黄土高原小叶杨与其他树种枯落叶混合分解对养分释放的影响

人工纯林的长期连续生长或连栽所引起的土壤性质极化是导致土壤退化和影响人工林生态系统稳定及可持续发展的重要原因,防治的根本途径是选择种间关系协调的树种进行混交改造。通过室内模拟混合分解试验,研究小叶杨与其他树种枯落叶混合分解对养分释放的影响,从而为人工纯林混交改造提供理论依据。研究结果表明:①对C释放的影响:辽东栎枯落叶表现为极强的促进作用,释放率提高21.32%,油松枯落叶表现为较弱的抑制作用,释放率降低14.78%,其他树种枯落叶作用不明显;②对N释放的影响:辽东栎枯落叶表现为极强的促进作用,释放率提高28.69%,樟子松、刺槐枯落叶促进作用较弱,释放率分别提高14.98%、13.36%,油松枯落叶表现为强烈的抑制作用,释放率降低20.33%,其他树种枯落叶作用不明显;③对P释放的影响:刺槐、辽东栎、沙棘枯落叶表现为超强的促进作用,释放率分别提高57.60%、43.06%、38.60%,紫穗槐枯落叶表现为强烈的促进作用,释放率提高22.64%,油松、樟子松枯落叶表现为超强的抑制作用,释放率分别降低62.63%、47.99%,其他树种枯落叶作用不明显;④对K释放的影响:油松枯落叶表现为较弱的抑制作用,释放率降低10.41%,其他树种枯落叶作用均不明显。

Influence of Nutrient-release of Mix-leaf Litter Decay of Populus simonii with Other Trees in the Loess Plateau

Soil polarization resulted from continuous growth and planting of pure forest stands is main cause of soil degradation and unbalanced or unsustainable development of artificial forest ecosystem.Fundamental way of controlling soil polarization is to select friendly tree species to form mixed forests.Indoor mixed decomposition experiment was conducted to study the effect of decomposition of mixed leaves of Populus simonii and other species on nutrient release,and to provide theoretical basis for artificial mixed forest formation.The results were as follows.(1).Quercus liaotungensis leaf litter strongly promoted organic carbon release with a promotion percentage of 21.32%,while Pinus tabulaeformi demonstrated suppression effect,and the release rate decreased by 14.78%.No significant effects on the organic carbon release were observed among the leaves of other tree species.(2) Q.liaotungensis leaf litter strongly increased nitrogen release with a promotion rate of 28.69%,showing significant promotion effect,for P.sylvestris var.mongolice and Robinia pseudoacacia leaf litters,however,the promotion effects were relatively weaker and nitrogen release rate increased by 14.98% and 13.36% respectively.P.tabulaeformis leaf litter exhibited strong inhabiting effect on nitrogen release,the release rate decreased by 20.33%.For the leaves of other tree species,no significant effects on nitrogen release were observed.(3) R.pseudoacacia,Q.liaotungensis,and Hippophae rhamnoides leaf litters very strongly promoted the phosphorus release rate with promotion percentages of 57.60%,43.06%,and 38.60% respectively.Amorpha fruticosa leaf litter strongly promoted phosphorus release,the promotion rate increased by 22.64%.P.tabulaeformis and P.sylvestris var.mongolica leaf litters significantly inhabited phosphorus release,the release rate reduced by 62.63% and 47.99%,respectively.The leaf litters of other tree species showed no significant influence on the phosphorus realeass.(4).Potassium(K) released:P.tabulaeformis leaf litter showed weak inhabiting effect on potassium release,the release rate reduced by 10.41%,no significant effects of others were observed.