Séminaire Carine Prêcheur

Carine Prêcheur, Vendredi 8 novembre 2013

Titre: Processus démographiques influant sur une colonie de petite taille d’un oiseau marin tropical :colonie de puffins d’Audubon en Martinique.  

Dans un contexte de changement climatique, il devient nécessaire d’établir des modèles de prévision afin d’évaluer l’effet du climat et des facteurs météorologiques sur la démographie et le comportement des populations naturelles ainsi que ses conséquences sur l’équilibre des écosystèmes.  Dans des problématiques de gestion et de conservation, ces modèles nous permettraient d’évaluer le risque potentiel d’extinction et analyser les facteurs qui pourraient réduire ce risque.

De par leur position dans la chaine trophique, les prédateurs marins supérieurs peuvent constituer de bons indicateurs des variations climatiques.

Ici, nous nous intéresserons aux processus démographiques d’une colonie de petite taille d’un oiseau marin tropical. 

Summer Friday Talk

Hi All,

Luca is gone for greener grass:

where he will have a lots of new things to do:

For us Friday seminar will continue this summer with three different sessions:

Friday August 2nd

11.30 am Aurélie Dupeyron:

Community structure of carabid beetles in agricultural landscape

Friday August 9th

11.00 am Laura Henckel & Hélène Deraison

 INTECOL seminar

Friday September 13th

Ronan Marrec
European Carabidologist Meeting Seminar




have a good one,

Nico

AgriPop Friday Talks

Friday's Agripop Talk

28 June 2013 - 11:30 - 12:30 Salle Ragondin
2 Master student project presentations

1. Bees and their landscape: 
Mapping the distribution of floral resources in agricultural landscapes and their use by wild bees

Lindy Mary Corredores Hurtado

Centre d’Etudes Biologiques de Chizé & Universidad Javeriana (Colombia)

 &

2. Rôle des adventices dans l’écologie de l’abeille domestique en plaine agricole

Yoanna Marescot

Centre d’Etudes Biologiques de Chizé

 You know, on average one in every three bites of food eaten by humans worldwide depends on bees and other pollinators for a succesful harvest (see here) and our markets and grocery stores would look quite empty without their services:

Source: http://io9.com/if-bees-go-extinct-this-is-what-your-supermarket-will-513604512

and see also this very interesting post on the story of hand pollination in China by Bug_Girl, a researcher in entomology and famous blogger about insects.

Bus so, why are bees declining worldwide? This is actually a tricky question, as there appear to be multiple causes at work (e.g. see here and here) and multiple stressors may be at work, such as parasites or pesticides. In intensive agricultural landscapes, however, one important problem appears also to be the supply of sufficient floral resources over the season. For example, where should bees go to once these massive blooms of rapeseed fields have disappeared after only few weeks and it will take several more weeks before the sunflowers start to open up? 

This is the problem tackeld by the projects of today's speakers, Lindy and Yoanna. 

Lindy will present us her results of an intensive mapping effort wild flower resources in our study area and the use of these resources by domestic bees. Yoanna has investigated the feeding ecology of the domestic bee in our study area, investigating how the bees can manage to cover the period without massive supply of flowers from the crops (rapeseed and sunflower). 

As this will be the first time you see Yoanna's project, here a short abstract, too:

Depuis la modernisation de l’agriculture, les paysages agricoles sont modifiés, s’appauvrissent en diversité écologique alors même qu’ils ont longtemps abrité une grande richesse spécifique, notamment au niveau de la flore herbacée des champs cultivés. Il s’agit plus précisément des adventices, qui voient, comme tant d’autres groupes végétaux ses populations régressées. Pourtant les adventices joueraient un rôle important comme apport alimentaire aux pollinisateurs et plus particulièrement à l’abeille domestique. Nous étudions ici le rôle des adventices  au sein d’une plaine agricole de Poitou-Charentes, caractérisée par deux périodes où les ressources pour l’abeille se trouvent en excès, floraison du colza puis celle du tournesol, et entre les deux: une période d’insuffisance alimentaire.

So, please come, listen, and discuss!

Agripop Friday talks

Friday's Agripop Talk

14 June 2013 - 11:00 - 12:00 Salle Seminaire

Relations plantes-criquets en milieu agricole: 
étude du lien entre l’abondance des criquets et les traits fonctionnels des plantes

Gaëtane Le Provost

Centre d’Etudes Biologiques de Chizé & Université Paris Sud XI

 

Photo by Richard Seaman. Downloaded from http://richard-seaman.com/Arthropods/Russia/

Exciting times - Gaetanne, our master student (M2) has submitted her thesis this week! But now the viva is looming -- it'll be next Monday! You better get prepared ... hence Gaetanne will do a mock talk tomorrow to receive feedback. Please all of you, do come along!

 Here a summary of her thesis:

Agricultural intensification has caused a dramatic loss of perennial lands, which has resulted in strong declines of plant diversity and invertebrate populations, leading to cascade effects at many trophic levels. Understanding the mechanisms involved in the structuring of communities is crucial to understand ecosystem responses to global change. 

In this context, applying the “Holy Grail” hypothesis and the “Response-effect” framework to the study of multitrophic systems will improve our ability to understand the underlying processes implicated in the relationship between functional diversity and ecosystem functioning. By studying the link between plants and grasshoppers in agroecosystems, we want to quantify the relative effects of land use on the functional composition of grasslands and on invertebrate herbivore communities. 

Through analyses of several plant traits and their impact on grasshopper abundance, we have identified the effect of different land use components and plant functional diversity on the relationship between plants and herbivores in grasslands. This work proposes that response traits of plants to land use change the abundance of different grasshopper species. Our results confirm the existence of a functional structure in plant communities in response to land use, affecting grasshopper communities.

 Ah, no, not THIS quest for the holy grail ...:

It refers to a work by Sandra Lavorel and collegues (e.g. see here) ...

Hence, please come all - if you ask nicely you might even get some precious tips about secret spots to do nice "sorties naturalistes" in the surrounding areas ... ;-)

Agripop Friday Talks

Friday's Agripop Talk

07 June 2013 - 11:00 - 12:00 Salle Seminaire

Coupled dynamics of traits and populations in response to environmental change

Prof. Arpat Ozgul

Institute of Evolutionary Biology and Environmental Studies, University of Zurich (Switzerland)

If the environment changes you better change, too -- in behaviour, appearance, size, etc. But how? And what are the time scales of these responses? Our invited speaker this week, Arpat Ozgul from the University of Zurich, will present us results form his recent and ongoing research on this topic.

Here, an abstract of the talk:

A major goal in population ecology is to predict how populations will respond to environmental change. Recent studies have highlighted rapid phenotypic changes accompanying and often preceding demographic regime shifts, indicating that a trait-based demographic approach can improve our ability to predict a population’s response to environmental change. 

Furthermore, these studies show that some species can adapt to environmental change more easily than others through a range of evolutionary and ecological mechanisms; understanding these differences is crucial for identifying species that are more susceptible. 

In this talk, I will present the links between the abiotic environment, population density, individual traits (such as body size) and demography using long-term data from two mammalian systems: Soay sheep and yellow-bellied marmots, and address the following questions: “How do populations respond demographically, ecologically and evolutionarily to environmental perturbations?”

And for the really keen and diligent ones, here a few papers relevant to the talk:

Ozgul A, Coulson T, Reynolds A, Cameron T, Benton T (2012) Population responses to perturbations: the importance of trait-based analysis illustrated through a microcosm experiment. American Naturalist

Ozgul A, Childs DZ, Oli MK, Armitage KB, Blumstein DT, Olson LE, Tuljapurkar S, Coulson S (2010) Coupled dynamics of body mass and population growth in response to environmental change. Nature

Ozgul A, Tuljapurkar S, Benton TG, Pemberton JM, Clutton-Brock TH, Coulson T (2009) The dynamics of phenotypic change and the shrinking sheep of St. Kilda. Science

Photo by Arpat Ozgul

Perhaps most importantly, Arpat will be around on Friday so there will be plenty of opportunities to interact with him - including during a:

  apero et soirée barbecue chez la riviere starting at around 18:00 in Chize. 

 Tous sont le bienvenus!

Apero et barbecue will be held here!

Finally, in case you wonder why the marmot is wearing a mask -- there is a long tradition of scientists engaging beyond the laboratory to try helping their communities (e.g. see here) and Arpat is a recent example. Whilst doing this, he even discovered a new species, the Chapulcu (G. chapullini): A gremlin species native to Anatolia. Spawns when wet, goes nuts when sprayed with pesticide ;-)

Agripop Talks

Agripop Talk

10 June 2013 - 11:30 - 12:00 Salle Ragondin

Dynamique d’occupation des habitats par un Coléoptère carabique dominant des paysages agricoles d’ouest de la France : Poecilus cupreus

Ronan Marrec

Centre d’Etudes Biologiques de Chizé (France)

Downloaded from: http://www.hlasek.com/poecilus_cupreus_bc4959.html

Ronan Marrec, PhD student in our lab, will soon present exciting results from his PhD at the forthcoming french conference on landscape ecology ("6èmes journées françaises de l’Ecologie du Paysage") in Rennes (11-14 June 2013). Ronan will present  his work in the session on 'AgroEcologie et Paysage' and would like to receive some feedback on his presentation. So, please do all come along and help out! Here a description of what you will hear about:


Dans les agroécosystèmes, les facteurs contraignant la distribution et l’abondance des espèces sont instables dans l’espace et dans le temps, les habitats étant dynamiques et subissant de fortes pressions anthropiques. De ce fait, persister dans les paysages agricoles est un défi pour les espèces. Certaines espèces, dites rudérales, savent pourtant tirer profit de cette instabilité spatio-temporelle, notamment via leur capacité à se disperser d’un habitat à l’autre. 

Poecilus cupreus (L.) (Coleoptera, Carabidae) fait partie des espèces très abondantes dans les paysages agricoles de l’ouest de l’Europe. Ce carabique présente l’intérêt de pouvoir agir comme auxiliaire de culture car c’est un prédateur opportuniste de ravageurs et d’adventices. Notre étude a pour objectif d’identifier les habitats de l’agroécosystème qui lui sont favorables à différentes échelles spatiales, de la parcelle au paysage. Elle se fonde sur l’échantillonnage pluriannuel des populations de P. cupreus au sein de la Zone Atelier Plaine et Val de Sèvre, plaine agricole de 450 km² située dans l’Ouest de la France. Les échantillonnages ont eu lieu de 2010 à 2012 au moyen de pots-pièges placés aléatoirement dans les cultures dominantes : céréales d’hiver, colzas, tournesols, prairies et luzernes. 

Notre étude montre que P. cupreus se distribue dans tous les types d’habitats, mais que son activité-densité est plus élevée dans le colza. L’analyse à l’échelle paysagère est basée sur la composition du paysage environnant dans un rayon de 200 m à 1000 m  autour des points d’échantillonnage. Elle montre une influence positive des surfaces en colzas  l’année d’échantillonnage dans les 500m autour du piège sur l’activité-densité de l’espèce. 

L’ensemble de nos résultats suggère que le colza occupe une place privilégiée dans la dynamique des populations de cette espèce. Plusieurs hypothèses sur les mécanismes sont discutées.

A stag stands in a neck high field of canola north of Cremona, Alta., July 31, 2011. THE CANADIAN PRESS/Jeff McIntosh

Yes, the image of a colza (= 'rapeseed' or 'canola') field is highly relevent for Ronan's results but, no, the deer has nothing to do here -- that's just my personal bias towards deer ;-)

Agripop Friday Talks

Friday's Agripop Talk

31 May 2013 - 15:30 - 16:30 Salle Seminaire

Managing and restoring biodiversity and ecosystem services in agricultural landscapes 

Prof. James Bullock

Centre for Ecology & Hydrology, Wallingford (UK)

Given that the Earth’s sixth mass extinction may be already approaching steadily (e.g. see here) and that farming is more damaging to wild nature than any other human activity (see here) you may understand why James looks so exhausted from his attempts to improve the prospects of biodiversity in agricultural landscapes ... 

However, not all is bleak and actually James' research highlights encouraging prospects for preserving biodiversity and the ecosystem services these landscapes provide to us. Here a summary of what you will hear about:

Agricultural intensification has greatly benefited humankind by providing abundant and cheap food, but there have been many detrimental consequences as well. Global biodiversity declines are linked in part to intensive farming, and certain ecosystem services have been compromised. Ecosystem services - the benefits that people derive from ecosystem - directly affected by modern farming include water quality, carbon storage and greenhouse gas emissions and flood water storage. Negative feedbacks onto the farming system may also be occurring, due to declines in pollinators, pest natural enemies, and soil structure and quality.

Actions to address declines can be broadly classified as land sharing and land sparing/separation. Agri-environment schemes are a land sharing option available across the whole EU. While these schemes are controversial, I present evidence that they can be very successful in reversing biodiversity declines. The impacts of these schemes on ecosystem services are unclear, although some positive evidence is emerging. At larger scales, sparing of land by protection or restoring semi-natural habitats has clear benefits for biodiversity, and we have shown linked increases in ecosystem services.

While such findings are encouraging, there is a large evidence gap in linking actions which aid biodiversity with increases in ecosystem services. We are carrying out meta-analyses and large-scale experiments to understand how biodiversity and ecosystem services are linked.

 

James' research interest extend also to several other areas, such as population dynamics, spatial ecology and dispersal, invasion biology, conservation ecology and policy. 

Thus, to favour interactions and discussions the talk will be followed by an apero et soirée barbecue chez la riviere starting at around 17:30. 

 Tous sont le bienvenus!

Friday Agripop Talks

Friday's Agripop Talk

17 May 2013 - 11:30 - 12:30 Salle Seminaire

Structuration fonctionnelle des communautés adventices en grandes cultures

Remi Perrone

Pôle GEAPSI, UMR Agroecologie, INRA Dijon, France

Downloaded from fineartamerica.com

And today we continue with our suite of talks on community ecology using the functional traits approach! We are happy to welcome Remi from Dijon who will present us work from his PhD on the community structure of weed species. Here is his summary:

La présentation s'intéressera à la structuration fonctionnelle des communautés à travers (i) une partie méthodologique résumant les développements récents d'une méthode analytique combinant null model et métrique fonctionnelle et (ii) des développements sur différents jeux de données traitant soit exclusivement de la variabilité interspécifique (approche basée sur la valeur moyenne d'un trait), soit de la variabilité intraspécifique en complément, dans le but de détecter des stratégies de développement des adventices selon
différents aspects de variabilité environnementale (notamment la pulvérisation herbicide, l'azote et la compétition pour la lumière avec la culture). Il est notamment mis en avant l'importance de la variabilité intraspécifique dans l'analyse de la structure des communautés adventices.

 See you soon!

Friday Agripop Talks

Friday's Agripop Talk

03 May 2013 - 11:00 - Salle Ragondin

Master student project presentations

Aurélie Dupeyron
Gaëtane Le Provost
Klervi Tocze

Cereal field, Vasilij Belikov 1921-1994; http://www.oceansbridge.com/oil-paintings/product/51382/cerealfield

You know, PLOS One just published an interesting systematic review of ecological research in the last 30 years (see here) and guess what was the result? Yeah, most ecologists still focus on single species (70% of the studies), whereas ecosystem and community studies together comprise only a quarter of ecological research.

And there are also strong biases regarding where and what ecologists study, with another recent paper in Frontiers in Ecology and Environment (see here) showing that most terrestrial ecolostis work in "... protected areas, temperate deciduous woodlands, and wealthy countries. Even within densely settled or agricultural regions, ecologists tend to study “natural” fragments." As a consequence, ecologists are missing "75% of the terrestrial world where humans live and work". Duh, time to change, isn't it?

Well, certainly that's what our Master students are doing! All three today will present interesting work on Community ecology, using study systems in highly intensive agricultural areas. OK, in a wealthy country (France), but all other tick marks are met.

Furthermore, Aurélie and Gaëtane will present work on insect community ecology, whereas Klervi is working on weed community ecology. So, also no bias towards fury/fluffy/feathered animals.

Hence, many reasons to come and listen to these presentations. And there is more - Aurélie and Gaëtane are using the functional traits approach to characterize and understand insect community structure. The functional traits approach is increasngly becoming a 'hot topic' in ecology. It has been especially applied to plant community ecology (e.g. see here; for recent publications by our group see here and here), but recent research has started to apply it to animal systems (e.g. see here) - including Aurelie and Gaetanne!

So, here are the abstracts of the talks -- en francais, bien sure!


Aurélie Dupeyron
Titre: Caractérisation des communautés de Coléoptères Carabidae au sein des paysages agricoles par une approche fonctionnelle

Abstract
Évaluer l'impact de l'agriculture sur la biodiversité est nécessaire pour mettre en place des mesures pour la protection de l'environnement tout en conciliant la production agricole. Dans ce contexte, une étude de la communauté de carabes, indicateurs écologiques de la qualité environnementale, a été mise en place . La caractérisation des communautés se fait par une évaluation des traits dans le but de déterminer la réponse des Coléoptères Carabidae face à l'instabilité des paysages. Les axes de travail de mon stage sont donc d'établir la structure fonctionnelle des communautés de carabes dans le paysage agricole en se fondant sur les espèces dominantes puis de déterminer les éléments structurant de ces communautés.


Gaëtane Le Provost
Titre: Relations plantes-criquets en milieu agricole: impact de la structure fonctionnelle de la communauté de plantes sur l’abondance des criquets par une approche « traits fonctionnels

Abstract
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 criquets seront analysés en fonction de facteurs liés à la structure fonctionnelle de la communauté de plantes : la qualité et quantité de ressource, la densité de prédateurs, le microclimat. Or la sensibilité des 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 de criquets et comprendre leurs réponses aux facteurs du milieu, à travers l’étude de leurs traits fonctionnels.


Klervi Tocze
Titre: La diversité des séquences culturales a-t-elle un rôle prépondérant dans la structuration des communautés adventices

Abstract
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. L'influence de ces derniers sont souvent étudiés sur la richesse spécifique des communautés mais peu sur leur composition.
    C’est pourquoi, lors de ce stage, j'étudie l’impact des facteurs temporels à travers l’effet des successions culturales sur la composition des communautés d’adventices. Dans un premier temps, j'essaye de caractériser les séquences culturales et leurs différences; puis de confronter ces dernières au différences observées dans la composition des communautés adventices.

Thus, see you there -- many reasons to come and support our students!

AgriPop Friday Talks

Friday's Agripop Talk

19 April 2013 - 11:30 - Salle Seminaire (!)

From habitat use to habitat selection: which key factors drive breeding little bustard distribution?

Pierrick Devoucoux

 This week's talk will be about a really cool species, the Little Bustard (Tetrax tetrax). This species is also of high conservation concern (Near Threatened on the IUCN Red List) as it prefers open grasslands and undisturbed habitat -- requirements which often conflict with agricultural practices.

Whilst the species has gone extinct in several parts of Europe, especially in the east, several populations still survive in southern and western France. One remarkably high density population lives in France, in the Costière Nîmoise, near the city of Nîmes in southern France, with around 700 breeding males in an area of just 40km length! Not surprisingly the area is protected since 2006 and a current question of interest is understanding which are the key factors allowing to obtain such high population densities, as this would be quite handy to know for improving the conditions for other breeding populations.

All fine, hence? Well, not really. This year a new TGV train line will start to be build right across this protected area...

 Yeah, indeed an unfortunate state of affairs. Apparently the decision cannot be reversed, but Pierrick's work is part of an initiative funded to find ways to mitigate the impact on this important breeding population. As part of this, Pierrick has already concluded one field season last year and will present us some new results on the patterns and drivers of Little Bustard breeding habitat selection. Here the official abstract of the talk:

Conservation measures generally act on landscape composition at large and fine scale. However, global distribution and local density are not only under environmental influences. Social factors play an important role, especially in species with complex mating system. Hence the real question is about habitat selection. This study will investigate the relative weight of social and environmental factors in habitat selection on  a protected species in a high sensibility  context of conservation.

Especially, the population lives in an agricultural landscapes and agricultural practices profoundly determine and change the landscape structure. The different roles of soil occupancy on vegetation type and structure, and hence foraging availability, will be studied and the role of intra and inter sexual interactions explored. Conclusions are expected to help managers to build efficient conservation measures.

So, a really interesting talk - and as you have seen Pierrick has taken also great pictures of Little Bustards during his last field season -- so come, listen, and enjoy! And let's hope his work will help improve mitigation measures, so that also in the future we'll be able to see flocks of this bird flying and breeding in this population.

AgriPop Friday Talks

Friday's Agripop Talk

05 April 2013 - 11:30 - Salle Ragondin

Musings on community ecology by a lonely plant ecologist stuck in the forest of Chizé: Can we infer process from pattern?

Nicolas Gross

 

Image from www.stuckincustoms.com/

Stuck in the forest. Can you imagine this happening to a guy who's spent most of his (research) life so far studying nice open grasslands? Well, our research centre is indeed in the middle (sort of) of a forest but Nico is surviving, has been making escapes to study grasslands in Spain (more on that on Friday) and even started to explore the grasslands in our study area outside the forest.

So, why does Nico study grasslands? Well, plants do not escape or hide from researchers and in general do not move (except as seeds or pollen). Hence, a quite convenient study system to investigate what drives the strcture of ecological communities - the main interest of Nico's research. 

OK, but what is that 'pattern vs. process' bit? Well, that's actually a highly contentious one - here an example (hey, I know, it's a paper from 1989, so what! Still interesting to read, isn't it?). A pattern is what we see, like the configuration or traits of a system, but what we actually want to understand is which processes did generate these patterns. Unfortunately, it is often the case that a multitude of contrasting processes could have created the same patterns, which has led to decade-long debates. In general this is related to the problem of distinguishing correlation from causation (here a recent paper on that). One key process that has been often debated is the role of biotic interactions and this is what Nico will talk about this Friday. To exemplify his points he will use a grassland study system in New Zealand, similar to this:

from: http://bit.ly/SSmJZb

Well, nearly -- just 500km more south of that. And the title will actually be slightly less informal. So, here's the official abstract:

Importance of biotic interactions in structuring plant communities: Moving from patterns to processes

How biotic interactions determine the structure of plant communities is a central question in ecology. Different approaches have been used to address this question. These can be broadly separated in two categories: (i) the individual-centered approach; (ii) the community scale approach. The first approach has mainly focused on the species response to local biotic interactions (competition, facilitation) along large ecological gradients. This approach has led to a better understanding on how the intensity of biotic interactions changes depending on local environmental conditions. However, it is difficult from this approach to evaluate how biotic interactions observed at the individual scale translate at the community level and determine the properties of the whole system. 

The second approach has focused on observed pattern of species similarities or dissimilarities within communities in order to evaluate the community scale impact of biotic interactions. In this context, the use of plant functional traits has been proposed as a key metric to quantify species convergence and divergence across communities, the central assumption being that trait divergence reflects competition while trait convergence reflects the effect of environmental filtering. 

However, inferring the impact of biotic interactions from community scale patterns remains challenging because many alternative processes can lead to similar trait distributions at the community scale. For instance, while competition has been primarily hypothesized to promote trait divergence at the community level, superior competitors can also have a disproportionally large effect on local resources and thus act as an environmental filter. Facilitation has also been shown to increase trait divergence at the community level by promoting the coexistence of functionally contrasted species. Finally, abiotic factors are usually considered to cause community trait convergence. They may also act as a disruptive force when different functional strategies exhibit equal fitness in response to similar abiotic constraints (e.g. stress-avoidance vs. tolerance strategies). 

Here, I present some results from a study conducted in highly invaded grasslands (New-Zealand) where we have evaluated how biotic interactions between alien and native species determine the success of aliens in their new environment. I will show how we have tried to merge species and community scale approaches to explicitly test the importance of biotic interactions at the whole community scale.

Figure 1. Highly invaded grasslands in New-Zealand. View from Mt Herbert, 920 m (Banks Peninsula, South Island). Semi-natural grasslands are constituted by a mix of native and alien species (tussock species are Poa cita and Festuca Novae-Zelandiae). Small alien plant species dominate inter-tussock area (e.g. Poa pratense; Lolium perenne; Agrostis capillaris), while tall alien species are more abundant close to the tussocks (e.g. Holcus Lanatus; Dactylis glomerata; Arrhenatherum elatius).

So, see you all this Friday, usual time (11:30) and place.

AgriPop Friday Talks

Friday's Agripop Talk - 29 March 2013

Hey, we've got a busy day ahead -- 2 talks on the same day!

29 March 2013 - 11:00 - Salle Seminaire

Learning trophic networks : apprehending patterns and generalities from real data

David Bohan

Who eats whome and how to find this out without the need to actually observe the act of predation, or without the need of lengthy analysis of the diet -- just come and listen how David uses commonly available distribution and abundance data to infer trophic relationships between carabid beetles and weeds in arable farmlands.

David worked until recently in the UK at Rothamsted, after which he moved to Dijon to take up a IINRA DR1 position.

 

Lindy Mary Corredores Hurtado

29 March 2013 - 15:30 - Salle Ragondin
Bees and their landscape: mapping the distribution of floral resources in agricultural landscapes and their use by wild bees 

Lindy will present us her sampling plan for mapping the distribution of wild flower resources, especially of poppy flowers, and assess their use by domestic bees. Please come all and help out Lindy - she'll be keen to hear your feedback and advise!

And, what better way to finish the week listening to a talk about bees and wild flowers ... just before pub time??? :-) So, see you all there et bon weekend!

AgriPop Friday Talks

Friday's Agripop Talk

21 March 2013 - 11:15 - Salle Ragondin

The structuring processes of passerine’s communities, the share of the stochastic, environment and biotic interactions

Laura Henckel

Actually, it's a thursday talk!

Which mechanisms drive the assembly of communities is a longstanding question in ecololgy. However there is a renewed of interest for this problematic since the last decades due to some original studies : coexistence theory of Chesson (2000), Hubbell’s unified neutral theory (2001), or due to new available tools (ie. phylogenetic). But notwhithstanding the numerous studies, the debate remain open and there is no consensus amoung the various theories. The controversies concern in particular the relative importance of the processes involved (stochasticity, dispersal, biotic interactions or environmental screen).

Because it is difficult to test directly the effect of these processes via a mechanistic model, a wide range of indirect approachs were proposed in recent years. This great diversity of methods can partly explained the divergence of conclusions. Furthermore, it appears that these results are strongly dependent on the scale of analysis (spatial extent and grain), on taxa and even on the characteristic of the study site. Another thing is that a wide part of the studies on community assemblages remain theoretical and most of the others concern micro-organisms or plant communities. For these reasons further studies are needed, combining both a consistent set of methods and a multi-scale approach in a way to strengthen the results and reduce biases or misinterpretation. We therefore use some of these methods in way to understand the assembly processes that structure the passerine community in the particular context of the intensive agro-ecosystems.

This question constitutes both a scientific and societal challenge in the context of the strong decline of farmland birds observed during the past decades due to agricultural intensification.  For this purpose I will use the point count data collected between 2009 to 2012 on the workshop area “Plaine et Val de Sevre”, which are distributed on the whole area (every 1km²) allowing me to conducted a multi-scale approach by varying the grain and the extent of analysis.  A set of different methods will be used to distangle the processes involved (ie. multiple regressions on distance matrix, co-occurrence analysis) and different models will be compared (stochastic vs different determist models) to try to identify which processes are involved and at which scale. This work constitutes a preliminary study for my PhD which will focus more specifically on the environmental factors and in particular on the landscape heterogeneity effect (crop composition and configuration) on farmland birds.