山西文峪河上游河岸林的土壤种子库与树种更新特征

以山西文峪河上游13种典型的河岸林为研究对象,通过土壤种子库和树种更新研究,分析群落种子库与林下更新随演替进展的变化趋势,以及该区河岸树种的繁殖对策。结果表明：13种群落的土壤种子库密度间于1290±103～3950±154粒/m2,63.5%的种子留存于0～5 cm的层次;种子库包含49种植物,以多年生草本为主,存在耐干扰种和湿地植物的种子;处于相同或相邻演替阶段的群落,种子库相似性较高;随演替进展,种子库密度、丰度、Shannon-Wiener指数及种子库与地上植被的相似性均呈降低趋势;处于演替后期的青杄Picea wilsonii林存在丰富的＂青杄幼苗库＂;先锋种白桦Betula platyphylla的种子存在于演替各阶段的群落中,储量丰富,其更新主要依赖于风媒种子,并存在少量萌蘖;青杄、白杄P.meyeri、华北落叶松Larix principis-rupprechtii、油松Pi-nus tabulaeformis和辽东栎Quercus liaotongensis的种子库损耗严重,没有或仅存少量种子,其中云杉和油松的更新幼苗幼树多,属持久幼苗库更新;华北落叶松幼苗幼树少,且仅出现于林缘或林窗等开阔地,属植被空隙中季节性更新;辽东栎主要依赖丰富的幼苗库进行更新,同时存在一定的萌蘖;青杨Populus cathayana以大量风媒种子更新结合营养扩展。

Characteristics of Soil Seed Bank and Tree Regenerations of Riparian Forests in the Upper Reach of Wenyuhe Watershed in Shanxi Province

The soil seed banks of 13 typical riparian forests in the upper reach of the Wenyuhe watershed in Shanxi Province were studied by seed counting and indoor germinations.Seedlings and saplings of tree species were examined.With forest succession,the trend of seed bank,understory regeneration and the tree reproductive strategy were also studied.Seed densities of the 13 communities were between 1290±103 and 3950±154 seeds per square meter,with 63.5% of seeds in the soil layer of 0-5 cm.These seeds belonged to 49 species,which were mainly perennial herbs.There were both seeds of interference-resistant species and typical wetland species.Seed bank similarity index was higher among communities of the same or adjacent succession stage.With forest succession,seed diversity,species number,Shannon-Wiener index,similarity between seed bank and above vegetation all decreased.In the Picea wilsonii forest community of latter succession stage,a large number of P.wilsonii seedling appeared.The seed density of pioneer species Betula platyphylla was the biggest.Betula platyphylla was mainly regenerated by numerous wind-dispersed seeds and fewer sprouts.Because of consumption,there were fewer seeds of P.wilsonii,P.meyeri,Larix principis-rupprechtii and Pinus tabulaeformis,and no viable seeds of Quercus liaotongensis in the soil.Results showed Picea wilsonii,P.meyeri and Pinus tabulaeformis could regenerate by their persistent seedling banks.But there were fewer seedlings and saplings of L.principis-rupprechtii,which only appeared in forest gaps and edges.L.principis-rupprechtii regenerated seasonally.while Q.liaotungensis regenerated by abundant seedlings as well as sprouts.Populus cathayana was regenerated with numerous wind-dispersed seeds and certain vegetative expansion.The results would provide theoretical and technical guidance for the protection and restoration of riparian forests in the Wenyuhe watershed.