Tropical montane forests provide an important natural laboratory to test ecological theory. While it is well-known that some aspects of forest structure change with altitude, little is known on the effects of altitude on above ground biomass (AGB), particularly with regard to changing height-diameter allometry. To address this we investigate (1) the effects of altitude on height-diameter allometry, (2) how different height-diameter allometric models affect above ground biomass estimates; and (3) how other forest structural, taxonomic and environmental attributes affect above ground biomass using 30 permanent sample plots (1-ha; all trees ≥ 10 cm diameter measured) established between 1250 and 2600 m asl in Kahuzi Biega National Park in eastern Democratic Republic of Congo. Forest structure and species composition differed with increasing altitude, with four forest types identified. Different height-diameter allometric models performed better with the different forest types, as trees got smaller with increasing altitude. Above ground biomass ranged from 168 to 290 Mg ha-1, but there were no significant differences in AGB between forests types, as tree size decreased but stem density increased with increasing altitude. Forest structure had greater effects on above ground biomass than forest diversity. Soil attributes (K and acidity, pH) also significantly affected above ground biomass. Results show how forest structural, taxonomic and environmental attributes affect above ground biomass in African tropical montane forests. They particularly highlight that the use of regional height-diameter models introduces significant biases in above ground biomass estimates, and that different height-diameter models might be preferred for different forest types, and these should be considered in future studies.
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机译：热带山地森林为检验生态学理论提供了重要的天然实验室。众所周知，森林结构的某些方面会随着海拔高度的变化而变化，但对于海拔高度对地上生物量（AGB）的影响知之甚少，尤其是在改变高度直径异径比方面。为了解决这个问题，我们研究了（1）高度对高度直径异速测量法的影响；（2）不同高度直径异速测量模型如何影响地面生物量估计值；以及（3）在民主东部的卡胡兹·比加国家公园（Kahuzi Biega National Park）的1250至2600 m小岛上建立的30个永久性样地（1公顷；测得所有直径≥10 cm的树木），对其他森林结构，分类学和环境属性如何影响地上生物量刚果共和国。森林结构和物种组成随海拔的增加而有所不同，确定了四种森林类型。随着高度的增加，树木越小，不同的高度-直径的异度模型在不同的森林类型中表现更好。地上生物量为168至290 Mg ha -1 ，但不同类型森林之间的AGB没有显着差异，随树的大小减小而茎密度随海拔升高而增加。森林结构对地上生物量的影响大于森林多样性。土壤属性（钾和酸度，pH）也显着影响地上生物量。结果表明，森林结构，分类学和环境属性如何影响非洲热带山地森林地上生物量。他们特别强调指出，使用区域高度直径模型会在地上生物量估计中引入明显的偏差，并且对于不同的森林类型，可能会更喜欢使用不同的高度直径模型，并且在以后的研究中应考虑这些因素。
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