Seasonal Variations of Clonal Propagation Characteristics of Populus pruinosa Schrenk,Organ Nutrient and Soil Fertility, and Their Coupling Associations in the Forest and Forest Edges
ZHENG Ya-Qiong, ZHAI Jun-Tuan, CHEN Jia-Li, HAN Zhan-Jiang, JIAO Pei-Pei, LI Zhi-Jun
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Propagation features elucidation is important for improving ecological service of poplar forests in arid regions. We studied the relationship between the occurrence of clonal organs of Populus pruinosa Schrenk and soil nutrient content during the clonal propagation, and their variations affected by the forest edge. The sample plot was set up vertical to channel of Tarim River upper reaches in Xinjiang, China, in the riparian forest(400 m away from the river channel) and forest edge(200 m away from the river channel) separately. The number of adventitious buds, underground ramets and unearthed ramets in two habitats was investigated every 20 days from April to October in 2014, and the nutrient contents of lateral roots and soil were also measured. The results show that:(1)The content of total nitrogen, total phosphorus, total potassium and organic carbon of lateral roots increased gradually from April to June, and decreased gradually from July to October, which is consistent with the trend of number variation of the adventitious buds and underground ramets during this period, and also show a spontaneously trend with gradually increased soil organic matter content, available nitrogen content, available phosphorus content and available potassium content or maintain at a high level from April to June, and decreased gradually thereafter from July to October. Whereas, the C/N ratio of lateral roots decreased gradually from April to June, after a slightly increasing and decreasing again, the N/P ratio also decreased gradually from April to June, but show an increasing trend in the forest edge or remain unchanging in the forest after a significant decrease in July. (2)The number of adventitious buds was affected by total nitrogen and nitrogen-phosphorus ratio of lateral roots, the number of underground ramets was affected by the content of total nitrogen, organic carbon and carbon-nitrogen ratio of lateral roots both in the forest and forest edge. In the forest edge, the number of adventitious buds was close related to the content of soil organic matter, alkali-hydrolyzable nitrogen and available potassium, and there was also a significant correlation between the underground ramets and the content of soil alkali-hydrolyzable nitrogen and available phosphorus, as well as a significant correlation between the soil nutrients and the total nitrogen, C/N ratio and N/P ratio of lateral roots, while, the main factors affected by soil nutrients in the forest were total nitrogen and N/P ratio of lateral roots. (3)The number of adventitious buds, underground ramets and unearthed ramets in the forest was significantly lower than that in the forest edge. Soil nutrient content affected the number of adventitious buds, underground ramets and unearthed ramets by influencing the nutrient content of lateral roots. P.pruinosa is one of the few national protected plants in P.pruinosa forest play an important role on ecological services in local area, our results provide a basic data support for the conservation strategy formulation based on the clonal propagation of P.pruinosa forest.