Structural analysis of the dry forest in the "La Tomatera" sector of the Portoviejo valley, Manabí, Ecuador

Abstract

The dry forest plays an important role in the conservation of the world's greatest biodiversity and in the understanding of its dynamics and structure. However, it is highly vulnerable to contemporary anthropogenic ecological threats. For this reason, analysis of its impact on the structural richness of the dry forest in the "La Tomatera" sector of the Portoviejo Valley was permitted. Twenty 20 x 25 m plots of were established at random in a 100-hectare forest fragment; individuals ≥1 cm DBH (1.30 m) and ≤4.99 m height were recorded. These were used to identify forest species, determine richness, horizontal and vertical structure, and estimate the ecological Importance Value Index, and Shannon-Weaver, Simpson, and Margalef’s richness indices, using nonparametric estimators in Estimates 9.1. In the forest inventory, 11 woody species corresponding to 9 botanical families were identified; the vertical and horizontal structure through the ACE and Chao1 accumulation curve showed a representativeness of 92% and 76%, respectively. In addition, its inverted J shape, with individuals mostly in the first diameter and altimetric classes, reflected a forest undergoing a recovery process. The ecological Importance Value Index showed that the most representative species are Ceiba trichistandra (A. Gray) Bakh., Cochlospermum vitifolium (Willd.) Spreng. and Neltuma juliflora (Sw.) Raf. The Shannon-Weaver and Simpson index estimated a diversity between medium and high, and the Margalef index established a low diversity and specific richness of forest species in the dry forest of the "La Tomatera" sector.