桂北土壤肥力质量对尾叶桉人工林连栽连作的响应

以桂北尾叶按三代连栽连作人工林为研究对象，分析20项土壤理化性质差异，筛选出尾叶按林地土壤肥力质量评价最小数据集，并对土壤肥力进行质量评价。结果表明：第三代尾叶按人工林大部分土壤理化指标比第一、第二代林土壤显著降低，其中第三代林土壤持水量、毛管孔隙度、有机质、全磷、有效磷、速效钾、有效元素含量显著低于第一代林、第二代林。基于主成分分析及皮尔逊相关性分析筛选出毛管孔隙度、有机质、全磷、有效磷、速效钾、有效硼、有效钙和有效锌含量，建成反映桉树人工林土壤肥力质量的最小数据集。评价发现，三代连栽尾叶按人工林土壤肥力为第二代（0.785）>第一代（0.642）>第三代林（0.566），土壤肥力质量先增加后降低，尾叶按连栽两代之后土壤理化性质显著退化。因此，建议在第二代林采伐后要及时补充因连栽下降的元素，以达到桉树速生丰产的目的。

Response of Soil Fertility Quality to Continuous Cropping of Eucalyptus urophylla Plantation in Northern Guangxi

The soil of 3 generation of Eucalyptus urophylla plantation in northern Guangxi was studied. Based on the determination of 20 soil physical and chemical properties, the minimum data set of soil fertility quality evaluation of Eucalyptus forest land was selected by principal component analysis, and the quality evaluation of soil fertility was carried out. The results show that the physical and chemical properties of the 3rd generation E. urophylla plantations are significantly lower than that of other generation forest. Soil water holding capacity, capillary porosity, organic matter, total phosphorus, available phosphorus, available potassium and effective elements in the 1st and 2nd generation are significantly higher than those of 3rd generation E. urophylla plantations. The minimum data set of capillary porosity, organic matter, total phosphorus, available phosphorus, available potassium, available boron, available calcium and effective zinc are selected as the minimum data sets for evaluating the soil fertility quality of E. urophylla plantation. The results show that the 2nd generation (0.785) > 1 st generation (0.642) > 3 rd generation (0.566). The soil quality increases first and then decreases. After 2 generations, the soil physical and chemical properties are significantly degraded. Therefore, after the 2nd generation forest harvesting, it is necessary to replenish the element content decreased by continuous planting in order to achieve the fast-growing and high-yield production of E. urophylla.