溪頭自然教育園區人工林枯落物之時間與空間變異：季節與植生種類的差異

森林枯落物是森林養分循環的重要過程，也是評估森林生產力的重要指標。本研究以溪頭自然教育園區為試驗地點，利用大面積（100ha）共48個枯落物收集網網格樣點的設置，進行兩年（2015年－2016年）的枯落物收集，研究目的為了解枯落物季節與植生種類的差異，並評估枯落物量與鄰近林分特性間的相關關係。調查結果顯示溪頭自然教育園區平均年枯落物量為3,867 ± 1,663 kg ha^(-1) yr^(-1)，不同植生種類間，以柳杉、台灣杉與紅檜人工林樣區枯落物量相對較高，年枯落物量介於4,123－4,702kg ha^(-1) yr^(-1)間，明顯高於復育闊葉林年枯落物量的790 ± 640 kg ha^(-1) yr^(-1)，草坪區幾乎無枯落物收集。在不同部位枯落物中，以葉部枯落物所佔比例最高，佔總枯落物量比例70%，繁殖體部位所佔比例次高，繁殖體部位枯落物以柳杉人工林所佔比例最高。不同月分枯落物量間，以颱風及梅雨期間的枯落物量最高，特別是2015年8月與10月與2016年9月與10月的颱風事件分別帶來2,707 ± 1,699 kg ha^(-1)與1,938 ± 1,185 kg ha^(-1)總枯落物量，佔全年枯落物量的66%與53%。個別樣點年枯落物量與收集網鄰近7.3m半徑的林分結構呈顯著相關，對所有調查樣點而言，當鄰近林分林齡愈大、林木平均DBH、樹高與材積量愈高時，樣點枯落量也愈高。不過，若僅考慮柳杉人工林樣區時，柳杉林人工林年枯落物量僅與鄰近林分材積量呈顯著相關，當鄰近林分材積量愈大，其收集枯落物量也相對較多。相較過去研究，本研究更完整地評估溪頭自然教育園區人工林之枯落物動態與枯落量，一方面在於較多且涵蓋不同植生種類的採樣數量，另一方面在於隨機網格採樣點的設置，網格採樣方式可降低人為設置樣點的偏差。由於枯物為植物養分回歸土壤的重要來源，後續研究將探討溪頭自然教育園區的養分回歸量及其時間與空間變異。

關鍵字

溪頭；人工林；枯落物；季節變化；林分特性

並列摘要

Litterfall is an important process of forest nutrient cycling and an indicator for assessing forest productivity. In this study, the litterfall was collected using a grid sampling set with a total of 48 litter traps over 100 ha area from 2015 to 2016 in the Xitou Nature Education Area. The objectives were to assess the differences of litterfall in different seasons and vegetation types, and to estimate the relationship between annual litterfall amount and stand characteristics. The results showed that the total amount of annual litterfall was 3,867 ± 1,663 kg ha^(-1) yr^(-1) in the Xitou Nature Education Area. The amounts of annual litterfall in Japanese cedar (Cryptomeria japonica), Taiwania cryptomerioides、Chamaecyparis formosensis stands, ranged from 4,123 to 4,702 kg ha^(-1) yr^(-1), were relatively higher than those in the restored broadleaf (790 ± 640 kg ha^(-1) yr^(-1)) and meadow sites. There was almost no litterfall collection in the meadow sites. The proportion of leaf litterfall was the highest component, accounting for 70% of total litterfall. The proportion of propagule litterfall was the second highest component, in which the Japanese cedar stands had a relatively higher proportion than other vegetation types. The highest amount of monthly litterfall occurred during the typhoon events and plum rain season. The typhoon events in August and October of 2015 and September and October of 2016 especially brought the total litterfall amounts to 2,707 ± 1,699 kg ha^(-1) and 1,938 ± 1,185 kg ha^(-1), accounting for 66% and 53% of total annual litterfall, respectively. The amount of annual litterfall was significantly correlated with the stand characteristics of the nearby 7.3 m radius circle. For all sites, the older stand age and higher mean diameter at breast height, tree height and volume, the higher amount of annual litterfall it was. However, for the Japanese cedar stands, the amount of annual litterfall was only significantly correlated with the stand volume of the nearby 7.3 m radius circle. When the stand volume was larger, not only the biomass of the trees was higher but also the amount of annual litterfall. Compared with past studies, the study more comprehensively assessed the litterfall dynamics and amounts for the plantations in the Xitou Nature Education Area, because of more sampling sites which cover more vegetation types and also the grid sampling set that may reduce the bias from sampling. As litterfall is a critical source of nutrient return, the following study will investigate the nutrient return and its temporal and spatial variations in the Xitou Nature Education Area.

並列關鍵字

Xitou ； Plantation ； Litterfall ； Seasonal variation ； Stand characteristics

國際替代計量

溪頭自然教育園區人工林枯落物之時間與空間變異：季節與植生種類的差異

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