Abstract For tropical tree species, wood density can vary greatly both within and between species depending on environmental conditions. In Amazonian seasonally flooded forests, yearly flood pulses influence tree growth and floodplain trees have developed specialised strategies to cope with prolonged submersion during flooding. We therefore hypothesised that seasonal floods significantly affect the capacity of trees to store carbon as woody biomass per unit volume and that forest hydrology would be an important factor in determining above-ground woody biomass and carbon stocks across the Amazon Basin. To test these hypotheses, we collected and analysed wood cores from 44 species occurring in both seasonally flooded (varzea) forests and adjacent unflooded (terra firme) forests along the Jurua River, western Brazilian Amazon. We used wood specific gravity (WSG) as a proxy of woody biomass and carbon. We compared WSG values within species, genera and families and found higher WSG in unflooded forest trees compared to their conspecifics in seasonally flooded varzea. Moreover, the effect of forest type on WSG was strongest at the family level and weakest at the species level. We further assessed the implications of WSG accuracy on above-ground woody tree biomass and found significant differences in AGWB as a function of WSG. Again, the differences became greater with lower taxonomic specificity, but also increased with lower site-specificity and greater tree dimensions. In conclusion, habitat specific WSG is important to quantify and map the spatial distribution of above-ground woody biomass and carbon in Amazonian forests.

中文翻译：

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森林类型影响亚马逊树种以木质生物量形式储存碳的能力

摘要 对于热带树种，根据环境条件，树种内部和树种之间的木材密度可能会有很大差异。在亚马逊季节性洪水泛滥的森林中，每年的洪水脉冲都会影响树木的生长，泛滥平原的树木已经制定了专门的策略来应对洪水期间长时间的淹没。因此，我们假设季节性洪水会显着影响树木将碳作为单位体积的木质生物量储存的能力，并且森林水文将是确定整个亚马逊流域地上木质生物量和碳储量的重要因素。为了验证这些假设，我们收集并分析了 44 个物种的木芯，这些木芯分布在巴西亚马逊西部朱鲁阿河沿岸的季节性洪水 (varzea) 森林和邻近的未洪水 (terra Firme) 森林中。我们使用木材比重 (WSG) 作为木质生物量和碳的代理。我们比较了物种、属和科内的 WSG 值，发现未水淹林树的 WSG 值高于季节性水淹 varzea 中的同种。此外，森林类型对 WSG 的影响在科层面最强，在物种层面最弱。我们进一步评估了 WSG 准确性对地上木本树木生物量的影响，并发现作为 WSG 函数的 AGWB 存在显着差异。同样，随着分类学特异性的降低，差异变得更大，但随着地点特异性的降低和树木尺寸的增加，差异也会增加。总之，栖息地特定的 WSG 对于量化和绘制亚马逊森林中地上木质生物量和碳的空间分布很重要。