Study On The Time Dynamics Of Clonal Growth Of Hippophae Rhamnoides L.ssp.sinensis In The Loess Plateau

Hippophae rhamnoides L. ssp. sinensis is a multiple purpose tree with great ecological and economic value. And it is also a typical clonal plant. It can grow up to thick forestry from a single mother ramet by clonal growth, and adapt to drought environment relying on physiological integration and foraging behavior caused from clonal growth. For the species, there have been some reports about the spatial dynamics of clonal growth of natural forests. While, such studies as time dynamics of plantation population are few. In order to understand the stability mechanism and ecology strategy of clone population, time dynamics for clonal growth of Hippophae rhamnoides L. ssp. sinensis plantation in Loess Plateau were studied. With the method of spatial series substituting for time series, the population structure, population density, population biomass and its allocation, population growth increment and clone growth form were analyzed, in the hopes of supplying some basic information for plantation design, vegetation restoration, sustainable management and adding more datum to woody clonal plant population ecology. The main results are as follows:(1) In the first 5 years, age structure and height class of clone population characterized an increasing type. At the age of 8th year, they became stationary. Afterwards, they tended to be mature and senescence in the 16th year. But the clone population could maintain or recover its stability by gap regeneration relying on physiological integration and foraging behavior caused from clonal growth.(2) From clonal growth prosperity stage to clonal growth senescence stage, daughter ramets population density increased first and then decreased, but mother ramets population density decreased as age increasing. At clonal growth recovery stage, the density of daughter ramets increased again, mother ramets population density stopped decreasing and maintained to a level. By such way, the clone population could maintain its stability for a long time. Furthermore, the percentage of mother ramets decreased and the ratio of daughter ramets number increased as the increasing of the age, such changes led to the decline of genetic diversity of the clone population.(3) From clonal growth prosperity stage to recovery stage, the biomass of clone population, branch, dead branch, leaves and root increased first and then decreased; trunk biomass increased all the time; clonal organ biomass increased first, then decreased, and increased again at the recovery stage. Aboveground biomass ratio decreased in the first 8 years and then increased after the 9th year, underground biomass ratio increased first and...