Vascular epiphytes contribute disproportionately to global centres of plant diversity

Abstract

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The Amazon Epiphyte Network: A First Glimpse Into Continental-Scale Patterns of Amazonian Vascular Epiphyte Assemblages

“…In general, the systematic composition of Amazonian epiphyte communities is highly predictable at the family level with Orchidaceae, Araceae and Bromeliaceae being the most speciesrich families (Kreft et al, 2004). This pattern was reported earlier by Taylor et al (2021), using inventories and distribution information for 27,850 epiphyte species derived from literature sources, where Orchidaceae comprises 67% of the epiphytic flora, Bromeliaceae (11%) and Araceae (4%) being the dominant plant families. Marcusso et al (2022) it also reported this same pattern for the Neotropics and our results confirm this for Amazonia.…”

“…Even in relatively close areas, where soil gradients cause changes in tree composition, marked differences are found in the composition of vascular epiphytes (Boelter et al, 2014;Quaresma et al, 2017). On the other hand, recent studies with vascular epiphytes on a global scale strongly suggest that epiphytes vary relative to trees in their responses to environmental gradients, with epiphytes responding more quickly to the atmospheric gradient due to their air and water-limited growth habit (Taylor et al, 2021).…”

“…Because epiphytes by definition are exposed in tree canopies and lack underground root systems, they are thought to be particularly vulnerable to local climate conditions (Nadkarni and Solano, 2002;Zotz and Bader, 2009;Zotz, 2016) and potentially respond more strongly to environmental gradients than most terrestrial plants (Taylor et al, 2021). Epiphytes, in addition, provide important ecosystem services as they play key roles in water retention, nutrient cycling, and provision of habitat shelter and food for several animals (Lowman and Schowalter, 2012;Gotsch et al, 2016;Nakamura et al, 2017).…”

Global variation in diversification rate and species richness are unlinked in plants

“…This result agrees with the importance of biotic interactions as prerequisites for biodiversity accumulation, which has been postulated on geological timescales ( 70 ). Specifically, it seems likely that high precipitation (in warm areas) allows tropical rainforest to occur, which in turn, allows a variety of growth forms to coexist [including an astonishing diversity of epiphytes ( 36 )]. This is not possible where rainforest cannot occur despite the right climate (e.g., for edaphic reasons [edaphic savannas, wetlands]).…”

“…Vegetation greatly modifies the environment by influencing local climatic and edaphic conditions and creating microhabitats, allowing for niche differentiation. For example, trees create a dynamic mosaic of light and shade ( 35 ) and form a complex substrate for epiphytes, which have recently been shown to contribute substantially to global plant diversity patterns ( 36 ). Although the distribution of biomes often mirrors the abiotic environment, such as climate and soils, this is not always the case ( 37 ).…”