Research On The Dynamic Changes Of Seed Rain And Seed Nutrient Status Of Pure Stand Of Quercus Variabilis Within Different Slope Positions

Quercus variabilis is widely distributed in our country,which is a kind of important tree species in forestry production,with many excellent features as well as high economic and ecological value.The seeds of Quercus variabilis are not only important materials to maintain the supply of ecosystem food,but also the origin of the restoration of Quercus variabilis forest,so in recent years they are more and more attentioned by domestic and foreign researchers.But the researches on the seed rain of Quercus variabilis are merely limited in the dynamics of numbers,which is one-sided,and the effects of seed slope position on seed rain has not yet been studied.Hence,this thesis present the dynamics of seed rain and the changes of the seed nutrition,determining the best time for collecting seeds of Quercus variabilis during the seed setting period,and the best seed slope position.We set up seed collection box to collect the pure forest seeds,studied on the effects of seed slope position on average seed numbers,biomass and nutritional contents of standing forests,and the following results were obtained.1.the drop interval of Quercus variabilis is August 18th to November 16th,totaled 90 days,15 days from September 22nd to October 7th,the bearing fruit quantity of per hectare accounts for 60.34%of the total,which is the fastigium of seed rain.2.The seed slope position has significant effects on bearing fruit quantity and biomass,and when the slope position is higher the seed numbers and biomass are lower.The total quantity of seeds and biomass per plant have the same trend in different slope position,which is Downhill position>Middle slope position>uphill position.3.Through the analysis of the contents of nitrogen,phosphorus and potassium in the seeds of Quercus variabilis,it was found that the growth of nutrients in the seed was lagging behind the growth of biomass and the lag time was 10 days.Seed biomass reached stable on 2nd September,while nitrogen,phosphorus and potassium reached stable on 12 September.4.Under the same slope conditions,the seed yield of the tree was significantly higher than the In the whole fall of a period,the top tree per plant fruit amount compared with the average level of 6.6%;compared with middle slope average total number of per plant seed,a high tree average per plant seed total 6.4%;compared with average,average individual fruit tree downhill high total 6.7%.In terms of biomass,high slope the total biomass of seed of select tree was 1.8%higher than the average;the middle slope total biomass of the superior tree was 1.9%higher than the average.Compared with the average,the downhill The average biomass of the dominant tree was 4.7%higher.This study has important guiding significance for the time of seed collection,the selection of slope position and the selection of excellent tree,which can provide theoretical support for the high efficiency of Quercus variabilis.