高寒草地不同坡向披针叶黄华蒸腾速率与叶性状的关系

The relationship of transpiration rate with leaf characters of Thermopsis lanceolate in different slopes of an alpine meadow

植物蒸腾速率(Tr)与叶性状间的协同变异关系,对理解异质性生境下植物叶片形态构建模式及其生态适应性具有重要意义。利用ArcGIS建立研究区域的数字高程模型(DEM),并提取样地坡度数据,研究了祁连山高寒草地不同坡向披针叶黄华叶性状与Tr的关系。结果表明:随着坡向由北坡向东坡、西坡、南坡转变,草地群落的密度、高度和土壤含水量逐渐减小,披针叶黄华叶面积(LA)与Tr呈减小趋势,而叶厚度呈增大趋势;在南坡和北坡披针叶黄华的Tr与LA之间存在极显著正相关关系(P<0.01),与叶厚度之间存在极显著负相关关系(P<0.01),在东坡和西坡披针叶黄华的Tr与LA之间存在显著正相关关系(P<0.05),与叶厚度之间存在显著负相关关系(P<0.05)。生长在南坡的披针叶黄华选择了小而厚的叶片和低的Tr,生长在北坡的披针叶黄华选择了大而薄的叶片和高的Tr,体现了异质生境中植物通过叶片生物量分配机制实现资源有效利用的生存策略。

Studying the relationship of the transpiration rate(Tr)of plants with leaf traits is important for understanding the adaptability of plant leaf function in heterogeneous habitats.The study aimed to explore the relationship of transpiration rate with leaf traits in different slopes.The study site was located in a degraded alpine grassland on the eastern Qilian Mountains,Gansu Province,China(101°32′34′—101°33′50'E,38°36′1′2′—38°17′N).The study area is selected which contains four standard slopes and is a relatively independent hill.The test method is as follows,first,the mountain is divided by four slopes in the topography.Second,along the four slopes every 30 m set a sample area(1 m×1 m)from the bottom to the top of the mountain elevation,each direction is 8 pieces,a total of 32 samples.Third,choose 6 plants from each samples,total 48 plants of each direction.The results showed that with the slopes turned from north to south,the height,coverage,density,and soil moisture of the grassland community gradually reduced,the height,leaf area(LA),Tr,stomatal conductance,and net photosynthetic rate of Thermopsis lanceolate decreased,and the leaf thickness increased.There was a highly significant positive correlation(P<0.01)between Tr and LA,and significant negative correlation(P<0.01)between Tr and leaf thickness on the northern and southern slopes,whereas significant positive correlation(P<0.05)between Tr and LA or between Tr and leaf thickness was found on the eastern and western slopes.Thermopsis lanceolate build up a small and thick leaves to realise low transpiration rate in the southern slope,in the northern slope,Thermopsis lanceolate select a large and thin blades to achieve low transpiration rate.It reflects the plant survival strategy through leaf biomass allocation mechanism to realize the effective utilization of resources in heterogeneous habitat.