Influence Rhythm Of Planting Density On Clonal Growth Of Hippophae Rhamniodes L.subsp Sinensis

Hippophae rhamnoides L.subsp Sinensis not only is fine multipurpose treespecies, and its ability of drought resistance (drought) is very strong, but also Is a typicalclonal plants, its ability of clonal propagation (commonly known as root shoot "string")also is very strong, and Hippophae rhamnoides L.subsp Sinensis has potential of "onetree make a forest"So they are awalys selected to afforestation in the three norths areawhere is the arid and semi-arid regions. In recent years, however, the phenomenon ofpopulation decline and death are emerging, one of the most important reason is thatdrought stress. On the one hand, drought stress is the result of rainfall. On the antherhand, When determining initial planting density ignored the cloning habits of Hippophaerhamnoides L.subsp Sinensis After forestation clonal propagation can make populationdensity and productivity more than vegetationcarrying capacity of soil water. Finally,result in the soil drying and dried soil layer, eventually will threaten the stability andpersistence of population. In order to solve this problem, Experimental study wasconducted at Mu Us sandy, the tested planting density were2500trees/hm2,4444trees/hm2,10000trees/hm2and40000trees/hm2respectively. Under the premise ofconsidering Hippophae rhamnoides L.subsp Sinensis cloning habits, analyzing therelationship between initial stand density and soil moisture, and studying the influencingrule of planting density on survival of stock plant, plant growth, clonal propagation andpopulation stability, and discussing initial stand density function rule from the point ofbiomass investment and distribution patterns.(1) Soil moisture showed the tendency of decrease with the increase of plantingdensity, high planting density will result in soil water deficit, and in turn, affect thesurvival of stock plant, plant growth, clonal propagation and population stability. Thebest planting density is4444trees/hm2and10000trees/hm2which are beneficial toplant growth, clonal propagation and population stability of Hippophae rhamnoidesL.subsp Sinensis. When initial stand density reach40000plants/hm2, soil moisture downto6%, and the survival of stock plant, plant growth, clonal propagation and populationstability decline. (2) The survival rate of stock plant showed the tendency of increase at the beginningand then dcline with the increase of planting density, and the best planting density is4444trees/hm2. Tree height increment showed the tendency of increase with the increaseof planting density, But there is no significant difference between different initialplanting density. Ground diameter and canopy showed the tendency of dcline with theincrease of planting density. When planting density be more than10000plants/hm2,canopy and ground diameter growth was significantly inhibited. Investigate its reasons,the planting density changed the increase rate of increment, fast-growing period,regulating the growth process.(3) The relationship between the clonal organ branching intensity, extension capacity,the ability of clonal propagation (ramet quantity) and irrigation intensity accorded withquadratic parabola. And there have cooperative effect among the clonal organ branchingintensity, extension capacity, the ability of clonal propagation. When initial plantingdensity is between the4444trees/hm2and10000trees/hm2, the organ branchingintensity, extension capacity, the ability of clonal propagation had reached the maximumvalue.(4) Obviously, the best planting density of population growth is different from clonalpropagation. Under the certain planting density conditions the population through biomassinvestment and adjust the pattern of distribution in the trade-off between growth andreproduction. Whereby, the regulation that is canopy, ground diameter and the distributionof aboveground decreases with the increase of initial planting density, is beneficial to keepthe population stability and durability; thehe regulation that is the distribution ofunderground increase with the increase of initial planting density, is beneficial to thepopulation in the case of initial planting density for more underground resources. But inunderground biomass redistribution, showed the tendency of increase at the beginning andthen dcline with the increase of planting density, so the ability of clone reproductive inmiddle initial planting density is (15000plants/hm2-20000plants/hm2) at maximum.(5) Biomass distribution of investment and the adjustment not only affect the growthof population and reproductive behavior, but also the result will ultimately affect the stability and persistence of the population. When the planting density is4444plants/hm2and10000trees/hm2, Individual growth level close to normal distribution; Or decreasewith the increase of density, individual growth level distribution deviation on both sides tostep by step. At the beginning of at the same time, along with the increase of plantingdensity, the individual gradually transition to a "thin and tall" form.(6) Population biomass distribution of investment and the adjustment influence thepopulation and individual behavior, and ultimately affect the population (stand)productivity and self-cultivating forest. The research results show that the population andits survival artifacts (vertical stem, branch, leaf, root) biomass is hyperbolic changes withthe increase of planting density, the change rule accords with in law of constant values ofoutput; Death parts (stick) biomass is rises (or falls) in a straight line with the increase ofplanting density, so means that the population autothinning strength increased with theincrease of planting density. Despite all this the speed of closing and reforest increase withthe increase of planting density.