Data standards

The mean of the values of tree height for 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. The tree height corresponds to the total vertical tree height from ground level to the upmost tip.

Difference between total height mean and the upper or lower bounds of the 95% confidence interval.

Turgor loss point is an index of sensitivity of leaves to drought. It always has negative values. High (close to zero) values indicates high sensitivity to loss of turgor in leaves under drought. Smaller (more negative) values indicate greater drought tolerance. It is measured in the leaves taken from apical branches of each tree. The point of turgor loss is measured by osmometry on sap extracted from leaves. It has units of pressure (MegaPascals).

The mean of the values of leaf turgor loss point for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m.

The variance of the values of leaf turgor loss point for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m.

Difference between leaf turgor loss point mean and the upper or lower bounds of the 95% confidence interval.

When a stem is drought stressed, it begins to form air bubbles inside its conduits, like in the blood of divers. These bubbles prevents the tree from being able to transport water from roots to leaves. If this continues, the tree eventually dessiccates at the top. The easyness by which these bubbles are formed is called vulnerability to embolism. It is an index of drought sensitivity (the inverse of resistance) of the wood of plants. Vulnerability to embolism is always a negative number. High values (close to zero) indicate high sensitivity to drought stress. Low values (more negative) indicate greater drought resistance. Tree level data. It is measured using a rotary instrument called cavitron. It is measured in the apical branches of each tree.

The mean of the values of xylem vulnerability to embolism for the apical branches of 10 measured adult dominant/co-dominant trees sampled either inside or in the vicinity of a representative circular plot with a 15 m radius. When a tree is droughted, its xylem is vulnerable to losing its capacity to conduct water to the leaves, i.e., its hydraulic conductivity, because of the formation of air emboli inside the xylem conduits.

The variance of the values of xylem vulnerability to embolism for the apical branches of 10 measured adult dominant/co-dominant trees sampled either inside or in the vicinity of a representative circular plot with a 15 m radius. When a tree is droughted, its xylem is vulnerable to losing its capacity to conduct water to the leaves, i.e., its hydraulic conductivity, because of the formation of air emboli inside the xylem conduits.

Difference between xylem vulnerability to embolism mean and the upper or lower bounds of the 95% confidence interval.

When a branch is under severe drought stress, it does not have the capacity to entirely stop its water losses. The branch continues to lose water slowly from the surfaces of its leaves and bark. This eventually leads to dessiccation and death of the living cells. Residual (or minimum) leaf conductance is an index of lack of drought resistance (its inverse, i.e., residual resistance, is an index of drought resistance). High values of conductance (low values of resistance) indicate a reduced capacity to minimise these losses. Small values (close to zero) indicate a high capacity to withstand long droughts. The residual conductance is the rate at which this unavoidable evaporation takes place. It is measured by weight loss under standard conditions in the laboratory. It is measured in the apical branches of each tree.

The mean of the values of leaf residual conductance for the apical leaves of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. During a severe drought, following the closure of the stomata, trees continue slowly to lose water. A high residual conductance implies a high sensitivity to severe droughts because it favours desiccation.

The variance of the values of leaf residual conductance for the apical leaves of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. During a severe drought, following the closure of the stomata, trees continue slowly to lose water. A high residual conductance implies a high sensitivity to severe droughts because it favours desiccation.

Difference between leaf residual conductance mean and the upper or lower bounds of the 95% confidence interval.

The mean of the values of hydraulic capacitance for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. Capacitance is the change in % relative water content (i.e., water content relative to its maximum value at saturation) per unit change in water potential. During a severe drought, if capacitance is high, the tree is capable of exploiting its own water reserves to delay desiccation.

The variance of the values of hydraulic capacitance for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. Capacitance is the change in % relative water content (i.e., water content relative to its maximum value at saturation) per unit change in water potential. During a severe drought, if capacitance is high, the tree is capable of exploiting its own water reserves to delay desiccation.

The Huber Value is the ratio of sapwood cross-sectional area to leaf area above the sapwood cross-section. It is an index of investment of dry matter in either leaves or wood. It represents the investment in the production of branch wood required for the conduction of water towards the transpiring leaves subtended by that cross-section. A high Huber value indicate an conservative plant, i.e., a plant that does not develop a large leaf area but rather prefers to build a large supporting wooden structure. A low Huber value indicates an acquisitive plant, with large leaf area, but low water supply capacity. It is measured in the apical branches of each tree. Tree level data.

The mean of the Huber values for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. The ratio of under-bark sapwood cross-sectional area to the leaf area distal to the cross-section is a measure of allocation of assimilates to build either leaf area for photosynthesis or sapwood (i.e., wood capable of conducting water) to supply the leaves with water. A tree with high Huber values is efficient in providing support to the leaves, but may not invest in high leaf areas. The Huber value is determined on one branch for each of the 10 measufred trees.

The variance of the Huber values for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. The ratio of under-bark sapwood cross-sectional area to the leaf area distal to the cross-section is a measure of allocation of assimilates to build either leaf area for photosynthesis or sapwood (i.e., wood capable of conducting water) to supply the leaves with water. A tree with high Huber values is efficient in providing support to the leaves, but may not invest in high leaf areas. The Huber value is determined on one branch for each of the 10 measufred trees.

Difference between Huber value mean and the upper or lower bounds of the 95% confidence interval.

A measure of tree size, tree basal crown height in m is measured with a clinometer. Tree level data.

Difference between basal crown height mean and the upper or lower bounds of the 95% confidence interval.

SLA is the ratio of investment of dry matter into leaves and the return in terms of area for photosynthesis. The area is projected for broadleaves but accounts for cylindrical geometry for conifer needles.

The mean of the values of specific leaf area for the apical leaves of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a 15 m radius. Specific leaf area (SLA) is a measure of the return of photosynthetic assimilates via leaf surface display per unit leaf biomiass investment. Leaves with high SLA are said to be acquisitive leaves. They are photosynthetically more productive per unit of mass invested and per unit of time, but they generally have a shorter lifespan, which lowers their cumulative return.

The variance of the values of specific leaf area for the apical leaves of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a 15 m radius. Specific leaf area (SLA) is a measure of the return of photosynthetic assimilates via leaf surface display per unit leaf biomiass investment. Leaves with high SLA are said to be acquisitive leaves. They are photosynthetically more productive per unit of mass invested and per unit of time, but they generally have a shorter lifespan, which lowers their cumulative return.

Difference between specific leaf area mean and the upper or lower bounds of the 95% confidence interval.

Wood density is an index of investments of dry biomass in wood. It represents the biomass invested per unit of wood volume. A plant with high values of wood density is a conservative plant. A plant with high values of wood density is an acquisitive plant. Wood density helps to maintain mechanical support. However, high wood density results in low capacity to transport water and store carbohydrates. It is obtained by weighing and following determination of volume. It is measured at the base of apical branches of each tree.

Mean of the values of branch wood density for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. Wood density is a measure of mass invested per unit of volume. High density wood is generally correlated with long wood lifespan, high resistance to pathogen attacks and mechanical damage. It also relates inversely to volumetric growth, hence trees with high wood density are said to be resource conservative.

Variance of the values of branch wood density for the apical branches of 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. Wood density is a measure of mass invested per unit of volume. High density wood is generally correlated with long wood lifespan, high resistance to pathogen attacks and mechanical damage. It also relates inversely to volumetric growth, hence trees with high wood density are said to be resource conservative.

Difference between wood density mean and the upper or lower bounds of the 95% confidence interval.

Assessment for each Functional Subset tree.

0 = 0 to 25% of defoliation

1 = 25 to 50%of defoliation

2 = 50 to 75 % of defoliation

3 = 75% to 99% of defoliation (dead = 100 % = not a FS tree).

See the WP2 protocol for more informations

Sapwood areas is calculated from:

- the under-bark total lenght of the core measured on the tree ring core after collection.

- the sapwood lenght measured on the tree ring core after collection.

- the bark lenght measured on the tree ring core after collection.

The calculation of sapwood area is weighted by the value of the breast height trunk circumference.

See the WP2 protocol for more information.

The mean of the values of the sapwood area across 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. The sapwood area is based on the measurement of the length of the sapwood estimated from a wood core collected at breast height (1.3 m). This sapwood area is the calculated (in cm2) using the Trunk circumference.

The variance of the values of the sapwood area across 10 measured adult dominant or co-dominant trees sampled either inside or in the vicinity of the representative circular plot with a radius of 15 m. The sapwood area is based on the measurement of the length of the sapwood estimated from a wood core collected at breast height (1.3 m). This sapwood area is the calculated (in cm2) using the [Trunk circumference].

year of birth of the tree estimated from the tree core collected at breast height on each FS tree by PHENOBOIS platform (INRAE, Frédéric LAGANE, Bordeaux).