In mountainous regions with substantial landmass, larger mountain systems often exhibit upward shifts in vegetation distribution, where comparable vegetation zones occur at higher elevations in interior areas than along peripheral slopes. This pattern has been widely documented in continental regions such as the Tibetan Plateau and is frequently attributed to temperature differences between interior and exterior mountain environments, a phenomenon known as the Mass Elevation Effect (MEE). In Taiwan, previous studies have reported mixed evidence regarding both vegetation-elevation patterns and the existence of MEE. This study aims to re-examine these vegetation distribution patterns and reassess the presence and potential drivers of MEE across Taiwan’s mountainous landscapes.

MEE strength is defined as the difference between observed surface temperature and free-air temperature derived from pressure-level reanalysis data. The study area is partitioned into 20 km × 20 km tiles, within which environmental predictors—including fog frequency, wind exposure, and landmass heating—are sampled and globally standardized to enable cross-tile comparison. For each tile, Ordinary Least Squares (OLS), Spatial Lag Models (SLM), Spatial Error Models (SEM), and Spatial Autoregressive Combined (SAC) models are compared using AICc. Where spatial dependence is present, total effects derived from impact decomposition are used for interpretation.

Preliminary analyses indicate substantial spatial heterogeneity in the relationships between environmental variables and MEE strength. The relative importance and direction of effects vary across regions, and no single factor consistently dominates across all tiles. These findings suggest that MEE-related temperature anomalies in Taiwan may be influenced by multiple interacting climatic processes. However, further analysis and refinement are required before drawing definitive conclusions about the mechanisms underlying vegetation-elevation patterns in this island mountain system.