A Study On Growth Characteristic And Biomass Of Poplar Plantation

Poplar is widely planted in the world, and it is also an important fast-growing timberspecies in China. At present,Chinese poplar plantation area is the No. 1 in the world. Researchon the growth characteristics, biomass and productivity changes in the law of poplar plantationis of great significance in the further excavation of poplar plantation potential production and inthe guarantee of its fast-growing.In the paper, in order to gain a more in-depth understanding of poplar plantation growthcharacteristics and biomass patterns, as well as planting density on the impact to poplarplantation, there is a study of Populus×xiaohei plantation planted in North China andPopulus×euramiricana plantation in South China.The study on growth characteristics,biomass and productivity law of Populus×xiaohei plantation in three densities in sand land ofNorth China and Populus×eurarniricana plantation in four densities in beach land in Yangtzeriver by a randomized complete block design is to master internal rules of poplar plantationgrowth, understand the different types of site, different species of poplar growth and thereasons for the different results to the future of the fast-growing poplar plantation, Intensivecultivation, decision-making and related research to provide the scientific basis. At the sametime, it will be to provide a theoretical basis which could improve the productivity of poplarplantation and better play their economic and social benefits through revealing the biomass lawof poplar plantation.The results showed that:(1) The growth process of Populus×xiaohei was divided into four periods: 0～3 a was theyoung stand period, 4～14 a was the fast-growing period, 15～16 a was the near matureperiod, 17～26 a was the overmature period.The growth of tree height was concentrated on theformer 10 a.4～10 a was the DBH's fast-growing period, 5～15 a was the volume's fast-growingperiod. The rotation of Populus×xiaohei was 16a.The growth process of Populus×euramiricana was divided into three periods: 0～4 a wasthe young stand period, 5～10 a was the fast-growing period, 11～14 a was the near matureperiod.2～8 a was the tree height's fast-growing period, 5～10 a was the DBH's fast-growingperiod, 5～8 a was the volume's fast-growing period. The rotation of Populus×euramiricanawould be 16～18 a.There were little difference in the growth of tree height among trees in Populus×xiaoheiplantation, but much difference in the growth of DBH and volume among trees, so was the Populus×euramiricana.Compared to the Populus×xiaohei, the growth of Populus×euramiricana had obvious advantages in height, DBH and volume in every stage,and thegrowth difference in DBH and volume had increased with age.In the fasting-growth stage ofDBH,if the suitable fertilizer management was carried on, it would be good to the cultivationof large and medium-sized diameter timber.(2)Stand density had greater impact on the growth of DBH and volume ofPopulus×xiaohei,but little impact on the growth of tree height.Low density could promote the growth ofDBH and volume. The Populus×xiaohei crown length,the ratio of crown length to tree height,the canopy breadth and the ratio of canopy breadth to DBH reduced along with forest standdensity increased, but clear bole height, the ratio of clear bole height to tree height and the ratioof tree height to DBH increased along with the density increased; The ratio of tree height toDBH had a inverse correlation with increasing diameter class; In the certain density scope, ithad a direct correlation with forest stand density; Before the ratio of tree height to DBHtending to stably, it had a inverse correlation with forest stand age. The Populus×xiaoheicrown length had a logarithmic correlation with DBH, the canopy breadth had a linearcorrelation with DBH, the tree height had a logarithmic correlation with DBH.The logisticgrowth model may accurately describe the growth process of Populus xxiaohei tree height andDBH.(3) Compared to the other regression model, the W=aD~b model may accurately estimatethe biomass of Populus×xiao hei and Populus xeuramiricana plantation.Stand density hadgreater impact on the biomass of Populus×xiao hei and Populus×euramiricana plantation.Inthe certain density scope,the biomass of Populus×xiaohei reduced along with forest standdensity increased.The biomass of Populus×euramiricana in four densities increased alongwith forest stand density increased.There was a closely relation between stand age and thebiomass,the biomass increased along with stand age increased.The biomass ofPopulus×euramiricana plantation was higher than the biomass of Populus×xiao heiplantation in the same density and stand age.The biomass distribution in diameter classes ofPopulus×xiaohei was a Normal Distribution.Low density could be good to the cultivation oflarge and medium-sized diameter timber.There were erratic fluctuations in the biomassdistribution in diameter classes of Populus×eurarniricana.Its aboveground biomass was 90%of the total biomass, including of the trunk 54%, branch 28%, bark 7% and leaves 1%, theunderground biomass was only 10% of the total biomass.