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Our community ecology group at University of Bern (led by Eric Allan) works on two interlinked questions: what maintains diversity within plant communities? And what effects do changes in community diversity have on the functioning of ecosystems and the services they provide?
We try to understand the biodiversity of plant communities from several different angles and we do experiments in the field and greenhouse and use statistical modelling to test these questions in large datasets.
On our website you can find more information on the major projects we are involved in, together with updates on our activities and interests.

Mushroom picking

Autumn time is mushroom time so on 18th of October 2019 the Allan Lab went on a mushroom-picking adventure in the Bremgartenwald near Bern. We were amazed by how many different species we saw and we even found a huge amount of edible ones – many Xerocomellus (Rotfussröhrlinge), some Boletus badius (Maronen-Röhrlinge), some Cantharellus (Eierschwämme), various puffball species and a few Suillus grevillei (Goldröhrling)!

We also visited the famous “Glasbrunnen” and in the evening we enjoyed a delicious meal and wine together at Provisorium 46.

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New preprint about sick plants in grassland communities

Slowly but steadily the results of the PaNDiv experiment start to be available. With many helping hands we piled up data about fungal infection, plant traits, community composition, biomass etc. and are now putting the pieces of the puzzle together. In the latest preprint we show that the functional composition of a plant community is a main driver of fungal infection and that the consequences of fungal infection are context dependent.

Sick plants in grassland communities, Cappelli et al. 2019 (preprint)

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Figure 1 Overview over the main hypotheses which we tested. Growth-defense trade-off hypothesis: Plant species adapted to resource-rich environments and able to compete well under nutrient rich conditions are often less defended against natural enemies. Nitrogen disease hypothesis: Higher nutrient content of the plant material following nitrogen fertilization should promote disease. Host dilution hypothesis: Many pathogens are dependent on the availability and density of host plants. At high plant diversity the abundance of each host plant is in average lower than in species poor communities, which is suggested to be the underlying mechanism of observed negative diversity-disease relationships.

 

3rd Wild Plant Pathosystems Conference

I (Seraina) am just back from the 3rd Wild Plant sick_ToPathosystems Conference in Frankfurt, which was all about “sick plants in the wild”. It was a very small meeting with excellent presentations of amazing scientists, a museum tour, wine tasting and walks in the forests. I was honoured to present my fungal pathogen results from the PaNDiv experiment and get the chance to talk to many interesting people, working with a wide variety of pathosystems. I learned a lot about viruses and fungal pathogens and their vectors, about the possibility to identify different Uromyces species based on their smell, about the pathogen communities on different plant species and much much more.

Conference impressions on twitter #wpp3 :

 

Group hike

On the 24th of June 2019 the Allan Lab made an excursion to the mountains in the Kandertal region.
We started in the morning from Bern by train and after changing to the “postbus” in Reichenbach we took the “chairlift” up to Ramslauenen. We hiked around the top and after a picnic followed a path back to Kiental. Despite the heat and the steep slopes, we enjoyed the blue sky, the fantastic panorama, the alpine flora and each other’s company.
We also used this opportunity to learn something about the vegetation – Debi showed us many species and explained to us their special characteristics and habitat.

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First results of PaNDiv on preprint

IMG_20171003_140655623After 840 litter bags sewed, 2.5 months of decomposition, 4 years of experiment running and more than a 100 helpers helping, we are happy to announce that we submitted last week the first results of the PaNDiv Experiment. This paper looks at the response of decomposition to direct and indirect effects of nitrogen enrichment, with a fancy structural equation model testing the relative importance of litter quality and soil biotic and abiotic conditions.

It highlights the importance of a plant community functional shift under nitrogen enrichment. And for those that can’t wait until the paper gets accepted, here is the submitted draft on bioRxiv:

Decomposition disentangled, Pichon et al. 2019 (preprint)

Final results of the structural equation model, showing effects of nitrogen enrichment, plant species richness and plant functional composition on decomposition. Dashed arrows show negative, full arrows positive path coefficients. The arrow size is proportional to the path coefficient. Double-headed grey arrows show covariances.

 

BES Annual Meeting 2018

The best thing about Christmas is the BES Annual Meeting. Some of the lab members – Seraina, Eric and Noémie – attended the venue in Birmingham and had the chance to follow an extraordinary selection of talks and posters. Among others, we saw a great session about long-term experiments, what has been done and what is to do next (Andy Hector, Alexandra Weigelt and others). To the question “are you also part of a long term experiment?”, we are now answering: “we just started one”. We also saw presentations about phylogenetic and functional traits linked to multifunctionality (Y. Le Bagousse-Pinguet), upscaling BEF experiments results to landscape diversity (G. Le Provost), a great citizen science project looking at herbivory drivers on oaks (E. Valdés-Correcher) and my personal favourite, tracing C and N flows in grassland plants and soil food webs (M. Chomel).

A whole wall was covered in drawings due to the Journal of Applied Ecology brilliant suggestion to “draw your study organism” (see Seraina’s work of art, #PaNDiv), and we could even play cards with the Catastrophic game supporting systems thinking (P. Holland).

Let’s not forget the great poster about sick plants in grassland communities (S. Cappelli) and a presentation disentangling nitrogen direct and indirect effects on decomposition (N. Pichon).

What a nice and motivating end to 2018 and look forward to 2019!

NP & SC

 

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Study organism drawings

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The vegetative traits are for sure right

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Noémie and the decomposition

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Another highlight of the conference: Phil Grime in front of his poster

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Seraina and sick plants

Fieldwork season wrap up

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The sheep are now back next to the PaNDiv field site, which means two things: winter is coming, and after a season outside the fieldwork is over!

Maintaining the experiment has already kept us quite busy over the last months: weeding three times the whole field to always have the same diversity in the plots, spraying fungicide for the pathogen exclusion treatment and fertilizing to study the effects of Nitrogen addition.

On top of that, we harvested this year again a lot of data. For all our species, we quantified fungal pathogen infection, looked at herbivory damage and measured classic functional traits (height, SLA, LDMC, etc). We assessed the percentage cover of all plant species growing on the field, and collected over 3000 biomass samples and 30 000 insects. This year we had a closer look at the belowground compartment, measuring soil respiration regularly and collecting more than 1000 soil samples.

We also welcomed researchers from other universities to collaborate on the PaNDiv project. Rodrigo Granjel (1), PhD student from Sevilla, Spain collected data to study coexistence mechanisms. Bjarke Madsen and Urs Treier (2) from Aarhus, Denmark, flew their drones over the field, to link ground measurements with remote sensing data.

In our greenhouses facility, we grew the 20 PaNDiv species and the most common weeds invading the plots with an N addition treatment, to get an array of functional traits in controlled conditions. We also used this opportunity to explore the variability and the response of morphological traits, for instance related to vegetative propagation, together with Mathieu Millan, a researcher in plant architecture from Montpellier, France

We couldn’t do that much without a dedicated team of PhD, Master students and technicians, and all our hard working field helpers. More than 50 different people came to work with us between April and November, thank you!

Now it’s time to process all these samples, analyse the data … and get ready for next fieldwork season!

(1) http://www.oscargodoy.com/
(2) https://twitter.com/UAS4Ecology

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March, a cold start of the fieldwork season

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In June the plants have grown big

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Spraying fungicide to study the effects of pathogen removal

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July, second weeding of the whole field

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Biomass cutting (photo Beatrice Schranz)

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Collecting insects with suction sampling

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Graphosoma italicum, one of the many insects found on the field (photo Tosca Mannall)

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Autumn soil sampling

ESP Europe Conference 2018

Some people from our Lab – Maria, Noëlle and Abiel – as well as Markus Fischer have been to the Ecosystem Services Partnership (ESP) Conference 2018 in San Sebastian, Spain.

We enjoyed a week of great talks and keynotes but also other “services” like local customs showcased during the conference, all kinds of pintxos, as well as the beautiful sights of the city and surrounding landscapes and see.

Our session T2b Linking land management and biodiversity change to ecosystem services organized by Maria was met with great interest by participants. We had lively discussion on how we can bridge from ecosystem functioning to ecosystem services to policy and how we should not forget that they are underpinned by biodiversity. We also agreed that a more mechanistic understanding would further the usefulness of the ecosystem service concept.

Twitter: #esp18eu

ESP session

Maria presenting her talk

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Basque stone-lifting before the poster session

San Sebastian sea

Noëlle and Maria on the beach