| Carbon is a stable carbonaceous material with rich pore structure,low density and abundant cation exchange capacity,and it is a good soil conditioner.It is often used in agricultural production to improve soil structure,reduce soil acidity,improve soil fertility and promote crop growth,but it is rarely used in forestry.In the planting area of Melaleuca alternifolia plantation,there are some phenomena such as soil hardening,weakening of flora and continuous decline of fertility.Biochar was used to improve the soil structure and soil fertility of Melaleuca alternifolia plantation,so as to improve the ecological and economic benefits of Melaleuca alternifolia plantation.Taking terpineol-4 type seedlings of Melaleuca alternifolia in March as the research object,through the standard experimental field model,the effects of biochar types(rice husk charcoal,bamboo charcoal)and amounts(3 t·hm-2,6 t·hm-2)on the growth of Melaleuca alternifolia seedlings,the biomass and nutrient content of each component,the carbon storage of tree layer,the physical and chemical properties of soil and the carbon storage of soil were explored.The results show that:(1)Applying biochar can significantly increase the tree height and biomass of each component of Melaleuca alternifolia plantation,but has no significant effect on the ground diameter.Compared with the control group,the tree height and total biomass of the four experimental groups increased by 9.6%～26.3%and 6.3%～20.1%respectively,and the proportion of root biomass of Melaleuca alternifolia plantation was significantly increased.The application of biochar also significantly affected the N,P,K contents in the trunk,branches and roots of Melaleuca alternifolia,with the highest increase of 28.3%.Application of biochar can increase the C content in the trunk and root of Melaleuca alternifolia in different degrees,among which two groups with high application of biochar can significantly increase the carbon storage of the trunk,root and whole tree,with the increase range of 8.5%～28.6%.(2)The application of biochar significantly reduced the soil bulk density in the middle and upper layer(0-40cm)of Melaleuca alternifolia plantation,and increased the soil porosity.Compared with the control group,the soil bulk density of the four experimental groups decreased by 7.9%～12.6%,and the total soil porosity increased by 7.6%～27.8%.The application of biochar had little effect on the bulk density and porosity of the lower layer(40-60cm).The application of biochar significantly changed the chemical properties of soil,significantly increased the soil pH of 0-40 cm and the content of available nutrients,with the highest soil pH rising to 5.19,the increasing range of alkali-hydrolyzable nitrogen,available phosphorus,available potassium and organic carbon being 4.1%-24.3%,11.3%-46.9%,2.7%-5.35%and 60%respectively.In 40-60cm soil layer,the application of biochar has no significant effect on these indexes.(3)Applying biochar significantly increased the coverage,biomass and carbon storage of grass-shrub layer.Compared with the control group,the coverage of grass and shrub layer,biomass and carbon storage of four experimental groups increased by 77.1%～142.8%,84.6%～232.1%and 115.6%～259.4%respectively.In the whole ecosystem,the proportion of soil carbon storage can reach 94.47%～95.33%,followed by tree layer,accounting for 3.75%～5.14%,and grass-shrub layer is the lowest,accounting for 0.39%～0.92%.Conclusion:The application of biochar can effectively promote the growth of Melaleuca alternifolia seedlings,increase the height of young forest,increase the contents of N,P and K of each component,and improve the biomass and carbon storage of tree layer in plantation.Application of biochar can reduce soil bulk density,increase soil porosity,increase soil pH value,increase total nitrogen,total potassium and available nutrient content in the middle and upper soil,and significantly improve soil carbon storage.At the same time,it also promotes the growth of undergrowth vegetation. |
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