Population Adaptability Of Quercus Liaotungensis In The Loess Region

Quercus liaotungensis forest is one of the typical zonal vegetation types in warm-temperate deciduous broad-leaved forest and subtropical evergreen and deciduous broadleaved mixed forest.The concentrated distribution zone of Q.liaotungensis in Shaanxi Province is in the Loess Plateau and the north slope of Qinling Moutain.This study mainly took Q.liaotungensis natural secondary forests as research object.Sample-plot survey,localization observation and statistical analysis were used to study the variation characteristics of community,adapting characteristics of Q.liaotungensis growing status of different origin across environmental gradients of Taibai,Huanglong and Yan’an.The influences of environmental parameters on the population,biomass,volume,carbon storage,reproduction characteristics and management measures were investigated,which will provide a scientific basis for the restoration and sustainable management for Q.liaotungensis natural secondary forest.The main results are as follows:1.To compare the characteristics of spatial distribution of forest carbon density and storages,thus to determine the carbon sink of Q.liaotungensis in Shaanxi province.Carbon density was significantly higher than other area of Q.liaotungensis in Qinling Mountains.The concentrated distribution zone of Q.liaotungensis in Shaanxi Province is in the Loess Plateau and Qinling Moutain,and adequate moisture is a particular environmental factor determing forest biomass accumulation.2.The variation characteristics of Q.liaotungensis community show that the indexes of height,diameter,community diversity,soil moisture and nutrient across environmental gradients were: Taibai Mout.>Huanglong Mout.>Yan’an.There existed some differences among species composition of Q.liaotungensis community in the three regions while shrub-grass undergrowth were more prosperous and composite structure formed with tree,shrub and grass to keep soil and water conversation.3.To compare the growth dynamics,biomass and volume of individual Q.liaotungensis in different regions,thus to determine the ecological function of oak forest in each region.Individual biomass and volume of Q.liaotungensis varied in three regions.After 10 years,the growth of Q.liaotungensis entered an increasing phase in the three regions.After 20 years,Q.liaotungensis in Taibai maintained the highest aboveground biomass and volume,while which were slight greater in Huanglong than in Yan’an.4.To compare the characteristics of sexual reproduction process of Q.liaotungensis in difference regions,we found a small difference in the duration of seed dispersal among the three regions,and all regions exhibited in different total seed volume production.Seed dispersal peaked from mid-September to the end of September(50% of seeds fell during this period)and then gradually decreased towards winter(early November).The results of this study suggest that promoting greater arborous species richness could enhance seedling establishment and thus encourage forest regeneration,which under the premise of guaranteeing the Q.liaotungensis is the dominant species.The seedling height,base diameter,crown width,leaf number,length of new branch and dry matter quantity of Q.liaotungensis generally showed quadratic curve equation with increasing of the seedling ages in different regions,while the some root system indexes of underground parts were showed power function with increasing of the seedling ages.There have a significant relationship among seedling morphological,dry matter quantity and environmental factors of Q.liaotungensis.From south to north,there are significant changes in its distribution range of Q.liaotungensis seedlings.Individual growth of Q.liaotungensis seedlings in Huanglong was the best.Combined with improved management measures,the recommendations can help to improve seedlings survival.The individual growing status and development of seedlings in large forest gap were better than that in other habitats,which promote it into a natural regeneration forest.5.To compare the characteristics of vegetative propagation process of Q.liaotungensis in difference regions,we found the sprouts of ground parts were showed increasing with the ages.The individual height,basal diameter and other sprouts growth indexes of aboveground were Huanglong>Yan’an>Taibai.Combined with improved management measures,the recommendations can help to improve sprouts survival.The individual growing status and development of seedlings in large forest gap were better than that in other habitats.6.Reasonably forest management is possible to make forest sustainable.Our research practice in adopting Close-to-Nature forest management measures,to explaining the indexes of height,diameter,community diversity,soil moisture and nutrient after close to nature management with different thinning measures.The 30% thinning strength should be drafted.7.Suggestions: The results of this study suggest that promoting greater arborous species richness could enhance forest development and thus encourage forest regeneration,which under the premise of guaranteeing the Q.liaotungensis is the dominant species.Tending thinning should be timely used in Q.liaotungensis natural secondary forest and open forest gap to promote seed setting and sprouts growing so as to increase the forest land coverage.Keeping water conservation forest are the main purpose of Q.liaotungensis forest in the north slope of Qinling Mout.,ungraded and diseased woods should be thinned to promote the sprouts development and larger diameter woods should be mainly cultivated.Keeping soil and water conversation forest is the main purpose of Q.liaotungensis forest in Loess Plateau,seedling should be mainly cultivated and stump sprouts should be used to recover the forest land rapidly.Low density-high quality wood should be cultivated in a stable canopy density.