中条山中段生态公益林典型森林群落天然更新特征及其影响因素

Regeneration characteristics and influencing factors of typical forest of ecological public welfare forest communities in middle section of Zhongtiao Mountain

明确森林更新特征及其影响因素,对提高森林涵养水源与水土保持效能有重要意义。中条山林区水土大量流失,植被退化严重。选取中条山中段7种典型森林群落为研究对象,从树种组成、数量特征和空间分布格局方面综合分析林下更新特征,并探究影响林下天然更新的关键因子。结果表明:1)7种群落更新树种组成差异显著(P<0.05),辽东栎为更新优势种,华山松次之。辽东栎林除外,各群落林下更新不良,更新密度最低仅为38株/hm^(2)。林下更新在2 m×2 m尺度上总体呈聚集分布,聚集强度指数最高3.36。2)枯落物与土壤厚度是影响幼苗更新的关键因子,其他因子只在特定林分发挥显著作用。山杨辽东栎混交林中,幼苗密度与枯落物厚度显著正相关(P<0.05),枯落物厚度2.7~3.7 cm时,幼苗密度较大(200~450株/hm^(2));油松辽东栎混交林中,幼苗密度与土壤厚度显著正相关(P<0.05),土壤厚度15~24 cm时,幼苗密度较大(250~675株/hm^(2))。3)同一林分内,幼树对林分密度变化的响应更敏感。后续森林经营中可通过清理枯落物、林窗补植,加快演替进程。研究结果可为该区植被的合理经营管理提供理论支持。

[Background]Because of the large amount of soil and water loss in Zhongtiao Mountains and the formation of fragmented topography over the years,the ecological environment has been destroyed,and the vegetation degradation is serious,therefore,the study of understory regeneration is of great significance for vegetation restoration and soil and water conservation.In order to clarify the present situation of natural regeneration of non-commercial forest,we should find out the key factors affecting natural regeneration,promote forest regeneration,and improve the efficiency of water and soil conservation.[Methods]Seven typical forest communities of ecological public welfare forest in the middle section of Zhongtiao Mountains were selected as the research objects,after setting plots,field investigation and data analysis,the characteristics of understory regeneration were analyzed from three aspects:species composition,quantitative characteristics and spatial distribution pattern,and the key factors affecting understory natural regeneration were explored.[Results]1)There was significant difference in species composition among the 7 species of community regeneration(P<0.05).Quercus wutaishansea was the dominant species,followed by Pinus armandii.Except Q.wutaishansea forest,the regeneration density was only 38 trees/hm^(2).The understory regeneration showed aggregation distribution on the 2 m×2 m scale,and the aggregation intensity index was the highest(3.36).2)Litter and soil thickness were the key factors affecting seedling regeneration,while topographic factors,stand density and coverage of shrub and grass only play significant roles in specific stands.In the mixed forest of Populus davidiana and Q.wutaishansea,the density of seedlings was significantly and positively correlated with the thickness of litter(P<0.05),and the density of seedlings was higher(200-450 trees/hm^(2))when the thickness of litter was 2.7-3.7 cm,while in the mixed forest of Pinus tabuliformis and Q.wutaishansea,the density of seedlings was significantly positively correlated with the thickness of soil(P<0.05),and the density of seedlings was higher(250-675 trees/hm^(2))when the thickness of soil was 15-24 cm.3)In the same stand,the seedlings and saplings responded differently to the change of stand density,and the saplings were more sensitive.[Conclusions]Scientific management measures should be taken in the follow-up forest management,which may accelerate the succession process by clearing litter and replanting gaps.This study may provide reference for adjusting stand structure and improving stand quality,and play an important role in improving protective function and comprehensive benefit of forest land and maintaining regional balance of nature.