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基于添加秸秆室外模拟实验后期的土壤呼吸的特征分析
王亭亭
学位类型硕士
导师王秀君 ; 赵成义
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业环境科学
关键词Co2 通量 土壤 Co2 浓度 日变化 季节变化 温度 模拟实验 添加秸秆 焉耆盆地
摘要分析干旱区农田的土壤呼吸变化特征以及人为管理和环境因素的影响对陆地碳循环的全面研究具有深远意义。本研究基于在焉耆盆地开展的添加秸秆室外模拟实验,添加秸秆模拟实验于2011年10月初开始,模仿大田秸秆还田,模拟试验包括 3 个处理:原土、含1.25% 和 2.5% 秸秆混合土。于2012年6月至2013年1月期间对地表CO2 通量和土壤 CO2 浓度进行了连续、同步观测。本研究的目的是明确添加秸秆的土壤经过秋季、冬季、春季的腐解后三个季度的土壤呼吸的变化特征,为探明干旱区典型陆地生态系统的土壤碳循环提供基础数据支撑。模拟本研究分为 4 个部分:首先分析地表 CO2 通量的日变化和季节变化特征;然后分析土壤剖面中 CO2 浓度的垂直分布以及日变化和季节变化特征;采用多种回归分析方法揭示地表 CO2 通量、土壤 CO2 浓度与温度的相关性;最后分析地表 CO2 通量和土壤 CO2 浓度的相关性。基于以上研究,初步得出如下结论: (1)原土、1.25% 秸秆混合土和 2.5% 秸秆混合土的地表 CO2 通量的日变化特征呈现单峰型曲线:最高值出现在 12:00~16:00,最低值在 5:00~7:00。3 种处理白昼总碳释放量占全天总碳释放量的比例差异不明显,约为 58%~70%。3 种处理的地表 CO2 通量的季节变化特征均十分明显并具有很大的相似性:峰值大约出现在 7 月中下旬和 8 月中下旬,最低值在冬季。 (2)3 种处理在夏季和秋季各土层的 CO2 浓度的日变化特征呈单峰型曲线,但峰值在各土层出现时间不一致: 10 cm 土层 CO2 浓度峰值出现在 19:00~21:00, 20、30 cm 土层 CO2 浓度峰值在 0:00~3:00, 50 cm 土层 CO2 浓度峰值在 9:00,土壤表面 CO2 浓度峰值在 7:00。 10 cm 土层 的CO2 浓度峰值滞后于 10 cm 土层温度 1 h,20、30 cm 土层的 CO2 浓度滞后 约 5 h,土壤表面和 50 cm 土层的 CO2 浓度则滞后更久。3 种处理土壤 CO2 浓度的季节变化特征都十分明显且具有很大相似性:大约在 7 月初和 8 月中下旬出现峰值。秸秆混合土的土壤 CO2 浓度在各土层均比原土同层的 CO2 浓度大。表层的CO2 浓度梯度明显大于底层,且在 11 月出现浓度梯度最小值, 在 6 月 和 9 月出现最大值。 (3)3 种处理的地表 CO2 通量和地表温度在夏季,均没有表现出相关性关系(P>0.05);在秋季,均表现为极显著正相关关系(R2>0.9,P<0.01);在冬季,秸秆混合土表现为显著正相关关系(R2>0.4,P<0.05),原土没有表现出相关性关系(R2=0.287,P>0.05);在整个观测期间,均表现为极显著正相关关系(R2>0.9,P<0.01)。3 种处理的土壤 CO2 浓度和土壤温度在夏季,10 cm 土层没有表现显著相关(P>0.05), 20、30 cm 土层均表现出相关关系(R2 >0.4, P<0.05);在秋季 10、20、30 cm 土层 CO2 浓度均与对应层的土壤温度表现为极显著相关(R2 >0.9, P<0.01);在整个观测期间,10 cm 土层 CO2 浓度与该土层土壤温度均呈显著相关; 20、30 cm 土层 CO2 浓度与该土层的土壤温度均表现为极显著相关性。3 种处理的地表 CO2 通量与土壤 10、20、30 cm CO2 浓度均呈极显著相关。
其他摘要Soil respiration is a major component of the global terrestrial carbon cycle. An incubation experiment with three treatments (soil only, and soil mixed with 1.25% and 2.5% of maize straw) was established in early October, 2011, on bare ground in the Yanqi Basin simulating of field straw returned. CO2 efflux and soil CO2 concentration at different depths were recorded from June, 2012 to January, 2013. Diurnal and seasonal variations of CO2 efflux and soil CO2 concentration were determined. The relationship between temperature, CO2 efflux and soil CO2 concentration were analysed using various Regression analysis methods. The results indicated that there was obvious diurnal variation of CO2 efflux under all three treatments. The maximum rate of CO2 efflux occurred during 12:00~16:00 (local time), the minimum during 5:00~7:00.On average, the total amount of carbon released during daytime accounted for about 58% ~70% of that for the whole day. There were strong seasonal variations of CO2 efflux under all three treatments, showing peaks in middle to late July and/or middle to late August and the minimum values occurred in winter. There was also obvious diurnal and seasonal variations of soil CO2 concentration at 10 cm、20 cm、30 cm and 50 cm. The maximum soil CO2 concentration was found between 19:00~21:00 at 10 cm, 0:00~3:00 and 9:00 at 20 cm、30 cm and 50 cm, respectively, and 7:00 near the surface. The peak of soil CO2 concentration was lagged by one hour at 10 cm, comparing with that of soil temperature. The peaks of soil CO2 concentration at 20 cm and 30 cm were lagged by five hours relative to soil temperature. Over the seasonal cycle, soil CO2 concentration peaked in early July and/or middle to late August. Soil CO2 concentration was higher with straw addition than without at all depths, and showed an increase with depth. The gradient of soil CO2 concentration over depth showed a decrease with depth. The minimum gradient of soil CO2 concentration was found in November, and the maximum in June and/or September. There were exponential relationships between CO2 efflux and soil surface temperature for all three treatments, which were highly significant in autumn (R2 >0.9, P<0.01), significant (R2 >0.4, P<0.05) of soil with straw and not significant (R2=0.287, P>0.05) of soil only in winter, but not significant in summer (P>0.05), highly significant during the whole observation. There were exponential relationships, a linear and nonlinear relationships between soil CO2 concentration and soil temperature at 10、20、30 cm soil for all three treatments, which were highly significant in autumn (R2 >0.9, P<0.01) and at 20、30 cm soil in summer (R2 >0.4, P<0.05), but not significant at 10 cm in summer (P>0.05), significant at 10 cm soil and highly significant at 20、30 cm soil for all three treatments. There were linear relationships between CO2 efflux and soil CO2 concentration at 10、20、30 cm soil for all three treatments, which were highly significant during the whole period.
学科领域环境科学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14632
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
王亭亭. 基于添加秸秆室外模拟实验后期的土壤呼吸的特征分析[D]. 北京. 中国科学院大学,2015.
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