巴丹吉林沙漠典型植物水势与导水率的时空变化

Temporal and spatial variations of water potential and hydraulic conductivity of typical plant species in Badain Jaran Desert

通过对巴丹吉林沙漠高大沙山不同部位以及距湖泊不同距离的土壤水势、植物水势、植物根、茎及叶的导水率进行测定,分析不同立地条件下4种典型植物霸王(Zygophyllum xanthoxylon)、油蒿(Artemisia ordosica)、沙茴香(Ferula bungeana)及白刺(Nitraria tangutorum)的水势日变化、导水率日变化差异,进而研究水分在沙漠典型植物体内的运移传输机理。结果表明:(1)所有植物水势值均表现为根>茎>叶,就植物种类而言,灌木白刺各器官平均水势最低,多年生草本沙茴香最高;就空间位置而言,同种植物在沙山上部各器官水势最低,在沙山下部最高;距湖泊100 m的白刺各器官水势最低,距湖泊20 m的白刺各器官水势最高;就日变化而言,所有植物均表现为黎明前水势最高。(2)各样地土壤水势随深度增加均呈现波动升高的趋势。(3)就植物种类而言,霸王导水率最高,沙茴香导水率最低;就空间位置而言,所有植物导水率均表现为沙山上部>沙山中部>沙山下部,白刺表现为距湖距离20 m<距湖距离50 m<距湖100 m;就日变化而言,所有植物均表现为正午导水率最小。植物水势与导水率之间存在一定的正相关关系,植物体能够在特殊生境中为保持自身水分动态平衡、维持自身生命活动形成一种适应性水分运输策略。

We measured soil water potential,plant water potential,and hydraulic conductivity of four typical plant species,namely Zygophyllum xanthoxylon,Artemisia ordosica,Ferula bungeana,and Nitraria tangutorum,in different locations of high sandy mountains in the Badain Jaran Desert and at different distances from the lake,with the aim to uncover the mechanisms of water transport. The results showed that:( 1) water potential values shared the same characteristics for all the four plant species,namely,root > stem > leaf. Among those species,the average water potential of various organs of the shrub N. tangutorum was the lowest,while that of the perennial herbaceous F. bungeana was the highest. In terms of location,the same species had the lowest water potential in the upper part of the sandy mountain,and the highest in the lower part of the sandy mountain. The lowest and highest water potential of each organ of N. Tangutorum was obtained at 100 m and 20 m away from the lake,respectively. In terms of diurnal variation,water potential values of all species were the highest before dawn.( 2) Soil water potential of all plots fluctuated and rose with increasing soil depth.( 3) Among the four species,hydraulic conductivity was highest in Z. xanthoxylon and lowest in F. bungeana. In terms of location,hydraulic conductivity of all species on the sandy mountain shared the same characteristics,namely,upper part > middle part > lower part. The hydraulic conductivity of N. Tangutorum at different distances from the lake showed as 20 m away from the lake < 50 m away from the lake < 100 m away from the lake. In terms of diurnal variation,hydraulic conductivity of all species was the lowest at midday. Our results suggest that plant water potential and hydraulic conductivity were positively correlated and that there is an adaptive water transport strategy for plants to maintain their water balance and support their growth in special habitats.