Ongoing experiments on the drought effects

After a very wet spring, a severe drought has occured from July to August with very low rainfall (20 mm for the two months) and high temperatures (days above 35°C). These weather conditions added to the harsh soil conditions of the Orleans forest led to significant stress for the trees. To better understand the effects of drought on tree functionning, experiments were conducted during the summer as part of the thesis of Jordan Bello (PhD student, Irstea). Two methods were carried out: the first method is based on measuring the base water potential of trees and the second is based on the measurement of oxygen isotope ratio in soil and wood. These methods make it possible to estimate the stress suffered by trees and the depth of water uptake by each species. The sampling was designed in order to see whether stress and depth of water uptake during drought depend on stand composition (monospecific or mixed).

 

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Installation of 210 traps to collect leaf litter and seeds

210 traps were set up between july and september in 21 plots of the OPTMix experiment in order to collect leaf litter. Leaf litter will be collected for two years at least. These data will be used by Jordan Bello (Irstea phd student) to calculate leaf area index for the different stand compositions (monospecific oak, monospecific pine and mixture) and for three stand densities (low, medium and high). These traps will also be used to estimate the seed production for the studies dealing with vegetation dynamic.

 

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A new set of hemispherical photographies

From June 20 to July 13, hemispherical photographies are performed on all plots of OPTMix experiment. These pictures (about 200), coupled with light sensors, will give estimates of transmittance under forest canopy in pure and mixed stands.

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French Forest Health Monitoring Agency meet OPTMix community, 10/06/2016

François-Xavier Saintonge head French Forest Health Monitoring Agency northwest inter-pole (DSF), Michel Sottejeau (National Forestry Office) Loiret’s corresponding observer and Aurelien Salle (Orléans University) meet a small delegation of researchers and technicians IRSTEA about OPTMix health monitoring. The target of this morning was twice. First, how to characterize each plot health status and in second time how to establish a specific monitoring during an attack (Erannis defoliaria this year).

French Forest Health Monitoring Agency expressed its expertise and reassured us about the current attack. Differents protocols have been raised and measures were planned.

Sandrine Perret et Vincent Seigner (Irstea)

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Project on glucidic reserves in trees, in collaboration with the University of Orléans

We started a collaborative project with Cécile Barbaroux and Aurélien Salé Biology Laboratory and Woody Crops ( LBLGC ) from the University of Orleans about tree reserves. We recently collected wood samples of the trees in trunks and roots of oak (mid -May) and pine (early June). The objective is to study how the competition within and between species change carbon tree reserves and the allocation between growth and reserves. Another sampling campaign is planned at the Autumn, and analysis of samples and data will be an internship Master 2 next year.

Nathalie Korboulewsky (Irstea)

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First thesis commitee of Jordan Bello, 10 may 2016

The first thesis committee of Jordan Bello (phd student, Irstea Nogent-sur-Vernisson) was held on May 10, 2016 in Paris (AgroParisTech).

His thesis, co-funded by the region Centre Val de Loire and ADEME, is based on the OPTMix experimental plots and aims at answering the following question:

“Mixing tree species and lowering stand density: Are these forestry strategies relevant to face climate change?”

The participants of this first thesis committee:

– Laurent Augusto, Inra Bordeaux
– Damien Bonal, Inra Nancy-Lorraine
– Cécile Vincent-Barbaroux, University of Orléans
– Nicolas Delpierre, University of Paris-Sud 11
– Miriam Buitrago, ADEME Angers
– Nathalie Korboulewsky, phd supervisor (Irstea)
– Patrick Vallet, co-supervisor (Irstea)
– Philippe Balandier, advisor (Irstea)
– Thomas Perot, advisor (Irstea)

A weather station is now available in the Orléans Forest

IRSTEA and the National Forests Office set up a reference weather station at the “Carrefour de la Résistance” in the middle of the Orleans Forest. Scientist and forest manager have now access to weather data as temperatures, relative humidity, precipitation, radiant light, wind speed and wind direction.

The station is operationnal since april 2016.

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T-Lidar measures on OPTMix, 14-18 march 2016

For the ScanComp project (Labex Arbre, coordinated by Ignacio Barbeito from INRA), a T-Lidar measure campaign was performed from 14 to 18 of March 2016.

The aim of the project is to study the influences of stand composition (monospecific or mixed stand) and trees status (small, medium, large) on the crown form of oak trees. The full sample will be made of 81 scanned trees.

 

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OPTMix annual meeting, 7-8 january 2016

The annual meeting of the project will take place on 7 and 8 January, 2016 at Irstea Nogent-sur-Vernisson.

Meeting on mixed forests, 8-9 june 2015

A meeting on mixed forests will take place in Irstea Nogent-sur-Vernisson (France) on 8 and 9 June 2015.
A half day will be devoted to visiting the OPTMix experiment.