Jun 15
Scots pine twigs were collected from May 31 to June 10, 2021 on OPTMix plots. These samples correspond to the end of the campaign carried out in 2020 as part of the Isy-BIOC project wich aimed at studying carbon fluxes and nutrient cycling in the forest ecosystem
May 15
As part of Juliette Brunaud’s Master 2 internship, a new protocol for monitoring the regeneration of sessile oak and Scots pine was developed. The objective of this new protocol was to estimate diameter and height annual increments for individuals between 30 and 60 cm in height. The first campaign was carried out in spring 2021.
May 15
As part of the ISY-BIOC project and Marine Fernandez’s post-doctorate, a dead wood inventory was carried out in the experimental plots in spring 2021. The objectives of this inventory were:
– to quantify the dead wood on the forest ground;
– to calculate the wood biomass on the ground and therefore the corresponding carbon stock. These data will be added to the data already acquired regarding carbon stock in soil, humus and litter;
– to estimate the return to the soil due to dead wood as part of the study of cycling matter and nutrient cycles;
– to link dead wood data to soil biodiversity data.
Jan 28
An article has just been published in the “Agricultural and Forest Meteorology” journal presenting the influence of Scots pine on sessile oak spring phenology. The authors showed that budburst date of Quercus petraea is delayed in mixed stands with Pinus sylvestris.
The article is available until March 16, 2021 here:
https://authors.elsevier.com/a/1cTfucFXJZ1AV
Summary:
Climate change is impacting temperate tree species phenology, especially the timing of budburst, which is mainly driven by air temperature. However, interactions with biotic or other environmental factors also influence the timing of budburst and are usually overlooked. We studied the influence of forest stand composition on the budburst date of adult trees belonging to two species: sessile oak (Quercus petraea, Matt. (Liebl.)) and Scots pine (Pinus sylvestris, L.). We monitored their budburst dates for seven consecutive years at 18 experimental plots located in central France. We compared the budburst dates of oaks and pines growing in monospecific stands with those of their counterparts in an oak-pine mixture. Our results show that sessile oak budburst date in mixed stands with Scots pine was delayed by 2.2 days on average (SE = 0.6) compared to its budburst date in monospecific stands. In years with early budburst, the delay was more pronounced – up to four days. For Scots pine, our results showed no difference between budburst dates in monospecific and mixed stands. We hypothesize that the persistent foliage of the Scots pine in the mixed stand intercepted a part of the solar radiation, which affected the temperature perceived by the oak buds, thereby delaying the heat accumulation needed for sessile oak budburst. This effect may be of interest for the management of sessile oak in the context of global warming. In the future, sessile oak may experience more frequent frost damage due to an earlier budburst. Managing sessile oak with an evergreen species could limit late frost damage to some extent by delaying budburst. Stand composition must obviously be taken into account when monitoring the phenology of temperate tree species and to enable robust comparisons of phenological events for a given tree species at different sites.
Jan 28
The annual meeting of the project took place on 14 January, 2021 at INRAE, research unit EFNO, Nogent-sur-Vernisson, France. The meeting was held by videoconference.
The morning was devoted to oral presentations. For the French versions of the presentations, please contact Nathalie Korboulewsky (see contact page).
Jan 15
An article has been published in the “Forest Ecology and Management” journal presenting the influence of tree species and mixture on soil organic carbon storage. Part of the data used in the article comes from the OPTMix plots (see article here).
Osei, R., H. Titeux, K. Bielak, F. Bravo, C. Collet, C. Cools, J.-T. Cornelis, M. Heym, N. Korboulewsky, M. Löf, B. Muys, Y. Najib, A. Nothdurft, M. Pach, H. Pretzsch, M. del Rio, R. Ruiz-Peinado and Q. Ponette (2021). “Tree species identity drives soil organic carbon storage more than species mixing in major two-species mixtures (pine, oak, beech) in Europe.” Forest Ecology and Management 481: 118752. https://doi.org/10.1016/j.foreco.2020.118752
Highlights:
– Species mixing effect on deep SOC storage was limited to pine-beech triplets;
Abstract:
Mixed forests are usually associated with higher aboveground carbon storage compared to the corresponding monocultures but information on the impact of tree species mixing on soil organic carbon (SOC) is still limited. Yet, maximizing SOC storage is crucial for ecosystem C sequestration and many other ecosystem services. This study used a triplet approach (ie. two-species mixed stand and respective pure stands at the same site) to assess the impact of tree species identity and mixing on SOC storage in eight pine-oak, eight pine-beech and five beech-oak triplets in Europe. We sampled the forest floor (FF) and 0–40 cm in the mineral soil per 10 cm interval. For each triplet type, we fitted basal area (BA) proportion of one component species (for species identity) and a BA-based plot-level True Shannon Diversity index (for species mixing) as explanatory variables for SOC stocks in linear mixed effects models, which included stone content and plot BA as covariates, and site as a random intercept. Considering the total soil depth (FF + 0–40 cm), species identity effect on SOC stocks was only significant for pine-beech and pine-oak triplets but explained more variability in SOC stocks than species mixing across triplet types. Species mixing effect was not significant for any triplet type in the total soil depth. While species identity consistently drove SOC storage in the topsoil layers across triplet types, species mixing explained more variability in SOC stocks in the deeper soil layers except for pine-oak triplets. The results showed that species identity is a stronger driver of SOC storage than species mixing. While tree species identity effect was strongly related to a conifers vs broadleaves signature, the drivers behind mixing effects remained elusive. The results suggest that targeted selection of tree species could better enhance SOC storage in European forests than a mere increase in species richness.
Jan 15
An article has been published in “Forest Ecology and Management” presenting the effect of tree species mixture on Collembola diversity and community structure in temperate broadleaf and coniferous forests. OPTMix device was one of the two study sites of this work :
Korboulewsky, N., C. Heiniger, S. De Danieli and J. J. Brun (2021). « Effect of tree mixture on Collembola diversity and community structure in temperate broadleaf and coniferous forests. » Forest Ecology and Management 482. https://10.1016/j.foreco.2020.118876
Highlights:
Abstract:
Springtails (Collembola) are the most abundant arthropods in terrestrial ecosystems and, are considered as key indicators of organic matter turnover and soil functioning. Mixture of tree species are often regarded as a mean to improve tree growth, soil fertility and biodiversity.
We compared α-diversity, taxonomic β-diversity and functional diversity of Collembola of mixed forest stands to pure stands in two forest sites, a mountain and a lowland site composed of a coniferous and a deciduous species for effect on. We choose sessile oak (Quercus petraea) and Scot pine (Pinus sylvestris) in lowland, and beech (Fagus sylvatica) and silver fir (Abies alba) in mountain stands.
In total 41 species Collembola were identified. We showed that richness and abundance in mixed stands were in between those found in the pure stands, with a more pronounced response of the soil fauna in lowland compared to mountain. In the lowland, Shannon diversity index followed the same pattern, and we found species richness from 6.3 to 11.7 mean species, and 4400 to 9000 ind.m−2, dominated by epedaphic group. In the mountain, we found species richness from 7 to 9 mean species, and 6600 to 103,000 ind.m−2, dominated by euedaphic group.
Among the 12 soil and litter characteristics, many differs between sites and/or stand type. The best predictors of the model explaining differences in mean Collembola were litter chemical composition including the lignin to N ratio and C to N ratio. Soil characteristics, such as humus index, organic layer thickness or pH, was also a good predictors for some life-forms and one or the other site.
In addition, mixture modified Collembola community structure with some species found only in the pure stands. Jaccard similarity index showed that mixture, even composed of different tree species, homogenized Collembola community structure.
We conclude that mixture of tree species in temperate forests can locally increase Collembola diversity, but this management should not be generalized to maximize the β-diversity.
Jun 02
The article can be downloaded here:
Abstract:
An artificial vision software that contain image processing and deep learning functions has been developed to detect animals on videos recorded by camera traps in forests. Monitoring by camera traps is used on the OPTMix experimental facility in the Orléans forest to estimate wild ungulate pressure (roe deer, red deer and wild boar) on study plots. Scientists and conservation biologists use camera traps to monitor wildlife populations and biodiversity. Automatic image processing that count animals and identify species could facilitate and improve the use of camera traps in biodiversity monitoring programs and make the methodology accessible to a greater number of end users.
Feb 03
The presentations made during the OPTMix annual meeting on January 9 and 10, 2020 are available by clicking on the download link below for a period of 30 days:
https://filesender.renater.fr/?s=download&token=ff89292b-0b68-38ae-5774-2ceff14b74a4
Jan 08
The annual meeting of the project will take place on 9, 10 and 13 January, 2020 at Irstea (INRAE) Nogent-sur-Vernisson.
French version of the meeting annoucement and full program for the 9 and 10 of january
