福山闊葉林四樹種綠葉的分解及氮動態變化

Green Foliage Decomposition and Its Nitrogen Dynamics of 4 Tree Species of the Fushan Forest

林國銓(Kuo-Chuan Lin) ； 張乃航(Nan-Hang Chang) ； 王巧萍(Chiao-Ping Wang) ； 劉瓊霦(Chiung-Ping Liu)

《台灣林業科學》 17卷1期 (2002/03) Pp. 75-85

https://doi.org/10.7075/TJFS.200203.0075

摘要

選擇福山闊葉林內，四種樹種：長葉木薑子(Litsea acuminata)、紅楠(Machilus thunbergii)、鋸葉長尾拷(Castanopsis carlesii var. sessilis)、及錐果椆(Cyclobalanopsis longinux)，用枝葉包法研究其綠葉的分解及氮的動態變化，分解期間爲3.5年。在初期的1.5年期間分解較快，各樹種的剩餘重量不同，大致以鋸葉長尾拷者分解最快，長葉木薑子最慢。此後1年分解速率幾乎停頓，各樹種剩餘重量相似。最後一年分解父加速，到3.5年時，紅楠分解最慢，其餘3樹種相似。以單一負指數分解模式可計算分解常數(k)，第一年k值爲0.60-0.97，至3.5年k值爲0.30-0.44，比大部分熱帶林的落葉分解爲慢，且與部分溫帶闊葉林相近。綠葉的氮濃度在分解期間呈上升趨勢。但氮剩餘量仍隨重量的減少而下降，可能由於氮只發生礦質化作用。木質素從50天即開始分解，但分解速率比重量減少速率慢。在各樹種初期濃度中，僅初期木質素濃度與第一年分解常數其有自線相關性。

關鍵字

枝葉包 ； 分解常數 ； 木質素 ； 淨生物固定作用 ； 礦質化作用

並列摘要

Decomposition processes and nitrogen dynamics of green foliage of 4 tree species, Litsea acuminata, Machilus thunbergii, Castanopsis carlesii var. sessilis, and Cyclobalanopsis longinux, were examined by the litterbag method for a period of 3.5 years in the Fushan broadleaf forest in northeastern Taiwan. The leaves decomposed quickly, and the mass of the remaining portion differed among tree species during the first 1.5 years: the remaining leaf mass of Castanopsis carlesii var. sessilis was the lowest, and that of the Litsea acuminata was the highest. After 1.5 years the decay rate had almost ceased, and the remaining mass was similar for the 4 tree species during the next year. During the final year of the study, leaves again decomposed quickly; foliage of Machilus thunbergii decomposed more slowly than did those of the other species. The annual decomposition constant (k) was determined by using a single negative exponential decay model. K values of the first year ranged from 0.60 to 0.97 and from 0.30 to 0.44 at the end of 3.5 years. These values are slow compared with the foliar decay rates reported for most tropical forests, but similar to those of some temperate broadleaf forests. The foliar N concentrations of the 4 tree species increased over 3.5 years. But foliar N of the remaining mass still decreased with decreasing mass, mainly due to mineralization. The lignin in leaves began degrading after about 50 days, and its decay rate was slower than that of mass loss. The initial lignin concentration by itself showed a linear relationship with the first-year k value.

並列關鍵字

litterbag ； decomposition constant ； lignin ； net immobilization ； mineralization