Knowledge Resource Center for Ecological Environment in Arid Area
| 干湿交替对不同生态系统土壤碳和氮释放的影响 | |
| 其他题名 | Impacts of drying and rewetting on soil carbon and nitrogen releases in different ecosystems |
| 欧阳扬 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 李叙勇 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 全球气候变化对降雨格局的影响下，土壤干湿交替现象在诸多生态系统中日益突出。由干湿交替引起的土壤碳、氮的短暂脉冲式释放很大程度上决定着长时间尺度温室气体释放的总量，是土壤碳、氮温室气体释放的关键过程。本研究依托中国生态系统研究网络，采集不同生态系统土样进行室内多重干湿交替实验和不同干旱持续时间-再湿润实验，对比探讨不同生态系统土壤干湿交替对碳、氮矿化和温室气体释放的影响模式；同时野外定位研究自然干湿交替过程中不同森林土壤微生物量和呼吸的变化。主要的结果如下：\n（1）随着干湿交替频率的增加，再湿润阶段CO2的释放速率减小。草原土壤中，2循环、5循环、7循环和14循环处理中CO2的平均释放速率比值为2.92：2.16：2.03：1.43，森林、农田和荒漠土壤CO2的释放速率表现出相似的响应模式。干湿交替处理也同样激发了N2O的释放速率和释放量。不同土壤中N2O释放对干湿交替频率的响应模式存在一定的差异。\n（2）干湿交替处理能够激发土壤酶活性，并且随着干湿交替的频率增加，β-葡糖苷酶和纤维素酶活性增强。虽然土壤中纤维素酶活性低于β-葡糖苷酶活性，但是干湿交替处理更有利于激发纤维素酶活性。14-循环处理中，森林、草地、农田和荒漠土壤纤维素酶活性，较之于恒湿处理，分别增加了706.21%、264.34%、158.59%和376.60%。β-葡糖苷酶活性分别增加了170.23%、73.16%、112.76%和136.51%。\n（3）干湿交替对土壤可溶性NH4+浓度没有影响。土壤可溶性NO3-库对干湿交替的响应较为显著，干湿处理都提高了土壤中可溶性NO3-浓度，并且随着干湿交替的频率增强，其浓度也随之增高。\n（4）随着持续干旱时间的增长，土壤中可溶性有机碳的含量增加,四种森林土壤40天干旱处理中土壤可溶性有机碳含量较之于10天干旱处理增加了2.2-3.5倍；干旱土壤中微生物量碳和氮的含量随之递减，四种森林土壤都表现出同样的响应模式。\n（5）自然降雨条件下，东灵山四种典型森林土壤呼吸对降雨的响应强度依次为：华北落叶松林>落叶阔叶混交林>桦树林>油松林。降雨量越大，土壤呼吸的释放速率和呼吸墒越大。如当降雨量从22mm变为12mm，油松林土壤呼吸和土壤呼吸墒分别减少了76.69%和59.2%。 |
| 英文摘要 | In the context of climate change impacts on the rainfall pattern, soil drying-rewetting cycles are becoming increasingly important in many ecosystem. Carbon and nitrogen releases caused by drying and rewetting cycles partly determine the total amount of emission of greenhouse gases for a long time. Our research work relied on Chinese Ecosystem Research Network(CERN). We collected soil from forest, agriculture, grassland and desert ecosystem along the precipitation and temperature gradient. Based on experiments with multiple drying and rewetting cycles, different drought durations and rewetting, we detected the mechanism of drying-rewetting impacts on soil carbon and nitrogen releases. Field work also carried out to research response of soil microbial biomass and activity on natural soil water variations. Our study should be helpful to better understand how climate change affects soil green house gaseous emission and soil nutrient leaches. The main conclusions were as followed.\n1. As drying and rewetting frequency increased, soil respiration rate in rewetting phrase decreased. In grass soil, the ratio of soil average respiration rate in 2-cycles, 5-cycles, 7-cycles and 14-cycles is 2.92:2.16:2.03:1.43. Forest, agriculture and desert soil also shared similar soil respiration pattern. Drying and rewetting cycles also stimulated the N2O release rate, unlike soil respiration, there were significant difference in response of N2O release on drying and rewetting cycles in different ecosystem soils \n2. Drying and rewetting can stimulate soil enzyme activity, and with the increase in the frequency of drying and rewetting, beta-glucosidase and cellulase activity enhanced. Although cellulase activity is more below than bata-glucosidase activity in all ecosystem soil, drying and rewetting is more conducive to stimulate cellulose activity. In 14-cycle treatment, compared to consistent moisture treatment, cellulase activity in forest, grassland, agriculture and desert soil increased by 706.21%、264.34%、158.59% and 376.60%, respectively, and beta-glucosidase activity increased by 170.23%、73.16%、112.76% and 136.51%.\n3. Soil soluble NH4+ concentrations in all soil types were low and were not affected by the drying and rewetting. However, soil soluble NO3- pool response strongly drying and rewetting, which had increased soil soluble NO3- concentrations in soils.\n4. With the growth of duration of drought time, soil dissolved organic carbon concentrations increased. Soil dissolved organic carbon concentrations of 40d-dry treatment compared to 10d-dry treatment increased by 220%-350% in four different forest soils. The duration of dry also deceased microbial biomass carbon and nitrogen in forest soils.\n5. Under natural rainfall conditions, the intensity of soil respiration response to precipitation in four typical forest in Dongling mountain as follows: larix principis-rupprechtii forest> deciduous broad-leaved mixed forest > birch forest> pinus tabulaeformis forest. The greater the rainfall, the higher the release rate of soil respiration. |
| 中文关键词 | 干湿交替 ; 温室气体 ; 土壤可溶性有机碳 ; 土壤酶活性 ; 微生物量 |
| 英文关键词 | drying and rewetting greenhouse gas soil dissolved organic carbon soil enzyme activity soil microbial biomass |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院生态环境研究中心 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287118 |
| 推荐引用方式 GB/T 7714 | 欧阳扬. 干湿交替对不同生态系统土壤碳和氮释放的影响[D]. 中国科学院大学,2012. |
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