天然次生林转变成长白落叶松人工林后土壤养分的变化

Change of Soil Nutrients after Converting Natural Secondary Forest into Larix olgensis Plantations

在东北林业大学森林实验站天然次生林地及天然次生林带状皆伐后营造的31年生长白落叶松(Larix olgensis)纯林地、长白落叶松水曲柳(Fraxinus mandshurica)混交林地、长白落叶松胡桃楸(Juglans mandshurica)混交林地,采集不同土层(h)0<h≤10 cm、10 cm<h≤20 cm、20 cm<h≤30 cm土壤样品,分析不同样地土壤中有机C、全N、全P、水解N、有效P的差异,探索天然次生林转化为长白落叶松人工林后土壤养分的变化。结果表明:①天然次生林转变成长白落叶松人工林后,各层土壤的有机C、全N、水解N质量分数显著降低,分别降低19.58%~66.07%、31.20%~55.26%、34.76%~64.92%;0<h≤10 cm和10 cm<h≤20 cm土层,全P质量分数降低3.16%~20.36%;0<h≤10 cm土层,有效P质量分数降低2.58%~33.32%。②长白落叶松水曲柳混交林,各层土壤的有机C、水解N质量分数、N元素活化能力,均显著高于长白落叶松纯林,分别提高19.90%~77.29%、15.39%~85.95%、2.81×10-3~9.35×10-3;长白落叶松胡桃楸混交林,各层土壤有效P质量分数、P元素活化能力,均高于长白落叶松纯林,分别提高3.52%~17.98%、1.20×10-3~4.12×10-3;长白落叶松水曲柳混交林,各层土壤有效P的供给、P元素活化能力,低于长白落叶松纯林,分别降低14.54%~29.63%、2.11×10-3~3.63×10-3;长白落叶松胡桃楸混交林,各层土壤全P质量分数低于长白落叶松纯林,降低9.88%~12.52%。③与长白落叶松胡桃楸混交林相比,长白落叶松水曲柳混交林其各层土壤的有机C、水解N的供给能力及N元素的活化能力更强,但其各层土壤有效P的供给能力及P元素的活化能力较差。若采用长白落叶松人工林恢复天然次生林采伐后的山地,从土壤保肥角度考虑,建议优先选择长白落叶松水曲柳混交林,并注意土壤有效P肥的及时补充。

With 31-a pure Larix olgensis plantation,L.olgensis and Fraxinus mandshurica mixed plantation,L.olgensis and Juglans mandshurica mixed plantation which was planted on the strip clear cutting land of natural secondary forest and natural secondary forest in the Forest Cultivation Experiment Station of Northeast Forestry University,the soil samples of different soil layers(h),0<h≤10 cm,10 cm<h≤20 cm,and 20 cm<h≤30 cm were collected to analyze the differences of organic C,total N,total P,hydrolyzed N,and effective P mass fraction in different soils,to explore the changes of soil nutrients after the transformation of natural secondary forest into Larch plantation.The results showed that:①Every soil layer of organic C mass fraction,total N mass fraction and available N mass fraction was reduced significantly,which was reduced by 19.58%-66.07%,31.20%-55.26%,and 34.76%-64.92%,respectively,after converting natural secondary forest into L.olgensis plantations.②Every soil layer of organic C,available N mass fraction and activation capacity of N element in L.olgensis and F.mandshurica mixed plantation were significantly higher than that of pure L.olgensis plantation,which were increased by 19.90%-77.29%,15.39%-85.95%,and 2.81×10^-3-9.35×10^-3,respectively.Every soil layer of available P mass fraction,activation capacity of P element in L.olgensis and J.mandshurica mixed plantation were higher than that in pure L.olgensis plantation,which were increased by 3.52%-17.98%and 1.20×10^-3-4.12×10^-3,respectively.Every soil layers of available P content in L.olgensis and F.mandshurica mixed plantation was lower significantly than that of pure L.olgensis plantation,which were reduced by 14.54%-29.63%and 2.11×10^-3-3.63×10^-3,respectively.Every soil layer of total P mass fraction in L.olgensis and J.mandshurica mixed plantation was lower than that in pure L.olgensis plantation,which was reduced by 9.88%-12.52%.③All soil layers of C content,available N content and activation capacity of N element in L.olgensis×F.mandshurica mixed plantation was significantly higher than that in L.olgensis and J.mandshurica mixed plantation.Every soil layers of available P content and activation capacity of P element in L.olgensis and F.mandshurica mixed plantation was significantly lower than that in L.olgensis and J.mandshurica mixed plantation.From the perspective of protecting soil fertility,if we recovered mountains with L.olgensis plantations after cutting the natural secondary forest,L.olgensis and F.mandshurica mixed plantation should be preferred,and available soil P fertilizer should be supplied in time.