In arid environments, shade provided by vegetation forms the crux of many facilitation pathways by providing other organisms with relief from high levels of solar radiation and extreme temperatures. Shade is an important determinant that structures arid ecosystem processes and functioning. While shade is considered an essential refuge for many organisms in arid environments, few studies have assessed how parasitic plants such as aerial mistletoes can influence the quality of shade provided by its host, and how this can subsequently influence species interactions. Here, we investigate how mistletoe influences the microclimate and daytime use of sub-canopy habitat by a large herbivore that seeks out shady micro-habitats to avoid daytime heat in Australia’s Strzelecki Desert. We experimentally removed the pale-leaved mistletoe (Amyema maidenii) from mulga trees (Acacia aneura) and monitored sub-canopy ambient temperatures and the daytime use of sub-canopy habitat by red kangaroos (Osphranter rufus). Results showed that average hourly temperature during the daytime and daily maximum temperature were cooler and that kangaroos were approximately three times more likely to shelter beneath trees where mistletoe was present (control) compared to where mistletoes had been removed (treatment). By showing that mistletoe can improve the quality of shade provided by their host trees, our study offers a novel insight into how mistletoes can facilitate the surrounding biota through modifying the abiotic environment beyond its physical structure. More broadly, the results of our study emphasise the prevalence of positive interactions within ecological communities and how they can occur in unexpected ways and indirectly between organisms that never come into direct contact.

在干旱的环境中，植被提供的阴影通过使其他生物免受高水平的太阳辐射和极端温度的影响而形成了许多促进途径的症结。阴影是决定干旱生态系统过程和功能的重要决定因素。虽然阴影被认为是干旱环境中许多生物必不可少的避难所，但很少有研究评估寄生植物（例如空中槲寄生）如何影响寄主提供的阴影质量，以及随后如何影响物种相互作用。在这里，我们调查槲寄生如何影响大型草食动物对亚冠层栖息地的微气候和白天利用，该草食动物寻找阴暗的微生境以避免澳大利亚的Strzelecki沙漠白天的高温。我们通过实验去除了淡叶槲寄生（Amyema maidenii从刺槐树（）合欢aneura）和监视的子篷的环境温度和由红袋鼠白天使用子篷栖息地（Osphranter鲁弗斯）。结果表明，白天的平均小时温度和每日的最高温度较低，袋鼠躲藏在有槲寄生（对照）的树下的可能性是除去了槲寄生（处理）的三倍。通过证明槲寄生可以改善寄主树提供的阴影质量，我们的研究为槲寄生如何通过改变其生物结构之外的非生物环境如何促进周围生物群提供了新颖的见解。更广泛地说，我们的研究结果强调了生态社区内部积极相互作用的普遍性，以及它们如何以意想不到的方式发生，以及在从未直接接触的生物之间间接发生。