Structural Analysis And Regeneration Of Cupressus Chengiana Population In The Bailong River Basin

Cupressus chengiana is a Endemic Tree Species,and is anational second-class protective plants in China.Distributed in Minjiang River drainage,Dadu River basin and middle and lower reaches of Bai longjiang Valley.It is a dominant species of coniferous forest in arid valley and plays an active role in water and soil conservation,water conservation and ecological benefits.However,the population distribution area of C.chengiana is getting smaller due to logging,stealing and timber trespass.The distribution area is more narrow,especially in the Bai longjiang Valley,which is now endangered.At present,only a few reports have been reported on C.chengiana in this region,which lacks systematic and in-depth researchand limits people's awareness and protection of the population.So,the study takes the natural forest of C.chengiana distributed in Han ban township of Zhouqu county as the research object,the geographical distribution,ecological characteristics,population structure and regeneration of population of Minjiang River were systematically studied by means of plot survey and social survey.The structure dynamics and regeneration mechanism of the population were systematically analyzed,and the population recovery plan was formulated.To preliminarily explore that the distribution status and bioecological characteristics of C.chengiana population in Bailong river basin.And the mechanism of population renewal was explained and a feasible population recovery strategy was proposed.It provides a theoretical basis for the restoration of the C.chengiana populationand ecological environment protection in the arid valley of the Bailong river basin.The survey and research results are as follow:1.The existing C.chengiana population in the Bailong river basin is all natural forest.The distribution area is narrow and small.There are few forests in the distribution,only around the town of Hanban township in Zhouqu county.Other distribution areas only exist around templesand homesteads in the form of scattered solitary trees.Most of them are in physiological decline,with poor seed yield,serious seed abortion and difficult population renewal.2.The population structure of C.chengiana presents a polarized distribution,which shows that the number of young forest and old forest is large and the number of middle aged forest is small,the young forest is mostly secondary forest formed by piling or seed germination,or the natural forest formed by natural regeneration,the old and middle-aged individuals survived mainly in the form of "Feng shui forest" and "Protecting temple forest".C.chengiana species survival curve between Deevey-? type and Deevey-? type,is a stable population.Time series analysis shows that after the next 2,4 and 6 age groups,the number of individuals in the population tends to increase.3.The structure of C.chengiana community is simple in Bailong river basin.There is a single tree species in the arbor layer,which is basically C.chengiana.Undergrowth shrubs and herbaceous layers are rare,It is difficult to renew cypress seedlings of C.chengiana community species diversity is low,the community structure stability is poor.4.Within the area,the individual capacity of the C.chengiana is poor,and high seed abortion rate,the ratio of empty grains is about 50%.The vigor of the full seed is 25%,seed germination rate is between 30% and 35% and seeds germinate in the optimal temperature of 15?.The seeding environment has great influence on the germination rate of seeds.5.For the protection and recovery of the C.chengiana population,the main protection is on-site conservation and the auxiliary protection is off-site preservation.According to local conditions,the scope of the protected areas shall be delimited,and measures shall be taken to seal off the mountains for afforestation.Thedestruction of human and animal activities shall be strictly prohibited and the natural renewal of the population shall be promoted.And collecting germplasm resources,establishing seed garden and nursery grounds to expand the propagation of artificial population.