摘要: 目的揭示西藏高原森林生态系统不同层次土壤CO ₂浓度变化特征及主要影响因素，为土壤呼吸CO ₂排放变异性机制提供科学依据、�/sec> 方法以西藏东南部典型森林生态区色季拉山（鲁朗段）为研究区，以急尖长苞冷杉林土壤为研究对象，原位监测不同层次（5�?0�?0�?0�?0 cm）土壤CO ₂浓度，分析不同层次土壤CO ₂浓度分布特征及对温度和含水量的响应、�/sec> 结果�?）各层次土壤CO ₂浓度日均值表现为40 cm > 60 cm > 20 cm > 10 cm > 5 cm，平均值分别为5094�?965�?613�?119�?925 μmol/mol，且各层次之间均极显著正相关＇�i>P< 0.01）。（2）在日变化尺度上�? �?0 cm层次土壤CO ₂浓度具有相反的变化特征，分别呈现“V”字型和“单峰型”特征，5 cm土壤CO ₂浓度最高值和最低值分别出现在22:00�?3:00�?2:00�?3:00之间�?0 cm层次分别出现�?6:00�?7:00�?0:00�?1:00之间，其他各层CO ₂浓度日变化特征不明显。（3）不同层次土壤CO ₂浓度对温度的响应存在一定的延迟效应，而表现出不同的响应曲线，其中表层5�?0 cm呈现近似“椭圆”的响应曲线；（4）表层（5�?0 cm）土壤CO ₂浓度主要受含水量的显著影响，而下层（40�?0 cm）主要受土壤温度的影响、�/sec> 结论温度和含水量对不同层次土壤CO ₂浓度具有不同的影响效应，并最终影响土体CO ₂的传输和动态、�/sec>

关键诌�
• 色季拉山/
• 森林土壤/
• 土壤CO₂浓度/
• 土壤温度/
• 土壤含水野�/a>

Abstract: ObjectiveThis paper aims to elucidate the variation characteristics and main influencing factors of soil CO ₂concentration at different depths of the Tibetan Plateau forest ecosystem, so as to provide a scientific basis for variation mechanism of soil respiration CO ₂emission. MethodWe selected Sejila Mountain (Lulang Section) in Tibet of southwestern China as a model area and a typical forest ecological area. Soil temperature ( S _t) and water content ( S _w) at different depths (5, 10, 20, 40 and 60 cm) were measured in situ for analyzing the distribution characteristics of soil CO ₂concentration at different levels and its response to S _tand S _win the Abies georgeivar. smithiiforest. Result(1) The daily mean value of soil CO ₂concentration at all levels was 40 cm > 60 cm > 20 cm > 10 cm > 5 cm, the mean values were 5094, 4965, 4613, 4119 and 3925 μmol/mol, respectively, and there was a significantly positive correlation among different depths. (2) On the diurnal variation scale, soil CO ₂concentrations at 5 cm and 10 cm layers had opposite variation characteristics, showing a “V�?shaped and a “single peak� curve, respectively. The peak value and valley value of soil CO ₂concentration at 5 cm layer appeared at 22:00�?3:00 and 12:00�?3:00, respectively, and the 10 cm appeared at 16:00�?7:00 and 00:00�?1:00, respectively, but no obviously diurnal variation in other layers. (3) The diurnal variations in the soil CO ₂concentration were not completely synchronized with the S _t, and showed a lagged behind changes, showing an approximate ellipse shaped curve in 5 cm and 10 cm layers. (4) The soil CO ₂concentration in the surface layer (5 and 10 cm) is mainly affected by water content, while the deeper layer (40 and 60 cm) soil is mainly affected by soil temperature. Conclusion S _tand S _whave different effects on soil CO ₂concentration at different depths, and ultimately affect soil CO ₂transport and dynamics.

Key words:
• Sejila Mountain/
• forest soil/
• soil CO₂concentration/
• soil temperature/
• soil water content

�?nbsp; 1不同深度土壤日均温度变化特征

Figure 1.Variation characteristics of daily average soil temperature at different depths

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�?nbsp; 2不同深度土壤日均含水量变化特�?/p>

Figure 2.Variation characteristics of daily average soil water content at different depths

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�?nbsp; 3不同深度土壤CO₂浓度日变化特�?/p>

Figure 3.Diurnal variation characteristics of soil CO₂concentration at different depths

下载: 全尺寸图牆�/a> 幻灯牆�/a>

�?nbsp; 4日变化尺度上不同深度土壤CO₂浓度与土壤温度的相关�?/p>

Figure 4.Correlations between soil CO₂concentration and soil temperature at different depths on the scale of daily variation

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�?nbsp; 5不同深度土壤CO₂浓度与土壤温度的相关�?/p>

Figure 5.Correlations between soil CO₂concentration and soil temperature at different depths

下载: 全尺寸图牆�/a> 幻灯牆�/a>

�?nbsp; 10 ~ 60 cm剖面不同层次土壤CO₂浓度相关系数

Table 1.Correlation coefficients of soil CO₂concentration at different layers of 0�?0 cm profile

土壤层次 Soil layer/cm	10	20	40	60
5	0.8798**	0.8701**	0.8360**	0.8940**
10		0.9930**	0.9391**	0.9725**
20			0.9540**	0.9865**
40				0.9647**
注：*表示P< 0.05＋�sup>**表示P< 0.01。下同。Notes:*meansP< 0.05,**meansP< 0.01. The same below.

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�?nbsp; 20 ~ 60 cm剖面土壤温度与CO₂浓度的相关系�?/p>

Table 2.Correlation coefficients between CO₂concentration and soil temperature at 0�?0 cm profile

指标 Item		土壤温度 Soil temperature
		5 cm	10 cm	20 cm	40 cm	60 cm
CO2浓度 CO2concentration	5 cm	0.2205	0.2646	0.4919*	0.7893**	0.8753**
	10 cm	�?.0845	�?.0024	0.3777	0.8109**	0.9455**
	20 cm	�?.1294	�?.0380	0.3724	0.8240**	0.9607**
	40 cm	�?.0599	0.0419	0.4463*	0.8264**	0.9022**
	60 cm	�?.1255	�?.0536	0.3437	0.8074**	0.9588**

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�?nbsp; 30 ~ 60 cm剖面土壤含水量与CO₂浓度的相关系�?/p>

Table 3.Correlation coefficients between CO₂concentration and soil water content at 0�?0 cm profile

指标 Item		土壤含水� Soil water content
		5 cm	10 cm	20 cm	40 cm	60 cm
CO2浓度 CO2concentration	5 cm	0.6381**	0.7133**	0.4336	0.2713	0.0723
	10 cm	0.8980**	0.8957**	0.4767*	0.2664	0.0408
	20 cm	0.9052**	0.9042**	0.4642*	0.2531	0.0202
	40 cm	0.8823**	0.9308**	0.5582*	0.3973	0.1608
	60 cm	0.8509**	0.8841**	0.4620*	0.2642	0.0241

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