Tree hollows can affect epiphyte species composition

Abstract

Tree hollows often harbor animals and microorganisms, thereby storing nutritive resources derived from their biological activities. The outflows from tree hollows can create unique microenvironments, which may affect communities of epiphytic organisms on trunk surfaces below the hollows. In this study, we tested whether the species richness and composition of epiphytic bryophytes (liverworts and mosses) and lichens differ above and below tree hollows of 𝘈𝘳𝘪𝘢 𝘫𝘢𝘱𝘰𝘯𝘪𝘤𝘢 and 𝘊𝘦𝘳𝘤𝘪𝘥𝘪𝘱𝘩𝘺𝘭𝘭𝘶𝘮 𝘫𝘢𝘱𝘰𝘯𝘪𝘤𝘶𝘮 in a Japanese temperate forest. The species richness of epiphytic bryophytes and lichens did not differ above and below hollows; however, the species composition of bryophytes differed significantly above and below hollows. Indicator species analyses showed that the moss species 𝘈𝘯𝘰𝘮𝘰𝘥𝘰𝘯 𝘵𝘳𝘪𝘴𝘵𝘪𝘴 and the liverwort species 𝘗𝘰𝘳𝘦𝘭𝘭𝘢 𝘷𝘦𝘳𝘯𝘪𝘤𝘰𝘴𝘢 were significantly more common below than above hollows, while the liverwort species 𝘙𝘢𝘥𝘶𝘭𝘢 𝘫𝘢𝘱𝘰𝘯𝘪𝘤𝘢 and four lichen species, including 𝘓𝘦𝘱𝘵𝘰𝘨𝘪𝘶𝘮 𝘤𝘺𝘢𝘯𝘦𝘴𝘤𝘦𝘯𝘴, occurred more frequently above than below hollows. Our results highlight that tree hollows can produce unique microenvironments on trunk surfaces that potentially contribute to the maintenance of epiphytic diversity on a local scale.