Research on Companion Planting Techniques in the Understory of Cunninghamia lanceolata Forest with Phoebe bournei Regeneration Layer

Using a completely randomized block experimental design,the influence of different companion planting ratios and companion tree species on the growth of Phoebe bournei planted in the understory was studied.The results showed that the companion planting ratio had a highly significant effect on the growth of Phoebe bournei in the understory.Specifically,at a lower companion planting ratio (5 Phoebe bournei to 1 Camphora officinarum),it significantly promoted the growth of Phoebe bournei,while at a higher companion planting ratio (1 Phoebe bournei to 1 Camphora officinarum),it had a highly significant inhibitory effect on the growth of Phoebe bournei.Different companion tree species had a highly significant impact on the growth of Phoebe bournei in the understory,companion tree species,and the overall stand.Early-growing species such as Camphora officinarum,Liquidambar formosana,Elaeocarpus sylvestris and Schima superba were all suitable companion tree species in the construction of mixed forests with Phoebe bournei in the understory.During the cultivation process of the understory Phoebe bournei layer,mixed planting ratios that promote the growth of Phoebe bournei were all below 20%.Moreover,companion tree species grow faster than Phoebe bournei.Therefore,selecting early-growing companion tree species and maintaining a lower ratio of companion tree species was key to the technology of promoting Phoebe bournei growth in the understory mixed plantation.For high mixed planting ratio models,early harvesting of companion tree species can be achieved through thinning and selective digging to adjust interspecies relationships,improve the growth environment,and nutrient supply,thereby promoting the growth of Phoebe bournei.