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Rescooped by Maud from Koter Info - La Gazette de LLN-WSL-UCL
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Ma Forêt


« A travers le regard d'un enfant, partez avec lui à la découverte de sa forêt faite de magie, de mystères et de rencontres... »


Le réalisateur belge, Sébastien Pins a reçu l’Award honorifique du meilleur court-métrage pour son film "Ma forêt" dont la musique originale est de Quentin Dujardin (voir sa lettre ouverte à l'Onem sur cette même page de La Gazette).


Duc


Prix remportés par ce film 


 

United Nations Award International Forest Short Film Festival (US-2013)Best Environmental Short Film Isle of Wight Film Festival (UK-2013)Best Narrative Short Film au Downtown Tyler Film Festival (US-2013)Prix du Jeune Public au Festival Rencontres Cinéma Nature (FR-2013)Mention honorable au Film Festival for Peace, Inspiration and Equality (IND-2013)Prix du Public Festival Environnemental de Poitiers (FR-2013)3ème Prix au Festival Internacional de Cine Estudiantil Fenacies (ES-2013)Best Short Film au Maine Outdoor Film Festival (US-2013)Best Documentary au Euroshorts Film Festival (PL-2013)Best Short at the Maine Outdoor Film Festival (US-2013)Best Documentary at the Euroshorts Film Festival (PL-2013)

 


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Combien y a-t-il d'espèces d'arthropodes dans une forêt tropicale ?

Combien y a-t-il d'espèces d'arthropodes dans une forêt tropicale ? | ecology | Scoop.it

Dans une étude publiée dans le numéro de Science du 14 décembre, une équipe internationale à laquelle ont participé plusieurs chercheurs français décrit, avec une précision inédite, la diversité des arthropodes vivant dans une forêt tropicale. Cet article est le fruit de près d'une décennie de travaux qui ont mobilisé une centaine de scientifiques de par le monde.


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Rescooped by Maud from Regulation of the plant-microbe interactions
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Pathogens and insect herbivores drive rainforest plant diversity and composition : Nature : Nature Publishing Group

Pathogens and insect herbivores drive rainforest plant diversity and composition : Nature : Nature Publishing Group | ecology | Scoop.it
Tropical forests are important reservoirs of biodiversity, but the processes that maintain this diversity remain poorly understood. The Janzen-Connell hypothesis suggests that specialized natural enemies such as insect herbivores and fungal pathogens maintain high diversity by elevating mortality when plant species occur at high density (negative density dependence; NDD). NDD has been detected widely in tropical forests, but the prediction that NDD caused by insects and pathogens has a community-wide role in maintaining tropical plant diversity remains untested. We show experimentally that changes in plant diversity and species composition are caused by fungal pathogens and insect herbivores. Effective plant species richness increased across the seed-to-seedling transition, corresponding to large changes in species composition. Treating seeds and young seedlings with fungicides significantly reduced the diversity of the seedling assemblage, consistent with the Janzen-Connell hypothesis. Although suppressing insect herbivores using insecticides did not alter species diversity, it greatly increased seedling recruitment and caused a marked shift in seedling species composition. Overall, seedling recruitment was significantly reduced at high conspecific seed densities and this NDD was greatest for the species that were most abundant as seeds. Suppressing fungi reduced the negative effects of density on recruitment, confirming that the diversity-enhancing effect of fungi is mediated by NDD. Our study provides an overall test of the Janzen-Connell hypothesis and demonstrates the crucial role that insects and pathogens have both in structuring tropical plant communities and in maintaining their remarkable diversity.

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Trends in Ecology and Evolution - Pathogen regulation of plant diversity via effective specialization

The Janzen–Connell (JC) hypothesis, one of the most influential hypotheses explaining forest diversity, is inconsistent with evidence that tree species share the same natural enemies. Through the discussion of seedling diseases from a pathogen-centered perspective, we expand the JC hypothesis to tie in host–pathogen–environment interactions at three levels: local adaptation, host specificity of the combined effect of multiple infections, and environmental modulation of disease. We present evidence from plant pathology, disease ecology, and host–parasite evolution relevant to (but not commonly associated with) forest species diversity maintenance. This expanded view of the JC hypothesis suggests ways to direct new experiments to integrate research on pathogen local adaptation, co-infection, and environmental effects on infection by using high-throughput molecular techniques and statistical models.


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Pathogens and insect herbivores drive rainforest plant diversity and composition

Pathogens and insect herbivores drive rainforest plant diversity and composition | ecology | Scoop.it

Tropical forests are important reservoirs of biodiversity1, but the processes that maintain this diversity remain poorly understood2. The Janzen–Connell hypothesis3, 4 suggests that specialized natural enemies such as insect herbivores and fungal pathogens maintain high diversity by elevating mortality when plant species occur at high density (negative density dependence; NDD). NDD has been detected widely in tropical forests5, 6, 7, 8, 9, but the prediction that NDD caused by insects and pathogens has a community-wide role in maintaining tropical plant diversity remains untested. We show experimentally that changes in plant diversity and species composition are caused by fungal pathogens and insect herbivores. Effective plant species richness increased across the seed-to-seedling transition, corresponding to large changes in species composition5. Treating seeds and young seedlings with fungicides significantly reduced the diversity of the seedling assemblage, consistent with the Janzen–Connell hypothesis. Although suppressing insect herbivores using insecticides did not alter species diversity, it greatly increased seedling recruitment and caused a marked shift in seedling species composition. Overall, seedling recruitment was significantly reduced at high conspecific seed densities and this NDD was greatest for the species that were most abundant as seeds. Suppressing fungi reduced the negative effects of density on recruitment, confirming that the diversity-enhancing effect of fungi is mediated by NDD. Our study provides an overall test of the Janzen–Connell hypothesis and demonstrates the crucial role that insects and pathogens have both in structuring tropical plant communities and in maintaining their remarkable diversity.

 

 


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Rescooped by Maud from Fungal molecular ecology
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What Plants Talk About

When we think about plants, we don't often associate a term like "behavior" with them, but experimental plant ecologist JC Cahill wants to change that. The University of Alberta professor maintains that plants do behave and lead anything but solitary and sedentary lives. 

What Plants Talk About teaches us all that plants are smarter and much more interactive than we thought!

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Jean-Michel Ané's curator insight, July 17, 2014 4:12 PM

Very cool documentary... They talk about mycorrhizae starting at 44-45 min.

Rescooped by Maud from Variétés entomologiques
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Les insectes au service de la forêt

Les insectes au service de la forêt | ecology | Scoop.it

 

[...] Ces myriades d’insectes sont aussi actifs que discrets : des végétariens broutent le feuillage, tandis que des prédateurs les attrapent au vol ou les chassent à l’affût, tapis dans les frondaisons.

 

Certains originaux s’installent dans les nids d’oiseaux, les fourmilières, les cavités d’arbres, les champignons ou la fourrure des cervidés; ils provoquent des galles ou parasitent d’autres insectes.

 

Enfin, une grande partie de ces modestes organismes, et même une majorité des coléoptères, s’emploient à une tâche aussi peu valorisée qu’indispensable : le recyclage. Qu’il s’agisse du minuscule collembole grignotant une feuille tombée, du nécrophore s’activant sur le cadavre d’un mulot, du bousier attiré par du crottin ou de l’impressionnante larve de lucane cerf-volant creusant sa galerie dans une souche pourrie, tous ces animaux œuvrent inlassablement à la santé de la forêt.

 

Une forêt sans insectes ressemblerait rapidement à une ville sans éboueurs. Leur action permet d’accroître la fertilité du sol en accélérant le recyclage de la matière organique.

 

 


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Comment se maintient la biodiversité en forêt tropicale primaire?

Comment se maintient la biodiversité en forêt tropicale primaire? | ecology | Scoop.it

Humanité et Biodiversité. « L'hypothèse dite "Janzen-Connell" suggère que les espèces comme les insectes herbivores et les pathogènes fongiques maintiennent une forte diversité en élevant leur efficacité à l'encontre des espèces végétales tendant à développer leurs populations. En gros, plus une plante tend à devenir commune, plus elle est attaquée. »

 

[...]

 

« L'étude fournit un test global de l'hypothèse Janzen-Connell et démontre le rôle crucial que les insectes et les agents pathogènes du sol ont à la fois dans la structuration des communautés de plantes tropicales et dans le maintien de leur diversité. »

 

[L'étude] Pathogens and insect herbivores drive rainforest plant diversity and composition

 

 

 

 

[Article dans Nature] Plant killers protect rainforest diversity


Via algrappe, Frédéric Liégeois, Bernadette Cassel, Hubert MESSMER @Zehub on Twitter
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Rescooped by Maud from Plant pathogens and pests
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Plant-Killing Fungi Found to Preserve Rainforest Diversity

Plant-Killing Fungi Found to Preserve Rainforest Diversity | ecology | Scoop.it

Voracious pests may be foes of individual plants, but they can benefit forests. A study in the humid rainforests of Belize shows that plant-killing fungi can help preserve diversity in such ecosystems.

The study, published today by Nature, provides experimental support for a leading ecological hypothesis on why any given plant species does not take over in species-rich forests. That proposal — the ‘Janzen–Connell hypothesis’ — posits that as the population of a plant species grows, so does the rate at which specialized pests dine on it. Those pests then keep dominant plants in check, giving other species room to flourish.

“The more common a plant is, the more aggressively it is attacked,” says Keith Clay, a plant ecologist at Indiana University in Bloomington, who was not involved with the study. “It’s a mechanism for maintaining diversity.”

Since the Janzen–Connell hypothesis was proposed more than 40 years ago, many research teams have gathered evidence that plant-munching insects and other predators keep populations of plant species in check. But few were able to establish that this mechanism also boosted plant diversity, says Clay.

Hypothesis testing
Owen Lewis, an ecologist at the University of Oxford, UK, and his colleagues decided to test the hypothesis experimentally. The team marked field plots in the Chiquibul Forest Reserve in southwestern Belize, where the ground is laced with thick, shallow roots and seeds fall from a thick canopy overhead. Some of the plots were treated with fungicides, and others with an insecticide. Control plots were sprayed with water.

Over the course of 17 months, the team found that species richness was reduced by about 16% in plots sprayed with fungicide. Although there was no decline in species diversity in plots sprayed with insecticide, this treatment altered the relative abundance of species present.

 

 


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Pathogens and insect herbivores drive rainforest plant diversity and composition (nature 2014)

Pathogens and insect herbivores drive rainforest plant diversity and composition (nature 2014) | ecology | Scoop.it

Tropical forests are important reservoirs of biodiversity, but the processes that maintain this diversity remain poorly understood. The Janzen–Connell hypothesis suggests that specialized natural enemies such as insect herbivores and fungal pathogens maintain high diversity by elevating mortality when plant species occur at high density (negative density dependence; NDD). NDD has been detected widely in tropical forests, but the prediction that NDD caused by insects and pathogens has a community-wide role in maintaining tropical plant diversity remains untested. We show experimentally that changes in plant diversity and species composition are caused by fungal pathogens and insect herbivores. Effective plant species richness increased across the seed-to-seedling transition, corresponding to large changes in species composition. Treating seeds and young seedlings with fungicides significantly reduced the diversity of the seedling assemblage, consistent with the Janzen–Connell hypothesis. Although suppressing insect herbivores using insecticides did not alter species diversity, it greatly increased seedling recruitment and caused a marked shift in seedling species composition. Overall, seedling recruitment was significantly reduced at high conspecific seed densities and this NDD was greatest for the species that were most abundant as seeds. Suppressing fungi reduced the negative effects of density on recruitment, confirming that the diversity-enhancing effect of fungi is mediated by NDD. Our study provides an overall test of the Janzen–Connell hypothesis and demonstrates the crucial role that insects and pathogens have both in structuring tropical plant communities and in maintaining their remarkable diversity.


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Rescooped by Maud from Plant pathology
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Trends in Ecology and Evolution: Pathogen regulation of plant diversity via effective specialization

Trends in Ecology and Evolution: Pathogen regulation of plant diversity via effective specialization | ecology | Scoop.it

Highlights•

Multihost enemies contribute to plant diversity through effective specialization.

Multihost pathogens could be locally adapted to local host species.

Host specificity results from the effect of co-infecting pathogens in a host.

Environment effects increase the complexity of multihost enemies × host interactions.

ABSTRACT: The Janzen–Connell (JC) hypothesis, one of the most influential hypotheses explaining forest diversity, is inconsistent with evidence that tree species share the same natural enemies. Through the discussion of seedling diseases from a pathogen-centered perspective, we expand the JC hypothesis to tie in host–pathogen–environment interactions at three levels: local adaptation, host specificity of the combined effect of multiple infections, and environmental modulation of disease. We present evidence from plant pathology, disease ecology, and host–parasite evolution relevant to (but not commonly associated with) forest species diversity maintenance. This expanded view of the JC hypothesis suggests ways to direct new experiments to integrate research on pathogen local adaptation, co-infection, and environmental effects on infection by using high-throughput molecular techniques and statistical models.

 


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fundoshi's curator insight, October 7, 2013 9:35 AM

Wikipediaより

ジャンゼン・コンネル仮説(ジャンゼン・コンネルかせつ、Janzen-Connell hypothesis)

: 森林生態系における樹種の多様性の確立について説明した仮説。

この仮説をほぼ同時に提唱した二人の研究者にちなみ、ジャンゼン・コンネル仮説として知られている。

森林生態系において親木となる成木からの距離が短いほど、その成木の種子や、実生にとって天敵となる特異的な病原菌、捕食者が多くなる。そのため実生や種子の死亡率が高くなり同種の樹木の更新が妨げられる。病原菌や捕食者の数は成木からの距離に反して減少するが、一方で種子散布数も成木からの距離に比例して減少する。

そのため成木の真下においては同種の更新が妨げられることで他の樹種が生育する余地が生まれ、そのことが多様性を確立する要因の一つになっていると考えられる。

Rescooped by Maud from Fungal molecular ecology
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The danger of mycorrhizal traps?

The danger of mycorrhizal traps? | ecology | Scoop.it

Conventional wisdom considers the mycorrhizal symbiosis as mutualistic because both the mycorrhizal fungus and the mycorrhizal plant potentially benefit from the exchange of nutrients and carbon (C). Cases in which mycorrhizal plants are smaller than nonmycorrhizal plants have been reported (Klironomos, 2003). While these cases are often considered exceptions, they raise an important question of partner control. How do plant and fungal partners ensure that they are getting a ‘fair-deal’ for the resources they are trading, and avoid being cheated (Ghoul et al., 2014)? Does engaging in a mutualistic partnership translate into consistent and measurable benefits? Recently, Näsholm et al. (2013) explicitly addressed the question of whether ectomycorrhizal fungi alleviate or aggravate nitrogen (N) limitation of conifers in boreal forests. They concluded that, in these systems, ectomycorrhizal fungi immobilize large quantities of N and thus drive N limitation for host plants. In this issue of New Phytologist, Franklin et al. (pp. 657–666) expand upon that hypothesis. In their paper they provide a model that predicts that trees associating with ectomycorrhizal fungi show reduced performance. The work explores the idea of how trees can become ‘trapped’ by these dynamics, unable to eliminate their mycorrhizal fungal partners under conditions where a nonmycorrhizal habit would be more beneficial, even if this appears to be ‘maladaptive’.


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