Comparison of Seasonal Variations in Carbon Dioxide Concentrations between a Natural Hardwood Stand and a Fir Plantation at the Guandaushi Subtropical Forest, Taiwan

臺灣關刀溪亞熱帶天然闊葉林和人工杉木林二氧化碳濃度時間變異比較

陳信佑(Shin-You Chen) ； 王志仁(Jyh-Ren Wang) ； 許博行(Bor-Hung Sheu) ； 劉瓊霦(Chiung-Pin Liu)

《台灣林業科學》 24卷4期 (2009/12) Pp. 271-283

https://doi.org/10.7075/TJFS.200912.0271

摘要

本研究目的為了解關刀溪天然闊葉林與人工杉木林於不同冠層高度二氧化碳濃度之分佈概況及垂直梯度的變化情形。採樣期間自2004年9月至2005年6月，於天然林與杉木林分別設置0.5 m、4 m、12m及冠層上3~4m等4個採樣高度，進行二氧化碳濃度的量測。結果顯示天然林與杉木林二氧化碳濃度分佈呈現梯度分層的現象，而其中以0.5 m處的二氧化碳濃度為最高，而12m處與冠層上二採樣點的二氧化碳濃度，在季節與近一年的變化皆無顯著差異。天然林與杉木林之二氧化碳濃度在季節的變化上，各採樣點之日夜間二氧化碳濃度的差異以春季及夏季較大，秋冬季則略小。由一年間監測的結果顯示，天然林由於土壤呼吸作用較旺盛，且冠層12m處光合作用固定二氧化碳的能力較低，因此在任何採樣點二氧化碳濃度均較人工杉木林為高，且此種差異在溫度較高的6月比較低溫度的12~1月更形顯著。

關鍵字

二氧化碳 ； 冠層 ； 時間變異 ； 空間變異 ； 亞熱帶森林

並列摘要

The purpose of this study was to understand variations in carbon dioxide concentrations at different canopy heights in a natural hardwood stand and a China-fir (Cunninghamia lanceolata) plantation at the Guandaushi subtropical forest. The measurements began in September 2004 and continued to the end of June 2005. There were 4 sampling heights, including 0.5, 4, and 12 m above ground level (agl) and 3~4 m above the canopy at the 2 stands. Results showed that the highest concentration of carbon dioxide was near the forest floor, and the lowest ones were at 12 m agl and 3~4 m above the canopy for both the natural hardwood stand and fir plantation. Seasonal and yearly variations of sampling heights between 12 m agl and 3~4 m above the canopy were not significant. The carbon dioxide concentrations of the 4 sampling heights were higher in spring and summer than in winter. Variations in carbon dioxide concentrations of the sampling height at 12 m in the natural hardwood forest were influenced by light intensity, regardless of daily or yearly variations. We concluded that the forest floor soil of the natural hardwood stand had a higher respiration rate, and there was a lower photosynthetic rate at the 12m level of the canopy. Therefore, at all sampling points, the concentrations of carbon dioxide were higher than these in the China-fir plantation. This concentration gradient was more significant in the higher-temperature season (June) than in the lower-temperature season (December to January).

並列關鍵字

carbon dioxide ； canopy ； seasonal variation ； spatial variation ； subtropical forest