發(fā)布時間：2018-11-03 12:09

【摘要】：土壤呼吸是生態(tài)系統(tǒng)碳循環(huán)過程中的重要環(huán)節(jié)之一,深入研究陸地生態(tài)系統(tǒng)土壤呼吸的動態(tài)變化及其影響因素有著重要意義。目前對土壤呼吸日變化、季節(jié)變化的研究相對較多,而對其年際變化的研究相對很少。為深入研究土壤呼吸的年際變化,我們在天龍山地區(qū)對一個退耕地和一個裸地的土壤呼吸及其土壤溫度和土壤水分進(jìn)行了為期10年每月1-3次的定位測量。旨在:1)研究退耕地和裸地不同年份土壤呼吸及土壤溫度、土壤水分的季節(jié)變化以及他們之間的關(guān)系;2)研究2個樣地土壤呼吸及其溫度敏感性的年際變化及其與土壤溫度、土壤水分年際變化之間的關(guān)系;3)估算2個樣地的年土壤呼吸總量;4)量化退耕地的根系呼吸對總土壤呼吸的貢獻(xiàn)率。主要研究結(jié)果如下:2個樣地土壤呼吸及其土壤溫度均呈現(xiàn)出明顯的季節(jié)變化規(guī)律:初春偏低、夏季初秋達(dá)到最高、秋季逐漸降低、冬季達(dá)最低。高斯3參數(shù)方程可以很好地模擬土壤呼吸及土壤溫度隨天數(shù)的變化規(guī)律。就單個測定年而言,2個樣地的土壤水分的季節(jié)變化規(guī)律不明顯,主要取決于降雨量及其季節(jié)變化,但是就10個測定年的各月測定的土壤水分平均值而言,土壤水分呈現(xiàn)出“橫置S”型特征,即夏末秋初較高、春末夏初較低。退耕地和裸地10年的土壤呼吸均值分別為4.11±3.12μmol·m~(-2)·s~(-1)和2.74±2.35μmol·m~(-2)·s~(-1)。最小值均出現(xiàn)在冬季,且均在1μmol·m~(-2)·s~(-1)之下。10個測定年退耕地和裸地的年碳釋放量平均值分別為1208.7 g C m~(-2) a~(-1)和805.8 g C m~(-2) a~(-1),不同測定年不同。10年間退耕地根系呼吸對土壤呼吸的貢獻(xiàn)率變化范圍為21.73%~42.13%。退耕地與裸地的土壤溫度與土壤呼吸的關(guān)系均可以用指數(shù)方程來描述,在多數(shù)測定年,退耕地和裸地的土壤溫度對土壤呼吸的解釋率分別為55%至92%和40%至84%之間,這表明,退耕地土壤呼吸對土壤溫度的依賴性要高于裸地。大多數(shù)年份兩樣地土壤呼吸與土壤水分的關(guān)系不顯著,但是裸地受土壤水分的影響大于退耕地。與單變量模型相比,包含土壤溫度和水分因子的雙變量方程可以更好地模擬兩樣地土壤呼吸的季節(jié)變化。擬合模型中的冪指函數(shù)模型的擬合效果均優(yōu)于乘積函數(shù)模型�；�5 cm、10 cm、15 cm深度土壤溫度計算的退耕地土壤呼吸的溫度敏感性值(Q_(10))分別為2.32、2.59、2.75,裸地分別為1.92、2.05、2.18。當(dāng)進(jìn)一步把10個測定年土壤水分進(jìn)行排序分級后進(jìn)行分析時,退耕地三個測定深度的最大Q_(10)值均出現(xiàn)在土壤水分含量大于21%的區(qū)間,而裸地三個深度的最大Q_(10)值出現(xiàn)在土壤水分為16%~21%的區(qū)間�；诓煌疃鹊耐寥罍囟扔嬎愕耐寥篮粑臏囟让舾行�(Q_(10))值、土壤溫度10℃時的土壤呼吸值(R_(10))不同。隨著土壤溫度測定深度的增加,Q_(10)值呈增加趨勢。除個別測定年,退耕地和裸地十年間R_(10)的變化分別在2.2μmol·m~(-2)·s~(-1)左右和1.3μmol·m~(-2)·s~(-1)左右。退耕地Q_(10)值與土壤水分的關(guān)系顯著,但裸地關(guān)系不顯著。
[Abstract]:Soil respiration is one of the important links in the process of ecosystem carbon circulation, and it is of great significance to further study the dynamic changes of soil respiration and its influencing factors in terrestrial ecosystem. At present, there are relatively many studies on soil respiration diurnal variation and seasonal variation, but the study of inter-annual variation is relatively rare. In order to further study the inter-annual variation of soil respiration, we measured 1-3 times a month for a 10-year period of soil respiration, soil temperature and soil moisture in Tianlongshan area. aims to: 1) study soil respiration and soil temperature, seasonal variation of soil moisture and their relationship among different years of uncultivated land and bare ground; 2) study the inter-annual variation of soil respiration and its temperature sensitivity in two samples and its relative soil temperature, 3) estimating the annual soil respiration of 2 samples; 4) quantifying the contribution rate of root respiration of cultivated land to total soil respiration. The main results are as follows: 2 samples of soil respiration and soil temperature show obvious seasonal variation: the first spring is low, the first fall of summer reaches the highest, the autumn decreases gradually, and the winter reaches the lowest. The Gauss 3 parameter equation can simulate the change of soil respiration and soil temperature with the number of days. For a single measurement year, the seasonal variation of soil moisture in two samples is not obvious, mainly depending on the rainfall and its seasonal variation, but the soil moisture content is presented in terms of the mean soil moisture mean value measured in every month of ten measurement years. "Transverse S" It is characterized by high early summer and late summer, low early spring and early summer. The average soil respiration of the cultivated land and bare land was 4.11, 3.12. mol 路 m ~ (-2) 路 s ~ (-1) and 2.74 ~ 2.35 umol 路 m ~ (-2) 路 s ~ (-1) respectively. The minimum values appeared in winter and were below 1. m ~ (-2) 路 s ~ (-1). The average annual carbon release in 10 measured years was 1208. 7 g C m ~ (-2) a ~ (-1) and 805. 8 g C m ~ (-2) a ~ (-1), respectively. The contribution rate of respiration to soil respiration was 21.73% ~ 42. 13% in 10 years. The relationship between the soil temperature of the uncultivated land and the bare ground and the soil respiration can be described by exponential equation. In most measures, the rate of soil respiration is 55% to 92% and 40% to 84%, respectively. The dependence of soil respiration on soil temperature was higher than bare ground. In most years, the relationship between soil respiration and soil moisture was not significant, but the effect of soil moisture on bare ground was greater than that of cultivated land. Compared with the single variable model, the double variable equation containing soil temperature and moisture factor can better simulate the seasonal variation of soil respiration. The fitting effect of the power finger function model in the fitting model is better than that of the product function model. The temperature sensitivity of soil respiration (Q _ (10)) calculated on 5 cm, 10 cm and 15 cm depth soil temperature was 2.32, 2.59, 2.75, respectively. The bare ground was 1.92, 2.05, 2.18, respectively. The maximum Q _ (10) value of the three measuring depths of the uncultivated land appeared in the interval of more than 21%, while the maximum Q _ (10) value of the three depths in bare land appeared in the interval of 16% ~ 21%. Temperature sensitivity (Q _ (10)) of soil respiration calculated based on soil temperature at different depths is different from soil respiration value (R _ (10)) at 10 鈩，

本文編號：2307746