Lira-Martins Demetrius, Quesada Carlos Alberto, Strekopytov Stanislav, Humphreys-Williams Emma, Herault Bruno, Lloyd Jon
Department of Life Sciences, Imperial College London, London, United Kingdom.
Department of Plant Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil.
Front Plant Sci. 2022 Apr 4;13:778403. doi: 10.3389/fpls.2022.778403. eCollection 2022.
Tropical trees store a large amount of nutrients in their woody tissues, thus triggering the question of what the functional association of these elements with other wood traits is. Given the osmotic activity of mineral elements such as potassium, sodium, and calcium, these elements should be strong candidates in mediating the water storing capacity in tropical trees. We investigated the role of wood nutrients in facilitating wood water storage in trees by using branch samples from 48 tropical tree species in South America and examined their associations with wood density (ρ). Wood density varied from 316 kg/m in Peru plots, where the soil nutrient status is relatively higher, to 908 kg/m in Brazil plots, where the nutrient availability is lower. Phosphorus content in wood varied significantly between plots with lowest values found in French Guiana (1.2 mol/m) and plots with highest values found in Peru (43.6 mol/m). Conversely, potassium in woody tissues showed a significant cross-species variation with in Brazil showing the lowest values (8.8 mol/m) and with in Peru having the highest values (114 mol/m). We found that lower wood density trees store more water in their woody tissues with cations, especially potassium, having a positive association with water storage. Specific relationships between wood cation concentrations and stem water storage potential nevertheless depend on both species' identity and growing location. Tropical trees with increased water storage capacity show lower wood density and have an increased reliance on cations to regulate this reservoir. Our study highlights that cations play a more important role in tropical tree water relations than has previously been thought, with potassium being particularly important.
热带树木在其木质组织中储存大量养分，这就引发了一个问题，即这些元素与其他木材特性之间的功能关联是什么。鉴于钾、钠和钙等矿质元素的渗透活性，这些元素应该是调节热带树木储水能力的有力候选因素。我们通过使用来自南美洲48种热带树种的树枝样本，研究了木材养分在促进树木木材储水方面的作用，并考察了它们与木材密度（ρ）的关系。木材密度在秘鲁样地中为316千克/立方米（那里土壤养分状况相对较高），到巴西样地中的908千克/立方米（那里养分有效性较低）之间变化。木材中的磷含量在样地间差异显著，法属圭亚那的样地中含量最低（1.2摩尔/立方米），秘鲁的样地中含量最高（43.6摩尔/立方米）。相反，木质组织中的钾呈现出显著的跨物种差异，巴西的含量最低（8.8摩尔/立方米），秘鲁的含量最高（114摩尔/立方米）。我们发现，木材密度较低的树木在其木质组织中储存更多水分，阳离子尤其是钾与储水呈正相关。然而，木材阳离子浓度与茎干储水潜力之间的具体关系取决于物种特性和生长地点。储水能力增强的热带树木木材密度较低，且对阳离子调节这个储水库的依赖增加。我们研究强调，阳离子在热带树木水分关系中所起的作用比之前认为的更为重要，其中钾尤为重要。
