克隆植物沙拐枣的母株和分株对风蚀沙埋的生理生态响应

以中国荒漠区优良的防风固沙克隆灌木沙拐枣为对象,研究了长期风蚀、沙埋环境下沙拐枣母株和克隆分株的同化枝对环境异质性的响应。结果发现:(1)风蚀母株、风蚀分株的叶绿素含量、净光合速率、气孔导度、蒸腾速率、胞间CO2浓度和水分利用效率只有沙埋分株的一半左右,导致同化枝的长度、数量、簇数也仅是沙埋分株的一半,而且风蚀母株的果实宽和果实长也都最小,但浅沙埋有利于沙拐枣的生长和繁殖,表明严峻的风蚀对母株和分株的生长与繁殖都产生了胁迫,但浅沙埋有利于沙拐枣的生长和繁殖。(2)风蚀母株倒伏后同化枝的形态特征是基部优于中部优于顶部,表明严峻风蚀下母株的死亡是从顶部-中部-底部逐渐舍弃的过程。(3)母株的全部根系以及风蚀水平根全部裸露在外但依然能够存活,间接证明沙拐枣克隆整合的方向性——不仅可在分株间进行传递,分株-母株间也可进行传递,否则遭受严峻风蚀胁迫的母株和克隆分株会直接死亡。本研究结果为沙拐枣克隆生长对风沙环境的生态适应机制提供了基础,也是对植物克隆生态学在自然异质环境中研究缺乏的有效补充。

Ecophysiological Responses of Mother and Daughter Ramets in Response to Wind Erosion and Sand Burial in the Clonal Shrub Plant Calligonum mongolicum

Our goal was to investigate the effects of environmental heterogeneity through wind erosion and sand burial on photosynthesis, morphological characteristics of assimilative branches and fruits production in mother and clonal ramets of clonal Calligonum mongolicum. Based on plenty of field surveys, we chose one typical mother ramet with one clonal fragment, that were exposed in the air due to strong wind erosion, and another sand buried clonal fragment in a mobile sand dune. Measurements were made on chlorophyll contents, net photosynthesis rate, leaf length, leaf number /cluster, cluster number /shoot, node number/ and fruit production in mother and clonal fragments of C. mongolicum under different environmental heterogeneity. The results showed: (1) under wind erosion environment, both the mother and daughter ramets had just half of the chlorophyll contents, net photosynthesis, stomatal conductance, transpiration rate, intercellular CO₂ concentration and water use efficiency as compared to the daughter ramets under sand buried environment. The lower photosynthesis had restricted the leaf length, leaf number/cluster, cluster number/ shoot and leaf node number to almost half in the assimilative branches with reduced fruit lengths and widths. (2) Morphological characteristics of assimilative branches in mother ramet were best in bottom and worst in the top, by what we can preview that the dying process of mother ramte was a stage from top to bottom. (3) Though all the root system was exposed in the air, the mother ramet had survived and completed its life stages. The results confirmed that the direction of clonal integration had not only passed among the sister ramets, but also from the sister to the mother ramets, or else those would die immediately in the absence of soil.