天童山森林土壤种子库的时空格局

Spatial and temporal patterns of natural forest soil seed banks on Tiantong Mountain

土壤种子库是植物群落的潜在物种库。在中国东部典型丘陵地区天童国家森林公园内选取8类微地形,分别于2008年9月、12月和2009年3月、6月进行野外调查取样和室内实验,从总计1,960份土样中挑选种子进行鉴定及分类统计,研究其时空格局,探讨自然森林土壤种子库的基本特征及分布规律。结果显示:(1)共检出有活力的种子5,024粒,共鉴定出68个种,其中定名种65个;落叶阔叶乔木和常绿阔叶小乔木物种数量以及种子数量均占优势;土壤种子库与地上植被共有种为48种,相似性系数为0.45。(2)2级和3级顶坡及下部边坡、麓坡、泛滥性阶地种子库储量较大,而高上部边坡、中上部边坡和低上部边坡种子库储量较小。雷公鹅耳枥(Carpinus viminea)和细枝柃(Eurya loquaiana)是各个微地形单元种子库的优势种。其他优势种中,上部坡面的微地形主要为格药柃(E.muri-cata)、短梗冬青(Ilex buergeri)、黑山山矾(Symplocos heishanensis)、四川山矾(S.setchuensis)等常绿树种,而下部坡面的微地形主要为南酸枣(Choerospondias axillaris)、橄榄槭(Acer olivaceum)、西川朴(Celtis vandervoetiana)等落叶树种。(3)土壤种子库储量在垂直空间上的分布是0-2cm土层>2-5cm土层>5-10cm土层>枯枝落叶层。(4)土壤种子库具有明显的季节动态,其储量在各个取样时间中的分布为12月>3月>9月>6月。

Soil seed bank represents a pool of potential species for a plant community.We analyzed spatio-temporal patterns of natural forest seed banks on Mt.Tiantong,a typically hilly region in East China.Eight micro-landform units,i.e.,second and third crest slopes,higher-,middle-and lower-upper sideslope,lower sideslope,foot slope,and flood terrace were used as classes in our analyses.Seeds were identified from a total of 1,960 samples collected in September 2008,December 2008,March 2009 and June 2009.The results are summarized as follows：（1） The total number of viable seeds was 5,024 and 68 taxa were identified,among which 65 species were identified to species level from the samples.Among these identified species 48 were present in the above-ground vegetation and the Czekanowski community similarity was 0.45.Deciduous broad-leaved trees and evergreen broad-leaved sub-canopy trees were the main components of soil seed banks according to the number of seeds and species.（2） The reserves on crest slopes and lower hillside areas were higher than those on the upper sideslopes（H-US,M-US and L-US）.Carpinus viminea and Eurya loquaiana dominated in nearly all the micro-landforms.Otherwise,evergreen trees such as E.muricata,Ilex buergeri,Symplocos heishanensis and S.setchuensis were the dominant species in upper hillside areas,while deciduous trees such as Choerospondias axillaris,Acer olivaceum,Celtis vandervoetiana dominated in lower hillside areas.（3） Reserves of four vertical soil layers varied in size,with the peak at 0-2 cm soil layer,followed by 2-5 cm soil layer and 5-10 cm soil layer,while those in the litter layer were the smallest.（4）The soil seed banks showed seasonal variation,with the peak of reserves found in December 2008,followed by March 2009,September 2008 and June 2009 in descending order.