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西南喀斯特区植被恢复对土壤氮素转化通路的影响
摘要点击 285  全文点击 108  投稿时间:2017-10-12  修订日期:2017-12-01
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中文关键词  植被恢复  氮素转化  氮矿化  自养硝化  异养硝化  喀斯特
英文关键词  vegetation restoration  nitrogen transformation  nitrogen mineralization  heterotrophic nitrification  autotrophic nitrification  karst
作者单位E-mail
杨怡 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验实, 长沙 410125
中国科学院环江喀斯特农业生态系统研究观测站, 环江 547200
中国科学院大学, 北京 100049 
haugtessa2010@live.cn 
欧阳运东 湖南省邵阳市第二中学, 邵阳 422000  
陈浩 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验实, 长沙 410125
中国科学院环江喀斯特农业生态系统研究观测站, 环江 547200 
chenhao10902@isa.ac.cn 
肖孔操 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验实, 长沙 410125
中国科学院环江喀斯特农业生态系统研究观测站, 环江 547200 
 
李德军 中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验实, 长沙 410125
中国科学院环江喀斯特农业生态系统研究观测站, 环江 547200 
 
中文摘要
      氮素是生态系统重要的限制性养分元素之一.研究氮素转化特征对于了解生态系统功能具有重要意义.然而,目前对喀斯特地区氮素转化特征的认识十分有限.同时,喀斯特地区正开展一系列的生态恢复工程措施,生态恢复将对土壤氮素转化过程产生何种影响尚不清楚.为此,本研究在广西环江县喀斯特区域选取3种典型的植被恢复阶段(草地、灌丛、次生林),以农田为参照,采集0~10 cm深度的土壤样品,测定了土壤净氨化速率(净氨化率、真菌氨化和细菌氨化)、净氮矿化速率(净氮矿化、真菌矿化和细菌矿化)、净硝化速率(净硝化、自养硝化、异养硝化、真菌硝化、细菌硝化)及相关土壤理化指标,研究喀斯特区植被恢复对土壤氮素转化速率的影响.结果表明,总体上喀斯特生态系统硝化速率很高,土壤无机氮主要以硝态氮形式为主,其中自养硝化和异养硝化分别占净硝化速率的80%和20%.添加真菌和细菌抑制剂后,氨化速率增加,而硝化速率下降.另外,随着植被的恢复,土壤氮矿化和硝化速率逐渐增加,而氨化速率逐渐下降.其原因与不同植被恢复阶段的土壤有机碳、总氮、硝态氮、微生物量及氮获取酶的活性有密切关系.这些发现为认识喀斯特生态系统氮素循环特征提供了关键的信息.
英文摘要
      Nitrogen (N) is an important element for plant growth in terrestrial ecosystems. Studying soil N cycling is crucial for understanding the structures and functions of an ecosystem. However, our knowledge of soil N dynamics in karst regions is still limited. In addition, while China's karst regions have conducted a series of vegetation restoration projects, the vegetation restoration effects on soil N pathways are still largely unknown. Therefore, this study selected four typical ecosystems representing four main vegetation restoration stages (i. e., cropland, grassland, shrubland, and forest) in a karst region in Huanjiang Province, southwest China. In these ecosystems, soil N pathways, including net ammonization rate (net ammonization, fungal ammonization, and bacterial ammonization), net nitrification rate (i. e., net nitrification, heterotrophic nitrification, autotrophic nitrification, fungal nitrification, and bacterial nitrification), net N mineralization rate (net N mineralization, fungal mineralization, and bacterial mineralization), and soil properties were measured. Our results showed that nitrification rate was high in all ecosystems, but the ammonization rate was low, resulting in nitrite being the main inorganic N form in karst soil. Autotrophic and heterotrophic nitrification rates accounted for 80% and 20% of the net nitrification rate, respectively. After the addition of fungal and bacterial inhibitors, ammonization rates increased for all treatments, but the nitrification rates decreased. Following vegetation restoration, soil N mineralization and nitrification rates all increased, but the ammonization rates significantly decreased. This pattern was significantly correlated with soil organic carbon, total nitrogen, nitrate, microbial biomass, and the activity of N-acquisition enzymes in these ecosystems. Our findings provide very useful information for understanding soil N cycling in the karst regions.

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