| Bamboo(Phyllostachy pubescens)is an important forest resource in Southern China.Bamboo plantations cover 3 million hm2 in China,which account for approximately 20%of the total bamboo forests in the world.In addition,the cultivated areas of bamboo plantations are still extent.As a result,bamboo plantations play a significant role not only in bamboo industry and economic trade,but also in carbon sequestration.Because of considerable differences in terms of stand structure,cultivated management practice and regional climate factors,large uncertainties have been introduced into the accurately estimating of carbon storage in bamboo plantation ecosystems.Particularly,stand age is a critical factor in controlling carbon accumulation and sequestration in bamboo forests.In the present study,biomass production and carbon storage were investigated in three aged stands of bamboo plantations in Taojiang county,Hunan province,China.The results showed that:(1).The soil is acid and is classified as mountain red earth in the studied bamboo stands,with pH values ranging of 4.41-4.54,soil bulk density of 1.117-1.163g·cm-3,and soil moisture of 48.97-65.91%.The mean organic matter content ranged from 38.96 to 46.51 g·kg-1 and the contents of total nitrogen and total potassium were 1.19-1.53 g·kg-1 and 3.31-4.98 g·kg-1,respectively.The content of phosphorus was relatively low with the values of 0.35-0.52 g·kg-1 in the study site.(2).Biomass of individual trees was 16.204,19.258 and 23.202kg in 1-,3-and 5-year-old bamboo plantations,respectively.Bamboo rod presented the highest proportion of the total biomass in all studied aged stands,accounting for 63.37-68.69%.The biomass was 20.254,25.036 and 55.685 t·hm-2 in the overstory(Bamboo)layer in the three aged stands,respectively,1739.520,1874.285 and 230.243 kg·hm-2 in the brush layer,and 2784.386,1917.472 and 59.042 kg·hm-2 in the herbivores layer.The biomass found on the litter layer was 1371.107,822.339 and 1731.242 kg·hm'2 in the three different aged stands.Biomass in the litter layer deceased in a order un-decomposition litter component>semi-decomposition component>completed decomposition component.(3).The carbon content was 389.334-534.051 g·kg-1 in various organs of bamboo and no significant difference was found in the carbon contents among the bamboo organs(P<0.05).The carbon content was 406.963-539.916 g·kg-1 in shrubs,397.916-549.745 g·kg-1 in herbaceous,and 213.302-275.569 g·kg-1 in litter layers.The carbon content in the soils ranged from 22.597 g·kg-1 to 26.980 g·kg-1.The organic carbon content was maximum in the topsoil and decreased with the depth of the soils.(4).The carbon storage was 10.490,11.802 and 28.226 t·hm-2 in 1-,3-and 5-year-old bamboo plantations,respectively.Carbon storage increased with increase of stand ages and there were significant differences of carbon storage among the different aged bamboo stands(P<0.05).Bamboo rod had the maximum proportion of the total carbon storage,while fine roots had the minimum.The carbon storage was 854.449,871.451 and 160.867 kg·hm-2 in shrub layer and 1288.200,882.914 and 31.999 kg·hm-2 in herb layer in the three aged bamboo stands.The carbon storage ranged from 0.307t·hm-2 to 0.420 t·hm-2 in the study site and decreased in a order un-decomposition litter component>semi-decomposition component>completed decomposition component.The carbon storage in the soils was around 117.339-138.978 t·hm-2 and increased slightly with aging stands.(5).The spatial distribution of carbon in the different aged stands of the bamboo plantation ecosystems showed that:The proportion of carbon was 9.70,0.24 and 90.06%in the vegetation,litter and soil component,respectively,in the 1-year-old stands.The proportion of carbon was 9.76,0.27 and 89.97%in the vegetation,litter and soil component,respectively,in the 3-year-old stands.The proportion of carbon was 16.93,0.25 and 82.82%in the vegetation,litter and soil component,respectively,in the 5-year-old stands.Overall,the carbon storage decreased in an order soil>vegetation>litter in bamboo plantation ecosystems. |
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