TRAIT

PREFFERED UNIT

DESCRIPTION

Relatively easily measured (“soft” traits)

Seed mass

mg

Oven dry mass of an average seed^1,2

Specific leaf area (SLA)

m² kg^-1

One sided leaf area of fresh leaf divided by its dry mass ^1,2,3

Plant height

m

Height of highest leaf tissue^1,2

Wood density

kg m^-3

Dry weight of wood sample divided by fresh volume of the same sample^4,5

Growth form

categorical

Based on canopy structure and height (e.g. tree, shrub, tussock, short basal)²

Life form

categorical

Raunkiear classification based on perennating tissue²

Clonality

categorical

Ability to reproduce vegetatively²

Spinescence

categorical

Degree of spines, thorns or prickles²

Flammability

compound, unitless

Ease of ignition of a species²

Leaf size

mm²

One sided projected leaf area²

Leaf dry matter content

mg g^-1

Oven-dry mass divided by water-saturated fresh mass²

Leaf nitrogen concentration

mg g^-1

Total amount of N per unit dry leaf mass^2,3

Leaf phosphorus concentration

mg g^-1

Total amount of P per unit dry leaf mass^2,3

Physical strength of leaves

N or N mm^-1

Resistance to fracture, force to cut at a constant angle or tensile strength, the force needed to tear a leaf²

Leaf lifespan

months

Time that a leaf (or analog) is alive and physiologically active^{2, 3}

Leaf phenology

months/year

Number of months per year that the leaf canopy is green²

TRAIT

Photosynthetic pathway

categorical

C₃, C₄ or CAM²

Leaf frost sensitivity

% electrolyte leakage

Sensitivity to freezing²

Leaf perimeter/area ratio

cm cm^-2

Length of leaf perimeter divided by fresh leaf area^6,7

Stem specific density

mg mm^-3

Oven-dry mass of main stem divided by fresh volume of same stem²

Twig dry matter content

mg g^-1

Oven-dry mass of terminal twig divided by fresh volume of same twig²

Bark thickness (& quality)

mm

Thickness of stem external to the xylem/wood²

Specific root length

m g^-1

Ratio of root length to mass; belowground analogue of SLA²

Root depth distribution

g m^-3

How is the root biomass distributed vertically in the soil²

95% rooting depth

m

Estimate of depth above which 95% of the root biomass is located²

Nutrient uptake strategy

categorical

Mechanisms to take up nutrients (e.g. N fixer, mycorhizzae, carnivorous)²

Dispersal mode

categorical

e.g. wind, ant, endo-zoochory²

Dispersule shape

unitless

Variance of three dimensions (length, width, thickness)²

Dispersule size

mg

Oven dry mass of entire reproductive dispersule²

Resprouting capacity after major disturbance

categorical

Capacity to resprout after desctruction of most of its aboveground biomass²

Cotyledon type

categorical

e.g. epigeal, hypogeal⁸

Short list of  more difficult to measure (“hard” traits)

Potential relative growth rate

g g^-1 d^-1

rate of growth as a function of existing mass

Photosynthetic capacity/respiration rate

μmol CO² g^-1 s^-1

maximum rate of photosynthesis per unit mass and dark respiration rate per unit mass³

Leaf hydraulic conductance

kg m^-2 s^-1 MPa^-1

hydraulic conductance of the leaf lamina⁶

Stomatal pore index

dimensionless

stomatal density multiplied by aperture length squared⁶

Stem hydraulic conductance

kg m^-2 s^-1 MPa^-1

Hydraulic conductance of stem tissue⁹

Plant biomass

g

Oven-dry weight of entire plant

Seed persistence

categorical or mo

length of time a seed remains viable