摘要:土壤有机质在森林生态系统中具有重要作用, 是估算土壤碳储量、评价土壤肥力和质量的重要指标。本文利用已发表文献中的数据, 从省域尺度上分析了杉木人工林土壤有机质的分布特征及其对土壤养分含量的影响, 为杉木(Cunninghamia lanceolata)人工林可持续经营提供理论依据。本文以文献中广东、广西、湖南、江西、浙江、福建6省22个林场1092个研究数据为基础, 分析了我国杉木人工林主产区表层(0~20 cm)土壤有机质含量特征、对土壤类型和地形等的响应及其对土壤养分的影响。结果显示, 杉木人工林表层土壤有机质平均含量为(31.02±13.44) g·kg?1, 养分等级为中, 变异系数为43.33%, 属中等变异水平; 有效磷含量为(5.41±8.01) mg·kg?1, 养分等级为富, 属高度变异, 变异系数为148.06%; 全磷含量(0.49±0.38) g·kg?1, 养分等级为极贫, 变异系数为77.55%, 属中等变异。不同土壤类型有机质含量差异较大, 山地黄壤的含量最高, 为(46.63±16.88) g·kg?1, 暗红壤最低, 为(15.81±4.38) g·kg?1。林分密度、海拔、坡度和土壤pH是杉木人工林表土有机质含量变化的主要影响因素, 相对贡献量分别为?0.35、0.28、0.11和0.11。土壤有机质对全氮、有效氮、全钾、有效钾的贡献程度较高, 相对贡献量分别为0.17、0.47、0.16和0.21。结果表明: 杉木人工林表层土壤有机质的养分等级为中。从样本量占比区间来看, 杉木人工林表层土壤有机质分布等级较为集中, 主要分级表现出“多中下, 少富级, 无极贫”的分布特征。海拔、坡度和土壤pH对土壤有机质含量变化的影响表现出明显的正效应, 林分密度则为负效应; 土壤有机质对土壤全氮、有效氮、全钾、有效钾含量有较明显的正面促进作用, 对全磷具有微弱的负面影响。
关键词:杉木人工林/
土壤有机质/
土壤养分/
环境因子/
逐步回归分析/
结构方程模型
Abstract:Soil organic matter plays an important role in forest ecosystems and is an important index for estimating soil carbon storage and soil fertility and quality. In this study, the distribution of soil organic matter and its influence on soil nutrients were analyzed on a provincial scale and the impact of environmental factors on changes in the soil organic matter content of Chinese fir plantations (CFPs) was assessed to provide a theoretical basis for the sustainable management of CFPs. Data from 1092 forest farms in six provinces of China (Guangdong, Guangxi, Hunan, Jiangxi, Zhejiang, and Fujian) were used to characterize the distribution of soil organic matter and its effect on the soil nutrients in the topsoil (0–20 cm) in CFPs. The results showed that the average soil organic matter content of the CFPs was 31.02±13.44 g·kg?1, the nutrient grade was at a medium level, and the coefficient of variation was 43.33%, which represented a moderate variation level. The available phosphorus (AP) content was 5.41±8.01 mg·kg?1, the nutrient grade was rich, and the coefficient of variation was as high as 148.06%. The total phosphorus (TP) content was 0.49±0.38 g·kg?1, which was extremely poor, and the coefficient of variation was 77.55%, being moderately variable. The soil organic matter content of different soil types varied greatly. The content in mountain yellow soil was the highest (46.63±16.88 g·kg?1), and that in dark red soil was the lowest (15.81±4.38 g·kg?1). Stand density, elevation, slope, and soil pH were the main factors that affected the soil organic matter content in the topsoil of CFPs, with relative contributions of ?0.35, 0.28, 0.11, and 0.11, respectively. The contributions of soil organic matter to total nitrogen (TN), available nitrogen (AN), total potassium (TK), and available potassium (AK) were positive, with relative contributions of 0.17, 0.47, 0.16, and 0.21, respectively. However, soil organic matter contributes less to soil TP, with a relative contribution of ?0.09. In general, the nutrient grade of soil organic matter in the surface layer of CFPs was medium. The main grading performance was mainly characterized by moderate to inferior levels, and few rich levels and no extremely poor levels were observed. Altitude, slope, and soil pH had positive effects on soil organic matter, whereas stand density had a negative effect. Soil organic matter had a positive effect on soil TN, AN, TK, and AK and a weak negative effect on TP. The contribution of soil organic matter to TP was low; therefore, the lack of phosphorus in the soil may be the main factor limiting Chinese fir growth.
Key words:Chinese fir plantations/
Soil organic matter/
Soil nutrients/
Environmental factor/
Stepwise regression analysis/
Structural equation model
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