Nitrogen Addition Under Simulated Vitex"Fertile Island" Effect To Two Kinds Of Forest Seedings Conservation

Arid and semi-arid areas,the reasonable utilization of the conservation of shrub "fertile island " function of artificial afforestation and vegetation restoration in arid regions has positive significance.Through simulation of Vitex shrubs “fertile island” effect of environmental conditions and used 1-year-old seedlings of Platycladus orientalis and Quercus variabilis in the low mountain hilly region of the Taihang Mountains as the research object in order to study the conservation mechanism of the growth and development of different tree seedlings,the growth characteristic of two kinds of seedlings after adding exogenous nitrogen,quest for the appropriate habitat and nutrient conditions of the seedlings,get the more suitable conservation and afforestation species which can provide the theoretical and technical basis for the afforestation experiment of "fertile island effect" of Vitex shrubs.Main research conclusions are as follows:(1)Vitex shrubs "fertile island " effect plays a conservation role for the seedlings which are under the crown.The survival rate of the two tree seedlings in the crown was significantly higher than that outside the crown.Under the same nitrogen application level,the seedling height,ground diameter,whole plant biomass,underground biomass,above-ground biomass(L0,L1,L2)of the seedlings> crown outside(L3,L4)seedlings;Vitex shrubs can be used as conservation plants in the construction of vegetation restoration in the hilly areas of the Taihang Mountains.(2)The effects of the Vitexshrubs on the seedlings were different.The overall survival rate of Platycladus orientalis seedlings was higher than that of Quercus variabilis seedlings.The survival rate of Platycladus orientalis was the highest at L1 in the crown,and it was slightly better than the other transplanting distance from the standpoint of seedling height,biomass,root morphological development and other factors.While the survival rate of the Quercus variabilis seedlings was the highest at L2 besides the crown and it was higher than that of other seedlings.(3)Nitrogen application significantly promoted the shrub Vitex "fertile island" effect under the 2 kinds of seedling height,ground diameter,whole plant biomass,above-ground biomass and underground biomass.low nitrogen level,Platycladus orientalis and Quercus variabilis seedlings root shoot ratio,root average diameter,rootsurface area the morphological indexes such as root volume,with the "fertile island" effect range increased significantly,the high nitrogen level changes with distance effects were not significant;the amount of nitrogen at 12 g Nm-2a-1,two seedling growth state is relatively the best under crown.(4)Root biomass and total root length,root surface area,was significantly positively correlated to root volume,but negatively correlated with the average root diameter;The root biomass and the height and ground diameter of Platycladus orientalis seedlings in the crown(L1)and Quercus variabilis at the crown edge(L2)is more relevant...