马占相思夜间树干液流的分配及其对整树蒸腾估算的影响

doi:10.17521/cjpe.2007.0099

摘要/Abstract

摘要：

采用Granier热消散探针测定了马占相思(Acacia mangium)的树干液流,结合Li-6400光合测定系统测定的夜间叶片气孔导度和蒸腾,将夜间液流区分为夜间树干水分补充和叶片气孔蒸腾。叶片的蒸腾作用微弱,因此,夜间液流主要用于补充贮水部位的水分亏缺。马占相思夜间水分补充量年内和年际的变化不明显,树形特征的差异是解释夜间水分补充量变化的重要因子,夜间水分补充量对于整树蒸腾量的贡献因季节和树木径级的不同而有明显变化,但对整树总蒸腾量计算造成的误差可以忽略。

关键词: 马占相思, Granier热消散探针法, 夜间液流, 夜间蒸腾

Abstract:

Aims This study was designed to analyze the partitioning of night sap flow in Acacia mangium and its implication for estimating whole-tree transpiration.

Methods Analyses were performed on the partitioning of night sap flow into refilling of internal water storage and transpiration in A. mangium. Sap flow of trees was monitored continuously with Granier's sensors for estimating whole-tree transpiration. Night sap flow data were used to calculate trunk water recharge. Possible night transpiration and stomatal conductance at leaf level in the canopy were measured with a Li-6400 photosynthesis measuring system.

Important findings Vapor pressure deficit (VPD) and wind speed (V) could not fully explain sap flow in A. mangium at night (night leaf transpiration and stomatal conductance were weak). Therefore, night sap flow of mature A. mangium trees was mainly associated with water recharge in the trunk. No significant change in night water recharge of the trunk was found at both seasonal and inter-annual scales. Morphological features of trees including diameter at the breast height (DBH), tree height, and canopy size could explain variances of night water recharge. Furthermore, the error caused by night water recharge on whole-tree transpiration was negligible. The mechanisms and ecological implications of night sap flow partitioning of A. mangium deserve further investigation.

Key words: Acacia mangium, Granier's thermal dissipation probe method, night sap flow, night transpiration

王华, 赵平, 蔡锡安, 王权, 马玲, 饶兴权, 曾小平. 马占相思夜间树干液流的分配及其对整树蒸腾估算的影响. 植物生态学报, 2007, 31(5): 777-786. DOI: 10.17521/cjpe.2007.0099

WANG Hua, ZHAO Ping, CAI Xi-An, WANG Quan, MA Ling, RAO Xing-Quan, ZENG Xiao-Ping. PARTITIONING OF NIGHT SAP FLOW OF ACACIA MANGIUM AND ITS IMPLICATION FOR ESTIMATING WHOLE-TREE TRANSPIRATION. Chinese Journal of Plant Ecology, 2007, 31(5): 777-786. DOI: 10.17521/cjpe.2007.0099

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2007.0099

https://www.plant-ecology.com/CN/Y2007/V31/I5/777

图/表 17

图1 马占相思平均液流密度的日变化(a)和最大径级(b,DBH=32.9 cm)、最小径级(c,DBH=16.9 cm)代表树木液流密度的日变化(2004年7月) DBH: 胸径Diameter at breast height 箭头指向的阴影区代表夜间液流 The shadow sections to which arrows pointed represent night sap flow

Fig.1 Daily variations of average sap flux density of all Acacia mangium sample trees (a), of the largest tree (b,DBH=32.9 cm) and of the smallest tree (c,DBH=16.9 cm) in July 2004

表1 2005年旱季与湿季马占相思夜间液流密度与水汽压亏缺、风速之间的相关分析

Table 1 Correlations between night sap flux density and vapor pressure deficit, wind speed of Acacia mangium in the dry and wet seasons of 2005

夜间液流密度 Night sap flux density (g H₂O·m^-2·s^-1)		水汽压亏缺 Vapor pressure deficit (kPa)	风速 Wind speed (m·s^-1)
旱季 Dry season	泊松相关系数 Pearson correlation	0.237^**	0.118^**
	显著度Sig. (2-tailed)	0.000	0.000
	样本数n	2 015	1 961
湿季Wet season	泊松相关系数 Pearson correlation	0.236^**	0.101^**
	显著度Sig. (2-tailed)	0.000	0.000
	样本数n	2 196	1 300

表2 夜间液流密度与水汽压亏缺、风速之间的曲线参数估计

Table 2 Curve parameter estimation between night sap flux density and vapor pressure deficit (VPD), wind speed

因变量 Dependent	自变量 Independent	Model fit方程 Model fit equation	R²	p
夜间液流密度 Night sap flux density (g H₂O·m^-2·s^-1)	2月夜间水汽压亏缺 VPD at night in February (kPa)	y=0.376 9+0.111 9x	0.156	0.000
	2月夜间风速 Wind speed at night in February (m·s^-1)	y=0.762 8-0.029 3x	0.005	0.191
	8月夜间水汽压亏缺VPD at night in August (kPa)	y=3.411 9+0.561 5x	0.061	0.001
	8月夜间风速Wind speed at night in August (m·s^-1)	y=3.926 7+0.156 7x	0.001	0.699

图2 马占相思夜间气孔导度和蒸腾速率的变化 ● 1号树 Tree No.1 ○ 2号树 Tree No.2 ▼ 3号树 Tree No.3

Fig.2 Changes of leaf stomatal conductance and transpiration rate in Acacia mangium during the night

图3 热消散法测定的液流密度与气体交换法测定的蒸腾速率之间的回归关系气体交换法(Li-6400)测定的蒸腾速率的单位是mmol H2O·m-2·s-1,为了方便比较,换算为热消散法测定的液流密度值的单位g H2O·m-2·s-1

Fig.3 Regression relationship between the night sap flow density measured by using the thermal dissipation probe (TDP) method and night transpiration rate measured by gas exchange method (Li-6400) For the comparison, the unit of transpiration rate (mmol H2O·m-2·s-1) measured by gas exchange method (Li-6400) is converted into the unit of sap flow density measured by TDP (g H2O·m-2·s-1)

图4 热消散法测定的夜间液流密度与气体交换法测定的夜间蒸腾速率的时间动态

Fig.4 Temporal dynamics of night sap flow density measured by the thermal dissipation probe method and night transpiration rate measured by gas exchange method

表3 马占相思树干各月份夜间水分补充量的方差分析

Table 3 One-way ANOVA on monthly night water recharge in Acacia mangium trees

年份 Year	夜间水分补充量 Night water recharge (kg·d^-1)	平方和 Sum of squares	自由度 df	方差 Mean square	F	显著度 Sig.
2004	组间 Between groups	54.171	11	4.925	1.961	0.036
	组内 Within groups	361.540	144	2.511	-	-
	总计 Total	415.711	155	-	-	-
2005	组间 Between groups	40.520	11	3.684	1.228	0.275
	组内 Within groups	396.054	132	3.000	-	-
	总计 Total	436.574	143	-	-	-

表4 马占相思夜间水分补充量与主要环境因子之间的相关分析

Table 4 Correlation between night water recharge in Acacia mangium and environmental factors

年份 Year	夜间水分补充量 Night water recharge (kg·d^-1)	土壤湿度 Soil moisture (m³·m^-3)	大气湿度 Air humidity (%)	大气温度 Air temperature (℃)	水汽压亏缺 Vapor pressure deficit (kPa)
2004	泊松相关系数 Pearson correlation	0.459^**	0.230^**	-0.055
	显著度Sig. (2-tailed)	0.000	0.000	0.056	0.388
	样本数n	252	252	252	252
2005	泊松相关系数Pearson correlation	-0.004	0.089	0.253^**	-0.041
	显著度Sig. (2-tailed)	0.956	0.221	0.000	0.594
	样本数n	188	191	191	168

表5 马占相思夜间水分补充量与主要环境因子之间的曲线参数估计

Table 5 Curve estimation between night water recharge in Acacia mangium and environmental factors

年份 Year	因变量 Dependent	自变量 Independent	R²	自由度 df	F	p
2004	夜间水分补充量 Night water recharge (kg·d^-1)	土壤湿度Soil moisture (m³·m^-3)	0.211	250	66.85	0.000
		大气湿度Air humidity (%)	0.053	250	13.97	0.000
		大气温度Air temperature (℃)	0.015	250	3.69	0.056
		水蒸汽压亏缺Vapor pressure deficit (kPa)	0.003	250	0.75	0.338
2005	夜间水分补充量 Night water recharge (kg·d^-1)	土壤湿度Soil moisture (m³·m^-3)	0.000	186	3.1E-03	0.956
		大气湿度Air humidity (%)	0.008	189	1.51	0.221
		大气温度Air temperature (℃)	0.064	189	12.89	0.000
		水蒸汽压亏缺Vapor pressure deficit (kPa)	0.002	166	0.29	0.594

图5 夜间水分补充量与胸径的回归关系

Fig.5 Regression relationship between night water recharge amount and diameter at breast height (DBH)

图6 夜间水分补充量与树高之间的回归

Fig.6 Regression relationship between night water recharge and tree height

图7 夜间水分补充量与冠幅之间的回归

Fig.7 Regression relationship between night water recharge and canopy size

表6 2004年和2005年间马占相思夜间水分补充量之间的独立t检验

Table 6 Independent samples test on night water recharge of Acacia mangium in 2004 and 2005

	方差齐性 Equal variances	方差同质性检验 Levene's test for equality of variances		平均数的t检验 t-test for equality of means
	方差齐性 Equal variances	F	显著度Sig.	t	显著度Sig.
夜间水分补充量 Night water recharge (kg·d^-1)	假设方差齐性 Equal variances assumed	0.112	0.741	1.255	-
	假设方差不齐 Equal variances not assumed	-	-	1.255	0.233

图8 2004年和2005年样地主要环境因子变化的比较

Fig.8 Comparison of major environmental factor changes in sample plot in 2004 and 2005

图9 2005年不同径级马占相思夜间水分补充量与总蒸腾量比率的季节变化

Fig.9 Seasonal changes in the ratio of night water recharge to total transpiration of Acacia mangium at different breast heights in 2005

图10 2005年马占相思总蒸腾量和日蒸腾量的年内变化

Fig.10 Inter-annual changes of total transpiration and daily transpiration of Acacia mangium in 2005

表7 马占相思总液流量与除去夜间液流的液流量之间的独立t检验

Table 7 Independent samples test between the total sap flow and the sap flow eliminating night sap flow of Acacia mangium

方差齐性 Equal variances	方差同质性检验 Levene's test for equality of variances		均值的t检验 t-test for equality of means
方差齐性 Equal variances	F	显著度Sig.	t	显著度Sig.
假设方差齐性Equal variances assumed	0.000	0.997	0.020	0.984
假设方差不齐Equal variances not assumed			0.020	0.984

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