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

  Objective  To explore a management regime that takes into account the cultivation of large-diameter tree and ecological benefits base 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 Pinus tabuliformis plantations in Wangyedian Experimental Forest Farm in Chifeng City as the research object, the data of sample plots under close-to-nature management (CTNM), conventional management (CM) and no human intervention (NHI) were collected in 2013 and 2019. Two-factor variance analysis was used to compare the effects of three management regimes 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 Pinus tabuliformis plantations under three management regimes (P < 0.05), CTNM was 0.40 cm/year and 3.55% respectively, CM was 0.36 cm/year and 1.44%, and NHI was 0.31 cm/year and 0.51%. The understory plants under CTNM increased 3 species in 6 years, while that decreased 5 species under CM and 9 species under NHI. The increase of Shannon-Wiener index and Simpson index of trees in 47- and 56-year-old stands in 6 years was CTNM > CM > NHI, 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 < NHI. The effects on tree growth, mortality and plant diversity under three management regimes disappeared over time. The mean DBH growth rate, Shannon-Wiener index and Simpson index of trees and herbs in 56-year-old stands were higher than that in 47-year-old stands under three management regimes.

  Conclusion  Forest management can increase the mean DBH growth rate, reduce the tree mortality and delay the decline of plant diversity of mature Pinus tabuliformis plantation, suggesting that mature plantation should be managed regularly to improve the economic and ecological benefits. Compared with CM and NHI, CTNM is the best to maintain the plant diversity of mature Pinus tabuliformis plantation as well as to cultivate large-diameter tree.