A multipurpose clone plant species, Hippophae rhamniodes has the capacity for indefinite longevity, although under successive drought stress it may often decline or die across large areas. Field trials were con- ducte...A multipurpose clone plant species, Hippophae rhamniodes has the capacity for indefinite longevity, although under successive drought stress it may often decline or die across large areas. Field trials were con- ducted over 2 years to examine the effects of varied irrigation intensities on modular growth and clonal propagation in a semi-arid area. Irrigation levels included a control, as well as two, four and six times the volume of water that was typically received via local annual average precipitation. Irrigation intensity significantly influenced clonal propagation capacity （number of daughter ramets）, aboveground modular growth （height, base diameter, and crown width）, belowground modular growth included root nodule dry weight, stretching capacity of lateral roots （length of the longest lateral roots, and diameter of first-grade lateral roots）, and branching intensity of lateral roots （number of lateral roots bifurcation grade, number of first- grade lateral roots）. The modular growth and the density of daughter ramets were small under non-irrigation or low irrigation, and became larger with increased irrigation intensity. Beyond a certain threshold, however, further increases in irrigation intensity resulted in a reversion to the development. The optimal irrigation intensities for growth and propagation were 3.48-5.29 times the volume of nominal local annual average precipitation. There were effects of irrigation intensities on the positive significant correlations between aboveground and belowground modular growths, and on clonal propagation capacities. Under various water treatments, H. rhamnoides may adapt to the environment through the regulation of growth and propagation. We concluded that water shortages act to weaken the growth and propagation of H. rhamniodes plantations.展开更多
Based on the measurement of all individuals of population at different successional stage and following excavation of clones, the density and biomass dynamics of Hippophae rhamnoides L. subsp. sinensis population in M...Based on the measurement of all individuals of population at different successional stage and following excavation of clones, the density and biomass dynamics of Hippophae rhamnoides L. subsp. sinensis population in Mu Us sandland were analyzed with the methods of plots arranged with age and reverse age class addition(RAA). The main results were as follows:(1)The density of clone population increased with the population growth before 5-year-old. The population biomass accumulating also increased by Logistic equation in the period of age structure of population developed from increasing type to mid-decreasing type. Then they tended to be decrease. While the population density, population biomass augmented again with the emergence of gap regeneration, and the dominant status of H. rhamnoides L.subsp. sinensis population and the stability of the community were maintained.(2)The decrease process of density of daughter ramets population lagged behind that of mother ramets population, and the numerical ratio of daughter ramets population within the population gradually enlarged. As the population thinned, the composition of population changed from more clones with less daughter ramets to less clones with more daughter ramets and the genetic diversity of population reduced.(3)The prosperous stage of biomass accumulation appeared from 8-year-old to 16-year-old and its peak appeared at 12-year-old. And the relationship between the individual mean weight and population density could be expressed by the law of power-3/2 in the period of age structure of population developed from stable type to decreasing type.展开更多
基金supported by the National Science Foundation of China(31070551/31570609)
文摘A multipurpose clone plant species, Hippophae rhamniodes has the capacity for indefinite longevity, although under successive drought stress it may often decline or die across large areas. Field trials were con- ducted over 2 years to examine the effects of varied irrigation intensities on modular growth and clonal propagation in a semi-arid area. Irrigation levels included a control, as well as two, four and six times the volume of water that was typically received via local annual average precipitation. Irrigation intensity significantly influenced clonal propagation capacity （number of daughter ramets）, aboveground modular growth （height, base diameter, and crown width）, belowground modular growth included root nodule dry weight, stretching capacity of lateral roots （length of the longest lateral roots, and diameter of first-grade lateral roots）, and branching intensity of lateral roots （number of lateral roots bifurcation grade, number of first- grade lateral roots）. The modular growth and the density of daughter ramets were small under non-irrigation or low irrigation, and became larger with increased irrigation intensity. Beyond a certain threshold, however, further increases in irrigation intensity resulted in a reversion to the development. The optimal irrigation intensities for growth and propagation were 3.48-5.29 times the volume of nominal local annual average precipitation. There were effects of irrigation intensities on the positive significant correlations between aboveground and belowground modular growths, and on clonal propagation capacities. Under various water treatments, H. rhamnoides may adapt to the environment through the regulation of growth and propagation. We concluded that water shortages act to weaken the growth and propagation of H. rhamniodes plantations.
文摘Based on the measurement of all individuals of population at different successional stage and following excavation of clones, the density and biomass dynamics of Hippophae rhamnoides L. subsp. sinensis population in Mu Us sandland were analyzed with the methods of plots arranged with age and reverse age class addition(RAA). The main results were as follows:(1)The density of clone population increased with the population growth before 5-year-old. The population biomass accumulating also increased by Logistic equation in the period of age structure of population developed from increasing type to mid-decreasing type. Then they tended to be decrease. While the population density, population biomass augmented again with the emergence of gap regeneration, and the dominant status of H. rhamnoides L.subsp. sinensis population and the stability of the community were maintained.(2)The decrease process of density of daughter ramets population lagged behind that of mother ramets population, and the numerical ratio of daughter ramets population within the population gradually enlarged. As the population thinned, the composition of population changed from more clones with less daughter ramets to less clones with more daughter ramets and the genetic diversity of population reduced.(3)The prosperous stage of biomass accumulation appeared from 8-year-old to 16-year-old and its peak appeared at 12-year-old. And the relationship between the individual mean weight and population density could be expressed by the law of power-3/2 in the period of age structure of population developed from stable type to decreasing type.
