Estimating The Carbon Sequestration Of Phyllostachys Edulis And Pleioblastus Amarus Plantations Based On Net Ecosystem Productivity

Forest is the largest carbon pool in the terrestrial ecosystems, accounting forest carbonsequestration scientifically and accurately is the key to evaluate forest functions of mitigatingCO₂concentration in atmosphere and responding to climate change. While special biologicaland ecological characters of bamboo increased the difficulty in accounting carbonsequestration greatly. Bamboo stands, as an important forest resource, have some advantagesover other forests for mitigating CO₂concentration and increasing carbon sink because of widedistribution, fast growth, high productivity and multi-purpose of them. Few studies on carbonsequestration of bamboo forest ecosystem in China, systematically and accurately carbonaccounting of bamboo forest ecosystem under Basin climate environment of Sichuan provincehas not been reported currently. From the perspective of net ecosystem productivity(NEP), abiometric approach was used to research the carbon storage, net primary productivity(NPP) ofPhyllostachys edulis and Pleioblastus amarus forest ecosystem in southern Sichuan Province,then their heterotrophic respiration(Rh) was measured by LI-8100, the capacity of carbon sinkwas also estimated by calculating the NEP(NPP minus Rh) in this paper. The results as follows:(1) Carbon stock：①The total carbon stock of P. edulis and P. amarus forest ecosystem was156.566t·hm^-2,156.823t·hm^-2, respectively, which stored in stumpage bamboo was40.920t·hm^-2,19.432t·hm^-2,and stored in soil was113.538t·hm^-2,132.568t·hm^-2respectively. In the ratio of totalcarbon storage of P. edulis and P. amarus forest ecosystem components, carbon stock ofstumpage bamboo was26.14%,12.39%,of soil was72.52%,84.53%,of litter andunderstorywas1.35%,3.08%,respectively.The total carbon stock of P. edulis and P. amarusforest ecosystem were approximation, but the carbon stock of stumpage bamboo of P. eduliswas2.11times more than P. amarus, and the soil carbon stock of P. amarus was1.17timesmore than P. edulis. ②The carbon content of P. edulis and P. amarus was472.818g·kg^-1,450.792g·kg^-1,respectively. Difference of carbon content between varying ages and organs in stumpagebamboo was not significant. More than half of stumpage bamboo carbon stocks of P. edulis andP. amarus were stored in stem, while stored in the over-ground parts (stem, branch, leaf) was26.760t·hm^-2,13.346t·hm^-2,respectively, accounted for65.39%,68.68%of whole stumpagebamboos,respectively. Carbon stored in above ground was1.89,2.19times more thanunderground for P. edulis and P. amarus respectively.③The soil carbon pool was the largest carbon pool of P. edulis and P. amarus forestecosystem. Soil organic carbon content of P. edulis and P. amarus was15.770g·kg^-1,19.410g·kg^-1, respectively, difference between varying layers were extreme significant. The soilorganic carbon of P. edulis and P. amarus stored in0³0cm soil layer accounted for69.02%,72.02%of total, respectively.(2) Net primary productivityNet primary productivity of the vegetation layer for P. edulis and P. amarus forestecosystem was9.428tC·hm^-2·a^-1,8.262tC·hm^-2·a^-1, equivalents to34.569t·hm^-2,30.294t·hm^-2of CO₂, respectively. Carbon sequestration capacity of P. amarus was greater than P. edulis.(3) Soil heterotrophic respiration①The soil heterotrophic respiration mean speed of P. edulis. and P. amarus were1.389μmol·m^-2·s^-1,1.939μmol·m^-2·s^-1, respectively. Annual and daily dynamic pattern of soilheterotrophic respiration of P. edulis. and P. amarus. were both similar to the soil temperaturein10cm depth, could be represented with a curve of one-peak type. The variation coefficientof soil heterotrophic respiration for P. edulis. was greater than P. amarus.②The amount of CO₂released in P. edulis and P. amarus forest ecosystem were16.72tCO₂·hm^-2·a^-1,23.414tCO₂·hm^-2·a^-1, respectively. The soil heterotrophic respiration of P.amarus was1.39times greater than P. edulis. Soil heterotrophic respiration in the the growingseason (from March to November) was significantly higher than non-growing season (fronDecember to February of next year). Soil heterotrophic respiration reached their highest value in July and August for P. edulis and P. amarus, respectively. Soil heterotrophic respiration of P.edulis was sensitive to temperature changes more than P. amarus.(4) Net ecosystem productivity and carbon sinkNet ecosystem productivity of P. edulis and P. amarus forest ecosystem was4.865tC·hm^-2·a^-1,1.876tC·hm^-2·a^-1, equivalents to17.840t·hm^-2,6.880t·hm^-2of CO₂, respectively.Carbon sequestration capacity of P. amarus was2.59times more than P. edulis. Carbonsequestration capacity of P. edulis and P. amarus forest ecosystem in sounthern of Sichuanprovince more than other common subtropical forests.In summary, P. edulis and P. amarus are important bamboo to be good at carbonsequestration, we should be to promote afforesting the P. edulis and P. amarus carbon sinkstands, in order to play more important role in mitigating CO₂concentration inhance andcoping with climate change. The results of this study can provide the basic datas and scientificreferences for making the carbon reduction policy, developing the ecological compensationmechanism, constructing the carbon trading market and international climate negotiations.