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林业科学 ›› 2022, Vol. 58 ›› Issue (1): 1-11.doi: 10.11707/j.1001-7488.20220101

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重庆金佛山3种喀斯特森林群落木本植物种子雨、土壤种子库与幼苗更新

夏虹,夏春燕,宋海燕,杜羽,陶建平*   

  1. 三峡库区生态环境教育部重点实验室 重庆市三峡库区植物生态与资源重点实验室 西南大学生命科学学院 重庆 400715
  • 收稿日期:2020-08-30 出版日期:2022-01-25 发布日期:2022-03-08
  • 通讯作者: 陶建平
  • 基金资助:
    国家重点研发计划项目(2016YFC0502304)

Seed Rain, Soil Seed Bank, and Seedling Regeneration of Woody Plants in Three Karst Forest Communities on Jinfo Mountain, Chongqing

Hong Xia,Chunyan Xia,Haiyan Song,Yu Du,Jianping Tao*   

  1. Key Laboratory of Eco-Environments in Three Gorges Reservoir Region of the Ministry of Education Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region School of Life Science, Southwest University Chongqing 400715
  • Received:2020-08-30 Online:2022-01-25 Published:2022-03-08
  • Contact: Jianping Tao

摘要:

目的: 研究重庆金佛山3种喀斯特森林群落(常绿落叶阔叶混交林、落叶阔叶林和常绿阔叶林)木本植物种子雨和土壤种子库的组成、动态、空间分布格局及幼苗萌发情况,揭示喀斯特森林的更新潜力与发展方向,为喀斯特森林管理提供理论依据。方法: 在每种林型中随机设置9个种子雨收集器,从种子下落初始到结束,每15天收集1次,共收集8次。同时在每种林型中随机挖取6个土壤种子库样方,分枯落物层、0~2 cm土层和2~5 cm土层取样,对种子雨、种子库所收种子进行分类鉴别,并分别统计完整、虫蛀、残缺和霉腐4类种子的数量,应用氯化三苯四氮唑(TTC)染色法对所有完整种子进行活性鉴定。采用样方法调查幼苗种类和数量。结果: 3种林型种子雨的下落时间和高峰期时间基本一致;常绿阔叶林种子雨强度最大(1 453颗·m-2),其次为落叶阔叶林(486.11颗·m-2),常绿落叶阔叶混交林(152.22颗·m-2)最低,林型间种子雨强度差异显著(P<0.05);3种林型种子雨中活性种子占比(活性种子数量占完整种子数量的比例)差异显著(P<0.05),表现为常绿阔叶林(55.41%)>常绿落叶阔叶混交林(47.41%)>落叶阔叶林(44.44%);种子雨中的虫蛀、残缺和霉腐种子占种子雨总量的比例均表现为常绿落叶阔叶混交林>常绿阔叶林>落叶阔叶林;在不同时期(8月和12月),土壤种子库总储量差异显著(P < 0.05),均表现为常绿阔叶林>常绿落叶阔叶混交林>落叶阔叶林;在种子雨下落前(8月),3种林型的种子均集中分布在0~2 cm土层,其次是2~5 cm土层,枯落物层最少,但在种子雨下落后(12月),常绿落叶阔叶混交林和常绿阔叶林表现为0~2 cm土层>枯落物层>2~5 cm土层,落叶阔叶林表现为枯落物层>0~2 cm土层>2~5 cm土层;3种林型中幼苗数量差异显著,落叶阔叶林最多,其次是常绿落叶阔叶混交林,最后是常绿阔叶林(P<0.05);3种林型的种子雨、土壤种子库及幼苗间的物种相似性均较低,种子雨和土壤种子库的物种组成相似性系数在常绿阔叶林中最高,在落叶阔叶林中最低,种子雨和幼苗的物种组成相似性系数在落叶阔叶林中最高,在常绿阔叶林中最低,土壤种子库和幼苗的物种组成相似性系数在3种林型均很低。结论: 金佛山喀斯特森林木本植物的种子雨强度、土壤种子库储量较大,且活性种子占比较高,该地区森林群落有较强更新基础与潜力。但种子雨、土壤种子库及幼苗数量在不同林型中均差异显著。木本植物幼苗在落叶阔叶林下最多,而在种源最充足的常绿阔叶林下最少,说明郁闭度高、土壤含水量低的生境不利于幼苗更新。管理喀斯特森林时,需重视林型差异对幼苗更新的影响,合理规划林分结构,改善林下光照、枯落物和土壤条件,降低种子损耗,为木本植物种子萌发、幼苗建立提供良好条件,从而促进喀斯特森林更新与恢复。

关键词: 喀斯特森林, 林型, 种子雨动态, 种子库空间分布, 幼苗萌发

Abstract:

Objective: The composition, dynamics and spatial distribution pattern of seed rain, soil seed bank and seedling germination of woody plants of 3 different Karst forest, types (evergreen and deciduous mixed broad-leaved forest, deciduous broad-leaved forest and evergreen broad-leaved forest) in Jinfo Mountain were studied in order to reveal the regeneration potential and development direction of Karst forest and provide theoretical basis for Karst forest management. Method: Seed rain receptors were randomly set up in each of the forest types and collected once every 15 days from the beginning to the end of seed falling, with a total of 8 collections. At the same time, samples of soil seed bank were collected from litter layer, 0-2 cm and 2-5 cm soil layers. The seeds collected from seed rain and seed bank were identified, and the classified into four categories of complete, moth-eaten, defect and mouldy seeds each of which was counted. Finally, the vitality of the complete seeds was identified by TTC staining. In May 2020, the species and quantity of seedlings were investigated. Result: The falling time and peak time of seed rain of the three forest types are basically the same. The seed rain of evergreen broad-leaved forest had the highest intensity, reaching 1 453 seeds ·m-2, followed by deciduous broad-leaved forest and evergreen and deciduous mixed broad-leaved forest, and the proportion of vital seeds of the seed rain was significantly (P < 0.05) different among the 3 forest types, with an order of: evergreen broad-leaved forest (55.41%) > evergreen and deciduous mixed broad-leaved forest (47.41%) > deciduous broad-leaved forest (44.44%). The proportions of moth-eaten, defect and mouldy seeds to the total seed rain were in an order of: evergreen and deciduous mixed broad-leaved forest > evergreen broad-leaved forest > deciduous broad-leaved forest. During different periods (August and December), the total seed reserves in the soil seed bank were significantly (P < 0.05) different among the 3 forest types with an order of: evergreen broad-leaved forest > evergreen and deciduous mixed broad-leaved forest > deciduous broad-leaved forest. The soil seed banks of all the 3 forest types prior to the seed rain (August) were mostly concentrated in the 0-2 cm soil layer, followed by the 2-5 cm soil layer, with the least in litter layer. However, after the seed rain (December), the seed bank distribution of: the evergreen and deciduous mixed broad-leaved forest and the evergreen broad-leaved forest was in an order of 0-2 cm soil layer > litter layer > 2-5 cm soil layer, while that of deciduous broad-leaved forest was in an order of litter layer > 0-2 cm soil layer > 2-5 cm soil layer. There was a significant (P < 0.05) difference in the number of newly regenerated seedlings among the three forest types, with the largest number in the deciduous broad-leaved forest, followed by the mixed evergreen and deciduous broad-leaved forest and the evergreen broad-leaved forest. The species similarity of the 3 forest types was low among the seed rain, the seed bank and the regenerated seedlings. The similarity coefficient between the seed rain and the seed bank was the highest in the evergreen broad-leaved forest and the lowest in the deciduous broad-leaved forest. The similarity coefficient between the seed rain and the regenerated seedlings was the highest in deciduous broad-leaved forest and the lowest in evergreen broad-leaved forest. The similarity coefficient between the seed bank and the regenerated seedlings was very low in all the 3 forest types. Conclusion: The seed rain intensity, soil seed bank reserves and vital seed proportion of woody plants in Jinfo Mountain Karst forest are all large, and the forest community in this area has a strong foundation and potential for regeneration. However, there are significant differences in the seed rain, the soil seed bank and the seedling regeneration among different forest types. The number of regenerated seedlings of woody plant is the highest in the deciduous broad-leaved forest, but the lowest in the evergreen broad-leaved forest with the most abundant sources of seeds, which indicates that the habitat conditions of high canopy density and low soil water content are not conducive to regeneration. The study shows that the management of Karst forest needs to pay attention to the influence of forest type difference on seedling regeneration. Rational planning of stand structure, improving light, litter and soil conditions under forest, and reducing seed loss can provide good conditions for seed germination and seedling establishment of woody plants, therefore promoting the regeneration and restoration of Karst forest.

Key words: Karst forest, forest types, seed rain dynamics, spatial distribution of seed bank, seedling regeneration

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