辽东山区次生林不同大小林窗土壤养分特征

Characteristics of Soil Nutrients Within Canopy Gaps of Various Sizes in Secondary Forests in Eastern Mountainous Regions of Liaoning Province,China

以辽东山区天然次生林中3种(大、中、小)林窗为对象,通过对林窗内土壤养分质量分数的监测,探讨了林窗形成早期对土壤养分状况的影响。结果表明:与非林窗(对照林分)相比,3种林窗对土壤有机碳、全氮和全磷的质量分数无显著影响;而土壤铵态氮、硝态氮、速效磷和微生物生物量磷的质量分数则显著增加(P<0.05),且增加幅度与林窗大小有关:土壤硝态氮、速效磷和微生物生物量磷的质量分数表现为小林窗高,中林窗居中,大林窗低;相关分析发现,土壤微生物生物量磷与速效磷、铵态氮及土壤含水量显著相关(P<0.05)。

Effects of gap sizes on soil nutrients in the early stage of gap formation were studied by observing soil nutrients within the gaps with three different sizes （large, medium and small） in secondary forests in eastern Liaoning Mountainous Region, China. Results showed that, compared with the forest stands （the control）, there were no significant differences in soil organic carbon, total nitrogen and total phosphorus among the three gaps of different sizes. Ammonium nitrogen, nitrate nitrogen, available P and microbial biomass P were significantly higher within gaps than those in the control. The concentrations of nitrate nitrogen, available P and microbial biomass P were the highest in the small gap, followed by the medium gap and the large gap in order. Moreover, microbial biomass P had significant positive correlation with available P, ammonium nitrogen and soil water content（ P〈0.05 ）. These results indicate that the fluctuations of soil available nutrients in the secondary forest gaps are closely related to gap sizes, and the soil available nutrients, especially available N and P, are better in the small gap than those in the medium and large gaps.