Mistletoes are emerging as important co-contributors to tree mortality across terrestrial ecosystems, particularly when infected trees are stressed by water limitations during drought. While the mechanistic effects of mistletoe infection on host physiology are reasonably well understood, quantifying the effects of mistletoe infection on stand productivity, canopy turnover and ecosystem structure remains challenging. Moreover, the potential devastating effect of mistletoe infection on host survival has distracted from the challenges that mistletoe populations are facing when increasing drought and heat stress threaten their survival in healthy populations. We coupled intensive observations of mistletoe population dynamics with measurements of host tree stem growth, canopy turnover and stand structure in a severely infected temperate eucalypt woodland to monitor how mistletoe infection alters aboveground biomass distribution and to assess ecosystem recovery from severe mistletoe infection during and after a three-year drought. We show that severe mistletoe infection reduces live standing biomass and canopy volume, with mistletoe leaves contributing up to 43% to total stand litter fall. We further identified that a mistletoe:host leaf area ratio above 60% significantly reduced basal area growth, which provides a threshold for productivity losses due to mistletoe infection in eucalypts. Yet, concurrent increases in basal area and the thickening of canopy volume indicate that host trees recover rapidly after the three-year drought combined with record summer heat nearly extinguished the mistletoe population. How common, or how widespread such dynamic changes in mistletoe population dynamics are within Australian or global ecosystems remains subject to further exploration.

杂草龟正在成为整个陆地生态系统树木死亡率的重要共同贡献者，特别是当干旱期间水分受限而使受感染树木受到压力时。尽管槲寄生感染对宿主生理的机械作用已得到相当充分的了解，但量化槲寄生感染对林分生产力，冠层周转和生态系统结构的影响仍然具有挑战性。此外，槲寄生感染对寄主生存的潜在毁灭性影响分散了槲寄生种群在干旱和热应激加剧威胁其在健康种群中生存时所面临的挑战。我们将对槲寄生种群动态的深入观察与寄主树茎生长的测量相结合，在严重干旱的温带桉树林中的冠层周转和林分结构，以监测槲寄生感染如何改变地上生物量分布，并评估三年干旱期间和干旱后从严重槲寄生感染中恢复的生态系统。我们表明，严重的槲寄生感染减少了活立生生物量和冠层体积，其中槲寄生叶占立枝凋落物总量的比例高达43％。我们进一步发现，槲寄生：寄主叶面积比超过60％会显着降低基础面积的增长，这为桉树中槲寄生的感染所造成的生产力损失提供了一个阈值。然而，同时增加的基础面积和冠层体积的增加表明，在三年的干旱和创纪录的夏季酷暑相结合后，寄主树迅速恢复，几乎消灭了槲寄生种群。