Prediction of potential distribution of Cupressus gigantea W. C. Cheng & L. K. Fu in China based on optimized MaxEnt modeling

Cupressus gigantea W. C. Cheng & L. K. Fu, a tree species endemic to Tibet and classified as a national first-class protected species in China, requires clear delineation of its potential suitable distribution for effective conservation, introduction, and breeding programs. This study established the MaxEnt model, using the “kuenm” R package to optimize model parameters, to predict the potential distribution of C. gigantea across China. Environmental variables influencing distribution were analyzed through percent contribution and Jackknife tests. The optimized model demonstrated superior predictive accuracy and reduced complexity compared to the default parameter model. Key factors influencing the distribution of C. gigantea included distance from rivers, temperature seasonality, isothermality, slope, and precipitation during the coldest quarter. Predicted suitable distribution areas were primarily located in Tibet and Sichuan, with the cities of Nyingchi, Lhoka, Lhasa, and Rikaze in Tibet encompassing the entirety of moderately suitable (2 298 km²) and highly suitable areas (746 km²). The high suitability area was exclusively distributed in Nyingchi (563 km²) and Lhoka (183 km²), representing about 0.062% of the total area of Tibet. The corridor between Lang County and Milin County emerged as the core habitat for C. gigantea, underscoring the need to prioritize conservation efforts in this critical region.