiveness of alternative approaches to conserve species. Especially given the high prevalence of highly altered, human-dominated landscapes, it is not trivial to understand how to conserve the biodiversity that persists in these areas.

Now, to make sure that I stop writing silly things, let's use Andrea's own words -- though I may continue inserting random pics :-)

Humans have used natural resources for thousands of years, and created and maintained extensive traditional landscapes that nowadays support important biodiversity in forested and open-land biomes. However, these landscapes have undergone massive changes during recent decades owing to the intensification of extraction regimes in forests and farmlands across large regions of the globe. As a consequence, most species that have adapted and thrived for centuries or millennia in traditionally managed landscapes are showing signs of population decline and regional extinctions. 

To revert the negative impacts of modern intensive practices, large sums of money and various conservation approaches have been implemented. Unfortunately, such large efforts have not always been based on solid and updated scientific evidence, and therefore they have achieved only mixed successes. In order to maximise the impact of limited conservation resources, it is crucial that evaluation studies are carried out. These would ultimately allow learning from past actions and take better decisions in the future. 

 from: http://bit.ly/Z9NPmk

Here I evaluate the effectiveness of species-specific conservation measures implemented in contrasting landscapes (from forest to farmland) and with different underlying approaches, from a voluntary inexpensive approach (only based on self-motivation of landowners), a voluntary market-based approach (where landowners are compensated), to a compulsory approach (where landowners have no choice; achieved through land reservation or legislation).

After evaluation of their benefit to wildlife, I show that some expensive and coercive management interventions may result unnecessary; some, like legislation, may not be effective at achieving their goal while others, such as inexpensive voluntary approaches, can achieve important results with very limited resources. 

Overall, the case studies presented here lead to a general conclusion that evaluating conservation interventions can reveal relevant and sometimes unexpected outcomes that have important implications for improving the cost-effectiveness of conservation efforts.

Interesting, isn't it? So, see you all Friday am!

AgriPop Community Ecology Working Group

Hey, you know what? Apparently there have never been so many people working on community ecology in our team as this year. Yeah, that kind of dudes contemplating entangled banks, making it sound that everything in ecology is inextricably complex -- or just a complex pattern produced by simple general laws (depending on one's preferences) -- and getting into heated debates if 'competition' or 'facilitation' is driving everything.

Now, slightly more seriously, today we've decided to form a working group on community ecology, with 3 aims:

1. Meet once every week to discuss in depth a paper on community ecology
2. Collect and share in a common repository (DropBox & Mendeley) the pdfs of papers
3. Join our efforts in surveying new papers of common interest to us.

 The papers we will aim to discuss will comprise theory, methods, review papers, as well as empirical papers. The format we aim for is more that of a workshop than a typical journal club. Cool idea, isn't it? So, after a brief bout of email exchanges today four of us (Nico, Ronan, Laura and myself) decided that we will meet every Wednesday @ 13:30. If you like the idea, please come and get in touch with us! Yep, we are thinking also about you, the new M2 students!

We will start it by discussing an apparently cool paper by Rzanny et al. currently in press at Oikos, based on experimental data from the fancy Jena Experiment:

"Bottom–up and top–down forces structuring consumer communities in an experimental grassland"

And Oikos has been nice enough to put up also a blog post about this paper, so please go and take a look here!

So, don't be shy and join us!

Friday's Agripop Talks

08 February 2013 - 11:30 - Salle Ragondin

The oilseed crop phenology influences life history traits of honey bees in intensive farmland landscapes

Fabrice Requier

Pollination is a key ecosystem service, a large part of which is provided by insects, especially bees. Also modern agriculture heavily relies on pollination services (e.g. see here estimates provided by the FAO), but modern intensive farming systems negatively impact bee populations. A key difficulty for bee population is that intensively farmed landscapes are  rather homogeneous and lack semi-natural vegetation patches which assure a continuous supply of food for bees. Instead, a massive supply of pollen and nectar is provided by farmed crops, such as oilseed rape, but only once during a very limited period. 

Understanding how highly concentrated distribution of food resources impacts bee populations and affects the life-history traits of individuals, is one of the aims of the PhD of Fabrice. To answer this question Fabrice uses a cool study system with RFID tags applied to individual bees living in hives in different landscapes.

To hear and discuss the newest results, come this Friday! 

Key-words: Honeybees, Apis mellifera L., agricultural landscape, nutritional stress, food availability, crop phenology, oilseed, life-history traits, temporal polyethism, RFID tags