STUDY ON EVALUATION OF THE ENVIRONMENTAL PROTECTION AND IMPROVEMENT CAPACITY OF Vernicia montana Lour FORESTS IN QUANG TRI PROVINCE

Abstract

A study on mixed-species protective forests in Quang Tri province was conducted, evaluating various forest types of different ages. The research assessed a 20-year-old mixed forest of Vernicia montana Lour and Pinus merkusii; a 20-year-old mixed forest of Vernicia montana Lour, Pinus merkusii and Hopea odorata; a 10-year-old mixed forest of Vernicia montana Lour and Liquidambar formosana Hance; a 10-year-old mixed forest of Vernicia montana Lour and Hopea odorata; a 5-year-old mixed forest of Vernicia montana Lour, Erythrophleum fordii and Hopea odorata; a 5-year-old mixed forest of Vernicia montana Lour and Hopea odorata. The findings identified that the mixed forests of Vernicia montana Lour and Pinus merkusii; Vernicia montana Lour and Liquidambar formosana Hance; Vernicia montana Lour, Erythrophleum fordii, Hopea odorata demonstrated significant protective capabilities, effectively improving soil and air environments. At age 5, these forests recorded a comprehensive structural index of forest vegetation (Z, %) of 172.7%, which increased to 297.8% by age 20. Compared to non-forested areas, soil temperature decreased by 1.4 - 2.5°C, soil moisture rose by 11.9 - 19.7%, and soil chemical properties improved, with pH ranging from 1.88 to 2.02, humus content from 2.01 to 2.95%, available nitrogen from 1.53 to 2.24 mg/100g soil, available phosphorus from 37.41 to 77.46 mg/100 g soil, and available potassium from 75.8 to 85.91 mg/100 g soil. Furthermore, air temperature under the canopy dropped by 3.4 – 6°C, air humidity increased by 5 - 11.2%. These results provide a scientific foundation for selecting suitable mixed-species protective forests incorporating Vernicia montana Lour for development in Quang Tri province.