落葉性樹種在秋季發生的大規模葉片顏色變化一直是自然界令人稱奇的現象之一。關於葉片顏色的變化，目前已知主要受到葉綠素降解及花青素生合成的影響，其分別扮演使綠色褪去和產生秋季各種不同顏色。關於葉片為何需要變色，卻有許多不同的說法，本文整理過去多篇有關葉綠素降解與花青素之生合成代謝途徑，討論落葉性樹種相關研究，並探討秋季葉變色之生理意義及在環境變遷下可能之變化。

Autumn leaf coloration of deciduous plant is one of the remarkable natural events in the world. The coloration is due to two major metabolic pathways: chlorophyll degradation for degreening and anthocyanin biosynthesis for autumn leaves color change. The reasons for leaves to change their colors in autumn and the number of biochemical pathways were reviewed, and associated enzymes and metabolites are identified in this study. In this article, the main reactions in chlorophyll degradation and anthocyanin biosynthesis were illustrated, and recent reports on autumn leaf coloration of deciduous trees were reviewed. Finally, the physiology benefits of leaf coloration and the effects of climate changes were discussed.