Design of the Experiment

In May 2006, we randomly located five rectangular plots in the Natural Park of Tamadaba where P. pinea was planted (Table I). The plots were of different sizes due to the features of the landscape, such as roads and ravines. In each plot we measured altitude and slope, and estimated canopy cover of the stand using a convex spherical densiometer (Lemmon 1957). We also visually estimated rock, bare soil, and litter cover within each complete plot on a scale of 1 to 10.

We defined trees as stems of at least 2.5 cm dbh and seedlings as stems taller than 10 cm originating from seed. Previous studies recommended these classifications in concordance with the physiognomy and phenology of these species (Salas 1994). We mapped all trees in the plots to an accuracy of 0.05 m. For the seedlings we located a transect 10 x 50 m in the middle of the plots in which all the individuals of this category were mapped. The transect was subdivided in five 10 x 10 m subplots and numbered from 1 to 5. In the subplots 2 and 4, all the pines were excluded from grazing with a protective circular metal fence 30 cm in diameter, avoiding grazing from rabbits, the only vertebrate grazer in the area.

Gran Canaria Island

Pinus pineo -P. canariense stand

Tamadaba Natural Parti b)

Gran Canaria Island

Pinus pineo -P. canariense stand

Tamadaba Natural Parti

Figure 1. a) Canary Islands archipelago and b) Gran Canaria Island indicating in grey the Natural Park of Tamadaba and in black the location of the study site (geographical coordinates are indicated).
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