哀牢山湿性常绿阔叶林林冠和林地腐殖质理化特性、微生物量及酶活性比较

Comparison of physical and chemical properties and microbial biomass and enzyme activities of humus from canopy and forest floor in a montane moist evergreen broad-leaved forest in Ailao Mts.,Yunnan

在热带、亚热带和温带高海拔潮湿生境的山地森林林冠层中,积累有较为丰富的林冠腐殖质(Canopy humus),是构成山地森林生态系统景观结构的重要组分,为丰富的附生植物提供了重要的生长基质和营养物质。通过对云南哀牢山山地湿性常绿阔叶林林冠腐殖质和其相应林下地表腐殖质的分析测定结果表明,由于林冠和林下地表腐殖质的来源、组成和空间分布的不同,它们之间的理化特性存在较大的差异,其中林冠腐殖质中有机C、全N及全Ca的含量、C/N以及阳离子交换量显著高于林下地表腐殖质,而全K和全Mg的含量则显著低于后者,全P含量差异不明显;林冠腐殖质的微生物量C、N和呼吸强度,以及蔗糖酶、脲酶和蛋白酶的活性均显著高于林下地表腐殖质,说明林冠腐殖质是一种具有较高生物活性的有机土类物质,在山地森林生态系统养分循环、林冠附生植物多样性格局形成及其维持方面具有重要的作用。

There are considerable amounts of canopy humus within the crowns of trees in tropical,subtropical and temperate montane moist forests.As an important structural component,the canopy humus provides essential substrates and nutrients for the growth of abundant epiphytes.In this study,the physical and chemical properties,microbial biomass and enzyme activities of humus from both canopy and forest floor were analyzed in a subtropical montane moist evergreen broad-leaved forest in Ailao Mts.,Yunnan.The significant differences in the physical and chemical properties and microbial activities were found between the canopy humus and humus from forest floor,due to differences in origins,composition of humus and spatial distribution patterns.The concentration of organic C,total N,total Ca,as well as C/N ratio and cation exchange capacity were significantly higher in canopy humus,whereas higher concentrations of total K and total Mg were observed in the humus from forest floor.There was no significant difference in total P concentration between two humus types.The microbial biomass C and N,respiration rate,as well as activities of sucrase,urease and protease were significantly greater in canopy humus than its terrestrial counterpart.These results indicated that canopy humus belong to a category of organic histosol with high nutrients content and microbial activities,and thus it could play important roles in nutrients cycling,maintenance of species diversity pattern of epiphytes in the montane moist evergreen broad-leaved forest ecosystems.