广西大青山西南桦人工林土壤养分特征及其与立地生产力的关系

目的]探讨西南桦人工林对土壤的适应性及土壤养分特征,揭示土壤养分状况与立地生产力的关系,为其造林地选择及人工林养分管理提供参考。方法]在广西大青山林区西南桦人工林内设置47块600 m2的典型样地,调查常规测树因子,采集土壤样品,测定10项常规土壤化学性质指标;按照土壤养分分级标准评价土壤养分状况,基于立地指数将样地分为高产和低产组,进一步比较分析两组立地间各养分指标的差异性,探讨土壤养分对立地生产力的影响。结果]表明:广西大青山西南桦人工林地土壤绝大部分为强酸性,有机质、有效N、全N含量中等偏上,有效P甚缺,其它养分含量中等偏下。高产和低产立地间土壤有机质和全K含量均呈极显著差异(P0.01),有效N含量差异显著(P0.05)。结论]西南桦对于低pH值、低P含量的土壤具有较强的适应性;有机质、全K和有效N含量是影响广西大青山西南桦人工林立地指数的关键土壤养分因子。

Assessing Soil Nutrient Status and Its Relationship with Site Productivity of Betula alnoides Plantations in Daqingshan Mountains, Guangxi

Objective] The soil nutrient status in Betula alnoides plantation was investigated to assess the soil fitness of the species and reveal the relationship between soil nutrient regimes and site productivity so as to provide reference for site selection and soil nutrients management of B. alnoides plantation. Method] Forty-seven plots with size of 600 m² were established in B. alnoides plantations in Daqingshan Mountains, Guangxi. Three soil samples were collected in each plot and their soil chemical properties were analyzed, the soil nutritional status was evaluated according to the classification standard of soil nutrition. The plots were then divided into two site groups with high and low productivity based on their site index, and the differences in soil nutrition were further analyzed between the site groups. Result] The soil in majority of B. alnoides plantation was strongly acidic. The soil organic matter and nitrogen contents were in upper-middle class, the available phosphorus was of heavy shortage, and the contents of other nutrients were in lower-middle class. The soil organic matter and total potassium contents were significantly different at the level of 0.01, and the available nitrogen content at the level of 0.05 between high and low productivity sites. Conclusion] B. alnoides has strong adaptability to soils with low pH value and phosphorus contents. The organic matter, total potassium and available nitrogen contents are the key soil nutrient factors influencing the productivity of B. alnoides plantations in Daqingshan Mountains.