Ecological Archives E093-111-A5

Don W. Butler, Sean M. Gleason, and Mark Westoby. 2012. Setbacks to shoot growth are common in woody plants, so how are shoots of some species safer than others? Ecology 93:1275–1282.

Appendix E (Table E1). Species traits and methods employed in their measurement.

Variable Method
Amass Light saturated photosynthetic rate on mass basis measured in the field for 4 reps per species with a portable photosynthesis system (LI-COR 6400xt) and consistent chamber CO2, VPD and temperature (388–402 ppm, 23–27 °C, 1.9–2.1 kPa respectively).
Bending SF Species average MOR/average of bending stress in main stems 80 cm from shoot tip, when tipped to horizontal orientation. Mean of four shoot per species (see Appendix B for more details)
Bark thickness Bark proportion of lead stem diameter 40 cm from the shoot tip, mean of four shoots per species
Dry mass to 80cm Average dry mass of leaves and stem in distal 80cm of lead shoots, measured with a precision laboratory balance for 4 shoots per species after drying to constant mass at 70 °C
Height (m) Typical maximum height for species based on field observations, species descriptions and herbarium specimen labels
Leaf area to sapwood area ratio Leaf area per sapwood area at 5 mm sapwood diameter. Calculated from regression predicting leaf mass from sapwood area (log-log) measured on 4 shoots per species, with leaf mass converted to leaf area via LMA
Leaf mass per area (g/m2) Leaf dry mass per fresh projected area (i.e. one-sided) for multiple leaves from five plants per species
Leaf N concentration Green leaf nitrogen concentration
Leaf size (cm2) One-sided projected area of a leaf, average of measurements on several fresh leaves from outer crown of five plants, measured with flatbed scanner
Midday leaf water potential (MPa) Measured with a pressure chamber (PMS 1000) on leaves or small twigs from the upper crown of least 3 plants per species. Material was mostly collected on sunny days and at relatively dry times of the year.
Modulus of rupture (MPa) 3-point bending test with general materials testing machine (Model 5542; Instron Corporation, Canton, MA, USA) on wet stems with bark on ~8 mm diameter & 200 mm span (few shorter). Average of 5 reps per species.
Sapwood conductivity per unit area (kg·m-1·s-1·MPa-1) Measured with a Sperry apparatus pushing filtered and degassed 0.02 M KCl at 100 kPa through stem sections 0.8 m long and distal sapwood diameter of 5 mm. Expressed as flow per unit distal sapwood area. 5 reps per species.
Stem specific gravity Oven dry mass (70 °C) per fresh volume for whole stem sections (bark, sapwood, and pith) ~8 mm diameter, expressed as ratio with density of water. Volume measured by mass-displacement method (Archimedes). Average of 5 reps per species.
Stem diameter Average lead stem diameter 40cm from shoot tip, measured over bark with digital calipers for 4 reps per species
Stem N content Nitrogen content of dry whole stem segments ~1 cm diameter

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