四川纳溪杉木成熟林土壤养分密度效应及化学计量学研究

发布时间：2018-05-16 09:14

本文选题：杉木人工林 + 土壤养分　；参考：《中国林业科学研究院》2017年硕士论文

【摘要】：本文以四川纳溪30年生杉木(Cunninghamia lanceolata)密度试验林为研究对象,通过对不同密度(5种密度分别为2m×3m(A)、2m×1.5m(B)、2m×1m(C)、1m×1.5m(D)和1m×1m(E)(即A为1667株/公顷;B为3333株/公顷;C为5000株/公顷;D为6667株/公顷;E为10000株/公顷)和不同土层(5个土层:0-20cm、20-40cm、40-60cm、60-80cm、80-100cm)杉木人工林土壤各养分元素特征规律及其化学计量学特征,并探讨土壤养分元素含量对林地立地指数的指示性,得到如下4点主要结论:(1)初植密度对杉木人工成熟林土壤养分具有明显影响,其中,有机质与有机碳在表土层0-20cm、水解氮、全钙含量随密度增大总体上呈先上升后下降变化趋势,在B密度(2m×1.5m,3333株·hm-2)时含量最大;全磷、全钾、速效钾含量随密度增大则呈先下降后上升趋势,在B密度含量最低,且全磷、全钾含量在E密度最高;全镁含量、pH总体随密度的升高而上升;有机质与有机碳在20cm以下土层以及全氮含量受密度影响不明显;表明B密度有利于表层土壤有机质及有机碳累积,有利于土壤不同层面水解氮与全钙的累积,而高密度E密度有利于全磷、全钾、全镁的累积及pH值的上升。养分元素含量的密度效应总体上随土层的增加而减弱。(2)全氮、水解氮、全磷、有机质、有机碳含量总体上随土层的加深呈极显著下降趋势;全钾、速效钾、全钙、全铁、全镁含量受土层变化的影响不明显;土壤pH值随土层的加深呈明显上升趋势;土层深度对养分元素含量及PH值的作用效果在土壤深度达60cm以后明显减弱。(3)5种密度杉木人工林土壤C:N平均值为19.44,高于我国平均值11.9;N:P和C:P平均值为2.89和43.07,低于我国平均值5.2和61;C:N:P为43:3:1,低于我国平均值60:5:1;初植密度对土壤C:N、N:P、C:P比值,尤其是在表层土壤,均具明显影响,且随密度的增大各比值呈先上升后下降的规律,均在B密度最高;N:P和C:P随土壤深度的增加呈近乎直线下降趋势,而随土层加深C:N呈先下降后上升的变化趋势。(4)有效磷、全镁含量对杉木林地生产力具有良好的指示性,表现为土壤有效磷含量越高、全镁含量越低,林地立地质量越高;0-100cm土层的土壤有效磷含量或0-20cm土层的土壤全镁含量可作为试验区杉木人工林立地质量评价指示性指标。
[Abstract]:The density of Cunninghamia lanceolata (Cunninghamia lanceolata), a 30-year-old Chinese fir forest in Naxi, Sichuan Province, was studied in this paper. In this paper, 5 different densities of 2 m 脳 3 m ~ 2 脳 1. 5 m ~ (m) B ~ (2 m) and 1 m 脳 1. 5 m ~ (-1) C ~ (2 m) and 1 脳 1 路1 m ~ (-1) C (A = 1667 plants / hm ~ (2) C = 3333 plants / hm ~ (2) C = 5000 plants / hm ~ (2) C = 6667 plants / hm ~ (2) and different soil layers (0 ~ 20 cm ~ 20 cm ~ 40 cm ~ (40) ~ 60 cm ~ (-1) ~ (60) cm ~ (80) cm ~ (-1) were studied in different soil layers of Cunninghamia lanceolata plantations under different densities (0 ~ 20 cm ~ (-1) ~ 20 cm ~ (-1). The characteristics of nutrient elements in soil and its chemometrics, The indicator of soil nutrient element content on site index of forest land was discussed. The main conclusions were as follows: (1) the initial planting density had obvious influence on soil nutrient of Chinese fir artificial mature forest, in which organic matter and organic carbon were 0-20 cm in topsoil layer and hydrolyzed nitrogen. The total calcium content increased first and then decreased with the density increasing, and the content of total phosphorus, total potassium and available potassium decreased first and then increased with the increase of density, and the content of total phosphorus, total potassium and available potassium was the lowest in B density, and the total phosphorus content was the lowest in B density, and the content of available potassium in B density was the lowest, and the content of available potassium in B density was the lowest. Total potassium content was the highest in E density, total magnesium content and pH value increased with density, organic matter and organic carbon content in soil layer below 20cm and total nitrogen content were not significantly affected by density. The results showed that B density was beneficial to the accumulation of organic matter and organic carbon in surface soil, to the accumulation of hydrolyzed nitrogen and total calcium in different layers of soil, and to the accumulation of total phosphorus, total potassium, total magnesium and the increase of pH value in high density E density. The density effect of nutrient element content decreased with the increase of soil layer. (2) Total nitrogen, hydrolyzed nitrogen, total phosphorus, organic matter, organic carbon content showed an extremely significant downward trend with the deepening of soil layer, total potassium, available potassium, total calcium, total iron, total potassium, total available potassium, total calcium, total iron, The content of total magnesium is not affected by the change of soil layer, and the pH value of soil increases obviously with the deepening of soil layer. The effect of soil depth on nutrient content and PH value was obviously weakened when the soil depth reached 60cm. The average value of C: n in Chinese fir plantation with five densities was 19.44, which was higher than the average value of 11.9% P and 43.07 in China, which was lower than that in China. The average value of 5.2 and 61% N: P is 43: 3: 1, which is lower than the average of 60: 5: 1 in our country. Especially in the surface soil, the ratio increased firstly and then decreased with the increase of density, and the ratio of N: P and C: P decreased almost linearly with the increase of soil depth at the highest density of B, and the ratio of N: P and C: P increased with the increase of soil depth. With the deepening of soil layer, the content of total magnesium had a good indicative effect on the productivity of Chinese fir woodland. The higher the content of available phosphorus, the lower the content of total magnesium. The higher the site quality is, the higher the soil available phosphorus content in 0-100 cm soil layer or the total magnesium content in 0-20cm soil layer can be used as an indicator for site quality evaluation of Chinese fir plantation in the experimental area.
【学位授予单位】：中国林业科学研究院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714

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