Structure and composition of natural holm oaks in the Slate Altitude from Viñales Municipality, Pinar del Río, Cuba Dahkkit: González-Menéndez, Modesto, Alonso-Torrens, Yatsunaris, Urrutia-Hernández, Isyoel, Miñoso, Yaumara, Santana, Isabel, Luis-Suárez, Jesús, González-Torres, Carlos Manuel