Mistletoes are considered keystone species on woodlands and savannas worldwide, providing a food resource for a diversified fauna, as well as a nutrient-enriched litter. Infections can be large (∼1–3 m) and, in some parts of the Amazonian savannas, parasitize up to 70% of hosts locally. Despite these facts, biomass of mistletoes is rarely investigated. Here we constructed allometric models to predict the biomass stock of the shrubby mistletoe Psittacanthus plagiophyllus in an Amazonian savanna. In addition, we determined whether host size could be used as a proxy for mistletoe biomass. Finally, we compared the biomass of mistletoes with that of trees, to evaluate their relative importance. We have shown that: (1) biomass of leaves (46.1% ± 13.5%) are as important as of stems (47.8% ± 13.5%), and relative contribution of stems increases as plant grows; (2) the model including width, breadth and vertical depth was the best (SE = 0.39, R2 = 0.9) for predicting individual mistletoe biomass; (3) mistletoe load and biomass per host had a positive, but weak (R2 = 0.11 and 0.09, respectively), relationship with host size, and thus such host information is a poor predictor of mistletoe biomass; and (4) in comparison with trees, mistletoes constituted less than 0.15% (0.5–22 kg ha−1) of the total above-ground biomass, suggesting that this life-form is irrelevant to the local biomass stock despite its unequivocal biological importance.

中文翻译：

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亚马逊热带稀树草原灌木槲寄生的地上生物量估计

槲寄生被认为是世界各地林地和稀树草原上的重要物种，为多样化的动物群提供食物资源，以及富含营养的垃圾。感染可能很大（~1-3 m），并且在亚马逊热带稀树草原的某些地区，当地高达 70% 的宿主寄生。尽管有这些事实，但很少研究槲寄生的生物量。在这里，我们构建了异速生长模型来预测灌木槲寄生的生物量存量鹦鹉螺在亚马逊大草原。此外，我们确定宿主大小是否可以用作槲寄生生物量的代表。最后，我们比较了槲寄生的生物量和树木的生物量，以评估它们的相对重要性。我们已经证明：（1）叶子的生物量（46.1%±13.5%）与茎的生物量（47.8%±13.5%）一样重要，并且茎的相对贡献随着植物的生长而增加；(2) 包括宽度、宽度和垂直深度的模型最好(SE = 0.39, R2= 0.9) 用于预测个体槲寄生生物量；(3) 每个寄主的槲寄生负荷和生物量呈正值，但较弱 (R2= 0.11 和 0.09），与宿主大小的关系，因此此类宿主信息不能很好地预测槲寄生生物量；(4) 与树木相比，槲寄生占不到 0.15%（0.5-22 kg ha-1) 的总地上生物量，表明这种生命形式与当地的生物量存量无关，尽管其具有明确的生物学重要性。