深圳丘陵地带不同植被类型森林土壤有机碳组分和团聚体分布特征研究

研究森林土壤有机碳组分和团聚体分布特征，对摸清森林土壤结构形成及其碳稳定机制有重要科学意义。本研究以深圳市丘陵地带针叶林、阔叶人工林和次生阔叶林等3种不同植被类型、70个调查点森林土壤为研究对象，各调查点按0~10 cm和＞10~30 cm剖面进行采样，对土壤有机碳组分和团聚体含量进行分析。结果表明，3种植被类型表层土壤（0~10 cm）的有机质（OM）和全氮（TN）含量存在显著差异（P＜0.05），而亚表层土壤（＞10~30 cm）养分间的差异均未达到显著水平。不同植被类型土壤各有机碳组分均存在差异，表层土壤有机碳组分均高于亚表层，且以活性有机碳含量最高。此外，不同植被类型表层土壤间的差异主要体现在微团聚体上（＜0.25 mm），亚表层土壤则主要体现在微团聚体和1~2 mm团聚体上。除表层土壤电导率（EC）与惰性有机碳间的相关性外，两层土壤的EC、OM和TN含量与4种有机碳组分均呈极显著正相关（P＜0.001）；＞10 mm团聚体对有机碳矿化有显著正向调控，＞2~5 mm团聚体则表现为显著负影响。由此认为，3种植被类型间土壤养分和有机碳组分含量存在差异，且表层土壤的含量总是高于亚表层；不同土壤团聚体间的差异主要体现在微团聚体上；土壤养分含量是调节有机碳矿化的关键因子。

Distribution Characteristics of Soil Organic Carbon Fractions and Aggregates in Different Forest Vegetation Types of Hilly Areas in Shenzhen City

The study on the distribution characteristics of forest soil organic carbon fractions and aggregates is of great scientific significance to understand the formation of forest soil structure and its carbon stabilization mechanism. In this study, soil organic carbon fractions and aggregate content of 70 forest soils in hilly coniferous forest, broad-leaved plantation and secondary broad-leaved forest in Shenzhen were analyzed by sampling at 0-10 cm and 10-30 cm profiles at each survey site. The results showed that there were significant differences (P<0.05) in the contents of organic matter (OM) and total nitrogen (TN) in topsoil (0-10 cm) of the three vegetation types, but the differences among the nutrients in subsoil (10-30 cm) were not significant. There were differences in the organic carbon fractions of different vegetation types. The organic carbon fractions of topsoil were higher than that of subsoil, and the content of activated organic carbon was the highest. In addition, the differences between the topsoil of different vegetation types were mainly reflected in microaggregates (<0.25 mm), while the subsoil were mainly reflected in microaggregates and 1-2 mm aggregates. Except for the correlation between electroconductibility (EC) and inert organic carbon in topsoil, the EC, OM and TN of two layer soils were significantly positively correlated with the four organic carbon fractions (P<0.001); soil aggregate which diameter was greater than 10 mm had a significant positive effect on organic carbon mineralization, while aggregate which diameter was the range of 2-5 mm had a significant negative effect. This paper concluded from the results of this study that the contents of soil nutrients and organic carbon fractions of vegetation types were different, and the contents of topsoil was always higher than that of subsoil; the differences among soil aggregates of different vegetation types were mainly reflected in microaggregates; soil nutrient contents were the key factors to regulate organic carbon mineralization.