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

Capítulo 3
Q. faginea exhibited the bigger acorns. At each species no differences in seed dry
mass were found between plots except for Q. pyrenaica, which exhibited bigger acorns
in plot one (P = 0.02). The distance between acorns of each species at each node was
about 20 cm. This minimized competition between individuals since Quercus plants
produce a pivot root.
Data collection
Seedlings were monitored for emergence and survival twice a month between
January and September 2007. Emergence rate was calculated as percentage of seeds
emerged from the sown seeds. Survival rate was calculated as percentage of seedlings
surviving from the emerged seeds and the seedling establishment success as
percentage of seedlings surviving from the sown seeds. Seedlings were subjected to
the following measurements: basal and apical length, and diameter of the main stem
and all secondary branches. The data were used to calculate the total stem volume for
each plant, using the truncated cone formula. Total leaf area was estimated according
to Poorter et al. (2004), using a point grid printed on a transparent sheet. The number
of grid intersections found within a certain area provides a good estimate of such an
area. Three sheets differing in grid size (3, 5 or 7 mm) were used depending on the size
of the leaves.
Stem and leaf biomass were estimated from the previous measurements from
the aerial fraction of a sample of seedlings consisting of 15–25 plants per species sown
in the experimental site but outside the two plots. Previously, the non‐destructive
measurements (leaf area and stem volume) were taken. All leaves were scanned with a
HP Scanjet 6300c scanner, and both stems and leaves dried in a stove at 70°C for at
least 48 h prior to obtaining the dry weight of each plant organ. Linear regressions
between stem volume and stem dry weight for each species and sampling date (r 2 >
0.75) were used to estimate stem mass from the previously calculated volume (Pérez‐
Ramos et al., 2010). The scanned leaf images were used to calculate the total leaf area
for each harvested seedling by using the software Image Pro‐plus 4.5 (Media
Cybernetics, Inc.). Leaf mass per unit area (LMA) was calculated as the ratio of leaf dry
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