【摘要】 为阐明不同林龄人工梭梭对干旱荒漠区土壤养分利用机制及时空演变趋势,选取了乌兰布和西南缘营建年限为2,5,10,15,30 a的人工梭梭为研究对象,通过野外调查与室内试验的方法,分析了不同林龄梭梭土壤养分空间分布及其富集效应。结果表明:(1)人工梭梭土壤养分表现出显著的成层化分布特征,整体表现为0—10 cm>10—20 cm>20—40 cm,其中表层土壤有机质、碱解氮、速效磷和速效钾均比深层平均高82.0%,228.2%,172.7%,39.0%,表层土壤养分积累更明显,说明表层土壤中的大部分养分主要从植物的枯落物质中获得。(2)水平方向土壤养分含量在15～30 a表现出显著差异,根部、灌丛内及株间空地土壤有机质、碱解氮、速效磷及速效钾分别增高了30.8%和38.0%,196.7%和15.6%,22.5%和8.3%,56.4%和10.6%,且富集率显著高于其他林龄,表层(0—10 cm,10—20 cm)表现出随林龄增高而增加的趋势,深层(20—40 cm)则先降低后升高。说明人工梭梭林在种植15 a后其土壤养分"肥岛"效应强于低林龄,而在10 a生长旺盛,养分消耗量大,"肥岛"效应较弱。(3)梭梭各生长指标均与有机质和碱解氮富集率显著相关(p<0.05),其中与有机质极显著相关(p<0.01),说明随着林龄的增加,土壤有机质与碱解氮含量累积较为明显。其中有机质的空间异质性最明显,而速效磷、钾时空异质性较弱。由此也进一步表明了干旱荒漠区人工梭梭与土壤养分间具有明显的时空耦合关系。更多还原

【Abstract】 In order to clarify the spatial and temporal evolution trend of soil nutrient utilization mechanism of planted Haloxylon ammodendron in arid desert areas, the planted Haloxylon ammodendron with the plantation ages of 2 years, 5 years, 10 years, 15 year, and 30 years in the southwestern margin of Ulan Buh were selected as the research samples. The spatial distribution and enrichment effects of soil nutrients in different ages of Haloxylon ammodendron were analyzed by field investigation and laboratory experiments. The conclusions were drawn as follows.(1) The soil nutrients of the planted sand bogs of different ages demonstrated the significant stratification distribution, the nutrient contents decreased in the order: 0—10 cm>10—20 cm>20—40 cm, among them, soil organic matter, alkali nitrogen, available phosphorus and available potassium of surface layer were 82.0%, 228.2%, 172.7% and 39.0% higher than the averages of deep layers, and the accumulation of nutrients in surface soil was more obvious, indicating that most of the nutrients in the topsoil mainly resulted from plants litter material.(2) The soil nutrient content in the horizontal direction showed significant difference in 15～30 years, soil organic matter, alkali nitrogen, available phosphorus and available potassium in roots, shrubs and intercropping increased by 30.8% and 38.0%, 196.7% and 15.6%, 22.5% and 8.3%, and 56.4% and 10.6%, respectively. The enrichment rates were significantly higher than other forest ages. The nutrients in surface layers(0—10 cm, 10—20 cm) increased with the increase of forest age, while the nutrients in the deep layer(20—40 cm) decreased first and then rose. The results showed that the soil ‘fertile island’ of the artificial Haloxylon ammodendron was stronger than that of the low forest age, because the nutrient accumulation rate was strong and the nutrient consumption was large in 10 years, the ‘fertile island’ was weak.(3) The growth indexes of Haloxylon ammodendron were closely related to the enrichment and distribution of soil organic matter and alkali nitrogen, indicating that soil organic matter and alkali nitrogen content are more heterogeneous in space-time heterogeneity. Spatial and temporal heterogeneity of potassium is weak, which indicates that there is a significant spatial and temporal coupling relationship between planted Haloxylon ammodendron and soil nutrients in the arid desert areas.更多还原