Responses Of Tissue Non-structural Carbohydrates, Total N And C/N To Altitude In Quercus Aquifolioides On Ba Lang Mountain

Quercus aquifolioides, belonging to a type of sub-alpine sclerophyllous oak forest, is a very special vegetation type in China. It is widely distributed in the hengduan mountains region, transiting from the forest to shrub continuously with the increasing of the elevation from south to north, which is a rare phenomenon. And it often forms a large climax community in the sunny slope of the alpine gorges. It has great water and soil conservation effect in the southwestern mountains for its well-developed root system, high sprouting ability and wide adaptability. As an important vegetation type of the sub-alpine timberline interlaced zone, its morphological, genetical and ecological researches, especially the biomass and community structure of Q. aquifolioides have been brought into focus recently, but the researches of the growth mechanism and distribution pattern from the physiology and biochemistry angel was just beginning. Non-structural carbohydrates (NSC), including glucose, fructose, sucrose, fructan and starch, is an important material to the physiological metabolism of plant. It is a measure of the relationship between the uptake and consumption of the carbon, and reflects the substance level for the plant growth. With the increasing of the altitude, plants carbon source and sink ratio would be imbalance caused by the lack of carbon balance, which directly affect the cell growth and tissue formation. It meant that the new cell formation rate would slow down or stop because of the absence of sufficient carbon, and resulted in the forest of a certain height can not continue to upward. Besides, the total nitrogen (TN) and C/N are both considered as comprehensive indexes to measure the adaptation of plant to the environment because they are closely related to the photosynthetic capacity. Therefore, this paper studied on the content of NSC, TN and C/N of the different organizations (leaf, branch and root) of Q. aquifolioides at different growth stages on Balang mountain of different elevation gradient, explored its physiological and ecological characteristics, reserve of growth substances and adaptation strategies to different habitats and its physiological response to global climate change, and supplied theoretical basis for restoration and reconstruction of the sub-alpine vegetation, ecosystem protection and resource utilization, as well as the research of the timberline formation processes of the world's largest mountain system. The results are as follows: (1) The NSC content of the leaves, branches and roots in Q. aquifolioides on Balang mountain all increased on different degree with the increasing of elevation except the sucrose content of the leaves and the starch content of branches, roots in the vigorous growth period, but the changes of the roots were obviously less than the branches and leaves. Besides, the glucose, fructose and sucrose content of the leaves were higher than that of branches. The TN content of different organizations at different growth stages all showed a rising trend with the increasing of elevation, while the C/N changed oppositely.(2) In rest period, all indexes were rising with the increasing of altitude except C/N, while there were remarkable differences among the different organizations in the vigorous growth period. In addition, the glucose, fructose content of the leaves and shoots, the sucrose content of the one year old leaves, TN content of all the organizations, and the C/N of the two year leaves in rest period were higher than the vigorous growth period, the rest showed an opposite trend.(3) The order of four kinds of NSC content in all organizations was showed as glucose>fructose>sucrose>starch, and there was great difference of the starch content of different organizations between the rest period and vigorous growth period. Besides, the glucose and fructose content increased significantly with the increasing of elevation. The sucrose content was relevant significantly to the elevation change, but trends of different organizations and period were inconsistent. The varying trends of starch content in different tissues and growth stages with the elevation change were also inconsistent.(4) In this study, a lot of data about the content of NSC, total nitrogen and C/N of Q. aquifolioides of different elevation at different growth seasons were obtained, and there was no evidence that the Q. aquifolioides on Balang mountain was carbohydrate deficiency.