Changes in soil organic carbon, nitrogen, pH and bulk density with the development of larch (Larix gmelinii) plantations in China
Changes in soil organic carbon, nitrogen, pH and bulk density with the development of larch (Larix gmelinii) plantations in China
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中国落叶松人工林发展对土壤有机碳、氮、pH和容重的影响
DOI：
10.1111/j.1365-2486.2011.02447.x
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发表时间：
2011-08-01
影响因子：
11.6
通讯作者：
Chen Xi-Quan
中科院分区：
文献类型：
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作者：
Wang Wen-Jie;Qiu Ling;Chen Xi-Quan
根据中国政府实施的“退耕还林”（RFTF）环保计划，约有2800万公顷的农田被改造成人工林。这导致了生物质碳的大量积累，但对地下碳相关过程知之甚少。对东北地区159个落叶松人工林的1个永久样地（25年观测）和4个时序样地系列进行了研究。两种方法均发现表层（0 ~ 20 cm）土壤有机碳（SOC）显著增加（96.4 g C m−2 yr−1），容重显著降低（5.7 mg cm−3 yr−1），但深层变化不一致，表明在RFTF计划下种植落叶松可以增加土壤有机碳储量，改善表层土壤物理性质。在较少的土壤中观察到氮消耗（4.1-4.3 g m−2 yr−1）、土壤酸化（0.007-0.022 pH单位yr−1）和碳/氮（C/N）比增加（0.16-0.46 /年），而在典型的深棕色森林土壤中没有发现显著变化。该土壤有机碳积累速率（96.4 g m−2 yr−1）可吸收该地区落叶松林总碳汇容量[净生态系统交换（NEE）]的39%，近似于中国东北所有落叶松人工林（4.5 Mha）， 20年土壤固碳总量可达87 Tg碳，显示了土壤碳积累在生态系统碳平衡中的重要性。与这些过程在农业利用中的速率相比，农业土地利用逆转的RFTF计划对土壤有机碳、土壤肥力和容重的恢复速度较慢（<农业利用耗损率的69%），因此通过RFTF计划恢复土壤地下功能需要更长的时间。全球在废弃农田上的人工林或具有保护农田功能的人工林呈稳定增长趋势，我们的研究结果可能对了解其地下碳过程具有重要意义。
Under the government of China's environmental program known as Returning Farmland To Forests (RFTF), about 28 million hectares of farmland have been converted to tree plantation. This has led to a large accumulation of biomass carbon, but less is known about underground carbon‐related processes. One permanent plot (25 years of observation) and four chronosequence plot series comprising 159 plots of larch (Larix gmelinii) plantations in northeastern China were studied. Both methods found significant soil organic carbon (SOC) accumulation (96.4 g C m−2 yr−1) and bulk density decrease (5.7 mg cm−3 yr−1) in the surface soil layer (0–20 cm), but no consistent changes in deeper layers, indicating that larch planting under the RFTF program can increase SOC storage and improve the physical properties of surface soil. Nitrogen depletion (4.1–4.3 g m−2 yr−1), soil acidification (0.007–0.022 pH units yr−1) and carbon/nitrogen (C/N) ratio increase (0.16–0.46 per year) were observed in lessive soil, whereas no significant changes were found in typical dark‐brown forest soil. This SOC accumulation rate (96.4 g m−2 yr−1) can take 39% of the total carbon sink capacity [net ecosystem exchange (NEE)] of larch forests in this region and the total soil carbon sequestration could be 87 Tg carbon within 20 years of plantation by approximating all larch plantations in northeastern China (4.5 Mha), showing the importance of soil carbon accumulation in the ecosystem carbon balance. By comparison with the rates of these processes in agricultural use, the RFTF program of reversing land use for agriculture will rehabilitate SOC, soil fertility and bulk density slowly (< 69% of the depletion rate in agricultural use), so that a much longer duration is needed to rehabilitate the underground function of soil via the RFTF program. Global forest plantations on abandoned farmland or function to protecting farmland are of steady growth and our findings may be important for understanding their underground carbon processes.