Abstract:

Characterizing the composition and diversity of soil seed banks in artificial forests within coal mining subsidence areas,along with their effects on understory vegetation regeneration,provide a scientific foundation for the quality and efficiency management of plantation forests in coal mining subsidence land.Taking Pinus sylvestris var. mongholica forests with differentrestoration years(1-2,3-5,6-10 and 11-15 years)in the coal mining subsidence land in the Yushenfu mining area as the research subject,we characterized the evolutionary characteristics of soil seed bank density,composition,and diversity;deciphered the coupling relationships between the soil seed bank and aboveground vegetation;and investigated ecological drivers regulating soil seed bank features through monitoring edaphic factors,understory plant communities,and litter traits.The results showed that:1)The species composition of the soil seed bank shifted from being dominated by annual plants at 1-2 years of restoration to predominantly perennial plants after 11-15 years of recovery.2)The soil seed bank density peakedat 196 seeds/m² in years 3-5,but soil seed bank density progressively declined with the increasing stand age.The densities of Chenopodiaceae,Poaceae,Asteraceae,and Fabaceae plants reached their maximum values at 97 seeds/m² for 1-2 years,86 seeds/m² for 3-5 years,78 seeds/m² for 6-10 years,and 35 seeds/m² for 11-15 years,respectively.3)The species richness index of the soil seed bank initially increased then decreased with stand age,peaking at 6-10 years,while the Pielou evenness index and Shannon-Wiener diversity index exhibited no statistically significant changes.4)The species similarity between the understory soil seed bank and aboveground vegetation was the lowest in 1-2 years of restoration,with 9 common species of annual plants;the similarity reached a maximum value of 0.48 in 3-5 years of restoration,with a total of 12 species including both annual and biennualplants and perennial plants;and there were 11 and 10 common species in years of 6-10 and 11-15,respectively,dominated by perennialplants.5)Aboveground vegetation biomass,soil water content and total nitrogen were the common factors affecting understory soil seed density,diversity and similarity of aboveground vegetation and soil seed bank in different restoration years.In addition,soil capacity and aboveground vegetation cover in 1-2 years,aboveground vegetation density and soil organic matter in 3-5 years,litter layer thickness and cover in 6-10 years,and soil crust thickness in 11-15 years were also the heterogeneous main factors affecting understory soil seed banks in Pinus sylvestris var. mongholica forestry,the characteristics of the soil seed bank in the early succession stage of Pinus sylvestris var. mongholica forests were primarily influenced by aboveground vegetation and soil properties.As community succession progresses,the accumulation of understory litter and the formation of biological crusts exert increasing influence on the soil seed bank.In Pinus sylvestris var. mongholica forests of coal mining subsidence areas,both density and diversity of the soil seed bank decline after 10 years of succession,leading to reduced understory vegetation regeneration,seed bank supplementation and habitat optimization can effectively enhance understory vegetation recovery and improve its ecological functions.

Key words: coal mining subsidence areas, Pinus sylvestris var. mongholica forest, soil seed bank, understory vegetation renewal, ecological restoration