Bai Chunmei, Zhao Wendi, Klisz Marcin, Rossi Sergio, Shen Weijun, Guo Xiali
Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China.
Dendrolab IBL, Department of Silviculture and Genetics, Forest Research Institute, 05-090 Raszyn, Poland.
Plants (Basel). 2025 Jan 21;14(3):313. doi: 10.3390/plants14030313.
Increased tree species diversity can promote forest production by reducing intra-specific competition and promoting an efficient unitization of resources. However, questions remain on whether and how mixed stands affect the dynamics of intra-annual xylem formation in trees, especially in subtropical forests. In this study, we randomly selected 18 trees from a monoculture of 63-year-old Masson pine () growing in pure stands and mixed them with 39-year-old in Pinxiang, southern China. A total of 828 microcores were collected biweekly throughout the growing season from 2022 to 2023 to monitor the intra-annual xylem formation. Cell production started in early March and ended in late December and lasted about 281 to 284 days. Xylem phenology was similar between mixed and pure stands. During both seasons, the Masson pine in mixed stands showed higher xylem production and growth rates than those in pure stands. The Masson pine in mixed stands produced 45-51 cells in 2022 (growth rate of 0.22 cells day) and 35-41 cells in 2023 (0.17 cells day). Growth rate, and not growth seasons, determined the superior xylem growth in the mixed stands. Our study shows that after 39 years of management, Masson pine and unevenly aged mixed stands have a significant positive mixing effect on Masson pine xylem cell production, which demonstrates that monitoring intra-annual xylem growth dynamics can be an important tool to evaluate the effect of species composition and reveal the mechanisms to promote tree growth behind the mixing effect.
树木物种多样性的增加可以通过减少种内竞争和促进资源的有效利用来提高森林生产力。然而，关于混交林是否以及如何影响树木年内木质部形成动态，尤其是在亚热带森林中，仍存在疑问。在本研究中，我们从中国南方平乡一片生长着63年生马尾松纯林的单一种植林中随机选取了18棵树，并将它们与39年生的[树种名称未给出]混交。在2022年至2023年的整个生长季节，每隔两周采集总共828个微芯，以监测年内木质部形成情况。细胞生产始于3月初，结束于12月底，持续约281至284天。混交林和纯林的木质部物候相似。在两个季节中，混交林中的马尾松均表现出比纯林中更高的木质部生产和生长速率。混交林中的马尾松在2022年产生了45 - 51个细胞（生长速率为0.22个细胞/天），在2023年产生了35 - 41个细胞（0.17个细胞/天）。生长速率而非生长季节决定了混交林中木质部的优势生长。我们的研究表明，经过39年的经营，马尾松与[树种名称未给出]的年龄不均一混交林对马尾松木质部细胞生产具有显著的正向混交效应，这表明监测年内木质部生长动态可以成为评估物种组成效应以及揭示混交效应背后促进树木生长机制的重要工具。
