基于同位素和灰分方法评估若尔盖泥炭地退化与恢复对土壤有机碳固存的影响

After decades of extensive degradation and artificial restoration, especially facing intense climate warming in the future, the changes in soil organic carbon (SOC) storage and stability are urgently needed to be accurately estimated and evaluated in Zoige peatland. However, traditional studies in changes of SOC storage and stability had three shortcomings: natural undisturbed peatland was unclear; the comparison of SOC storage was not made in the same accumulated years due to changes in soil layers after degradation and restoration; and there was lack of comparative studies on long-term SOC stability of degraded and restored peat. This study explores to use δ13C and δ15N changes along peat profile to determine the undisturbed natural peatland in Zoige area; use ash and 14C methods to solve the problem of soil layer changes after degradation and restoration, determine SOC with the same cumulative age, and then accurately estimate the changes of SOC storage in different degraded and restored peatlands; and combined with environmental factor control experiments, reveale impacts of degradation and restoration on the long-term SOC stability under future intense warm climate. This study aims to use new methods to accurately assess the influence of degradation and restoration on peatland SOC storage and stability in Zoige peatland, and provide a theoretical basis for accurately predicting long-term changes in regional carbon budget. Meanwhile, it will provide a reference for similar researches in other regions.

若尔盖泥炭地经历了几十年大范围的退化和人工恢复，未来面临着强烈的气候变暖，土壤有机碳（SOC）储量及其稳定性（固存）变化急需得到准确的评估。但目前关于若尔盖泥炭地SOC固存变化的研究存在着3个不足：一是原始未受干扰泥炭地难以确定；二是因退化与恢复后土层变动，而无法比较累积年代相同的SOC储量；三是缺少退化与恢复后SOC长期稳定性的对比研究。本课题探索运用泥炭剖面δ13C和δ15N变化来确定若尔盖不同区域的原始泥炭地；运用灰分和14C方法解决退化与恢复后泥炭地土层变动问题，确定累积年代相同的SOC，准确估算泥炭地不同程度退化与恢复后的SOC储量变化；并结合室内环境因素控制实验，揭示泥炭地退化与恢复后SOC稳定性在未来气候变暖条件下的变化规律。本研究旨在探索运用新方法在若尔盖准确评估泥炭地退化与恢复对SOC固存的影响，为预测区域碳收支的长期变化提供依据，同时为其它地区类似研究提供借鉴方案。

若尔盖泥炭地经历了几十年大范围的排水退化和禁排恢复，未来又面临着强烈的气候变暖，泥炭碳固存及其稳定性变化急需得到准确的评估。但目前关于若尔盖泥炭碳固存的研究存在着3个不足：一是原始未受干扰泥炭地难以确定；二是因排水退化与恢复后土层变动，而无法比较累积年代相同的碳储量；三是缺少排水退化与恢复后有机碳稳定性对升温响应的对比研究。本项目研究表明通过泥炭剖面δ13C和δ15N变化可以区分若尔盖区域不同条件下的排水泥炭地、恢复泥炭地和未排水泥炭地，为确定泥炭地的不同退化程度和不同区域的原始泥炭地提供可行方法；运用灰分可以计算排水退化与恢复后泥炭地的土层变动，确定相同累积年代的泥炭层，为准确估算不同程度排水退化与恢复后泥炭地的碳储量变化提供可借鉴的方法；通过水位、酸碱度、植物组成和生物量、凋落物量、泥炭C/N、微生物群落、泥炭可溶性碳含量及稳定性（SUVA254），深入综合分析排水导致泥炭有机物分解和碳固存变化的原因，表明排水主要通过泥炭C/N、微生物群落和SUVA254影响泥炭碳固存变化；并通过室内控制实验，表明泥炭地排水退化与恢复后有机碳稳定性对温度上升会产生不同响应，泥炭排水退化后具有更高的碳排放量。本研究为准确评估若尔盖泥炭地排水退化与恢复对泥炭固存的影响提供了新方法，为预测区域碳收支的长期变化提供依据，同时为其它地区类似研究提供借鉴方案。