臺灣中部低海拔復育造林對土壤呼吸及有機碳與氮儲存量的影響

本研究目的將針對低海拔復育造林過程對土壤呼吸及土壤有機碳與全氮儲量影響，以及釐清控制土壤呼吸季節變化之影響因子。本研究中烏心石單一樹種與混植復育造林地年平均土壤呼吸速率分別2.7及3.3μmol m^(-2)s^(-1)，換算年土壤呼吸量分別為10.2及12.5 Mg C ha^(-1)year^(-1)）。土壤呼吸呈現季節性變化，並顯示夏季達最高值，冬季達最低值。比較兩個造林地土壤有機碳與全氮儲量，烏心石單一樹種復育造林地土壤有機碳與全氮儲量分別比混植復育造林地增加15及11%呈顯著差異。兩造林地土壤呼吸季節變化與表土0-5 cm土壤溫度呈現顯著正相關，其中烏心石單一樹種與混合復育造林地土壤溫度解釋土壤呼吸速率以及Q_(10)值分別為88.2與94.8%及2.20與1.78。主成分分析結果顯示土壤呼吸受到生物因子（土壤有機碳與全氮儲量）及非生物因子（土壤溫度與土壤水分含量）之影響。由主成分分析結果導入結構方程模式中顯示，土壤溫度不但直接顯著影響土壤呼吸，而且影響土壤有機碳儲量進而間接影響土壤呼吸。本研究結果顯示復育造林初期地表覆蓋率降低，土壤有機物因溫度增加，分解速率增快，因而增加土壤二氧化碳釋放，也降低土壤有機碳與全氮儲量。

關鍵字

土壤呼吸；土壤溫度；土壤水分含量；復育造林

並列摘要

This study aimed to explore the effects of reforestation process on soil respiration (Rs), soil organic carbon (SOCS) and total nitrogen (TNS) stocks at low-elevation montane area in central Taiwan to c larify fa ctors t hat control seasonal va riations of Rs. The mean annual R s rates at t he Michelia single s pecies- and m ixed- afforested plantation sites were 2.7 and 3.3 µmol m^(-2)s^(-1), respectively, which were in c orrespondence with an annual magnitude of 10.2 and 12.5 Mg C ha^(-1) year^(-1). The results showed seasonal variations of Rs, of which the highest and lowest values occurred in s ummer a nd w inter, re spectively. The S OCS and T NS of Michelia single s pecies af forested plantation were significantly increased by 15 and 11% than those of afforested plantation. The seasonal variations of Rs in the two a fforested plantations were significantly and positively correlated with soil temperature at depths of 0-5 cm. The c ontribution of soil temperature and Q_(10) values to the Rs rates of Michelia single species- and mixed- afforested plantations were 88.2 and 94.8%, and 2.20 and 1. 78, respectively. Through the principal c omponent a nalysis (PCA), re sults showed t hat R s w ere a ffected by t he bi otic fa ctors (SOCS a nd T NS) a nd a biotic fa ctors (soil temperature a nd s oil moisture). M oreover, c onducting the PCA re sults I nto the s tructure e quation model, results showed that not only the Rs but SOCS were mainly controlled by soil temperature. In conclusion, this study de monstrated a decrease of t he surface coverage ra te a t the I nitial s tage of reforestation, and an increase of the decomposition rate of soil organic matter due to the increase in temperature, which in turn re sulted in an increase of t he e mission of s oil c arbon di oxide a nd a decrease of SOCS and TNS.

並列關鍵字

Soil respiration ； Soil temperature ； Soil moisture ； Reforestation

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