Effect Of Biochar And Silicon Fertilizer On Soil Greenhouse Gas Emissions And Ecosystems Carbon Sequestration Capacity In Moso Bamboo Forest

The rising concentration of greenhouse gases represented by CO₂ has led to a series of global environmental problems such as global warming,sea level rise and threats to biodiversity,which have affected the sustainable development of all mankind.As an important technical means of carbon emission reduction,carbon sequestration increase via forest management has become an important strategic choice for China to cope with climate change and fulfill the commitment of greenhouse gas emission reduction.As an important part of China's subtropical forest,Moso bamboo forest contains huge carbon reserves and carbon sequestration potential,and is an indispensable strategic resource for China's forestry to cope with climate change.At the same time,bamboo's unique maturity and harvesting characteristics play an important role in the implementation of ecological security barriers,national wood security,ecological and cultural prosperity strategy and promoting social and economic development in mountainous areas.Therefore,it is an inevitable choice for forestry to cope with climate change to explore technical means to improve the carbon sink capacity of Moso bamboo forest ecosystem,which has important practical and research significance for guiding the construction of carbon sink forestry of Moso bamboo forest in China and realizing the sustainable development of Moso bamboo forest.However,long-term intensive management will lead to serious soil acidification,soil fertility decline,soil structure change,productivity decline and increasing greenhouse gas emissions,which adverse to the improvement of carbon sink capacity of the ecosystem and sustainable management of Moso bamboo forest.This study takes advantage of biochar and silicon fertilizer as exogenous substances,by setting the randomized block experiment,arranging the Moso bamboo forest fixed sample,for observing the aboveground carbon sequestrations of Moso bamboo ecosystems,Phytolith and PhytOC in bamboo leaves and soil,and the dynamics of soil greenhouses gases emissions after the implement of biochar and silicon fertilizer,in order to reveal the effects of the compound with biochar and silicon fertilizer on stability of Moso bamboo forest ecosystem carbon morphology formation and the influence of soil in greenhouse gas emissions,which can improve the stability of Moso bamboo forest ecosystem carbon sink formation and provide a scientific basis for improving the capacity of Moso bamboo forest to adapt to climate change.The main conclusions are as follows:?1?In biochar and high efficiency of silicon fertilizer applied in the first year,the average carbon stocks were 20.81 CO₂-eq Mg hm^-2 in the water soluble high silicon fertilizer Si1 treatment,and there were significant differences between CK and B1 level,and B1Si1,B1Si3,B3Si3?biochar and efficient silicon fertilizer compound?and Si1 treatment?P<0.05?;In biochar and high efficiency of silicon fertilizer applied into the second year,the water soluble high silicon fertilizer Si 3 levels into the conditions,the average carbon stocks of sample plots were 36.60 CO₂-eq Mg hm^-2.Compared with the others treatment,water-soluble high silicon fertilizer Si3 and Si1 treatments had significantly increased the carbon stocks.Whether in biochar and silicon fertilizer applied the first or second years,biochar applied,efficient silicon fertilizer applied and compound applied in all sampling sites had increased the carbon stocks of shrub and herb,but the carbon stocks increase of shrub layer and herb layer did not reach significant level;Compared with CK treatment,the average soil carbon stocks had significantly increased by 57.63 CO₂-eq Mg hm^-2 in biochar B1 level;?2?In the first year after the application of biochar and silicon fertilizer,two levels of high-efficiency silicon fertilizer?Si1 and Si3?significantly increased the Phytolith content of bamboo leaves sample in Moso bamboo forest?P<0.05?,which increased by 58.53%and 75.80%respectively.In the second year after the application of biochar and silicon fertilizer,the Si1 and Si3 levels of high-efficiency silicon fertilizer as well as the combined application of biochar and high-efficiency silicon fertilizer at all levels significantly increased the Phytolith content of bamboo leaves sample in Moso bamboo forest?P<0.05?,while the two levels of biochar?B1 and B3?did not significantly increase the Phytolith content of bamboo leaves sample in Moso bamboo forest.Two levels of high-efficiency silicon fertilizer?Si1 and Si3?were applied,and only in the first year of application significantly increased the Phytolith carbon content in bamboo leaves sample of Moso bamboo forest?P<0.05?.Other treatments did not significantly increase the carbon content of Phytolith in bamboo leaves sample of Moso bamboo forest?P<0.05?.In the first and second years after the application of biochar and silicon fertilizer,each treatment did not significantly increase the Phytolith content and Phytolith carbon content in the 0-40 cm soil layer in the sample of Moso bamboo forest;?3?Biochar applied at different levels?CK,B1,B3?under the Moso bamboo forest sample plots of soil CO₂ flux has obvious characteristics of seasonal variation,in the test cycle,the sample area soil cumulative CO₂ emissions were 58.03±2.13,73.05±2.74 and 73.44±2.45 CO₂-eq Mg ha^-1,compared with the control plot CK,soil CO₂ cumulative emissions flux was increased by 25.88%and 26.55%,respectively;Soil N₂O emission fluxes showed obvious seasonal variation during the test cycle.In the whole test cycle,the cumulative emission fluxes of soil N₂O were 1.47±0.02,1.22±0.04 and 1.13±0.03CO₂-eq Mg ha^-1,and compared with CK in the control plot,the cumulative emission fluxes of soil N₂O were decreased by 16.98%and 23.33%,respectively.Soil CH₄ absorption fluxes showed obvious characteristics of seasonal variation during the test period.Soil CH₄ cumulative absorption amounts were0.32±0.01,0.37±0.01 and 0.34±0.02 CO₂-eq Mg ha^-1,respectively.Compared with CK in the control plot,soil CH₄ cumulative absorption fluxes increased by 16.45%and 6.70%,respectively;?4?Water soluble silicon fertilizer applied at different levels?CK,Si1,Si3?under the Moso bamboo forest sample plots of soil CO₂ flux has obvious seasonal variation characteristics,in the whole test cycle,the sample area soil cumulative CO₂ emissions were 58.03±2.13,40.99±1.41 and 40.53±1.01 CO₂-eq Mg ha^-1,compared with the control group CK,soil CO₂ cumulative emissions flux were increased by29.37%and 30.15%respectively;Soil N₂O emission fluxes showed obvious seasonal variation during the test period.The cumulative emission fluxes of soil N₂O were 1.47±0.02,1.00±0.03 and 0.89±0.02 CO₂-eq Mg ha^-1,respectively.Compared with CK in the control group,the cumulative emission fluxes of soil N₂O was reduced by 32.11%and 39.65%,respectively.Soil CH₄ absorption fluxes showed obvious seasonal variation during the test period.The cumulative absorption amounts of soil CH₄ were 0.32±0.01,0.36±0.01 and 0.43±0.02 CO₂-eq Mg ha^-1,respectively.Compared with CK in the control group,the cumulative absorption fluxes of soil CH₄ increased by 13.55%and 35.35%,respectively;?5?Under different application combinations of biochar and silicon fertilizer?CK,B1Si1,B1Si3,B3Si1,B3Si3?,the soil CO₂ emission flux of the sample plot in Moso bamboo forest presents obvious characteristics of seasonal variation.The cumulative CO₂ emission flux of the sample plot is respectively58.03±2.12,62.64±1.81,56.49±1.39,62.56±1.89 and 52.44±1.35 CO₂-eq Mg ha^-1.The cumulative CO₂emission fluxes of soil in the sample plot increased by 7.59%,-2.66%,7.80%and-9.63%,respectively.Soil N₂O emission fluxes showed obvious seasonal variation during the test period.The cumulative emission fluxes of soil N₂O were 1.47±0.08,1.15±0.07,1.07±0.06,1.15±0.05 and 1.12±0.07 CO₂-eq Mg ha^-1,respectively.Compared with CK in the control group,the cumulative emission fluxes of soil N₂O were reduced by 22.17%,27.48%,21.87%and 23.91%,respectively.Soil CH₄ absorption fluxes showed obvious seasonal variation during the test period.The cumulative absorption amounts of soil CH₄ were0.32±0.01,0.38±0.02,0.41±0.03,0.35±0.01 and 0.39±0.02 CO₂-eq Mg ha^-1,respectively.Compared with CK in the control group,the cumulative absorption fluxes of soil CH₄ increased by 18.26%,26.20%,10.08%and 21.01%,respectively.?6?In general,biochar,and silicon fertilizer,and combination application can significantly promoted the capacity of carbon sequestration in Moso bamboo forest ecosystem.Further,the effects of silicon fertilizer on the capacity of Moso bamboo forest ecosystem carbon sequestration were significantly better than biochar and their combination application.However,from the perspective of the utilization of silicon fertilizer and the improvement of carbon sequestration capacity of phytolith,combination application is one of the better choices for the long-term management of Moso bamboo forest ecosystems.