普洱市周边地区4种土地利用类型土壤种子库特征

通过对云南普洱市周边地区次生季风常绿阔叶林、针阔混交林、人工更新形成的针叶林及茶园等4种土地利用类型的野外调查及土壤种子库的萌发实验,探讨其土壤种子库的密度大小、物种丰富度和组成及与地上植被的关系。结果表明:干扰强度与频度不同导致土地利用类型之间土壤种子库密度与物种丰富度存在较大差异,土壤种子库密度大小顺序为:针叶林(248.67±116.86)粒·m-2>针阔混交林(186.00±43.27)粒·m-2>次生季风常绿阔叶林(107.33±16.48)粒·m-2>茶园(51.67±10.17)粒·m-2;茶园土壤种子库物种丰富度要显著低于其他类型。4种土地利用类型土壤种子库生活型组成差异极显著,主要以草本植物组成,以菊科与禾本科占优势;针阔混交林的草本植物种子密度最多,非森林的原生物种是草本植物的主要组成;针叶林外来物种的种子密度要显著高于其他类型,紫茎泽兰(Eupatorium adenophorum)是其主要组成。土壤种子库与地上植被的相似性系数较低,其大小顺序为:次生季风常绿阔叶林(0.175)<针阔混交林(0.176)<针叶林(0.215)。

Soil seed bank characteristics of four land use types in the surrounding areas of Pu'er City, Yunnan Province of Southwest China

Based on the field survey data and the germination experiment of the soil seed banks of four land use types (secondary monsoon broad-leaved evergreen forest, coniferous and broad-leaved mixed forest, coniferous forest formed after human-assisted natural regeneration, and Camellia sinensis var. assamica plantation) in the surrounding areas of Pu’er City, this paper studied the soil seed bank density, its species richness and composition, and its relationships with aboveground vegetations of the four land use types. There existed greater differences in the soil seed bank density and its species richness and composition among the four land use types, due to the different disturbance intensity and frequency. The soil seed bank density was the highest in coniferous forest formed after human-assisted natural regeneration (248.67±116.86 seeds·m-2), followed by in coniferous and broad-leaved mixed forest (186.00±43.27 seeds·m-2), secondary monsoon broad-leaved evergreen forest (107.33±16.48 seeds·m-2), and C. sinensis var. assamica plantation (51.67±10.17 seeds·m-2). The species richness of the soil seed bank in C. sinensis var. assamica plantation was significantly lower than that in other land use types. There also existed significant differences in the life forms of the soil seed banks among the four land use types. Herbaceous plants, especially Poaceae and Compositae, dominated the soil seed banks. Coniferous and broad-leaved mixed forest had the highest proportion of herbaceous plants (mostly native plants) in its soil seed bank, while coniferous forest had the highest proportion of non-native herbaceous plants (mainly Eupatorium adenophorum) in its soil seed bank. The similarity coefficient of the species composition between soil seed bank and aboveground vegetation was relatively low, and was the highest in coniferous forest formed after human-assisted natural regeneration (0.215), followed by in coniferous and broad-leaved mixed forest (0.176) and secondary monsoon broad-leaved evergreen forest (0.175).