The EUCFLUX Network: Comparison of Eucalyptus genetic material under contrasting environmental and silvicultural conditions

Comparison of Eucalyptus genetic material under contrasting environmental and silvicultural conditions

Itatinga municipality, São Paulo State, Brazil (Network's center: 22°58 0 04″S et 48°43 0 40″W)

https://www.ipef.br/eucflux2/

The EUCFLUX network consists of 10 sites located along a gradient with contrasting soils (texture, slope). Each site (~3ha) comprises 16 plots installed between 2009 and 2018, and 9 additional plots installed from 2018 onwards. Each plot was planted with differing Eucalyptus genetic material in a regular grid pattern (3*2 m). The studied genotypes (25 per site) belong to different species of Eucalyptus (E. grandis, E. urophylla, E. camaldulensis, E. longirostrata, E. dunnii, E. pilularis, E. pelita, E. tereticornis) and their hybridses, clones and seminal material. One of the plots is planted with Corymbia citriodora.

Between 2009 and 2018, 8 sites were paired (4 x 2) to ensure the maximum homogeneity of environmental conditions within each pair. Since 2018, the sites within each pair have been managed differently: one in coppice, the other as a regular high stand. This new phase makes it possible to study the two different types of management. Two sites were not paired (called unassociated sites).

The two unassociated sites will be replanted for one, and uncut for the other, so that the behaviour of different Eucalyptus genotypes can be studied at one site far beyond the usual commercial rotation age (the trees will reach the age of 15 at the end of the cycle, while a typical  rotation is only 6 years). The other replanted site will increase the number of sites to study the effects of soil gradients.

The EUCFLUX Network offers the opportunity to quantify the importance of environmental conditions, genome and management for productivity and biogeochemistry in commercial Eucalyptus plantations. The number of genetic materials compared, the size of the individual plots and the quality of the monitoring carried out make this an important network for studies of this type at the global level. The EUCFLUX Network regularly monitors carbon fluxes and storage as well as productivity (carbon allocation, litterfall, gross primary productivity, wood production, soil CO2 emissions, soil carbon). Foliar ecophysiology (photosynthesis, stomatal conductance) and the environmental constraints that determine it, particularly water constraints, are also monitored at some sites for some of the materials. A meteorological station is located at the centre of the network. One of the objectives of the network is to link individual productivity or growth trajectories to simple functional traits both within genotypes (spatial variability) and among different genotypes (inter-genotypes).

Models representingecophysiological processes also provide estimates of water and nutrient consumption and light absorption at different sites and for different materials. Ultimately, this makes it possible to combine observations and simulations to study the resource-use efficiency of different genetic materials. These models must use data from an instrumented site (Eddy-covariance and soil water monitoring) located at the centre of the Network. The network is located in one of the measurement areas of the Venµs satellite (https://venus.cnes.fr/en/VENUS/index.htm), which will make it possible to assess the potential of this type of new-generation satellite (with high spatial and temporal measurement resolution) to characterize the canopy properties (LAI, leaf angles) of the different Eucalyptus genetic materials.

The network is coordinated by Joannès Guillemot and Guerric Le Maire (CIRAD researchers, UMR Eco&Sols, based in Brazil near to the Network's site). The Network also benefits from the support of Brazilian partners (private and public) to ensure the monthly monitoring operations.

The network is partly funded by a consortium of Brazilian companies in an inter-professional structure (IPEF, http://www.ipef.br/). Therefore,  sharing raw data for scientific cooperation is subject to the agreement of these partners. The Networ carries out many measurements at different time steps (from bi-weekly to annual). The work includes dendrometric inventory campaigns, biomass measurements, litter collection and weighing, as well as measurements carried out with specific equipment (see last section).

The network encourages and facilitates scientific cooperation of all durations and budgets as much as possible. For further information, contact the Network coordinators directly.

The minimum cost of standard maintenance and monitoring at the Network (i.e., excludinglarger punctual measurement campaigns) is estimated at 60 k€ per year.

For some sites: micrometeorological stations, soil water content, water table height, soil temperature, soil CO₂ emission (Li-8100, Li-COR®), flow tower, measurement of foliar ecophysiology (Li-6400, Li-COR®)