Studying vascular epiphytes is very hard!

The post provided by Glenda Mendieta-Leiva & Gerhard Zotz

This post (and video inside) refer to the article EpIG‐DB: A database of vascular epiphyte assemblages in the Neotropics by Mendieta-Leiva et al. published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.12867).

Any field biologist who has ever collected vascular epiphytes can attest to the amount of work and frustration that goes into studying this exciting and challenging component of tropical diversity. Epiphytes grow on trees thereby covering the branches and trunks and providing lushness and exuberance to rainforests!

In the last decades, canopy researchers have come up with numerous and fun ways to access the canopy, thus contributing to the renaissance of epiphyte research. Nowadays, some canopy researchers are inspiring the joy for canopy and teaching epiphyte research to the new generation. Although traditional direct observations and the use of binoculars have always been used and useful.

Access to the canopy is not the single challenge that epiphyte ecologists need to overcome. Vascular epiphytes are very diverse with an estimated 30 000 species and c. 80 families worldwide. This hyper diversity is also reflected in the very high number of species found locally or even at the tree level; for example, one could encounter up to 200 species in a single Ficus tree! Another challenge is that the taxonomy of some families is still largely unresolved (e.g. Orchidaceae and several fern families), especially in the most diverse and remote sites. This problem is heavily accentuated by the lack of information, given that several countries in diversity hotspots do not have their local Floras or these are outdated. Thus, one could say that epiphyte diversity is as outstanding as unknown.

Epiphytes are generally liked by researchers and naturalists, especially because the majority of orchid species are epiphytes. Nonetheless, they are largely understudied in comparison to lianas, shrubs and trees. Vascular epiphytes are not only exotic because they live on trees, an ever-changing substrate with its own dynamics, but also because they are thought of as ecosystem engineers by fulfilling essential ecological functions related to the hydrology and nutrient cycle of the forests. Most importantly, they are secondary stepping stones, the primary ones being trees, which amplify biodiversity through the significant number interactions with other taxa, e.g. animals. Because of their structural dependence and reliance on the atmosphere, since they do not have roots on the soil but a strong coupling with the atmosphere, epiphytes are expected to be different, in several ecological aspects, to soil-rooted plants. Understanding the main ecological aspects of this highly diverse group is expected to provide us with a better understanding of tropical biodiversity, its maintenance and the underlying mechanisms.

In 2018 we got funding from the DFG (German Council of Research) to establish an international cooperation network, to bring together researchers who collected or have collected vascular epiphyte inventory data throughout the Neotropics. The main objective of the initiative was to organise, collate and standardise a large amount of data collected independently by several researchers throughout Latin America. A first workshop took place in the University of Marburg, Germany, in August 2018, where we brought together 25 researchers of a diverse degree of expertise (from undergrads to senior researchers), geographical background (from Latin America and Europe) and fields of study (ecologists, data scientists & macroecologists).

During this workshop, we discussed the structure of the future epiphyte vascular database and the methodological particularities of collecting epiphyte inventory data. These issues were raised by the database first draft version, which was put together before the workshop. Two tools made it possible for us to build this draft database, the global list of vascular epiphyte species and the database management program Turboveg. The worldwide vascular epiphyte list is Gerhard Zotz life’s work. The version of Turboveg we used was kindly adapted by Stephan Hennekens to fulfill the particular needs of vascular epiphytes.

As a result of this workshop, we formed the Epiphyte Inventory Group (EpIG), a consortium of epiphyte researchers as a platform to network and push forward the agenda on epiphyte research. The group includes around 50 researchers currently. The first output of this group is the paper published in the Journal of Vegetation Science, to which this post refers to: “EpIG‐DB: A database of vascular epiphyte assemblages in the Neotropics”.

We aim at using this database, EpIG-DB, to test the generality of the findings of individual case studies to define large scale diversity patterns of epiphyte diversity. We also plan to use EpIG-DB to test general ecology diversity hypotheses of interest for the development of ecological theory and the understanding of the mechanisms underpinning diversity, not only in the tropics but also in other ecosystems.

Brief personal summary: Glenda Mendieta-Leiva is an ecologist who uses vascular epiphytes as a model system to understand the mechanisms underpinning tropical diversity. She has worked in different Tropcial countries (Ecuador, Panama and Peru) and currently leads the EpIG consortium.

Get to know some more of our co-authors and consortium members in their field sites: