環山地區台灣二葉松地面松針分解動態變化

近年來二葉松林及其地面堆積松針，常被認為是林火蔓延的主要原因之一。為了解二葉松地面松針分解動態變化，本研究於環山地區，東勢林管處大甲溪事業區45林班地之34年生台灣二葉松(Pinus taiwanensis)林地，自2003年6月至2004年12月，採取現地立木枝葉，內裝相當於二十公克氣乾重的松針，製作枝葉包(Litter bag)，進行現地分解試驗。為了解地面松針是否能添加硝酸氮，透過加速生物分解作用之方式，減少其蓄積量，本研究亦在鄰近樣區，以每年每公頃五公斤氮量平均施加硝酸氮於樣區，與對照組比較分解速率。結果在十八個月的期間，兩者平均枝葉包絕乾重均下降55%。於十八個月期間，經統計分析後施加硝酸氮與無施加硝酸氮者分解速率相近，均為0.52（1/年）。枝葉包松針醇苯抽出物含量隨處理時間增加而持續降低，自17%下降至5%以下；枝葉包松針卡拉森(Klason)木質素含量隨處理時間比例有上升的趨勢，自42%上升至58%以上。由彈氧熱卡計測得枝葉包松針單位發熱量，自6,300cal/g下降至4,700cal/g；而枝葉包內含松針總發熱量，自124,000cal下降至42,000cal。

關鍵字

台灣二葉松；枝葉包；分解速率；彈氧熱卡計；發熱量

並列摘要

Taiwanese pine and its accumulated litters were generally suspected to contribute flame spread in recent forest fires. In order to investigate litter decomposition dynamics of Pinus taiwanensis in Huan-Shan area, in situ litter bag decomposition experiments were con-ducted in 34-year-old Pinus taiwanensis plantation stand from June 2003 to December 2004 at Division 45 of Dajia Creek Business District, Dongshih Forest District Office, Taiwan Forest Bureau. Pine needles were primed from lower matured branch in situ, then air-dried before being put into litter bag. Each litter bag contained equivalent to 20 grams air dried weight needle. Result showed that 45% oven dried mass remained in each litter bag after 18 months. Additional nitrogen was fertilized at 5kg N per year per hectare at the other side of plot. Decomposition rates of both groups were close, at 0.52 year^(-1)up to 18 months. For both groups, extractable contents were decreased from 17% to below 5%. Klason lignin contents were increased from 42% to above 58%. Measured by oxygen bomb calorimeter, heat contents of litter bag material were decreased from 6,200cal/g to 5,000cal/g. Overall average heat contents for each litter bag were decreased from 124,000cal to around 42,000cal.

並列關鍵字

decomposition rate ； heat content ； litterbag ； oxygen bomb calorimeter ； Pinus taiwanensis

國際替代計量

環山地區台灣二葉松地面松針分解動態變化

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