中国沙棘克隆生长对灌水强度的响应

为了解中国沙棘克隆生长调节对土壤水分资源供应水平的响应规律并寻找最佳灌水强度，研究了种群生长量、生物量、子株数量、克隆器官延伸能力、克隆器官分枝级数等种群参数与同灌水强度的关系。结果表明：（1）种群参数增幅与灌水强度之间呈二次抛物线关系，即种群参数增幅随着灌水强度的增加先升后降。小于最佳灌水强度，种群参数增幅随着灌水强度的增加而上升；大于最佳灌水强度，种群参数增幅随着灌水强度的增加而下降。（2）不同种群参数增幅最大时的最佳灌水强度具有一定差异，种群及其构件生物量的最佳灌水强度为每月4.0次、相当于本地年均降水量的2.0倍，子株数量、克隆器官延伸能力、克隆器官分枝级数增幅的最佳灌水强度为每月3.0次、相当于本地年均降水量的1.5倍。（3）适当灌水能够促进中国沙棘种群生长、提高克隆繁殖能力，但在一定灌水强度下生长和繁殖之间存在权衡关系，而种群生长和生物量积累之间、克隆子株数量与克隆器官延伸能力和克隆器官分枝级数之间则有协同作用。（4）在不同土壤水分资源供应水平下，中国沙棘主要通过个体大小、种群生物量分配、子株数量、克隆器官延伸能力、克隆器官分枝强度等调节做出响应，这些调节直接影响种群的稳定性和克隆的持久性。

The clonal growth of Hippophae rhamniodes L. ssp. sinensis in response to irrigation intensity

The survival, growth, breed and the population succession direction of Hippophae rhamniodes L. ssp. Sinensis is seriously effected by water for the average precipitation is lack. The annual average precipitation is 500-600mm at the suitable distribution area. Hovewer the annual average precipitation is only 200mm and the aridity is 2.0-4.0 at the Loess Plateau, Mu Us Sandland and Feldspathic sandstone zone where are the distribution centers of Hippophae rhamniodes L. ssp. Sinensis. One of the solving ways are irrigation, so it has the important ecological meaning and guidance meaning of planting forest that research on the clonal growth of Hippophae rhamniodes L. ssp. sinensis in response to irrigation intensity. The experiments of different irrigation intensities were done in plantation which included four treats, three repetitions. The experiment adopted 2×2 regression design and took the advantage of Latin layout. It can get the mathematical statistics repetitions more than 6 times. The irrigation respectively is 0 times (it is controlled trial), 1.0 times, 1.5 times, 2.5 times of annual average precipitation. The relationships between the growth, biomass, the number of daughter ramet, clonal indexes and different irrigations were researched. The results showed: (1) Relationship between the population parameters and irrigation intensity was accord with quadratic parabola. It meant each population parameter has an certain optimum irrigation intensity, the parameters increased below the optimum irrigation intensity and decreased above the optimum irrigation intensity with the increasing of irrigation intensity. (2) The optimum irrigation intensities were difference among different population parameters. The optimum irrigation intensities of height, ground diameter and crown width were 4.0 times per month, which was equivalent to 2.0 times than local annual average precipitation. The optimum irrigation intensities of population and its modular biomasses were 4.0 times per month, which was equivalent to 2.0 times than local annual average precipitation. And the optimum irrigation intensities of daughter ramet number and stretching as well as branching capacity of clonal organ were 3.0 times per month, which was equivalent to 1.5 times than local annual average precipitation. (3) The appropriate irrigation could not only increase the population growth but also improve the capacity of clonal propagation, but there was a trade-off relation between population growth and clonal propagation at the certain irrigation intensity. The increasing of underground biomass was beneficial to promote the clonal breed, stretching and branching of clonal organ while the increasing of aboveground biomass inhibited them. However, the relationship show cooperative effect between population growth and biomasses accumulation, between the number of daughter ramet and the stretching capacity as well as the branching intensity of clonal organ. They jointly accomplished the adaptability adjustment of clonal breed. (4) To the number of daughter ramet and the foraging growth pattern, it is a continuum of ecological strategy that the clonal growth in response to irrigation intensity. With the increasing of irrigation intensity, the numbers of daughter ramet from few to more then to few, the foraging growth pattern from guerrilla type to phalanx type and then to guerrilla type, population fitness from low to high then to low. This adjustment result of clonal growth has made the adaptability population characteristics and ecological adaptability strategy to irrigation intensity. Thus these conclusions were drawn: The less water must lead to drought stress, unfortunately the more water must lead to the temperature and the permeability decrease. They all inhibit the growth. But proper irrigation can promote the growth of Hippophae rhamniodes L. ssp. sinensis in Mu Us Sandland where is drought and strong sunlight illumination. In the production practice, the irrigation can be controlled in 1.5-2.0 times of local annual average precipitation. In same time, Hippophae rhamniodes L. ssp sinensis does response to different soil water resource supplying levels by adjustments of individual size, population biomass distribution, the number of daughter ramet, stretching capacity and branching intensity of clonal organ. These adjustments can improve the clonal breed of population and be beneficial to population stability maintenance and clonal growth persistence.