PRINCIPAL COMPONENT ANALYSIS OF ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF TRIBULUS TERRESTRIS L. IN THE SOUTHERN KHANH HOA REGION

Abstract

This study investigates the ecological distribution of the Tribulus terrestris L., a  species listed in the Vietnamese Red Book (EN), which commonly grows wild in coastal areas of Khanh Hoa Province. The study focuses on analyzing the climatic characteristics and principal physicochemical composition of soil samples taken from Thai An hamlet, My Tan hamlet, and Do Vinh ward, and their impact on the natural distribution of Tribulus terrestris. The results show that the study area is characterized by a hot and very dry climate, with high seasonal temperatures and humidity. The soil’s physicochemical index is predominantly sandy, but also exhibits neutral to moderately alkaline pH (7.45 - 8.77) and low nutrient concentrations. Principal component analysis also reveals differences in environmental factors among these study sites. Specifically, at Thai An, clay content shows a positive correlation with K₂O and a negative correlation with organic matter. At My Tan, the positive relationship between clay and K₂O is stronger, and the positive correlation between pH, EC, and sand is even stronger in areas with high clay content. At Do Vinh, strong positive correlations are observed among pH, EC, and readily available nitrogen, whereas P₂O₅ and K₂O exhibit weak correlations in soil layers with higher concentrations. EC and readily available N are strongly correlated, while pH shows only moderate positive correlations with nutrient content.