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马尾松—油茶针阔混交林土壤肥力评价

Soil fertility evaluation in mixed forests of Pinus massoniana and Camellia oleifera

  • 摘要: 以广西国有派阳山林场马尾松—油茶混交林为例,研究马尾松针阔混交林与纯林土壤肥力的差异,对马尾松人工林阔叶化改造有重要意义。分析马尾松—油茶混交林和马尾松纯林8项土壤化学指标(pH值、有机质、全氮、全磷、全钾、碱解氮、有效磷和速效钾含量)的差异,采用5种方法(秩和比综合评价法、优劣解距离法、主成分分析法、多准则妥协解排序法和熵值法)综合评价土壤肥力,确定不同化学指标在土壤质量评估中的权重,对比马尾松—油茶混交林和纯林的土壤肥力差异。结果显示:混交比例7∶3的马尾松—油茶混交林土壤化学指标评价等级分别为有效磷二级水平,有机质四级水平,pH值、全氮、全钾和全磷五级水平,速效钾和碱解氮六级水平;马尾松纯林的各项化学指标数值均低于该混交林,其中全磷和有效磷差异明显,均为六级水平。土壤肥力综合评价结果表明,马尾松混交林土壤肥力高于纯林,马尾松与油茶的混交比例7∶3优于5∶5,表层土壤肥力高于亚表层土壤。土壤化学指标权重分析结果表明,有效磷权重最高,在综合评价中具有关键判别作用,全磷和速效钾次之,三者在土壤肥力评价中占据核心地位。马尾松与油茶复层异龄混交,有助于增加土壤有机质和养分含量,缓解南亚热带酸性红壤区土壤酸化趋势,提高土壤肥力,是马尾松人工林阔叶化改造的有效经营策略。

     

    Abstract: Taking the mixed forest of Pinus massoniana and Camellia oleifera in the state-owned Paiyangshan Forest Farm of Guangxi, China as an example, studying the differences in soil fertility between the mixed coniferous and broad-leaved P. massoniana forest and the pure forest is significant for the broad-leaved transformation of P. massoniana plantations. The differences in eight soil chemical indicators, including pH value, organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzable nitrogen, available phosphorus and available potassium content, between the mixed forest of P. massoniana and C. oleifera and the pure forest of P. massoniana were analyzed. Five evaluation methods, namely the rank- sum ratio comprehensive evaluation method, technique for order preference by similarity to ideal solution, the principal component analysis method, the multi-criterion compromise solution ranking method and the entropy method, were used to conduct a comprehensive evaluation of soil fertility, to determine the weights of different chemical indicators in soil quality assessment and compare the differences in soil fertility between mixed forests of P. massoniana and C. oleifera and pure forests. The evaluation grades of soil chemical indicators for the mixed forest of Pinus sasanqua and C. oleifera (7∶3) are as follows: available phosphorus level 2, organic matter level 4, pH value, total nitrogen, total potassium and total phosphorus level 5, available potassium and alkali-hydrolyzable nitrogen level 6. All the chemical index values of the pure P. massoniana forest were lower than those of the mixed forest. Among them, the differences in total phosphorus and available phosphorus were significant, both reaching the sixth grade level. The comprehensive evaluation results of soil fertility show that the soil fertility of the mixed forest of P. massoniana is higher than that of the pure forest. The mixed ratio of P. massoniana and C. oleifera in 7∶3 is better than 5∶5, and the fertility of the surface soil is higher than that of the sub-surface soil. The analysis of weight results of soil chemical indicators shows that available phosphorus has the highest weight and plays a key discriminating role in the comprehensive evaluation, followed by total phosphorus and available potassium. The three occupy a core position in the evaluation of soil fertility. The multi-layered intercropping of C. oleifera and P. massoniana at different ages helps increase soil organic matter and nutrient content, alleviate acidification trend in the acidic red soil of the Southern subtropical zone, and enhance soil fertility. It is an effective management strategy for the broad-leaved transformation of P. massoniana plantations.

     

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