Growth Process And Tree Rings Climatology Of Schima Superba In Subtropical Area Of China

The growth of trees is significantly affected by climate change.Schima superba is the important fire-resistant species and it was widely used in fire forest belt which is in the ridge of a mountain in southern China.The growth characteristics of Schima superba can reflect the changes of local meteorological factors well.In this paper,Schima superba species in Paiyashan of Hunan Province were studied.Analyzed the characteristics of local climate change;the growth process of the overtopped,average and dominant tree was studied by using the trunk analysis data.The growth equation of height,DBH and volume of these three kinds of trees were fitted with single wood growth model.At the same time,the relationship between radial growth of Schima superba and climatic factors was analyzed.Which provided the theoretical basis for the cultivation and management of subtropical woods in China,provided measured data and basic information for the study of historical climate change and the prediction of future climate change.The main findings are as follows:(1)Climate change in the study area:The average temperature range from 1951 to 2015 is 15.8?18.4 0C,the temperature slope is 0.34?/10a;there is a significant warning in 1960?1966 and 1983?2015;in 1986,a mutation from low temperature to high temperature occurred.The precipitation range is 1020.0?1827.7 mm in recent 60 years,and the slope is 16.3 mm/10a;the precipitation increased significantly in 1996?2006 years.The relative humidity slope is-0.46%/10a;the overall range of variation is between 72.8%and 85.6%.(2)The growth process of classified Schima superba:the DBH,height and volume of these three classified trees have a similar growth process,there was a fluctuation phenomenon in the current annual growth process.There are multiple intersections between the current annual growth curve and mean annual growth curve of DBH of dominant and overtopped tree,but without effective intersection;while the two growth curves of DBH of average tree appeared effective intersection in the 22nd year,now,the mean annual increment of DBH of average tree reached the maximum value of 0.41 cm�a-1.There were multiple intersections between the two growth curves of height of the three classified trees,and without effective intersections.There was no intersection between the current annual growth curve and mean annual growth curve of volume of these three classified trees.(3)The growth process of classified Schima superba:edited Weibull model can fit the growth process well,with the highest R2(0.9912)and lowest RMSE(0.2329).Schima superba belongs to early fast-growing tree species,with a high growth rate in the early stage of growth.At the young stage,the current annual increment and mean annual increment were increased with age,but the current annual growth rate was higher than the mean annual growth rate.When the mean annual increment curve reached the maximum,it intersects the current annual increment curve,then the current annual growth rate has been less than mean annual increment.The time when the mean annual growth curve of volume reached the maximum value is the mature age,and the mature age of dominant,average and overtopped tree is 128a,87a and 28a,respectively.(4)The relationship between radial growth of Schima superba and climatic factors:the residual chronology of ring width of Schima superba in the study area is better representative than the standard chronology.Radial growth is sensitive to the changes in the surrounding environment,but the sensitivity is not high,affected by the climate of the previos year is not significant.The radial growth of Schima superba have significant positive correlation with the precipitation in August of the current year(p<0.05)and the temperature in September of current year(p<0.05).The mutation from low temperature to high temperature in 1986 caused the narrow ring phenomenon in study area.