| 氮添加对亚热带森林土壤有机碳氮组分的影响 |
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| 引用本文： | 林伟,马红亮,裴广廷,高人,尹云锋,林燕语.氮添加对亚热带森林土壤有机碳氮组分的影响[J].环境科学研究,2016,29(1):67-76. |
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| 作者姓名： | 林伟 马红亮 裴广廷 高人 尹云锋 林燕语 |
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| 作者单位： | 1.福建师范大学地理科学学院, 福建 福州 350007 ; |
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| 基金项目： | 国家自然科学基金项目(41271282,31170578)；教育部创新团队项目(IRT0960) |
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| 摘 要： | 为了研究氮添加对森林土壤有机碳氮组分稳定性的影响,选取我国亚热带典型常绿阔叶林(浙江桂天然林和罗浮栲天然林)和针叶林(杉木人工林),开展为期5年的野外模拟氮沉降试验,分别设置对照〔0 kg/(hm2·a),以NH4NO3中的N计,下同〕、低氮〔75 kg/(hm2·a)〕和高氮〔150 kg/(hm2·a)〕3个氮添加水平,用H2SO4分2步酸水解获得LPⅠ(活性有机库Ⅰ)、LPⅡ(活性有机库Ⅱ)和RP(惰性有机库),定量研究土壤活性和惰性有机碳氮组分以及微生物生物量碳氮对氮添加的响应. 结果表明:氮添加仅对w(LPⅡ-C)(LPⅡ-C为活性有机碳Ⅱ)有显著影响,而对其他活性和惰性有机碳氮组分的影响不显著,并且对不同林分的影响存在差异. 与对照处理相比,低氮处理下浙江桂天然林、罗浮栲天然林和杉木人工林土壤w(LPⅡ-C)的增幅分别为15.3%、29.8%、68.8%；高氮处理下杉木人工林土壤w(LPⅠ-C)(LPⅠ-C为活性有机碳Ⅰ)、w(LPⅠ-N)(LPⅠ-N为活性有机氮Ⅰ)和w(RP-C)(RP-C为惰性有机碳)的增幅分别为32.4%、78.6%、28.7%；氮添加使得土壤w(SMB-C)(土壤微生物生物量碳)的增幅为18.1%~202.5%、w(SMB-N)(土壤微生物生物量氮)的增幅为0%~103.6%；在氮添加处理下,除杉木人工林土壤SMB-N/LPⅠ-N〔w(SMB-N)/w(LPⅠ-N)〕是随着氮添加水平的增加而降低外,微生物对其他林分土壤活性有机氮的利用均表现为随着氮添加水平的增加而增加. 研究显示,氮添加对阔叶林和针叶林土壤活性和惰性有机碳氮组分的影响存在差异,但差异不显著,这与它们归还土壤的凋落物性质差异有关,并且凋落物的分解差异也可能是影响土壤不同碳氮组分变化的原因.
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| 关 键 词： | 氮添加 酸水解 活性和惰性有机碳氮组分 微生物生物量 林分 |
| 收稿时间： | 2015/7/21 0:00:00 |
| 修稿时间： | 2015/9/28 0:00:00 |
Effects of Nitrogen Addition on Soil Carbon and Nitrogen Pools in Mid-Subtropical Forest |
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| LIN Wei,MA Hongliang,PEI Guangting,GAO Ren,YIN Yunfeng and LIN Yanyu.Effects of Nitrogen Addition on Soil Carbon and Nitrogen Pools in Mid-Subtropical Forest[J].Research of Environmental Sciences,2016,29(1):67-76. |
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| Authors: | LIN Wei MA Hongliang PEI Guangting GAO Ren YIN Yunfeng and LIN Yanyu |
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| Affiliation: | 1.School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China ;2.State Key Laboratory Breeding Base of Humid Subtropical Mountain Ecology, Fujian Normal University, Fuzhou 350007, China |
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| Abstract: | Nitrogen deposition affects soil nutrient transformation and ecosystem stability to various degrees. There are different transformation rates and chemical characteristics in different organic matter compositions. In terrestrial soils, carbon (C) and nitrogen (N) fluxes are primarily controlled by small but highly bio-reactive labile pools, while C and N storage over the long term is determined by the long-lived recalcitrant fraction. Changes in the size of labile, recalcitrant and microbial carbon and nitrogen pools as well as redistribution among them may considerably affect C and N storage in the terrestrial soil and turnover rates. Different soil organic carbon and nitrogen fractions are sensitive to nitrogen deposition rates rather than the total amount. Soil labile and recalcitrant carbon and nitrogen pools can be also used as an indicator to show soil carbon and nitrogen stabilization under different vegetation's response to nitrogen addition. To investigate the effects of nitrogen addition on the forest soil organic stabilization, an experiment was carried out in subtropical broad-leaved forest species (Cinnamomum chekiangense and Castanopsis fabri) and conifer forest (Cunninghamia lanceolata) with three nitrogen levels applied as NH4NO3:control (0 kg/(hm2·a)), low nitrogen (75 kg/(hm2·a)) and high nitrogen (150 kg/(hm2·a)). Soil samples were collected from the topsoil (0-15 cm) using a drill. Several soil cores were taken from each subplot, and samples from the same treatment were pooled together after field experiments going on for five years. The labile pool Ⅰ, Ⅱ and recalcitrant were evaluated following the two-step H2SO4 hydrolysis method. Then, the effects of N addition on labile and recalcitrant C or N fractions and soil microbial biomass C (SMB-C) and microbial biomass N (SMB-N) were investigated. The results showed that nitrogen addition significantly affected only w(LPⅡ-C), while the effects on other labile and recalcitrant C and N fractions were not significant. The different effects of forest types were found not to be significant. Light nitrogen treatment increased soil w (LPⅡ-C) of Cinnamomum chekiangense, Castanopsis fabri and Cunninghamia lanceolata by 15.3%, 29.8%, and 68.8% respectively compared with the control; high nitrogen treatment increased soil w(LPⅠ-C), w(LPⅠ-N) and w(RP-C) of Cunninghamia lanceolata by 32.4%, 78.6% and 28.7%, respectively. Nitrogen addition significantly enhanced w(SMB-C) from 18.1% to 202.5%, and w(SMB-N) from 0% to 103.6% compared with the control. Except for SMB-N/LPI-N ratio of Cunninghamia lanceolata decreasing with nitrogen addition, the utilization of soil labile N in the other forests by microorganism increased with nitrogen addition, and the ratio of SMB-N/LP-N was greater than SMB-C/LP-C. The results indicated that the differences of soil labile and recalcitrant organic carbon nitrogen pools between broad-leaved and conifer forest were related to the quality of litter, and the differences in litter decomposition might provide some evidence for the change of soil carbon and nitrogen pools. Furthermore, much more sensitive and rapid response of carbon and nitrogen pools to nitrogen deposition in fractionation of soil and organic-mineral complexes are recommended for deep information about nitrogen transformation. |
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| Keywords: | nitrogen addition acid hydrolysis labile and recalcitrant organic carbon and nitrogen pool soil microbial biomass forest types |
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