不同造林措施对桉树人工林地土壤养分的影响

针对桉树人工林地力退化问题,通过比较两种造林措施下桉树人工林地土壤肥力特征发现,皆伐和造林时的人为活动对浅土层(0～20 cm)的土壤有松动作用,在一定程度上降低土壤容重,部分提高土壤持水量和孔隙度,但造林后林地土壤物理特性变差,炼山+机械挖桩造林措施对林地土壤物理性质破坏作用要明显高于伐根催腐造林;与皆伐前相比,两种造林措施均导致了林地土壤pH向酸性化方向发展;伐根催腐造林使得林地土壤有机质含量、全N、全K、Ca和Mg含量均较皆伐前大,炼山措施导致大量养分烧失和流失,故其最小;土壤微量元素中除了Cu以炼山造林地最大外,Fe、Mn、Zn、B均以伐根催腐造林地最大。

Effect of Different Methods of Forestation on Eucalypt Plantation Soil Fertility

In order to understand soil fertility changes under euealypt plantations, the soil fertility in eucalypt plantations under two methods of site preparation were compared. The results showed that the superficial layer of soil （0 - 20 cm） became looser, because of human activities of clear cutting, site preparation and re - plant- hag. Such activities reduced soil bulk density, which improved soil water holding capacity and porosity, but the soft physical characteristics deteriorated after re - planting. Physical properties of forest softs were detrimen- tally affected by controlled burning combined with soil ripping and ploughing with stump removal compared to site preparation methods that leave stumps in place to rot. Compared with soil nutrient levels in plantations be- fore harvesting, both measures increased forest plantation soil acidity（pH declined）. Ieaving stumps in place to rot results in higher soil organic matter content and higher total N, total K, Ca and Mg contents than before clear - cutting of the plantation. Burning after felling of plantations resulted in significant loss of many nutrients, but increased soil content of the trace element nutrients Fe, Mn, Zn and B element.