Predicting Species Occurrence of Litsea leytensis Merr. in the Provinces of Laguna and Quezon, Philippines

Abstract

Litsea leytensis Merr. is an endemic and premium hardwood species in the Philippines used for wood carving. It is a threatened species that survival in the wild is impossible with persistent causal factors. The study estimated the species probability of occurrence in Laguna and Quezon based on local knowledge, published records of species distribution, and environmental variables using the Maximum Entropy (MaxEnt) model. Six pre-models were generated: one climatic model, four partial models of variable groups combined with climatic variables, and one full model with 31 original variables. The Final model had 19 highly correlated variables after variable selection and reduction using Jackknife and multi-collinearity tests. Analysis of variable importance revealed that L. leytensis’ occurrence was mostly determined by climatic (62.0%), edaphic (21.76%), and anthropogenic variables (9.53%), while topographic (5.15%) and vegetation-related variables (1.34%) had lesser contributions. The Area Under the Receiver Operating Characteristic Curve (AUC) and True Skill Statistics (TSS) measured model accuracy; and the Final model performed best at AUC = 0.9489 and TSS = 0.7175. Modeling species probability of occurrence could help key sectors in Laguna and Quezon to formulate appropriate conservation strategies for L. leytensis as a reforestation and industrial tree plantation species.