Vertical Distribution and Seasonal Dynamics of Soil Organic Carbon in Phyliostachy edulis Plantations and P. edulis-Cunninghamia lanceolata Mixed Forests in the Hilly Region of Central Hunan, Southern China | 湘中丘陵区毛竹纯林、毛竹-杉木混交林土壤有机碳垂直分布与季节动态

صينى. 研究湘中丘陵区毛竹纯林、毛竹一杉木混交林土壤总有机碳（SOC）、微生物量碳（MBC）、热水浸提有机碳（HWC）、水溶性有机碳（WSOC）和易氧化态碳（ROC）含量的垂直分布、季节动态及其土壤环境影响因子。结果表明：不同季节土壤SOC，MBC，HWC，WSOC和ROC含量均随土壤深度增加而下降，0～60cm土层SOC和WSOC平均含量以1月最高，MBC平均含量以7月最高，ROC平均含量10月最高，毛竹纯林7月、毛竹-杉木混交林1月土壤平均HWC含量最高；与毛竹纯林相比，毛竹一杉木混交林不同形式活性有机碳含量及所占比例均较高，但稳定性较差；温度、湿度与WSOC含量极显著负相关（P〈0．01），而与MBC含量极显著正相关（P〈0．01）；降低土壤密度，改善土壤通气持水性能，有利于增加土壤有机碳含量；有机质含量与SOC，MBC和HWC含量极显著正相关（P〈0．01），与ROC含量显著正相关（P〈0．05）；土壤全氮、有效磷含量与SOC含量及全氮含量与MBC含量极显著正相关（P〈0．01）；水解氮、全磷、全钾含量与SOC和MBC含量，速效钾含量与SOC含量，有效磷含量与MBC含量显著正相关（P〈0．05）；细菌、放线菌数量增加有利于毛竹林土壤有机碳的积累，而真菌数量的增加不利于土壤有机碳的稳定；过氧化氢酶较其他酶与土壤有机碳含量关系更密切，与SOC和ROC含量极显著正相关（P〈0．01）。

إنجليزي. The vertical distribution, seasonal dynamic of soil total organic carbon （SOC）, micro - biomass carbon （ MBC）, hot water - extraction organic matter （ HWC）, water - soluble organic carbon （ WSOC ）, easily oxidized organic carbon （ROC） and the soil environmental factors were studied in pure Phyllostachy edulis plantations, P. edulis and Cunninghamia lanceolata mixed forests in the hilly region, central Hunan Province. The result showed that： The content of SOC, MBC,HWC,WSOC, and ROC decreased with the increase of soil depth, and in the soil layer of 0 - 60 cm, SOC and WSOC had the highest average contents in January, while MBC in July and ROC in October. However, HWC in P. edulis plantations had the highest content in July, while that in P. edulis and C. lanceolata mixed forests had the highest content in January. P. edulis and Cunninghamia lanceolata mixed forests had higher the contents and the ratios of different types of organic matters, but with lower stability than the pure P. edulis plantations. Temperature and moisture were very significantly negatively correlated with WSOC （P 〈 0.01）, but very significantly positively correlated with MBC （P 〈 0. O1 ）. Decrease in soil density and increase in soil ventilation and water - holding capacity were conductive to increasing soil organic matter; soil organic matter was very significantly positively correlated with SOC, MBC, and HWC （P 〈 0. O1 ） , while significantly positively correlated with ROC （ P 〈 0. 05 ）. Moreover, there existed very significantlypositively relationships between the contents of total N and available P with SOC, and between total N content with MBC （P 〈 0.01 ） ,and there were significantly positively relationships between available N, total P and total K with SOC and MBC, available K with SOC, and between a~ailable P with MBC. Increasing quality of bacteria and actinomycetes was beneficial to SOC accumulation, however, increase in fungi was not beneficial for stability of SOC; catalase was more closely correlated with SOC compared with the other enzymes and significantly positively correlated with SOC and ROC.