Zhu Jing, Jiang Lan, Chen Lyuyi, Jin Xing, Xing Cong, Liu Jinfu, Yang Yongchuan, He Zhongsheng
Key Laboratory of Fujian Universities for Ecology and Resource Statistics, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China.
Entomology and Nematology Department, University of Florida, Gainesville, FL, United States.
Front Plant Sci. 2023 Jun 2;14:1099139. doi: 10.3389/fpls.2023.1099139. eCollection 2023.
Plants allocate growth to different organs as a strategy to obtain limiting resources in different environments. Tree seeds that fall from a mother tree settle on, within, or below the forest floor and litter layer, and their relative positions can determine seedling biomass and nutrient allocation and ultimately affect survival to the sapling stage. However, how emerged seedling biomass and nutrients of each organ are affected by seeds in different positions is not yet completely understood in subtropical forests. Therefore, an experiment was conducted with seeds positioned above the litter layers of different thicknesses, on the forest floor, and beneath the litter layer, and the influences of seed position on biomass allocation and nutrient use efficiency of emerged seedlings of was examined. The aim of the study was to determine the optimal seed position to promote regeneration. Allocation strategies were well coordinated in the emerged seedlings from different seed positions. Seedlings from seeds positioned above litter layers of different thicknesses (40 and 80 g of litter) allocated growth to leaf tissue at the expense of root tissue (lower root mass fraction) and increased nitrogen (N) and phosphorus (P) accumulation and nutrient use efficiency. Seedlings from seeds positioned beneath a deep litter layer allocated most growth to roots (high root: shoot ratio, root mass fraction) to capture available resources at the expense of leaf growth. Seedlings from seeds positioned on the forest floor allocated most growth to roots to obtain limiting resources. Further, we also found that these traits were clustered into three groups based on trait similarity, and the cumulative interpretation rate was 74.2%. Thus, seed relative positions significantly affected seedling growth by altering the allocation of resources to different organs. The different strategies indicated that root N:P ratios (entropy weight vector was 0.078) and P nutrient use efficiency were essential factors affecting seedling growth in the subtropical forest. Of the seed positions analyzed, beneath a moderate litter layer (40 g of litter) was the most suitable position for the growth and survival of seedlings. In future studies, field and lab experiments will be combined to reveal the mechanisms underlying forest regeneration.
植物将生长分配到不同器官，作为在不同环境中获取有限资源的一种策略。从母树上掉落的树木种子落在森林地面和枯枝落叶层之上、之中或之下，它们的相对位置可以决定幼苗的生物量和养分分配，并最终影响到幼树阶段的存活。然而，在亚热带森林中，不同位置的种子如何影响出土幼苗的生物量和各器官的养分，目前尚未完全清楚。因此，我们进行了一项实验，将种子放置在不同厚度的枯枝落叶层之上、森林地面以及枯枝落叶层之下，研究种子位置对出土幼苗生物量分配和养分利用效率的影响。本研究的目的是确定促进再生的最佳种子位置。不同种子位置出土的幼苗中，分配策略得到了很好的协调。来自不同厚度（约40克和80克枯枝落叶）枯枝落叶层之上种子的幼苗，将生长分配到叶片组织，以根系组织为代价（较低的根质量分数），并增加了氮（N）和磷（P）的积累以及养分利用效率。来自深枯枝落叶层之下种子的幼苗，将大部分生长分配到根系（高根:茎比、根质量分数），以牺牲叶片生长为代价来获取可用资源。来自森林地面种子的幼苗，将大部分生长分配到根系以获取有限资源。此外，我们还发现，这些性状根据性状相似性聚为三组，累积解释率为74.2%。因此，种子的相对位置通过改变资源向不同器官的分配，显著影响幼苗生长。不同的策略表明，根氮磷比（熵权向量为0.078）和磷养分利用效率是影响亚热带森林幼苗生长的关键因素。在所分析的种子位置中，中等厚度（约40克枯枝落叶）的枯枝落叶层之下是[具体树种]幼苗生长和存活的最合适位置。在未来的研究中，将结合野外和实验室实验来揭示森林更新的潜在机制。
