森林疏伐對土壤氮素礦化及硝化作用之影響

In Uences of Forest Thinning on Soil Nitrogen Mineralization and Nitrification

莊舜堯(Shun-Yao Zhuang) ； 陳岳民(Yue-Min Chen) ； 王明光(Ming-Kuang Wang) ； 郭幸榮(Shin-Rong Kuo) ； 黃正良(Jeen-Lian Hwong) ； 金恒鑣(Hen-Biao King)

《台灣林業科學》 20卷2期 (2005/06) Pp. 167-177

https://doi.org/10.7075/TJFS.200506.0167

摘要

本文以現地埋藏袋法比較竹東人工柳杉林不同程度疏伐處理對土壤氮淨礦化和淨硝化作用之影響。試驗樣區按疏伐程度分別設置對照、輕度、中度及強度疏伐等四個處理。在每個樣區中選擇相近海拔高度之三個樣點放置埋藏袋，現地測定土壤氮之淨礦化及硝化作用速率。結果顯示，土壤無機態氮（銨態氮及硝態氮）含量在不同疏伐處理中並無顯著差異，但隨季節而有明顯的變化，一般在9月份達到最大。土壤氮之最大淨礦化速率出現在6~9月份期間，對照、輕度、中度及強度四個疏伐處理分別為0.182，0.246，0.303及0.560 mg N kg^(-1) d^(-1)，與疏伐程度有很好的一致性。同時，結果也顯示，土壤全年累計礦化氮量及所占土壤全氮的比例也均與疏伐處理程度有很高的一致性，在強度疏伐下，全年土壤中淨氮礦化量為107.9 mg N kg^(-1)，土壤總氮礦化率約為12%，而對照處理僅為440 mg N kg^(-1)。結果表明，在短期內（二年），疏伐處理使土壤氮礦化量顯著提高，而礦化氮之淋失量也可能相應加劇。

關鍵字

森林疏伐 ； 土壤氮 ； 礦化作用 ； 硝化作用

並列摘要

In this paper the buried bag method was employed to investigate the in uences of forest thinning on soil net nitrogen mineralization and net nitrification in Cryptomeria japaonica forests. According to the thinning intensity, 4 study plots were set up and included a control as well as light-, medium-, and heavy-thinning treatments. Three points were selected for burying bags at close to the same elevation in each plot to measure net nitrogen mineralization and net nitrification in situ. Results showed that the contents of soil inorganic nitrogen (including ammonium and nitrate) did not differ among these various treatments, but all varied with the season. The seasonal maximum nitrogen mineralization rates of the 4 treatments were 0.182, 0.246, 0.303 and 0.560 mg N kg^(-1)d^(-1), respectively, during the period from June to September which was corresponded to the thinning intensity. Moreover, the total annual net mineralized N and its ratio to soil N were correlated to the thinning treatment. In the heavy thinning treatment, the total mineralized nitrogen was 107.9 mg N^(-1)kg^(-1), and the mineralization ratio was 1.2% which were much higher than those in the control treatment (44.0 mg N kg^(-1) and 0.6%). Overall, the results revealed that forest thinning treatments can increase soil nitrogen transformation rates that might lead to a higher potential for nitrogen leaching in the forest.

並列關鍵字

forest thinning ； soil nitrogen ； mineralization ； nitrification