毛乌素沙地不同类型生物土壤结皮-土壤呼吸的季节变化特征

doi:10.13866/j.azr.2021.04.07

摘要/Abstract

摘要：

2018年以毛乌素沙地西南部发育良好的苔藓结皮和藻类结皮为研究对象,以流沙作为对照,采用土壤碳通量测定,系统观测了不同季节生物土壤结皮-土壤呼吸的日动态,探讨了生物土壤结皮-土壤呼吸与环境因子之间的关系,分析了季节变化对生物土壤结皮-土壤CO₂释放量和温度敏感性的影响。结果表明:(1) 不同季节生物土壤结皮-土壤呼吸速率均呈“单峰”曲线,但其峰值出现的时间存在差异,春季和夏季不同类型生物土壤结皮-土壤呼吸速率峰值出现时间均为13:00左右,但冬季和秋季,藻类结皮-土壤和流沙呼吸速率出现时间为15:00左右,滞后于春季和夏季2 h。(2) 不同季节,不同类型生物土壤结皮-土壤CO₂日释放量:苔藓结皮>藻类结皮>流沙,且达到显著水平(P<0.05)。(3) 春季至冬季,生物土壤结皮-土壤CO₂日释放量呈先增加后降低的趋势,主要表现为:夏季>春季>秋季>冬季,且达到显著水平(P<0.05)。(4) 通过对不同季节生物土壤结皮-土壤呼吸速率与环境因子的主成分分析,与5 cm土壤温度相比,2 cm土壤温度是不同季节生物土壤结皮-土壤呼吸的主要影响因子,其次为近地层空气湿度。(5) 不同季节生物土壤结皮-土壤呼吸速率与2 cm土壤温度的关系均可用指数模型较好的描述,以该函数为基础计算呼吸的温度敏感性,发现温度敏感性的变化范围为1.33~3.85;随季节的变化,温度敏感性呈先降低后升高的趋势:冬季>秋季>春季>夏季,即温度越高,生物土壤结皮-土壤呼吸的温度敏感性越低。

关键词: 生物土壤结皮, 不同季节, 呼吸, 毛乌素沙地, 温度敏感性

Abstract:

Biological soil crust is an important type of surface cover in arid and semi-arid areas, and it is an important component of the carbon cycle in desert ecosystems. However, research on seasonal changes in biological soil crust-soil system respiration is still very scarce, and it is difficult to accurately assess the carbon cycle processes of desert ecosystems over time. We examined the well-developed moss crust and algae crust in the southwest of Mu Us Sandy land in 2018, and we used moving sand as a control. The soil carbon flux measurement system was used to observe the daily dynamics of respiration of the biological soil crust-soil system in different seasons. The relationship between biological soil crust-soil system respiration and environmental factors was explored, and the effects of seasonal changes on biological soil crust-soil CO₂ release and temperature sensitivity were analyzed. The results showed that there was a single peak in the biological soil crust-soil system respiration rate in different seasons, but the timing of the peak varied. The peak time of different types of biological soil crust-soil system respiration rates in spring and summer was 13:00, but in winter and autumn, the algae crust-soil system and moving sand respiration rate appeared around 15:00, lagging behind spring and summer by 2 h. In the same season, different types of biological soil crust-soil systems released different amounts of CO₂: moss crust>algae crust>moving sand (P<0.05). With the change of season, the amount of CO₂ released by the biological soil crust-soil systems first increased and then decreased, and the pattern mainly manifested as: summer>spring>autumn>winter (P<0.05). By analyzing the principal components of the biological soil crust-soil system respiration rate and environmental factors, we found that compared with the 5 cm temperature, the 2 cm soil temperature was the primary influencing factor of biological soil crust-soil system respiration in different seasons. The relationship between the biological soil crust-soil system respiration rate and the 2 cm soil temperature in different seasons showed a good fit with the exponential model. Based on this function, the temperature sensitivity of respiration was calculated. It was found that the temperature sensitivity varied from 1.33 to 3.85. With the change in seasons, the temperature sensitivity first decreased and then increased: winter>autumn>spring>summer. Therefore, the higher the temperature, the lower the temperature sensitivity of the biological soil crust-soil system respiration.

Key words: biological soil crusts, different season, respiration, Mu Us Sandy Land, temperature sensitivity

王荣女. 毛乌素沙地不同类型生物土壤结皮-土壤呼吸的季节变化特征[J]. 干旱区研究, 2021, 38(4): 961-972.

WANG Rongnv. Seasonal variation characteristics of different types of biological soil crust-soil system respiration in Mu Us Sandy Land[J]. Arid Zone Research, 2021, 38(4): 961-972.

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结皮类型	盖度/%	厚度/cm	生物量/(mg·cm^-2)
苔藓结皮	>30	1.56 ± 0.03	4.73 ± 0.41
藻类结皮	>35	1.03 ± 0.04	3.57 ± 0.16

季节	T/℃(CV)	T2/℃(CV)	T5/℃(CV)	PAR/(μmol·m^-2·s^-1)(CV)	RH/%(CV)	VWC2/%(CV)	VWC5/%(CV)
冬季	-3.2(-104.70%)	-1.4(-568.78%)	-3.8(-175.28%)	167.1(144.87%)	42.90(21.36%)	0.07(8.67%)	1.41(3.23%)
春季	17.1(19.77%)	20.6(35.82%)	19.4(45.71%)	426.9(121.45%)	30.21(34.19%)	1.10(31.28%)	3.32(8.00%)
夏季	28.8(15.33%)	33.6(30.81%)	33.7(29.78%)	537.9(113.96%)	52.23(16.49%)	1.82(9.86%)	2.87(8.16%)
秋季	2.7(198.19%)	5.8(244.15%)	1.8(543.03%)	166.8(153.95%)	38.04(44.63%)	0.07(32.88%)	2.25(15.42%)

结皮类型	季节	回归方程	R²	Q₁₀	P
苔藓结皮	冬季	y=0.0785e^0.1194^x	0.78	3.30	P<0.01
	春季	y=0.1173e^0.0513^x	0.85	1.67	P<0.01
	夏季	y=0.3632e^0.0359^x	0.84	1.43	P<0.01
	秋季	y=0.0256e^0.0939^x	0.70	2.56	P<0.01
藻类结皮	冬季	y=0.0385e^0.1347^x	0.67	3.85	P<0.01
	春季	y=0.1138e^0.0418^x	0.79	1.52	P<0.01
	夏季	y=0.2673e^0.039^x	0.83	1.48	P<0.01
	秋季	y=0.0298e^0.087^x	0.79	2.39	P<0.01
流沙	冬季	y=0.0386e^0.104^x	0.50	2.83	P<0.01
	春季	y=0.0076e^0.0492^x	0.61	1.64	P<0.01
	夏季	y=0.2246e^0.0286^x	0.79	1.33	P<0.01
	秋季	y=0.0203e^0.0843^x	0.81	2.32	P<0.01