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

Reforestation with Quercus ilex L. and Q. suber L. by direct seeding and planting in southern Spain
older Q. ilex and Q. suber seedlings (3–4 years) in larger containers (1000–3000 cm 3 ).
This has allowed the initial growth period in the field to be shortened and more visible
results to be obtained within a shorter time after planting. However, planting taller
seedlings has increased associated costs (Stanturf et al., 2004). Also, older plants may
exhibit abnormal root growth by effect of cultivation in small containers (Pemán et al.,
2006) and develop inadequately after planting as a result (Dey et al., 2008), thereby
being at an increased risk of dying during the first summer drought. However, Zaczek
et al. (1996) found their oldest, tallest plating stock to exhibit the highest survival after
6 years. Moreover, although larger seedlings are more expensive to plant than are
smaller seedlings, the former can be planted at lower densities in order to reduce costs
(Dey et al., 2008).
Seedling quality and growing conditions can also be highly influential on plant
establishment success (Villar‐Salvador et al., 2004a; Zida et al., 2008). Nursery growth
of container seedlings is affected by the type of substrate, container size, and watering
and fertilization regimes used (Aphalo and Rikala, 2003; Zida et al., 2008). Thus,
seedlings grown in deep containers have root systems similar to those of naturally
grown plants, and exhibit an increased root development capacity and hydraulic
conductance than those growing in not so deeper containers (Pemán et al., 2006;
Chirino et al., 2008). Plant morphology dictates growth and survival potential in the
field (Navarro‐Cerrillo et al., 2007). Various attributes including aerial biomass, height
and the root/shoot biomass ratio have frequently been used to predict seedling
performance in the field (Davis and Jacobs, 2005; Jacobs et al., 2005); there is,
however, no general agreement as to what is the most suitable plant morphology for
the Mediterranean environment. Some authors have found no relationship between
plant survival and seedling morphology; also, plant early response is believed to be
more markedly dependent on the particular local conditions (Dey et al., 2008; Zida et
al., 2008; Palacios et al., 2009).
One of the main causes of failure in reforestation actions is summer drought.
Water stress affects planting stock and seedling establishment (Grossnickle, 1988), and
can reflect in changes in stomatal conductance (Stewart and Bernier, 1995;
136