Rogers George King
Horticulture Department, Palm Beach State College, Palm Beach Gardens Campus, 395 Mallard Pt., Jupiter, FL 33458, USA.
Biology (Basel). 2025 Apr 9;14(4):391. doi: 10.3390/biology14040391.
The study of woody dicot xylem structure in relation to habitats has a long but geographically incomplete history, generating generalizations and questions still in need of expanded data. One understudied area is localized cross-habitat studies under identical climate conditions. Also sparse are intraspecific cross-habitat data. Both of these weaknesses are addressed in the present project for unstudied S. Florida. Six surveys of woody dicot branchlet microtome cross-sections allowed the microscopic comparison of vessel element (VE) diameters and VE densities. The project took place in a small area within short timeframes per survey to assure near uniformity in weather and in seasonal growth cycles. The multispecies Initial Survey and single-species Survey addressed the question of adjustments in VE diameters and/or VE densities in shaded vs. sunny habitats, finding significant downward average adjustment in VE densities in shaded hammock vs. open pineland habitats (112 shade vs. 182 VE/mm sun) but not in VE diameters. Single-species (, ) surveys examined adjustments in VE diameters and VE densities in swamp vs. scrub (diameter mean: 42.5 µm swamp, 49.2 µm scrub; density means: 179.9 swamp, 154.0 scrub). , having arguably the greatest environmental breadth and having the largest mean vessel element diameters in the project, was the sole species to adjust VE diameters only across habitats. Coefficients of variation in VE density exceeded those in VE diameters in every survey. This project sets the stage for future work in Florida and beyond aimed at isolation of environmental variables with respect to xylem traits and aimed at causal mechanisms, especially mode of xylem adjustment in relation to conductive risk.
关于木本双子叶植物木质部结构与栖息地关系的研究历史悠久，但在地域上并不完整，由此得出的一些概括和问题仍需要更多数据来充实。一个研究不足的领域是在相同气候条件下进行的局部跨栖息地研究。种内跨栖息地的数据也很稀少。本项目针对佛罗里达州南部未被研究的地区，解决了这两个不足之处。对木本双子叶植物小枝切片进行的六次调查，使得能够在显微镜下比较导管分子（VE）的直径和密度。该项目在一个小区域内进行，每次调查的时间框架较短，以确保天气和季节性生长周期近乎一致。多物种初始调查和单物种调查解决了在阴凉与阳光充足的栖息地中导管分子直径和/或密度的调整问题，发现与开阔松林栖息地相比，阴凉的吊床栖息地中导管分子密度有显著的平均下调（阴凉处为112个/毫米，阳光充足处为182个/毫米），但导管分子直径没有变化。单物种（，）调查研究了沼泽与灌丛中导管分子直径和密度的调整情况（直径平均值：沼泽为42.5微米，灌丛为49.2微米；密度平均值：沼泽为179.9个/毫米，灌丛为154.0个/毫米）。，可以说是该项目中环境跨度最大且导管分子平均直径最大的物种，是唯一仅在不同栖息地间调整导管分子直径的物种。每次调查中，导管分子密度的变异系数都超过了导管分子直径的变异系数。该项目为佛罗里达州及其他地区未来的研究奠定了基础，这些研究旨在分离与木质部特征相关的环境变量，并探究因果机制，特别是木质部调整与传导风险相关的模式。
