Rhizosphere soil characteristics at different stand ages affect on plant organs’ nutrient distribution of Dendrocalamus giganteus forests following recovery of half-clump harvesting

The traditional harvesting practice for bamboo forests is selective cutting, which targets culms older than four years. In order to reduce labor and harvesting costs, new methods have been proposed in recent years, including strip harvesting for monopodial bamboos and clump harvesting for sympodial bamboos. These approaches not only lower management inputs but also emphasize the integrity and sustainability of bamboo forest ecosystems by retaining a certain number of bamboo clumps to promote natural regeneration and ecological restoration. Dendrocalamus giganteus, commonly known as Dragon bamboo, is a large, clump-forming bamboo species widely cultivated in southwestern Yunnan, China. It serves as an important raw material for construction, papermaking, and furniture manufacturing, with substantial practical and economic value. In previous studies, the research team focused on D. giganteus and investigated the growth conditions of bamboo stands under four different harvesting intensities (conventional selective harvesting, 1/3 clump harvesting, 1/2 clump harvesting, and complete clump harvesting). The results showed that 1/2 clump harvesting had the highest overall evaluation. To investigate the variation patterns of rhizosphere soil characteristics and their effects on organ nutrient distribution in D. giganteus with different stand ages after 1/2 clump harvesting restoration, 1- to 4-year-old D. giganteus were selected as the research objects. The nutrient content in plant organs, soil chemical properties, enzyme activity levels, and rhizosphere soil microbial community structure were measured. Variation patterns were analyzed, the key soil chemical factors driving changes in soil bacterial and fungal communities were identified, and a model of the influencing factors of soil chemical properties and microbial community structure on organ nutrient distribution in D. giganteus was constructed using partial least squares path modeling (PLS-PM). The main findings were as follows: (1) Rhizosphere soil nutrient contents of older bamboo culms were higher than those of younger ones after 1/2 clump harvesting recovery. (2) The dominant bacterial phyla were Proteobacteria, Acidobacteriota, and Chloroflexi, while the dominant fungal phyla were Basidiomycota and Ascomycota, 1/2 clump harvesting altered the composition of dominant fungal taxa across stand ages. (3) Soil pH, SOM, and NH4+-N were the primary factors influencing bacterial community assembly (p < 0.01), whereas fungal communities were primarily regulated by AP, pH, NH4+-N, and NO3−-N (p < 0.01). (4) Nutrient contents in roots and culms were mainly influenced by bacterial communities, while branch nutrients were more affected by soil chemical properties, and leaf nutrients were largely governed by fungal communities. The variation patterns of organ nutrient content, rhizosphere soil microbial community, and the driving factors of soil chemical properties across the age gradient of D. giganteus after 1/2 clump harvesting restoration were elucidated in this study. Important theoretical foundations and practical guidance were provided for the sustainable management of bamboo forest ecosystems.