Establecimiento de cuatro especies de Quercus en el sur de la ...

Whithin population variability influences early seedling establishment on four Mediterranean Oaks
availability, rather than the three light categories described above, unless specified
otherwise.
To estimate soil moisture, the volumetric water content of the topsoil (20 cm
depth) was monthly measured using a time‐domain reflectometer (TDR model 100;
Spectrum Technologies, Inc., Plainfield, IL, USA Spectrum). Three measurements were
taken at each experimental plot from December to May, when soil in the upper layers
was almost dry. Measurements were pooled from December to February to account
for soil moisture in the pre‐emergence period, and from December to May to reflect
spring soil water availability.
Experimental plots were visited every two weeks for the first year and once
every three months for the second year. Seedling performance was evaluated through
seedling emergence (i.e. percentage of seeds emerged from the sown seeds), time to
emergence (number of days after sowing when seedlings emerged), survival in two
successive growing seasons (percentage of seedlings surviving from the emerged seeds
in the first and second year of the experiment) and an overall quantification of
seedling establishment success at the end of the experiment (percentage of seedlings
surviving from the sown seeds).
To assess seedling morphological traits a subsample of the emerged seedlings
was randomly selected (7‐18 seedlings per mother tree, except for one mother tree for
which only 3 seedlings could be used) and non‐destructive measurements in stems and
leaves were taken in the field at end of the growing season (May‐July 2007). Stem
volume was estimated measuring length and diameter of stems and branches at two
positions (at the base and at the top) and applying the formula for conical frustums.
Total leaf area was estimated in the field following Poorter et al. (2004) using a point
grid printed on a transparent sheet. The number of grid intersections found within a
certain area is a good estimator of that area. Three sheets with different grid sizes
were used (3, 5 and 7 mm) depending on leaf size.
To estimate stem biomass from the non‐destructive measurements, 10‐15
additional seedlings per species were harvested at the end of the growing season and
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