Dynamics of Foliar Nutrients in Major Species of a Broadleaf Forest in the Fushan Experimental Forest, Northeastern Taiwan

福山試驗林闊葉林重要樹種葉部養分動態研究

鹿兒陽(Erh-Yang Lu) ； 劉育延(Yu-Yen Liu) ； 顏江河(Chiang-Her Yen)

《台灣林業科學》 22卷3期 (2007/09) Pp. 307-319

https://doi.org/10.7075/TJFS.200709.0307

摘要

本研究於福山試驗林進行，該天然闊葉林主要組成為樟科、殼斗科及其他科的植物，本研究涵蓋了其中8種主要植物（台灣雅楠、長葉木薑子、紅楠、鋸葉長尾栲、三斗石櫟、長梗紫苧麻、綠樟、烏皮茶）。其中唯一的灌木長梗紫苧麻與台灣雅楠主要生長於溪谷，其他樹種則分布在中坡及稜線上。本研究的目的在了解這些樹種間及節間的養分濃度變化，並探討養分與土壤特性的關係，此外以一年生葉部的氮、磷濃度來評估養分再吸收作用。
8種植物之間的葉部養分有顯著的差異，生長在溪谷的灌木長梗紫苧麻葉部養分濃度較其他木本植物為高。三種樟科植物中，以生長在溪谷的雅楠葉部有較高的N、P、K。除了樹種本身遺傳因子所造成的差異之外，溪谷及中坡/稜線間土壤特性的差異也可能是造成樹種葉部養分組成差異的主因。
8種主要樹種葉部的N、P與K濃度均隨著葉齡增加而減少，相反的，葉部Ca濃度均隨著葉齡增加而上升，葉部Mg濃度在樟科植物（台灣雅楠、長葉木薑子、紅楠）與綠樟會隨著葉齡增加而上升，但是在殼斗科植物（鋸葉長尾栲、三斗石櫟）與烏皮茶卻在不同葉齡間卻無明顯變化趨勢。4月29日到6月3日間是葉部開展成熟階段，稀釋效應可能是此時期植物葉部養分濃度下降的主因。8種樹種一年生葉部的氮濃度在1.12及3.02%之間，磷濃度則在0.05及0.06%之間，以一般再吸收度(resorption proficiency)的臨界值評估後發現磷的再吸收較氮的再吸收完全，顯示在福山試驗林中磷為生長較重要的限制因子。

關鍵字

福山試驗林 ； 葉部養分 ； 季節變化形式 ； 地形 ； 養分再吸收

並列摘要

This study was carried out in a subtropical rainforest of the Fushan Experimental Forest, one of the long-term ecological study sites in Taiwan. The forest is mainly composed of hardwood species of Lauraceae, Fagaceae, and other families, including 8 major species investigated in this study, Phoebe formosana (Phfo), Litsea acuminata (Liac), Machilus thunbergii (Math), Castanopsis cuspidata var. carlesii f. sessilis (Cacu), Pasania hancei var. ternaticupula f. ternaticupula (Paha), Oreocnide pedunculata (Orpe), Meliosma squamulata (Mesq), and Pyrenaria shinkoensis (Pysh). Orpe, the only shrub in this study, was mainly found in the valley along with Phfo. The other 6 tree species grow on the hillsides and hilltops. This study investigated the concentrations and seasonal patterns of foliar nutrients in these species and the relationship between foliar nutrients and soil properties. The concentrations of N and P in 1-yr-old leaves were also used to estimate the resorption rates of N and P.
Foliar nutrient concentrations significantly differed among the 8 species. Orpe, the valley
shrub, had higher foliar nutrient concentrations than the other species. Among the 3 species of Lauraceae, Phfo, a valley tree, also had higher foliar N, P, and K levels than Liac and Math. The significant differences in soil properties between the hillside/hilltop and the valley may have con-tributed to differences in the foliar nutrient composition among species from different topographic locations.
Foliar concentrations of N, P, and K usually decreased and foliar Ca increased as the leaves aged. The seasonal patterns of foliar Mg concentrations differed among species. The foliar concentrations of N, P, K, Ca, and Mg consistently dropped 1 mo after leaf emergence, suggesting the dilution effect of leaf expansion. Nitrogen concentrations in 1-yr-old leaves ranged between 1.12 and 3.02%, and P concentrations between 0.05 and 0.06%. Comparisons with the general thresholds of resorption proficiency suggested that within 1 yr, P was resorbed more completely than N. Therefore, P is probably more limited in the Fushan forest.

並列關鍵字

Fushan experimental forest ； foliar nutrients ； seasonal pattern ； topography ； nutrient resorption