Abstract: Moso bamboo is an important species with integrated economic and ecological values. Strip harvesting is a new, efficient, and mechanized management mode of moso bamboo. Fertilization is an important measure to accelerate restoration of moso bamboo stand after harvesting. To investigate the response of understory vegetation diversity to nutrient input, we conducted a two-factor and three-level experiment in pure stands of old-growth moso bamboo after strip harvesting in 2019, with three fertilization ratios of N∶P₂O₅∶K₂O=2∶1∶1, 3.5∶1∶2, and 5∶1∶2.5 (A1, A2, A3) and three fertilization rates of 450, 600, and 750 kg·hm^-2 (B1, B2, B3). The results showed that: (1) In the year of harvesting, the diversity of understory vegetation increased with the proportion of N and K fertilizer. The Shannon index (H) and Gleason species richness index (D′) showed a significant increasing trend, with an inhibition at low proportion and a promotion at high proportion compared with the control treatment. The Simpson index (D) and Pielou evenness index (E) showed a significant unimodal trend. There was no difference in each index among different fertilization rates. (2) The significant change trend of H and D′ disappeared in 2021. D and E maintained a significant unimodal trend, peaking at A2 treatment. (3) In terms of temporal dynamics, the effect of treatments on understory vegetation diversity showed a pattern of “promotion followed by suppression”, with a decreasing trend of H, D′ and D, and an increasing trend of E in 2021 compared to 2019. (4) Similar to diversity, biomass of understory vegetation was affected by fertilization. Fertilization significantly increased understory vegetation biomass in the year of harvesting, but with a significantly negative effect in the first major-minor period after harvesting and the lowest biomass under A2 fertilization ratio. Therefore, fertilization can promote the growth of understory vegetation and increase species diversity. Under the fertilization treatment with the ratio of N∶P₂O₅∶K₂O=3.5∶1∶2, understory vegetation can make full use of nutrients, which is conducive to improving the stability of moso bamboo stand and achieving sustainable development.

Key words: moso bamboo, strip harvesting, fertilization, understory vegetation, species diversity.