| 题名 | 川西亚高山森林土壤呼吸研究 |
| 作者 | 罗淑政 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘国华 |
| 关键词 | 桦木次生林 原始冷杉林 土壤呼吸 自养呼吸 异养呼吸 Birch secondary forest fir primary forest soil respiration heterotrophic respiration autotrophic respiration |
| 其他题名 | Study on soil respiration in subalpine forests in western Sichuan, China |
| 学位专业 | 生态学 |
| 中文摘要 | 土壤是一个巨大的碳库，全球每年由土壤释放的CO2量，仅次于全球总初级生产力，等于或超过全球陆地生态系统的净初级生产力，远远高于化石燃料燃烧而释放的CO2，是化石燃料燃烧释放的CO2的10倍以上。土壤碳库的微小变化能显著地减缓或加剧大气中CO2的增加，进而影响气候变化。 本研究的研究区位于四川省理县米亚罗林区，以该区位于海拔2910 m-3492 m的桦木次生林和海拔3760 m-4109 m的原始冷杉林为研究对象。2010年6月，分别在海拔2910 m，3135 m，3300 m，3492 m，3760 m，3919 m和4109 m选取样地。为了计算土壤呼吸及其组分，我们设置了对照，去凋落物和去凋落物+去根三种样地，去除根系采用的是壕沟法。根据不同样地及不同样地之间的差值来计算土壤呼吸、凋落物呼吸、地下异养呼吸、异养呼吸和自养呼吸。2010年6月，2011年7月和9月采用LI-cor 8100便携式CO2分析仪（Li-Cor, Nebraska, USA)对土壤呼吸进行测量。 研究表明：（1）2010年6月，2011年7月和2011年9月，桦木次生林土壤呼吸速率的平均值分别是2.89 ± 0.08（mean ± SE）μmolCO2/m-2s-1，3.54 ± 0.08 μmolCO2/m-2s-1和2.10 ± 0.08 μmolCO2/m-2s-1。2010年6月，2011年7月和2011年9月，原始冷杉林土壤呼吸速率的平均值分别是1.92 ± 0.13 μmolCO2/m-2s-1，2.17 ± 0.19 μmolCO2/m-2s-1和2.04 ± 0.11 μmolCO2/m-2s-1。在两种植被类型中，土壤呼吸与土壤温度有显著相关关系（p < 0.05），而与土壤水分无显著相关关系（p > 0.05）。并且，土壤呼吸与土壤温度之间存在着显著的指数回归关系，在桦木次生林，回归方程为y = 0.826*exp(0.126*x)（R2 = 0.695; p = 0.000; n = 65)，在原始冷杉林，回归方程为y = 1.196*exp(0.102*x)（R2 = 0.349; p = 0.000; n = 44)。这说明，在海拔高，温度低，雨量充足，水资源丰富的米亚罗林区，土壤温度是土壤呼吸的重要控制因子，而土壤水分变化对土壤呼吸影响不大。 （2）土壤呼吸沿海拔升高呈下降趋势。土壤呼吸在海拔2910 m，3135 m，3300 m，3492 m，3760 m，3919 m和4109 m的速率分别是3.25 ± 0.40，2.73 ± 0.56，2.62 ± 0.41，2.76 ± 0.43，2.77 ± 0.19，1.77 ± 0.04和1.62 ± 0.06 μmolCO2/m-2s-1。尽管土壤水分、0-10cm和10-20cm土壤总碳、土壤有机碳、总氮、总磷和总钾沿海拔变化有其自身的变化规律，但是逐步多元回归分析表明这些因子与土壤呼吸沿海拔的空间变化未有显著的相关性，土壤呼吸速率（Y）沿海拔高度的空间变化只与土壤温度（x）呈显著的线性相关关系，回归方程为：Y = 1.015 + 0.196x (p < 0.05，R2 = 0.751，n = 7)。土壤温度可以解释土壤呼吸沿海拔的空间变化的75%。 （3）在桦木次生林和原始冷杉林，去除凋落物处理降低了土壤呼吸，土壤呼吸的降低可能是因为凋落物数量及土壤有机质输入下降，而这又会对土壤微生物造成影响，从而降低土壤呼吸。挖沟隔离也降低了土壤呼吸，挖沟隔离有效地切断根与树之间的联系，因此中断了光合产物向根系的运输，自养呼吸被抑制，土壤CO2通量降低。 （4）在桦木次生林，异养呼吸对土壤呼吸的百分比贡献为84%，其中67% 来自于土壤有机质分解，17% 来自于凋落物分解。在原始冷杉林，异养呼吸对土壤呼吸的百分比贡献为77%，其中57%来自土壤有机质的分解，20%来自凋落物的分解。很明显，异养呼吸是土壤呼吸的主要部分，而异养呼吸又主要来自于它的地下部分。 （5）在桦木次生林和原始冷杉林，自养呼吸的温度敏感性均大于异养呼吸的温度明感性。并且，土壤呼吸，自养呼吸和异养呼吸的Q10均高于1，说明该区域森林生态系统的土壤呼吸，自养呼吸和异养呼吸与土壤升温之间的正反馈关系仍然处于主导地位。 |
| 英文摘要 | Soil respiration is a major flux in the global carbon cycle, second in magnitude to gross primary productivity and equal to or greater than the estimated global terrestrial net primary productivity. Carbon fluxes from soil to the atmosphere via decomposition of organic matter plus root respiration are approximately 10-fold greater than fossil fuel. Hence, soil respiration undoubtedly exerts a great effect on atmospheric CO2 concentration, and consequently on global warming. The experiment was carried out in the Miyaluo Forest District (31.4°−31.92°N, 102.58°−103.07°E), administratively belonging to Miyaluo Town, Li Country, ABa Tibet-Qiang People’s Autonomic District of Sichuan Province, China. We established no litter plots, control plots and no litter-no root plots by litter removal and trenching at altitudes of 2910 m to 3492 m，3760 m，3919 m and 4109 m in this district. The vegetation is the secondary birch forest from 2910 m to 3492 m and is the primary fir forest from 3760 m to 4109 m. Soil CO2 efflux was measured with a Li-Cor 8100 (Li-Cor, Nebraska, USA) portable infrared gas analyzer in June, 2010 and in July and September, 2011. We calculated soil respiration, heterotrophic respiration, autotrophic respiration, litter respiration and underground heterotrophic respiration based on the soil CO2 efflux measured in the different treatment plots. The main results of this research were as follows: (1) In June, 2010, July 2011, and September 2011, the soil respiration rates (mean ± SE) were 2.89 ± 0.08, 3.54 ± 0.08 and 2.10 ± 0.08 μmolCO2/m-2s-1 in the secondary birch forest and 1.92 ± 0.13, 2.17 ± 0.19 and 2.04 ± 0.11 μmolCO2/m-2s-1 in the primary fir forest. Soil respiration rate had a significant exponential regression relationship with soil temperature (p < 0.05), but was not significantly correlated with soil water content (p > 0.05) in the two forests. Furthermore, soil respiration had an exponential regression relationship with soil temperature in the secondary birch forest (y = 0.826*exp(0.126*x）; R2 = 0.695; p = 0.000; n = 65) and in the primary fir forest (y = 1.196*exp(0.102*x）; R2 = 0.349; p = 0.000; n = 44). Our results suggest in Miyaluo Forest District with high altitudes, low temperature, sufficient rain and rich water resources, soil temperature was an important controlling factor of soil respiration, while soil water content influenced soil respiration little. (2) Soil respiration rate decreased with elevation. At altitudes of 2910 m, 3135 m, 3300 m, 3492 m, 3760 m, 3919 m and 4109 m, soil respiration rates were 3.25 ± 0.40, 2.73 ± 0.56, 2.62 ± 0.41, 2.76 ± 0.43, 2.77 ± 0.19, 1.77 ± 0.04 and 1.62 ± 0.06 μmolCO2/m-2s-1. Although soil water content, total soil carbon, soil organic carbon, total nitrogen, total phosphorus and total potassium at 0-10 cm and 10-20 cm had their own trends along the altitudinal gradient, the result of the stepwise multiple regression analysis showed that soil respiration was not significantly correlated with them along the altitudinal gradient, it only had a significant linear regression relationship with soil temperature (Y = 1.015 + 0.196x, p < 0.05, R2 = 0.751，n = 7). Soil temperature accounted for 75% of variation in soil respiration along the altitudinal gradient. (3) In the secondary birch forest and the primary fir forest, litter removal reduced soil CO2 efflux. Litter removal leads to a decline in litter quantity and soil organic matter in the soil surface layers, which affects microbial communities and generally causes a decrease in soil respiration. Trenching also reduced soil CO2 efflux. With the insertion of a barrier in the soil within a certain area, trenching effectively ended the connection between the roots and the tree and thus also the transport of photosynthetic products to the roots. Therefore, autotrophic respiration was suppressed, and soil CO2 efflux was reduced. (4) In the secondary birch forest, the contribution of heterotrophic respiration to soil respiration averaged 84%, of which 67% from soil organic matter (SOM) and 17% originated from litter. In the primary fir forest, the contribution of heterotrophic respiration to soil respiration averaged 77%, of which 57% originated from SOM and 20% originated from litter. It is clear that heterotrophic respiration rather than autotrophic respiration is the dominant component of soil respiration. In addition, heterotrophic respiration mainly derived from its belowground part. (5) In the secondary birch forest and the primary fir forest, autotrophic respiration was more sensitive to soil temperature than heterotrophic respiration. The Q10 values of autotrophic respiration, heterotrophic respiration and soil respiration were higher than one, which suggests the potential positive feedback exist between increasing temperature and enhanced soil respiration, autotrophic respiration as well as heterotrophic respiration. |
| 公开日期 | 2015-07-07 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15614]  |
| 专题 | 生态环境研究中心_城市与区域生态国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 罗淑政. 川西亚高山森林土壤呼吸研究[D]. 北京. 中国科学院研究生院. 2014. |
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