| 氮添加对我国喀斯特农田和森林生态系统土壤有机碳及其组分影响的Meta分析 |
| 摘要点击 3470 全文点击 897 投稿时间：2023-09-11 修订日期：2023-12-14 |
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| 中文关键词 氮添加 喀斯特生态系统 碳循环 农田土壤 森林土壤 碳汇 |
| 英文关键词 nitrogen addition karst ecosystem carbon cycling farmland soil forest soil carbon sink |
| DOI 10.13227/j.hjkx.20240940 |
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| 中文摘要 |
| 近年来随着人类活动加剧,大气氮（N）沉降持续增加. 氮沉降影响生态系统的碳（C）循环,尤其是喀斯特脆弱生态系统. 喀斯特生态系统被认为是重要的碳库,为评估N沉降对其C组分的影响,通过收集整理截至2023年3月底已经发表的14篇英文文献,共460组实验数据,利用Meta分析研究方法,分析了不同水平的N添加对喀斯特生态系统土壤有机碳（SOC）及其组分[土壤可溶性有机碳（DOC）、 土壤微生物生物量碳（MBC）、 颗粒有机碳（POC）和土壤易氧化有机碳（ROC）]的影响. 结果表明：①N添加水平[≤ 50 kg·（hm2·a）-1、 50 ~ 100 kg·（hm2·a）-1和>100 kg·（hm2·a）-1,以N计]影响农田和森林土壤SOC及活性组分含量对N添加的响应. 低N和高N添加显著提高了农田土壤SOC含量,中N添加则显著增加森林土壤SOC含量；高N添加增加农田土壤活性碳含量；中、 低N增加森林土壤活性碳含量. ②不考虑N添加水平时,N添加显著提高农田和森林土壤有机质（SOM）矿化,并增加农田土壤SOC含量；不同活性组分的响应存在差异,农田土壤POC和ROC含量增加,但DOC没有显著变化；森林土壤DOC和POC含量增加,但对MBC无显著影响. ③农田和森林土壤SOC及其组分对N添加的响应比（RR）受不同环境因子的影响. 在农田系统中,土壤SOC的响应比受年平均气温和土壤pH的影响,DOC响应比则受年平均气温、 年均降水量及施N量的影响,POC响应比仅与施N量有关；在森林系统中,年平均气温、 年均降水量和土壤pH显著影响土壤SOC的响应比,对DOC、 POC和MBC响应比的影响不显著. 上述结果表明,N添加有利于喀斯特农田和森林土壤SOC含量的增加,促进其土壤碳汇能力提升,但该效应受施N量的影响. 研究结果为预测未来气候变化背景下喀斯特农田和森林生态系统土壤碳汇功能提供了科学依据. |
| 英文摘要 |
| In recent decades, with the intensification of human activities, atmospheric nitrogen （N） deposition has been increasing. N deposition affects carbon （C） cycling in terrestrial ecosystems, especially in fragile karst ecosystems. Karst ecosystems are considered to be an important C pool. To evaluate the impact of N deposition on soil organic C （SOC） and its fractions in karst ecosystems of China, we collected and collated 14 English literature published through the end of March 2023, yielding a total of 460 sets of experimental data. The meta-analysis examined the effect of N addition levels [low N: ≤50 kg·（hm2·a）-1, medium N: 50-100 kg·（hm2·a）-1, and high N: >100 kg·（hm2·a）-1, in terms of N] on SOC and its fractions [particular organic C （POC）, readily oxidized organic C （ROC）, microbial biomass C （MBC）, and dissolved organic C （DOC）]. The results showed that N addition levels significantly affected the responses of farmland and forest soil SOC and their active fractions to N addition. Specifically, low and high N additions significantly increased SOC concentration in farmland ecosystems, whereas medium N addition significantly increased SOC concentration in forest ecosystems. In addition, soil active C fraction concentrations increased under high N addition in farmland ecosystems and under low and medium N addition in forest ecosystems. Without considering the level of N addition, N addition significantly enhanced soil organic matter （SOM） mineralization in both farmland and forest ecosystems and increased the SOC concentration in farmland ecosystems but not forest ecosystems. The responses of different active C fractions to N addition were diverse. In farmland ecosystems, the POC and ROC concentrations increased, but DOC did not change with N addition. In forest ecosystems, the DOC and POC concentrations increased, but there was no significant effect on MBC. Moreover, the response ratios （RR） of SOC and its fractions in different ecosystems to N addition were influenced by different environmental factors. In farmland ecosystems, the response ratio of SOC was related to the annual average temperature and soil pH. The response ratio of DOC was affected by the annual average temperature, mean annual precipitation, and N addition rate. The POC response ratio was related to the N addition rate. In forest ecosystems, the effects of N addition on the SOC response ratio were significantly altered by the annual average temperature, mean annual precipitation, and soil pH. However, the response ratios of DOC, POC, and MBC were not affected by the annual average temperature, mean annual precipitation, soil pH, and N addition rate. Consequently, these findings indicate that N addition could enhance soil SOC concentration and promote soil C sequestration in farmland and forest ecosystems in karst regions, but this effect relies on the level of N addition. This provides a scientific basis for predicting the soil C sink function in karst ecosystems under climate change scenarios. |
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