喀斯特森林优势树种蒸腾特征及其对气孔和气象因子的响应

Transpiration characteristics of dominant tree species and their responses to stomatal and meteorological factors in karst regions

【目的】开展茂兰喀斯特森林优势树种的水分生理生态适应性研究,深入认识喀斯特原生林的水文生态过程和稳定性维持机制,为岩溶地区退化生态系统修复和喀斯特森林生态系统保护提供依据。【方法】采用热扩散探针(TDP)对喀斯特森林6种树种树干液流连续监测,结合电子显微镜观测叶片气孔特征,同步测定气温、太阳辐射、相对湿度、降水量环境因子,采用相关分析法分析不同时间和季节尺度下植物蒸腾特征对叶片气孔及气象因子的关系。【结果】1)不同树种的日均蒸腾速率呈青冈栎582.61±42.01 g/(m^(2)·h)>柿树472.58±73.05 g/(m^(2)·h)>朴树365.98±17.14 g/(m^(2)·h)>光叶山矾309.22±50.03 g/(m^(2)·h)>刺楸269.08±62.42 g/(m^(2)·h)>小花梾木181.42±35.80 g/(m^(2)·h);2)月蒸腾量表现为常绿树种大于落叶树种,观测季节月蒸腾量表现为青冈栎>光叶山矾>小花梾木>朴树>柿树>刺楸。3)气孔密度大小为青冈栎>柿树>朴树>光叶山矾>刺楸>小花梾木,不同树种之间的气孔密度呈显著差异(P<0.05),气孔密度越大,气孔长度、宽度与保卫细胞也越大。4)6种树种的气孔密度与自身蒸腾速率之间表现出显著正相关(P<0.05)或极显著正相关(P<0.01),表明气孔密度越大,蒸腾速率越强,其中光叶山矾、青冈栎、柿树和小花梾木的蒸腾速率对气孔密度的响应最强。5)气象因子对树种的气孔密度影响不明显,但对气孔长度或宽度产生显著影响。【结论】叶片气孔形态特征及气象因子共同调节树种蒸腾速率,有较高气孔密度的树种抵御水分胁迫的能力较强,可作为喀斯特地区生态修复的优选树种。

【Objective】The research on the water physiological and ecological adaptability of dominant tree species in Maolan Karst forests is helpful for understanding the hydrological ecological process and stability maintenance mechanism of the original karst forest,providing the basis for the restoration of degraded ecosystems and the protection of forest ecosystems in the karst area.【Method】The TDP tree stem flow monitoring system was used to analyze the sap flow of six tree species in the karst forest.Combined with the stomatal characteristics of leaves observed by electron microscope,the environmental factors such as temperature,solar radiation,relative humidity and rainfall were measured synchronously.The correlation analysis method was used to analyze the relationship between leaf stomata and meteorological factors at different time and seasonal scales.【Result】1)The average daily transpiration rate of the six tree species showed:Cyclobalanopsis glauca 582.61±42.01 g/(m^(2)·h)>Diospyros kaki 472.58±73.05 g/(m^(2)·h)>Celtis sinensis 365.98±17.14 g/(m^(2)·h)>Symplocos lancifolia 309.22±50.03 g/(m^(2)·h)>Kalopanax septemlobus 269.08±62.42 g/(m^(2)·h)>Swida parviflora.181.42±35.80 g/(m^(2)·h).2)The monthly transpiration of evergreen tree species was higher than that of deciduous tree species,and the monthly transpiration in the observation season was as follows:C.glauca>S.lancifolia>S.parviflora>C.sinensis>D.kaki>K.septemlobus.3)The order of stomatal density was as follows:C.glauca>D.kaki>C.sinensis>S.lancifolia>K.septemlobus>S.parviflora.There were significant differences in the stomatal density among different tree species(P<0.05).The larger the stomatal density,the larger the stomatal length,width and guard cell.4)The stomatal density of the six species showed a significant positive correlation or an extremely significant positive correlation(P<0.01)with their sap flow rate(P<0.05),indicating that the greater the stomatal density,the stronger the transpiration rate.Among them,the sap flow rate of C.sinensis,C.glauca,D.kaki and S.parviflora had the strongest response to stomatal density.5)The sap flow rate of trees was also affected by meteorological factors.Meteorological factors had no obvious effect on the stomatal density of tree species,but a significant effect on the stomatal length or width.【Conclusion】Leaf stomatal morphological characteristics and meteorological factors jointly regulate the transpiration rate of trees.The tree species with higher stomatal density are more resistant to water stress and can be used as the preferred tree species for ecological restoration in karst areas.