Given the high-level physiological functions and nutrient concentrations of bark that cover the entire trunks of huge trees, research into bark nutrient traits and the development of models that estimate the bark biomass of tropical trees is essential when it is sought to understand forest nutrient cycling and tree ecological traits. This study investigated the concentrations of six bark nutrients (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na)) by individual tree size and the soil nutrient concentrations for two major pioneer species (Macaranga gigantea and M. hosei) of Malaysia. To estimate bark biomass, allometric equations using tree diameter, height, and crown diameter were developed by combining previous data from adjacent forests with the present data. We found no significant relationship between tree size and most bark nutrient concentrations, though all nutrient concentrations of the two pioneer trees were significantly higher than those of primary forest tree species. Surprisingly, no relationship was found between the soil and bark nutrient concentrations for either species. All the size parameters used in the allometric equations accurately estimated bark biomass. There were no differences in equations between the two species when diameter served as an explanatory variable, but differences were apparent when height and crown diameter were so used. A comparison of allometric equations that yielded the bark biomasses of different types of forest showed that the bark biomass of the tropical secondary forest trees was less than half of that of tropical dry forest trees of the same diameter. Thus, the use of inappropriate equations and nutrient concentrations increases the possibility of serious errors in estimating bark biomass and forest nutrient cycles.

中文翻译：

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马来西亚热带次生林树木的树皮生物量和养分浓度


鉴于覆盖巨大树木整个树干的树皮的高水平生理功能和营养浓度，在寻求了解森林养分循环和树木生态特性时，研究树皮营养特性和开发估计热带树木树皮生物量的模型至关重要。本研究调查了马来西亚两种主要先锋物种（Macaranga gigantea 和 M. hosei）的树皮养分浓度（氮 （N）、磷 （P）、钾 （K）、钙 （Ca）、镁 （Mg） 和钠 （Na））的浓度以及土壤养分浓度。为了估计树皮生物量，通过将相邻森林的先前数据与当前数据相结合，开发了使用树径、高度和树冠直径的异速生长方程。我们发现树木大小与大多数树皮营养浓度之间没有显著关系，尽管两种先驱树的所有营养浓度都显著高于原始森林树种。令人惊讶的是，这两个物种的土壤和树皮养分浓度之间都没有发现任何关系。异速生长方程中使用的所有大小参数都准确估计了树皮生物量。当直径作为解释变量时，两个物种之间的方程式没有差异，但当使用高度和冠径时，差异很明显。对产生不同类型森林树皮生物量的异速生长方程的比较表明，热带次生林树木的树皮生物量不到相同直径的热带干旱森林树木的一半。 因此，使用不适当的方程式和养分浓度会增加在估计树皮生物量和森林养分循环时出现严重错误的可能性。