Plantations are playing an increasingly important role in providing forest products and improving the ecological environment, but they also face many challenges, such as low biodiversity, severe pest and disease problems, reduced productivity, and diminished soil fertility. Reasonable management strategies are vital for their sustainability. In this study, we took a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation as an example to demonstrate the effects of thinning and mixing on the species diversity and structural diversity of plantations at the stand level over a rotation period (1993–2018). An intermediate thinning (26% of plant abundance) was conducted in a Chinese fir pure plantation in mid-age (2008), and a mixed forest stand of Chinese fir and Michelia macclurei Dandy was established directly. Thinning and mixing greatly increased the species diversity at the stand level, enhanced the mixture, transformed the pattern from regular to random distribution, and made the size differentiation of trees random. Thinning and mixing also greatly improved the mixture and dominance of Chinese fir. M. macclurei had an obvious advantage in tree size and maintained a high mixture proportion. Moreover, the diameter classes of the stands were bimodal. Chinese fir and M. macclurei showed a unimodal distribution of diameter, but other later-coming species with a larger number of individuals displayed a typical reverse J-shaped distribution. Our results suggest that both thinning and mixed planting may promote species diversity and structure over a long timescale, but thinning achieves these characteristics earlier because thinning directly manipulates structure in a way that accelerates stand development.

人工林在提供森林产品和改善生态环境方面发挥着越来越重要的作用，但它们也面临许多挑战，例如生物多样性低，严重的病虫害问题，生产力下降和土壤肥力降低。合理的管理策略对其可持续性至关重要。在这项研究中，我们以杉木（Cunninghamia lanceolata（Lamb。）Hook。）人工林为例，以证明在轮伐期（1993年）间伐和混交对林分水平上人工林物种多样性和结构多样性的影响–2018）。在中年（2008年）的一个杉木纯人工林中进行了中度间伐（植物丰度的26％），以及杉木和含笑含笑的混交林分丹迪直接成立。间伐和混合极大地增加了林分水平上的物种多样性，增强了混合度，将模式从规则分布转变为随机分布，并使树木的大小分化变得随机。稀释和混合也大大改善了杉木的混合性和优势度。Macclurei分枝杆菌在树木大小上具有明显优势，并保持高混合比例。此外，林分的直径类别是双峰的。杉木和M. macclurei表现出直径的单峰分布，但是其他后来出现的具有大量个体的物种则表现出典型的反向J形分布。我们的结果表明，间伐和混种均可长期促进物种多样性和结构，但间伐可更早地实现这些特征，因为间伐直接以加速林分发育的方式操纵结构。