本研究探討臺灣杉(Taiwania cryptomerioides)人工林疏伐處理後2年內疏伐枯落物分解與土壤養分變化。選擇溪頭29年生臺灣杉人工林，進行40%株數疏伐與對照組比較，並設置分解試驗並監測土壤養分變化。臺灣杉疏伐處理對新鮮枯落物殘留率與時間呈指數相關，疏伐後枯落物年分解係數(k)為0.60。新鮮落葉分解隨時間增加而減少，分解過程中可交換性一價陽離子易受到淋洗等因素移出造林地，而可交換性鈣離子受到新鮮落葉分解與疏伐過程土壤擾動而增加。¹³CPMAS NMR結果示碳水化合物(如纖維素與半纖維素)持續由微生物分解轉化為微生物分解後的產物，並逐漸進入分解木質素階段。

This study investigated short-term soil nutrient variation and litter decomposition after 2 years thinning treatment of Taiwania cryptomerioides plantation. The 29-year-old Taiwania cryptomerioides plantation was selected for 40% stem removal and control treatments, in which litter decomposition and soil nutrients were monitored and compared. The fresh litter mass remaining rate of Taiwania crypotomerioides had a significantly exponential relationship with time (p<0.01). The coefficient (k) of litter decomposition was 0.60 after thinning treatment. Fresh litter decomposition rate decreased with time. Exchangeable monovalent cations were easily leached out in the decomposition process, and exchangeable Ca²⁺ increased with fresh litter decomposition and soil disturbance during the thinning process. The results of ¹³CPMAS NMR showed that carbohydrate, such cellulous and hemi-cellulous, continued to be decomposed by microorganisms into microbial decomposition products, and gradually entered the stage of decomposing lignin.