| 短期氮添加对黄土高原人工刺槐林土壤有机碳组分的影响 |
| 摘要点击 3236 全文点击 871 投稿时间：2022-05-07 修订日期：2022-07-22 |
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| 中文关键词 人工林 氮沉降 有机碳 有机碳组分 微生物生物量化学计量比 |
| 英文关键词 plantation forest nitrogen deposition organic carbon organic carbon fraction microbial biomass stoichiometry ratio |
| 作者 | 单位 | E-mail | | 简俊楠 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100
黄龙山森林生态系统国家定位观测研究站, 延安 716000 | jianjunnan@nwafu.edu.cn | | 刘伟超 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100
黄龙山森林生态系统国家定位观测研究站, 延安 716000 | | | 朱玉帆 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100
黄龙山森林生态系统国家定位观测研究站, 延安 716000 | | | 李佳欣 | 西北农林科技大学农学院, 杨凌 712100 | | | 温宇豪 | 西北农林科技大学农学院, 杨凌 712100 | | | 刘付和 | 西北农林科技大学农学院, 杨凌 712100 | | | 任成杰 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100
黄龙山森林生态系统国家定位观测研究站, 延安 716000 | | | 韩新辉 | 西北农林科技大学农学院, 杨凌 712100
陕西省循环农业工程技术研究中心, 杨凌 712100
黄龙山森林生态系统国家定位观测研究站, 延安 716000 | hanxinhui@nwsuaf.edu.cn |
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| 中文摘要 |
| 人类活动背景下，氮（N）沉降持续影响着生态系统的碳循环.氮沉降对土壤有机碳的影响与不同碳组分的差异性响应有关.为探究短期氮沉降背景下土壤有机碳组分变化及其影响因素，基于野外氮添加试验，以刺槐人工林为研究对象，共设置4个氮添加梯度：0（CK）、1.5（N1）、3（N2）和6（N3） g ·（m2 ·a）-1，分别在6月和9月进行取样，测定土壤理化性质、微生物生物量和酶活性.结果表明：①外源氮输入降低了土壤pH，促进可溶性有机碳含量的增加，增加了土壤氮素有效性.②短期氮添加显著降低了土壤有机碳含量，且有机碳各组分对氮添加响应不同.其中，易氧化有机碳含量显著降低，且在N2处理下达到最低，与对照相比分别降低了54.4%和48.2%，惰性有机碳含量增加，但增加不显著.氮添加降低了土壤碳库活度，提高了土壤碳库的稳定性.土壤碳库活度分别在N3和N2处理下达到最低，与对照相比分别降低了53.3%和52.80%.③随机森林模型表明，短期氮添加下土壤微生物生物量化学计量比、微生物生物量碳和AP是驱动土壤有机碳活度变化的关键因子，分别解释了易氧化有机碳和惰性有机碳变化的65.96%和66.68%.结构方程模型验证了随机森林模型的结果，土壤微生物生物量化学计量比显著影响了碳库活度.短期氮添加主要通过增加土壤氮素有效性和促进土壤酸化两个途径，改变刺槐人工林土壤微生物生物量及其计量比，抑制胞外碳水解酶活性，从而改变土壤碳组分比例，参与土壤有机碳循环过程. |
| 英文摘要 |
| Nitrogen (N) deposition in the context of human activities continuously affects the carbon cycle of ecosystems. The effect of N deposition on soil organic carbon is related to the differential responses of different carbon fractions. To investigate the changes in soil organic carbon fraction and its influencing factors in the context of short-term N deposition, four N addition gradients:0 (CK), 1.5 (N1), 3 (N2), and 6 (N3) g·(m2·a)-1 were set up in acacia plantations based on field N addition experiments, and the soil physicochemical properties, microbial biomass, and enzyme activities were measured in June and September. The results showed that:① exogenous N input reduced soil pH, promoted the increase in soluble organic carbon content, and increased soil nitrogen effectiveness. ② Short-term N addition significantly reduced soil organic carbon content, and the response of each component of organic carbon to N addition was different. Among them, the content of easily oxidized organic carbon was significantly reduced and reached the lowest value under the N2 treatment, with 54.4% and 48.2% reduction compared with that of the control, respectively, and the content of inert organic carbon increased, although the increase was not significant. Nitrogen addition reduced the soil carbon pool activity and improved the stability of the soil carbon pool. Soil carbon pool activity reached its lowest under the N3 and N2 treatments, with a decrease of 53.3% and 52.80%, respectively, compared to that of the control. ③Random forest modeling indicated that the soil microbial biomass stoichiometry ratio, microbial biomass carbon, and AP were the key factors driving the changes in soil organic carbon activity under short-term N addition, explaining 65.96% and 66.68% of the changes in oxidizable organic carbon and inert organic carbon, respectively. Structural equation modeling validated the results of the random forest modeling, and soil microbial biomass stoichiometric ratios significantly influenced carbon pool activity. Short-term nitrogen addition changed soil microbial biomass and its stoichiometric ratio in the acacia plantation forest mainly through two pathways, i.e., increasing soil nitrogen effectiveness and promoting soil acidification and inhibiting extracellular carbon hydrolase activity, thus changing the soil carbon fraction ratio and participating in the soil organic carbon cycling process. |
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