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Scientia Silvae Sinicae ›› 2022, Vol. 58 ›› Issue (1): 1-11.doi: 10.11707/j.1001-7488.20220101

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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

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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