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大气CO2浓度升高和氮(N)添加对土壤碳库的影响是当前国际生态学界关注的一个热点。为阐述土壤不同形态有机碳的抗干扰能力,运用大型开顶箱,研究了4种处理((1)高CO2浓度(700μmol·mol–1)和高氮添加(100 kg N·hm–2·a–1)(CN);(2)高CO2浓度和背景氮添加(CC);(3)高氮添加和背景CO2浓度(NN);(4)背景CO2和背景氮添加(CK))对南亚热带模拟森林生态系统土壤有机碳库稳定性的影响。近5年的试验研究表明:(1)CN处理能明显地促进各土层中土壤总有机碳含量的增加,其中,下层土壤(5–60 cm土层)中的响应达到统计学水平。(2)活性有机碳库各组分对处理的响应有所差异:不同土层中微生物生物量碳(MBC)的含量对各处理的响应趋势基本一致,各土层中的MBC含量均为CN>CC>NN>CK,其中0–5 cm、5–10 cm、10–20cm 3个土层的处理间差异都达到了显著水平;10–20 cm与20–40 cm两个土层中的易氧化有机碳处理间有显著差异;而对于各土层中水溶性有机碳,处理间差异均不明显。(3)各团聚体组分中的有机碳含量的响应也有所差异:20–40 cm与40–60 cm土层中250–2 000μm组分的有机碳含量存在处理间差异;40–60 cm土层中53–250μm组分的有机碳对各处理响应敏感,CC处理和NN处理都有利于该组分碳的深层积累,尤其CN处理下的效果最为明显;在各处理10–20 cm、20–40 cm及40–60 cm土壤中,<53μm组分中的碳含量间差异显著。大气CO2浓度上升和N添加促进了森林生态系统中土壤有机碳的增加,尤其有利于深层土壤中微团聚体与粉粒、黏粒团聚体等较稳定组分中有机碳的积累,增加了土壤有机碳库的稳定性。
The impact of elevated atmospheric CO2 and nitrogen (N) on the soil carbon pool is currently a hot topic of concern to the international community of ecology. In order to elucidate the anti-interference ability of soil organic carbon with different forms, four kinds of treatments (1 high CO2 concentration 700μmol · mol-1 and high nitrogen addition 100kg N · hm-2 · (2) High CO2 concentration and background nitrogen addition (CC); (3) High nitrogen addition and background CO2 concentration (NN); (4) Background CO2 and background nitrogen addition (CK) Impacts of soil organic carbon pool on the stability of forest ecosystems in South Subtropical China. Nearly five years of experimental studies have shown that: (1) CN treatment can significantly promote the increase of soil total organic carbon in each soil layer, of which, the response in the lower soil layer (5-60 cm soil layer) reached a statistical level. (2) The response of each component of active carbon pool to treatment was different: the MBC content in different soil layers was basically consistent with the response trend of all treatments, MBC content in each soil layer was CN > CC> NN> CK, among which the differences among the treatments of 0-5 cm, 5-10 cm and 10-20 cm soil layers all reached the significant level. Among the two soil layers of 10-20 cm and 20-40 cm There was a significant difference between the treatments of EOOCs. However, there was no significant difference between the treatments for water-soluble organic carbon in the soil layers. (3) The response of organic carbon content in each aggregates also varied: the organic carbon content of 250-2000μm in 20-40 cm and 40-60 cm soil layers was different between treatments; 40-60 cm The organic carbon of 53-250μm in soil layer was sensitive to each treatment. Both CC treatment and NN treatment were beneficial to the deep accumulation of carbon in this soil, especially under CN treatment. Under the treatment of 10-20 cm, In 20-40 cm and 40-60 cm soil, the carbon content in the <53 μm fraction differed significantly. The increase of atmospheric CO2 concentration and N addition promoted the increase of soil organic carbon in forest ecosystem, especially for the accumulation of organic carbon in the more stable components such as microaggregates and silt aggregates in deep soils, and increased soil Organic carbon pool stability.