Study On Reproduction Ecology And Living Strategy Of The Xanthoceras Sorbifolia Population

Xanthoceras sorbifolia was not only one of the unique oil trees, but also important medicinal and ornamental plants in China, which had played an important role in promoting economic development, treating disease and improving the ecological environment. For these reasons, the study on Xanthoceras sorbifolia becomes extremely necessary, especially that on the growth and reproductive characteristics of it had not only important theoretical value, but also had practical significance. In this paper, the Loess Plateau in Shaanxi Province in which the distribution of Xanthoceras sorbifolia was the most concentrated was tested, the geographical distribution, biological characteristics, population dynamics, reproductive ecology and the parameters of photosynthetic and water potential of it were studied, and the trends of population are analyzed, which provided a theoretical basis for the sustainable use of Xanthoceras sorbifolia. The main results were as follows:1. The distribution of Xanthoceras Sorbifolia was widespread, of which the loess plateau was the most centralized distribution area. Cluster analysis on the importance value of Species in all plots revealed, Xanthoceras sorbifolia in the Loess Plateau in Shaanxi could be divided into five community types. The characteristics and average growth potential were different in different community types because of the different conditions each other. The growth of Xanthoceras sorbifolia seedling mainly focused on the underground in natural conditions.2. Overall, the individuals of younger age-class were adequate and the population increased steadily in the natural populations in the Loess Plateau. There were better environmental conditions in the populations A and D, but population B showed a declining trend, because in which there were more the individuals of older age-class and the seed could not be settled after the fall. The natural populations of Xanthoceras sorbifolia were difficult to be updated in population C, because in which tall trees were more and tree canopy density was high. In population E, the transformation from seedlings to senior-level individual was interrupt because of the serious interference of human and livestock, resulting the individual of Xanthoceras sorbifolia in more than 10 years was lost.3. There were large numbers of flowering and small numbers of fruit in Xanthoceras sorbifolia. The testa of the Xanthoceras sorbifolia seed was very thick and difficulty to absorb water, so the seed should be treated using the method of being stored in sand and soaked in water of 80℃before sowing. The seedlings could germinate from the injury sites when Xanthoceras sorbifolia was injured by cutting stake and roots, and the capacity of seedlings germination was enhanced as the level of damage site was increased.4. The net photosynthetic rate curve was single peak type in HabitatⅠ, however, which was double peak type in HabitatⅡ. The diurnal variation curve of water potential of Xanthoceras sorbifolia showed partial distribution tendency, and the lowest point of water potential was at 4 pm in two habitats. Four indicators of water potential parameters were calculated by the technology of PV curve, which showed that the individual had stronger ability to adapt to the arid environment in habitatⅡthan habitatⅠ.5. The survival rate of transplant in sunny-slope higher than shady-slope, stumping and plastic film mulching in the sunny-slope could make the survival rate more than 90%. In five treatments, the growth potential of the aboveground of Xanthoceras sorbifolia was the best in the treatment of plastic film mulching, and in the treatment of shady-slope, the root diameter and the dry weight of the aboveground was the largest, but the proportion of the dry weight of root in whole plant was the minimum(44%). In sunny-slope, the height of Xanthoceras sorbifolia was lower by stumping than by uneven stubble and conventional farming, the growth potential were similar between the treatment of plastic film mulching and stumping, the length of main root were different. The proportion of primary and secondary roots in all levels root was higher in conventional cultivation in the sunny-slope than in the shady-slope.