天山中部天山云杉林土壤种子库年际变化

通过定点采样,采用萌发法对天山中部天山云杉(Picea schrenkiana Fisch.et Mey.)近熟林(101-120a)和成熟林(121-160a) 2004-2011年(8a)土壤种子库物种组成、种子密度的年际变化和不同间隔年限土壤种子库物种组成的相似性进行了分析.结果表明:(1)土壤种子库中共萌发鉴定出种子植物87种,隶属29科70属,其中乔木种子植物2种,灌木种子植物2种,草本种子植物83种,土壤种子库中草本植物种子密度远远大于木本植物种子密度；8个采样年份土壤种子库恒有种仅有6种；(2)土壤种子库种子密度及其中天山云杉种子密度存在巨大的年际变动,且不具有同步性；土壤种子库种子密度最大(2009年)值为(953.75±66.12)粒/m2,最小(2008年)值为(186.50±20.37)粒/m2,其中天山云杉种子密度最高(2006年)达到(584.50±53.58)粒/m2,最低(2005年)仅有(0.25±0.26)粒/m2；(3)天山云杉林土壤种子库年际间物种组成的相似性不高,Czekanowski相似系数均值仅为0.344,并随间隔年限的增加呈现减小—增大—减小的变化趋势.天山云杉林土壤种子库物种组成和种子密度稳定性差,年际间相差悬殊,物种组成的相似性不高,种子库中天山云杉种子密度主要受其种子库采样前一年天山云杉结实丰歉的影响,属间断型.土壤种子库年际变化特征可为天山森林的更新恢复和可持续经营提供科学依据.

Interannual variation of soil seed bank in Picea schrenkiana forest in the central part of the Tianshan Mountains

Species composition, inter-annual variations of seed density, similarities at different intervals of the species composition in soil seed bank were examined using germination method in the P. schrenkiana near mature forest (101-120a) and mature forest (121-160a) from 2004 to 2011. Total 87 species which belonged to 29 families and 70 genera were identified from soil seed bank. Among them, 2 kinds of tree plants, 2 kinds of shrub plants, and 83 kinds of herb plants were concluded. Additionally, the density of herb seeds in soil seed bank was far greater than that of woody. There were only 6 constant species among 8 sampling years of soil seed bank. There was a huge inter-annual variation which was not synchronous in the seed density of soil seed bank and the seed density of P. schrenkiana. The maximum value of density of soil seed bank which appearing in 2009 was (953.75 ± 66.12) seeds/m², and the minimum value in 2008 was (186.50±20.37) seeds/m². The highest value of seed density of P. schrenkiana reached to (584.50±53.58) seeds/m² in 2006, while the lowest was only (0.25±0.26) seeds/m² in 2005. Inter-annual variations of species composition in soil seed bank of P. schrenkiana forest had not the similarity. The average of Czekanowski similarity coefficient was 0.344, which showed decrease- increase-decrease trend with the increase of the year's intervals. Species composition and seed density in soil seed bank of P. schrenkiana was not consistency, the differences between inter-annuals were significant,the similarity of species composition was not high. The seed density of P. schrenkiana in soil seed bank which changed in discontinuous was mainly influenced by the production of seed harvests at the year before. The research of inter-annual variation of the soil seed bank could provide scientific basis for forest regeneration, restoration and sustainable management in the Tianshan Mountains.