Experimental Study on the Relationship between Density Adjustment and Understory Vegetation Restoration of Larix kaempferi in Wolong Nature Reserve

In order to explore the suitable ways to improve the habitat quality of Giant Pandas, the transformation experiment of Larix kaempferi plantations with different intensities and models were conducted in nine different areas in Wolong National Nature Reserve. Four years later, through the QUADRAT survey, the understory vegetation status of the transformed and untransformed areas, before and after transformation, artificial restoration model and natural restoration model were compared and analyzed. The results showed that: (1) Before and after the transformation, there was a strong correlation between the density of Larix kaempferi plantation and canopy density, understory shrub coverage and herb coverage. When the density of Larix kaempferi plantation after the transformation was still more than 1000 trees·hm⁻², the species and quantity of understory shrubs and grasses increased little and did not change in natural restoration. (2) When the density of Larix kaempferi was below 1000 plants·hm⁻², the species and quantity of understory shrubs and grasses increased obviously, and the growth trend was to increase with the decrease of Larix kaempferi density. When the density of Japanese Larix kaempferi was below 600 trees·hm⁻², the growth of other associated trees was more favorable than that of Larix kaempferi. (3) According to the investigation of artificial restoration experimental plots, the local common native species and bamboos, Acer davidii and Fargesia robusta, had lower survival rate and poorer growth, while the local pioneer tree species resistant to poor soil condition, Magnolia Officinalis and Alnus cremastogyne had higher survival rate and better growth.