| Melaleuca alternifolia is a plantation species with important economic value.In order to find out the change characteristics of aboveground biomass of Melaleuca alternifolia in different cutting periods and find out a more high and stable yield management mode;And reveal the change characteristics of soil nutrients of Melaleuca alternifolia in different cutting periods,providing scientific basis for soil fertility maintenance,scientific fertilization and sustainable development.Taking Melaleuca alternifolia planting base in Taiping town,ningyuan county,Hunan province as the research object,the change characteristics of aboveground biomass and soil fertility of Melaleuca alternifolia in different cutting periods were studied through field investigation and sampling,indoor testing analysis and computer data processing.Fuzzy mathematics analysis was used to evaluate the comprehensive soil fertility quality of Melaleuca alternifolia in different cutting periods,and linear simulation was used to analyze the change relationship between soil main nutrient elements and aboveground biomass.The main results are as follows:(1)The annual aboveground biomass,trunk biomass and branch biomass of annual felling are 2.655 kg/plant,1.284 kg/plant and 1.371 kg/plant respectively.Two-year one-felling is 2.525 kg/plant,1.424 kg/plant and 1.101 kg/plant respectively.The three-year annual felling is 2.251 kg/plant,1.423 kg/plant and 0.829 kg/plant respectively.The average annual aboveground biomass and the average annual branches and leaves biomass are as follows:annual cutting>annual cutting>annual cutting>annual cutting>annual cutting of 3 years;The average annual trunk biomass is as follows:annual felling for two years>annual felling for three years>annual felling for one year.(2)1n terms of soil fertility index,there is no significant difference in soil bulk density,soil total porosity,capillary porosity and soil water content between different cutting periods or different soil layers.With the increase of forest age or soil layer,soil bulk density gradually increases,total porosity and capillary porosity gradually decrease,and soil water content first decreases and then increases.Total nitrogen,total phosphorus,total potassium,alkali-hydrolyzable nitrogen,available phosphorus and available potassium have different degrees of differences in different cutting periods or among different soil layers.Soil main nutrients have a decreasing trend with the increase of forest age,and a first increasing and then decreasing trend with the increase of soil layers.Trace elements in soil have different degrees of difference in different cutting periods or different soil layers,and have a decreasing trend with the increase of forest age or soil layers.(3)The ranking of soil comprehensive fertility quality of Melaleuca alternifolia in different cutting periods is:One year one cutting(first cutting)(0.589)>two years one cutting(0.501)>one year one cutting(second cutting)(0.492)>three years one cutting(0.367)>one year one cutting(third cutting)(0.311),which is negatively correlated with biomass changes.(4)The correlation between aboveground biomass,branches and leaves biomass and soil main nutrients(including soil total nitrogen,total phosphorus,total potassium and organic matter)has a good linear-fit between different soil layers,with most R2 above 0.85.The correlation between biomass and soil main nutrients shows negative correlation to varying degrees.The conclusions show that the annual cutting management mode has the highest annual aboveground biomass and annual mass production of branches and leaves.It is suggested that the production enterprises adopt this management mode.At the same time,the management mode of annual cutting has the greatest consumption of soil fertility,of which nitrogen and potassium are consumed at the fastest rate.Soil nutrients should be supplemented in time to avoid economic losses caused by insufficient soil fertility. |
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