Biomass And Carbon Storage Of Chinese Fir Plantations In Anhui Province, China

Chinese fir(Cunninghamia lanceolata)is an endemic native species and the most important timber species in the southern China,and is the most widely distributed with the most long cultivation history.It plays an important role in plantation development and economic construction in our country.Therefore,it is of great significance to study the biomass and carbon storage of Chinese fir plantation.In this study,we explored the changes in biomass carbon storage and productivity of Chinese fir plantations in Anhui Province by using biomass model and biomass expansion factor continuous function method and the data from five forest resource inventories in Anhui from 1989 to 2009,and in combination with the sampling plot survey data from the different distribution regions(Dabieshan Mountains,southwest of Anhui and south of Yangzi River).The results of the study are as follows.Based on forest resource continuous inventory data,the total areas of Chinese fir plantations in Anhui increased consistently from 27.93×10~4 hm~2 in 1989 to 57.14×10~4hm~2 in 1999,and then slowly decreased to 48.82×10~4 hm~2 in 2009.The total volumes increased consistently from 1051.85×10~4m~3to 3961.09×10~4m~3during the survey periods.During the survey periods,the total amount of each age class of Chinese fir plantations was changing over the time.The area of the mid-aged forests was the largest at all survey periods except in 1994 when the area of the young forests was the biggest.But the volume in the mid-aged forests was the maximum in all the survey periods.From 1989 to 2004,the relative volume of the mid-aged forests firstly decreased and then increased(ranged from 55.15% to 64.99%),but the relative volume decreased sharp to 47.90% in 2009.During the survey periods,the total biomass carbon storage increased from 5.65 Tg C in 1989 to 14.87 Tg C in 2004,then decreased to 14.53 Tg C in 2009,which is associated with the reduction in areas of Chinese fir forests.The biomass carbon storage in the prematured and matured forests showed a consistent increasing trend.The biomass carbon storage in the over-matured forests firstly decreased and then increased over time.However,the biomass carbon storage in the young forests was in contrast trend.The carbon storage in the mid-aged forests was the largest in all the periods,and was significantly increased from 1989 to 2004,but decreased 25.03% in 2009 compared with that in 2004.The decreasing magnitude was greater in the mid-aged forests than in the young forests.In the survey periods,the average annual carbon accumulation rate was 0.444 Tg C/a,implying that Chinese fir forests in Anhui were effective carbon sinks.The annual average productivity per unit area of this forests increased consistently from 2.032Mg/hm~2·a in 1989-1994 to 3.449 Mg/hm~2·a in 1999-2004,while decreased to 3.189Mg/hm~2·a in 2004-2009,implying that the damage or impact on Chinese fir forests were greater in 2005-2009 than in the other periods.For each age class,the damage or impact on the mid-aged forests were the greatest in 2005-2009.On the other hand,based on the sampling plot survey data,the biomass carbon storages were,respectively,46.85 Mg C/hm~2 for 14-year-old,54.49 Mg C/hm~2 for15-year-old,47.80 Mg C/hm~2 for 21-year-old,54.96 Mg C/hm~2 for 27-year-old,50.56 Mg C/hm~2 for 30-year-old and 59.16 Mg C/hm~2 for 33-year-old in the southwest of Anhui;in the south of Yangzi River,they were 39.42,40.07,32.11,37.96,38.04,44.53 and 57.71 Mg C/hm~2 for 11-year-old,17-year-old,23-year-old,27-year-old,30-year-old,32-year-old,and 43-year-old,respectively;and in the Dabieshan Mountains they were60.74,58.62,134.02,196.24 and 130.38 Mg C/hm~2 for 10-year-old,22-year-old,45-year-old,48-year-old,and 50-year-old,respectively.The order of biomass carbon storage per unit area for different age classes of Chinese fir forests in each region was Dabieshan Mountains > southwest of Anhui > south of Yangzi River.In conclusion,my result shows that the biomass based on sampling plot survey is generally greater than the results based on forest resource inventory data.Although the quality of Chinese fir forests in Anhui is at a high level in the general production region,the biomass carbon storage of Chinese fir forests in Anhui was at a low level compared with the central production region.On the national scale,the quality of Chinese fir forests in Anhui is still at a lower level.Production region,site conditions,forest age,and stand density are the decisive factors affecting the growth of Chinese fir.Compared with other plantations,the biomass of Chinese fir forests in Anhui is generally low.The appropriate extension of the rotation period can promote biomass carbon storage in Chinese fir forests.