模拟氮磷沉降和凋落物处理对两种林型红松林土壤有机碳组分的影响

【目的】阐明模拟氮(N)磷(P)沉降和凋落物处理对两种林型红松(Pinus koraiensis)林土壤有机碳(SOC)组分的影响，为该地区红松林的合理施肥提供参考。【方法】以黑龙江省伊春市带岭区凉水国家级自然保护区红松人工林与阔叶红松林为对象，每个林型设置3块20 m×30 m样地，每块样地间隔20 m,每块样地内布设12个样方，共计72个样方。每个样方实施两种处理：(1)凋落物处理：2017年10月进行该处理的去除(R)、添加(A)和原状(CK1)3个水平的试验，每个水平设定3个重复；(2)模拟氮磷沉降处理：2018年与2019年的5—10月，每月进行1次该处理的试验，分别使用(NH₄)₂SO₄和(NH₄)₂HPO₄作为氮源和磷源配置成不同质量浓度的液体肥，施肥量设置低剂量(L,N、P添加量均为5 g/m²)、中剂量(M,N添加量为15 g/m²,P添加量为10 g/m²)、高剂量(H,...

Effects of simulated nitrogen and phosphorus deposition and litter treatment on soil organic carbon components in two types of Pinus koraiensis forests

【Objective】 The aims of this research are to elucidate the effects of simulated nitrogen (N) and phosphorus (P) deposition and litter treatment on soil organic carbon (SOC) components in Pinus koraiensis forests, to provide a theoretical basis for improving soil fertility, ecosystem productivity and stability of P. koraiensis forests. 【Method】 Taking broad-leaved P. koraiensis forest and P. koraiensis piantation in Liangshui National Nature Reserve of Heilongjiang Province were studied. Each forest type was set with three plots of 20 m×30 m, and 12 quadrats were set in each plot. Each quadrat was subjected to treatments. (1) Litter treatment: three levels were removed (R), addition (A) and unchanged (CK1) were tested in October 2017, and three replicates were set for each level. (2) Simulated N and P deposition treatment: from May to October in 2018 and 2019, the experiment was carried out once a month. Four levels were set: low (L) (N and P supplemental levels are 5 g/m²), middle (M) (N is 15 g/m², P is 10 g/m²), high (H) (N is 30 g/m²,P is 20 g/m²), and no N and P (CK2), and three replicates were set for each level. The amounts of N and P were 2 L for each quadrat, and the same volume of stream water was sprayed for the control. In May, August and October of 2018 and 2019, three sampling sites were randomly selected in each quadrat. Collected the soil samples at 0-20 cm soil layer, and pick out plant roots, rocks larger than 2 mm and soil animals, then put it in a cool and ventilated place for natural air drying. After that it was extracted according to the extraction method of SOC for each component and measured using a TOC elemental analyzer. Finally, SPSS 21.0 and Canoco 5.0 were used for statistical analysis. 【Result】 (1) In the first year of the experiment, the low dose N and P deposition treatments significantly affected the SOC components. (2) In the second year, the middle dose significantly affected the SOC components. (3) For the two years, the SOC content was the highest in the broad-leaved P. koraiensis forest. The contents of mineral-bound, easily oxidized organic carbon, and total organic carbon were the highest in August. Litter removal and addition treatments had no effect on the SOC components. 【Conclusion】 (1) In the first year of the experiment, the low dose of N and P promoted the accumulation of SOC components. (2) In the second year, the middle dose treatments promoted the mineralization of SOC components. (3) In the second year of the experiment, the broad-leaved P. koraiensis forest was beneficial to the accumulation of SOC components. Environmental conditions in August is favorable for the formation of mineral-bound, easily oxidized organic carbon and total organic carbon. Litter removal and addition can promote the release of SOC components.