疏伐對中臺灣柳杉人工林土壤呼吸之影響

Thinning Effect on Soil Respiration in Crypotomeria japonica Plantation Forest in Central Taiwan

余瑞珠(Jui-Chu Yu) ； 江博能(Po-Neng Chiang) ； 王亞男(Ya-Nan Wang)

《國立臺灣大學生物資源暨農學院實驗林研究報告》 36卷2期 (2022/06) Pp. 113-128

https://doi.org/10.6542/EFNTU.202206_36(2).0003

摘要

了解森林疏伐對土壤呼吸（RS）反應與組成的影響有助於評估森林管理對碳循環影響。因此本研究於溪頭柳杉人工林進行不同程度疏伐，並將土壤呼吸以斷根法區分自營性土壤呼吸（Ra）與異營性呼吸（Rh），以評估疏伐程度對土壤呼吸之影響。土壤呼吸每月以土壤二氧化碳通量量測系統進行量測，同時也測定土壤溫度與土壤水份含量。重度疏伐（HT）之土壤呼吸及異營性土壤呼吸（Rs=5.20 μmol m^(-2)s^(-1), Rh=4.10 μmol m^(-2)s^(-1)）顯著大於輕度（LT）（Rs=3.29 μmol m^(-2)s^(-1), Rh=2.43μmol m^(-2)s^(-1)）及對照組（CK）（Rs=3.02 μmol m^(-2)s^(-1), Rh=2.24μmol m^(-2)s^(-1)）。不同疏伐間Rh/Rs介於73.7-78.6%間並隨疏伐程度增加而增加。不同疏伐間土壤溫度、土壤水分均與土壤呼吸呈顯著相關。不同疏伐間異營性土壤呼吸溫度敏感係數（Q_(10)）介於2.05-2.94間。不同疏伐程度之林地，以結合土壤溫度及土壤水分雙因子與土壤呼吸進行回歸分析，其結果解釋土壤呼吸、異營性土壤呼吸與自營性土壤呼吸速率分別介於91.8%-96.2%、84.9%-95.8%及82.3%-92.2%。研究中經疏伐處理樣區之異營性土壤呼吸較自營性土壤呼吸對溫度更敏感。

並列摘要

Understanding the response of soil respiration (Rs) to forest thinning is critical in evaluating the impact of forest management on the carbon cycle. To assess the effect of thinning on soil respiration, different thinning treatments were conducted in the Cryptomeria japonica plantation in Xitou, and applied the trench method to investigate autotrophic respiration (Ra) and he terotrophic respiration (Rh) of the soil respiration Rs . Rs, soil temperature, and soil moisture were measured by the soil CO_2 flux measurement system every month. Results showed that both Rs and Rh under heavy thinning (HT) (Rs = 5.20 μmol m^(-2)s^(-1), Rh = 4.10 μmol m^(-2)s^(-1)) were significantly larger than those under light thinning (LT) (Rs = 3.29 μmol m^(-2)s^(-1), Rh = 2.43 μmol m^(-2)s^(-1)) and controlled treatment (CK) (Rs = 3.02 μmol m^(-2)s^(-1), Rh = 2.24 μmol m^(-2)s^(-1)). Results also found that Rh/Rs among different thinning treatments varied from 73.7 to 78.6 % and increased with the thinning level. Soil temperature and soil moisture showed significant relation to different thinning treatments. The temperature sensitivities of Rh va ried from 2.05 to 2.94 among different thinning treatments. The relationship between combined soil temperature and soil moisture and Rs, Rh, and Ra were 91.8 %-96.2 %, 84.9%-95.8 %, and 82.3 %-92.2 %, respectively. These results suggest that Rs is more sensitive to temperature than Ra among different thinning treatments.