不同经营方式对油松成熟人工林生长和植物多样性的影响

Effects of different management methods on growth and plant diversity in mature Pinus tabuliformis plantations

【目的】基于油松成熟人工林,探索一种兼顾生态效益的大径级用材林培育方式,为我国成熟人工林的科学经营提供参考。【方法】以赤峰市旺业甸实验林场47年生和56年生油松人工林为研究对象,选取2013年和2019年调查的近自然经营、常规经营、封育管理样地乔灌草数据,采用双因素方差分析方法比较3种经营方式对油松成熟人工林胸径增长速度、死亡率、幼树更新以及乔灌草多样性的影响差异。【结果】3种经营油松成熟人工林年均胸径增长速度和6年死亡率差异均显著(P<0.05),近自然经营为0.40 cm/a和0.51%,常规经营为0.36 cm/a和1.44%,封育管理为0.31 cm/a和3.55%。6年间,近自然经营的林下植物种类增加3种,常规经营和封育管理分别减少5种和9种。47年生和56年生林分的乔木Shannon-Wiener指数和Simpson指数增长排序为近自然经营>常规经营>封育管理,更新树苗死亡率和47年生林分的草本Shannon-Wiener指数和Simpson指数下降排序为常规经营<近自然经营<封育管理;3种经营对油松成熟人工林的乔木胸径生长和死亡率以及乔灌草多样性的影响差异具有时效性。3种经营56年生油松人工林的年均胸径增长速度、乔木和灌木的Shannon-Wiener指数、Simpson指数均高于47年生人工林,但草本Shannon-Wiener指数、Simpson指数为47年生林分高于56年生林分。【结论】对油松成熟人工林进行合理经营可提升乔木胸径生长速度,降低死亡率并延缓林分植物多样性下降,表明仍有必要对成熟人工林进行合理经营,以获取更好的经济和生态效益;综合比较3种经营对油松成熟人工林大径级林木培育和植物多样性保护的效果,近自然经营是一种理想的经营方式。

[Objective]This paper aims to explore a management method that takes into account the cultivation of large-diameter tree and ecological benefits based on the mature Pinus tabuliformis plantation,as well as to provide a reference for mature plantation management in China.[Method]Taking 47-and 56-year-old P.tabuliformis plantations in Wangyedian Experimental Forest Farm in Chifeng City,Inner Mongolia of northern China as the research object,the data of sample plots under close-to-nature management(CTNM),conventional management(CM)and no human intervention(N_(H)I)were collected in 2013 and 2019.Two-factor variance analysis was used to compare the effects of three management methods on mean DBH growth rate,mortality,seedling regeneration and diversity of trees,shrubs and herbs.[Result]There were significant differences in mean DBH growth rate and 6-year mortality of mature P.tabuliformis plantations under three management methods(P<0.05),CTNM was 0.40 cm/year and 0.51%,respectively,CM was 0.36 cm/year and 1.44%,and N_(H)I was 0.31 cm/year and 3.55%.Over a span of 6 years,the number of understory plants species under CTNM increased by 3,while CM and N_(H)I decreased by 5 and 9 species respectively.The increase of Shannon-Wiener index and Simpson index of trees in 47-and 56-year-old stands in 6 years was CTNM>CM>N_(H)I,while the decrease of tree seedling mortality and the Shannon-Wiener index and Simpson index of herbs in 47-year-old stands was CM<CTNM<N_(H)I.The effects on tree growth,mortality and plant diversity under three management methods disappeared over time.The mean DBH growth rate,Shannon-Wiener indices and Simpson index of trees and shrubs in 56-year-old stands were higher than those in 47-year-old stands under three management methods.However,the Shannon-Wiener and Simpson indices of herbs were higher in the 47-year-old stands compared to the 56-year-old stands.[Conclusion]Forest management can increase the mean DBH growth rate,reduce the tree mortality and delay the decline of plant diversity of mature P.tabuliformis plantations,suggesting that mature plantation should be managed regularly to improve the economic and ecological benefits.Compared with CM and N_(H)I,CTNM is the best to maintain the plant diversity of mature P.tabuliformis plantation as well as to cultivate large-diameter tree.