不同造林抚育干扰下桉树幼林地水土流失特征

目的]探讨不同造林抚育措施对桉树幼林地水土流失及其养分损耗的影响,为桉树人工林的科学栽培和可持续经营提供理论依据。方法]建立8个地表径流小区,以桉树采伐地灌草坡做对照(CK),研究人工割灌割草清理林地和除草、只施基肥不追肥的植苗更新2代林地(A处理),火烧清理林地、化学除草、施基肥和追肥的植苗更新2代林地(B处理)和人工割灌割草清理林地和除草、施基肥和追肥的萌芽更新2代林地(C处理)的水土流失特征。结果]B处理林地的地表径流量、泥沙流失量和N,P,K养分流失总量年均值分别为129.35 mm,642.52kg/(hm2·a)和32.923kg/(hm2.a),比A处理的分别高出7.93%,90.03%和46.89%,比C处理的分别高出4.95%,70.82%和49.17%,比CK(对照)的分别高出4.98%,109.93%和50.91%;各试验林地的地表径流量和泥沙流失量与降水量之间均呈极显著线性正相关(R=0.717~0.853)。结论]火烧清理林地、化学除草、频繁施肥等人为干扰活动及大量级降水驱动是桉树幼林林地水土流失及其养分损耗较为强烈的主要原因。

Features of Soil and Water Loss of Eucalypt Young Forest Under Different Afforestation-tending Disturbances

Soil erosion and nutrients loss of Eucalyptus young forest by different kinds of afforestation and tending measures were studied to promote the scientific management of Eucalyptus plantation.Methods] Two runoff plots in each of three afforestation-tended lands(management treatments A, B and C) and of a Eucalypt-deforested land(CK) were set up to study the characteristics of soil erosion and water loss of Eucalyptus young forest. Managemsnt A was located on a regenerated Eucalypt seedling land with basic fertilization but no topdressing after the woods and weeds were manually cut and removed. Management B was on a regenerated seedling forest land with both of basic fertilization and topdressing after of fire clearing and chemical weeding. Management C was on a sprout regenerated forest land with both of basic fertilizing and topdressing after it was artificially cleared of woods and weeds.Results] The annual average of surface runoff, sediment erosion and the total nutrients losses of N, P, K of management B were 129.35 mm, 642.52 kg/(hm²·a) and 32.923 kg/(hm²·a), respectively, which were higher than that of A-manage by 7.93%, 90.03% and 46.89%, respectively; and were higher than that of C-manage by 4.95%, 70.82% and 49.17%, respectively; and also were higher than that of CK by 4.98%, 109.93% and 50.95%, respectively. There were extremely significant and positive linear correlations among rainfall, the surface flow and the sediment erosion of the experiment woodlands(R=0.717~0.853).Conclusion] Artificial interferences such as clearing land with fire, chemical weeding, frequently fertilization, and a large number of precipitation level are the main causes of heavy soil erosion and the nutrient loss of Eucalyptus young forest woodland.