哀牢山森林凋落物与腐殖质及土壤的生态化学计量特征

Ecological Stoichiometry Characteristics of the Litterfall-Humus-Soil Continuum Systems under Different Successional Stages of the Subtropical Forest in SW China

以哀牢山原生中山湿性常绿阔叶林及其受损后处于恢复演替中的滇南山杨林的凋落物、腐殖质和表层土壤(0~20 cm)作为研究对象,测定不同组分的C、N、P和土壤表层有效养分含量,结果为:C、N含量表现为凋落物>腐殖质>土壤,P含量则表现为腐殖质>土壤>凋落物;铵态氮、硝态氮、有效磷含量均为腐殖质>表层土壤;凋落物的C与N呈负相关,N与P呈极显著正相关;从不同林型看:凋落物中的C、N、P含量为常绿阔叶林<滇山杨林;土壤中的C、N、P含量为常绿阔叶林>滇山杨林(p<0.05);腐殖质与表层土中的铵态氮、有效磷含量均为常绿阔叶林>滇山杨林;常绿阔叶林凋落物、腐殖质、土壤的C∶N∶P分别为615∶18∶1、159∶11∶1、84∶6∶1,滇山杨林凋落物、腐殖质、土壤的C∶N∶P分别为518∶16∶1、172∶11∶1、86∶6∶1。研究结果表明,富含P的腐殖质可能是哀牢山亚热带常绿阔叶林不存在P匮乏的主因,而两种林型各组分的C、N、P比值表明恢复演替中的滇山杨林地上、地下养分循环已经达到相对稳定的水平。

The stoichiometry of carbon（ C）,nitrogen（ N） and phosphorus（ P） in forest ecosystems indicate the nutrient turnover. In this study,we investigated nutrient（ C,N and P） variations in litters,humus soils and top mineral soils in primary evergreen broadleaved forest and restored Populus rotundifolia forest in Mt. Ailao. We observed that C and N contents were in litters in humus mineral soils,while P contents were in humus in litters mineral soils. Ammonium nitrogen,nitrate nitrogen,and available phosphorus in hums were higher than in mineral soils. Significantly negative correlation was observed between C and N,while positive correlation for N and P in litters. The C,N,and P contents exhibited distinct difference in different forests. The C,N and P contents in litters of primeval forests were significantly lower,while in mineral soils were elevated. The Ammonium nitrogen and available phosphorus in humus were both higher in primeval forest than the restored forest. Overall,for primeval forests,the C∶ N∶ P in litters,humus,and mineral soils were 615∶ 18∶ 1,159∶ 11∶ 1,84∶ 6∶ 1,respectively; for restored forest,C∶ N∶ P in litters,humus,and mineral soils were 518 ∶ 16 ∶ 1,172 ∶ 11 ∶ 1,86 ∶ 6 ∶ 1,respectively.Our results indicate the P is not the biolimiting element for two forests because of rich P in liters and humus,and relatively stable nutrient cycling has reached for two forests.