Anatomical foliar variation on natural population of Pinus tropicalis Pinar del Río

Abstract

The variation of anatomical traits is crucial to assess ecological adaptability, so important for forest management and the conservation of endemic species. Pinus tropicalis is an endemic species distributed mainly in the province of Pinar del Río, Cuba. It occupies a great variety of ecotopes in continuous pure populations or in sympatry with Pinus caribaea var. caribaea. The objective of this study is to determine the anatomical variation of Pinus tropicalis needles as an adaptive differential response to environmental conditions determined by lithology, altitude and slope. Twenty to thirty individuals were sampled from all the ecotopes where the species grows naturally. Cross sections were made from 10 needles of each tree and 12 anatomical variables were evaluated. The results of the statistical analysis revealed significant differences between ecotopes, mainly in quartzite sands with high silica content. The principal component analysis showed a relationship between anatomical variables related to water economy and assimilation. The discriminant distinguished groups defined from the relationship of the anatomical variables with the lithology. The variables that contributed the most to discriminate between ecotopes were those related to water regulation, the number and diameter of the resin canals, and the thickness of the cuticle. The availability of water and the oligotrophic substrates are the factors that influence anatomical variation. The results are a contribution to ecology and silvicultural management of the species.