Biomass And Carbon Storage Of Cunninghamia Lanceolata And Castanopsis Hystrix Plantations In South Subtropical China

Cunninghamia lanceolata and Castanopsis hystrix are important precious fast-growing species in subtropical China.Cunninghamia lanceolata has been planted in China for about 2 000 years,and Castanopsis hystrix has benn developed as a valuable native tree species in south China in recent decades.The development of Cunninghamia lanceolata and Castanopsis hystrix plantations has attracted much attention in the society and academia In this study,we selected Cunninghamia lanceolata and Castanopsis hystrix plantations with the same site condition for field investigation,sampling and laboratory analysis in the experimental center of Tropical Forestry China Forestry Research Institute of Guangxi Pingxiang Fubo experimental field.The biomass,productivity and carbon storage of Cunninghamia lanceolata and Castanopsis hystrix plantations were comparatively studied.The major results are as follows:(1)We measured the biomass of each organs of Cunninghamia lanceolata and Castanopsis hystrix sample trees,and established the regression equation of biomass of Cunninghamia lanceolata and Castanopsis hystrix organs by using the mathematical model Wi=aDb with tree DBH as independent variable.After significant test,we found out that the comparison biomass of each organ had reached a significant and very significant level,and the fitting degree of the equation was higher,which could be applied to estimate the biomass in the actual production.(2)There were significant differences in tree layer biomass between Cunninghamia lanceolata and Castanopsis hystrix plantations.The individual plant biomass of Cunninghamia lanceolata(172.49 ± 32.23 kg per plant)was significantly higher than that in Castanopsis hystrix plantations(152.84 ± 3.80 kg per plant).The total biomass of tree layer in Cunninghamia lanceolata plantation(147.99 ± 3.07 t/hm~2)was also significantly higher than that of Castanopsis hystrix plantations(107.75 ± 13.75 t/hm~2),indicating that the biomass of Cunninghamia lanceolata was higher than that of Castanopsis hystrix.(3)The biomass allocation of tree layer in Cunninghamia lanceolata and Castanopsis hystrix plantation was the same.The size order of the proportion of each component biomass to total biomass was:Stem>Root>Branch>Bark>Leaf.The biomass of tree trunks was the organ that accounts for the largest proportion of tree layer biomass,followed by the root,and leaves the smallest proportion in the biomass per plant.The biomass ratio of Cunninghamia lanceolata stem biomass(56.69%)was greater than that of Castanopsis hystrix(54.99%),but the shoot biomass ratio(11.21%)was less than that of Castanopsis hystrix plantations.(4)The biomass of understory vegetation layers in Cunninghamia lanceolata plantations(Shrub layer:1.507±0.512 t/hm~2;Herb layer:0.990±0.457 t/hm~2)was significantly higher than in Castanopsis hystrix(Shrub layer:1.093±0.358 t/yhm~2 t/hm~2;Herb layer:0.814±0.919 t/hm~2).While,biomass of litter layers in Castanopsis hystrix(1.387±0.089 t/hm~2)was significantly higher than in Cunninghamia lanceolata plantations(0.814±0.919 t/hm~2).(5)The total ecosystem biomass in Cunninghamia lanceolata plantations was 151.30 ± 2.79 t/hm~2,which is significantly higher than in Castanopsis hystrix(110.32± 13.78 t/hm~2).(6)There was significant difference in tree layer productivity between Cunninghamia lanceolata and Castanopsis hystrix,plantations.The total productivity of tree layer of Cunninghamia lanceolata plantations(6.37 ±0.14 t/hm~2 · a)was 30.36%higher than that of Castaopsis hystrix,plantations(4.68 ±0.60 t/hm~2 · a).Trunk contributes the most to total productivity.The Cunninghamia lanceolata plantations productivity(3.83 ± 0.08 t/hm~2 · a)was 35.99%higher than that of the Castanopsis hystrix plantations(2.45 ± 0.31 t/hm~2 · a).The aboveground productivity of the upper part of the Castanopsis hystrix is higher than that of the Cunninghamia lanceolata plantations,but the productivity of the Cunninghamia lanceolata is partly 1.41 times of that of the red plantations.The underground productivity of the Cunninghamia lanceolate plantations,is 1.40times that of the Castanopsis hystrix plantations.The underground productivity of the Cunninghamia lanceolate plantations is 1.53 times that of the Castanopsis hystrix plantations.(7)The ecosystem carbon storage of Cunninghamia lanceolate plantations is not significant difference with that of Castanopsis hystrix plantations.The distribution pattern of ecosystem carbon storage of Cunninghamia lanceolate plantations was as follows:soil layer(66.37%)>tree layer(32.93%)>shrub layer(0.32%)>herb layer(0.19%)>litter alyer(0.14%),while the rank for Castanopsis hystrix plantations is:soil layer(72.81%)>tree layer(26.59%)>litter alyer(0.35%)>shrub layer(0.24%)>herb layer(0.02%).The total carbon storage(217.56 ± 17.29 t·C/hm~2)of the Cunninghamia lanceolate plantations ecosystem was higher than that of the Castanopsis hystrix plantations(195.05 ± 17.85 t·C/hm~2),but the difference was not significant.Carbon storage in soil layer was 144.55±14.54 t·C/hm~2 and 142.04±14.51 t·C/hm~2 in Cunninghamia lanceolate and Castanopsis hystrix plantations respectively without significant differentce.Carbon stock in tree layer(71.48±2.74 t · C/hm~2)and understory(1.147 ± 0.220 t · C/hm~2)in Cunninghamia lanceolate plantations was significantly higher than that in Castanopsis hystrix plantations(tree layer:51.82±6.84 t · C/hm~2;understory:0.512 ± 0.083 t · C/hm~2).