植物分佈是地球環境許多作用中重要因子之一，本文目標是使用主成份因子分析方法分析北美地區植物特性之空間變化，研究地區範圍從西經120度到50度及北緯10度到70度，研究結果顯示主成份因子1，2及3分別解釋73%，25%及2%之北美地區4類植物特性變異(常綠樹，落綠樹，闊葉樹及針葉樹)，主成份因子1與針葉樹及常綠樹呈高度正相關，主成份因子2與闊葉樹及落綠樹呈高度正相關，本文使用群落分析方法研究北美地區植物特性，研究結果顯示有11個主要植物群落。

　　　　　Vegetation cover is an important variable in many Earth system processes. The aim of this research is to analyze spatial variations in vegetation characteristics of North America using principal component analysis. The study area is from 120°W to 50°W and 10°N to 70°N. The results show that the principal components 1, 2, and 3 explain 73%, 25%, and 2% of the variance in the original 4 vegetation maps (evergreen, deciduous, broadleaf, and needleleaf maps). Component 1 is highly correlated with needleleaf and evergreen vegetation. Component 2 is highly correlated with broadleaf and deciduous vegetation. This research used cluster analysis to generate 11 North American vegetation clusters.