岩溶石漠化区不同植被类型表土孢粉组合特征——以重庆市南川区南平镇石漠化区为例

Features of spore-pollen assemblage in topsoil under different vegetation types in karst desert——A case in Nanping Town,Nanchuan District,Chongqing

通过对南平次生林地、杂草丛、坡耕地不同植被类型表土调查和采样,利用LuoPacias孢粉鉴定系统对所采的表土样品进行分析鉴定,以研究该区表土的孢粉组合特征。结果显示：（1）样品植物孢粉共由123种植物组成,其中以草本和蕨类植物占据优势,其孢粉含量为46.40%~76.47%,平均为65.55%,其次是乔木（主要为马尾松）,花粉含量为17.73%~46.84%,平均为26.40%,灌木植物花粉含量最小,为5.79%~12.50%,平均为8.26%,显示该区植被退化严重;（2）不同植被类型的表土孢粉组合差别明显,次生马尾松林和次生樟树林的孢粉组合特征依次为马尾松—火棘—大楼梯草—里白和樟树—火棘—构棘—泽芹;杂草丛为裂叶荨麻—圆叶藜—车前子—里白;坡耕地为异叶花椒—裂叶荨麻—剑叶凤尾蕨—玉米,与其相应的实际植被情况大致相同,较好地反映出了石漠化地区现代植被的基本状况。

Through survey and sampling to the topsoil under secondary forests,weeds and slope farmlands in Nanping,spore-pollen is identified by means of LuoPacias method to study the features of the spore-pollen assemblage.The result shows that：（1） the spore-pollen is composed of 123 species,among which,herbs and ferns dominate in quantity with the spore-pollen content of 46.40%～76.47% and averaged 65.55%;the arbors（mainly Pinus massoniana Lamb.） takes the 2nd place with the content about 17.73%～46.84% and averaged 26.40%;and the shrub spore-pollen is the least,about 5.79%～12.50% in content and averaged 8.26%,that indicating a serious degradation of local vegetation;（2） there is obvious differentiation in different vegetation types.The spore-pollen assemblages of the secondary masson pine forest and the secondary camphor forest are listed as Pinus massoniana Lamb.-Pyracantha fortuneana Li.-Elatostema umbellatum Bl.-Hicriopteris glauca Thunb.and Cinnamomum camphora L.-Pyracantha fortuneana Li.-Cudrania cochinchinensis L.-Sium suave Walt.respectively;the spore-pollen assemblage of weeds is Urtica fissa Pritz.-Chenopodium acuminatumPlantago asiatica L.-Hicriopteris glauca Thunb.;the pollen assemblage of the slope farmland is Zanthoxylum dimorphoppyllum Hemsl.-Urtica fissa Pritz.-Pteris ensiformis Burm.-Zea mays L.,which corresponding to the actual vegetation and reflecting the present conditions of the modern vegetation cover in the karst desert.