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臺灣中部觀山天然闊葉林枯落物動態及養分研究

Litterfall Dynamics and Nutrients of a Natural Hardwood Forest in Guanshan of Central Taiwan

摘要


本研究以南投縣臺大實驗林和社營林區30林班之觀山天然闊葉林為調查對象,自2002年5月至2004年4月兩年期間,每月收集一次枯落物以了解枯落物動態及其所含養分濃度。本闊葉林第一、二年之年枯落量分別為7,945、10,043 kg ha^(-1),由於颱風的影響,第二年的枯落物明顯高於第一年;枯落物的組成以落葉佔的比例最高,枝條次之;7個優勢樹種的落葉佔總落葉量的四分之三,以霧社楨楠落葉量最高,木荷次之。第一年枯落物最高峰為7月,第二年則以9月為最高峰,7月次之,7月大量的枯落物主要是老葉汰換所致,第二年9月則來自颱風打落的枝葉、樹皮與碎屑等。落葉的高峰與總枯落物相似,最低的時期也同樣在10月至次年2月間。7個優勢樹種中,紅楠、霧社楨楠、長葉木薑子、山香圓的落葉自3月明顯增加,瓊楠、長尾柯、木荷落葉開始的時間則較為延後。 落葉的養分濃度普遍較枝條為高,而繁殖體的鉀濃度則高於落葉與枝條。7個優勢樹種間養分濃度及氮磷(N/P)重量比均具顯著差異,紅楠落葉的氮、磷、鉀濃度最低,長葉木薑子的鈣、鎂濃度最低,而山香圓則有最高的磷、鉀、鈣、鎂濃度及最低的氮磷重量比,落葉養分的差異顯示樹種間養分需求、利用、保存上的不同。將兩年中主要樹種落葉最低氮、磷濃度與Killingbeck (1996)提議的臨界值相比較,多數優勢樹種的磷再吸收作用相當完全,但僅紅楠具有完全之氮再吸收作用,這顯示本闊葉林中磷缺乏之狀況較為嚴重,7個優勢樹種落葉氮磷重量比在18.8~29.3之間,皆較磷缺乏臨界比值(16)為高,支持本闊葉林中磷較缺乏的狀況。

關鍵字

觀山 天然闊葉林 枯落物 養分

並列摘要


This study is carried out in a natural hardwood forest of Guanshan, which is located in the thirtieth compartment of Heshe district, the Experimental Forest, National Taiwan University. The litterfall was collected monthly from May of 2002 to April of 2004 to analyze the seasonal patterns of litterfall and the nutrient compositions of major litterfall components. The annual litterfall mass was 7,945 and 10,043 kg ha^(-1) in the first and second years, respectively. The increase in the litterfall mass of the second year was mainly caused by the typhoon. The leaf fall is the most important component of annual litterfall, followed by perennial organs. The leaf fall of seven dominant species accounts for three quarters of the annual leaf fall. The major litterfall peaks occurred in July of the first year and September of the second. There was also one more peak in July of the second year. In July, the peak litterfall came mainly from the displacement of senescent leaves by new leaves, whereas in September, the typhoon blew off twigs/branches and caused premature leaf fall. Similar to the total litterfall, the leaf fall was scarce from October to February of the following year. Machilus thunbergii, Machilus zuihoensis var. mushaensis, Litsea acuminata, and Turpinia formosana began to increase their leaf fall in March, while Beilschmiedia erythrophloia, Castanopsis carlesii, and Schima superba began in later months. The nutrient concentrations are usually higher in the leaf fall than in the perennial organs. However, the K concentration is highest in reproductive organs. Among seven dominant species, Machilus thunbergii has the lowest N, P, and K concentrations of the leaf fall, Litsea acuminata the lowest Ca and Mg, and Turpinia formosana the highest P, K, Ca, and Mg and the lowest N/P weight ratio. The variations in the nutrient compositions of the leaf fall suggest the differences in nutrient demand, utilization and conservation. The comparisons of the minimum N and P concentrations in the leaf fall with the resorption thresholds suggested by Killingbeck (1996) indicate that most dominant species have the complete P resorption but only Machilus thunbergii has the complete N resorption. This suggests that P is more limiting in this hardwood forest. The N/P weight ratios (18.8-29.3) of seven dominant species are all higher than the threshold ratio (16) of P-limitation, supporting the greater P limitation in this forest.

被引用紀錄


劉子揚(2012)。臺灣東北部天然闊葉林與柳杉人工林林下光照環境及林下植物多樣性之比較〔碩士論文,國立臺灣師範大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0021-1610201315272883

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