EVALUACIÓN DEL EFECTO DE LAS PLANTAS NODRIZAS EN EL ESTABLECIMIENTO DE UNA PLANTACIÓN DE Quercus L.

Resumen

Oak seedlings were planted on a disturbed site corresponding to the lava flow of the Xitle, in the piedmont of the Ajusco Hills in Mexico City, in arder to assess: a) the effect of shading by nurse plants on survival and growth of one year old seedlings of Quercus rugosa and Q. castanea, and, b) the effect of nurse plants and seedling age (one vs. two-year-old Q. rugosa seedlings) on the same variables. 250 one-year-old seedlings of each species were planted in three similar patches. Half of them were planted in the open, while the other half were planted under the shade provided by established nurse plants. The effect of seedling age was c:nalyzed with 250 two-year-old seedlings of Q. rugosa that were planted in addition, under the same conditions. The beneficia! effect of nurse plants on survival of one-year-old seedlings of both species was evident, with higher survival of both species under shade. Two-year-old seedlings of Q. rugosa had higher survival rates than one-year-old seedlings, and no differences between open and shaded conditions were detected, so it was concluded that the importance of nurse plants decreases with seedling age. In neither case was there a net increase in mean seedling height after a year, due to the high herbivory levels observed in the dry season. Regrowth during the following rainy season did not compensate for the previous loss in seedling height.