Desolate plant world

Oceanic islands provide useful models for ecological, biogeographical, and evolutionary research. Many groundbreaking discoveries – including Darwin’s theory of evolution – emerged from the study of island species and their interactions with the living and non-living environment. Now, an international research team led by the University of Göttingen has investigated the flora of the Canary Island of Tenerife. The results were surprising: the island’s plants displayed an extraordinary diversity of forms. But they differ little from land plants in functional terms. However, unlike mainland flora, Tenerife’s is dominated by slow-growing woody shrubs with a “low risk” survival strategy. The results are published in Natural.

Researchers investigated how Tenerife plants differ in functional terms from plants from other parts of the world. They conduct extensive research and field measurements at more than 500 sites using the latest functional ecology methods. The sites are scattered across the island at elevations from sea level to mountainous areas above 3,300 meters. Scientists recorded approximately 80% of the seed crops as native to Tenerife, and surveyed eight plant characteristics: plant size, specific wood density, leaf thickness, absolute and specific leaf area, leaf dry matter, nitrogen concentration in leaf tissue, and seed weight. They compared their data with that of more than 2,000 plant species found on land.

“Our study shows, for the first time and against all expectations, that the group of species that evolved in the Canary Islands did not contribute to the expansion of the range of different traits. This means they do not lead to more functional diversity,” explains the study leader, Professor Holger Kreft, and the University of Göttingen Biodiversity, Macroecology and Biogeography research group. Previous comparisons show that species present on islands can differ significantly from their mainland relatives. A well-known example is provided by the Galapagos giant tortoise: this species is found only in the Galapagos Islands and, as a result of adaptation to its environmental conditions, is much larger than mainland tortoises. The research team expected similar differences between island and mainland plants, but this was not the case. “In contrast, we saw that most species obeyed the constraints of an island climate. Thus, medium-sized woody species develop. They tend to live with limited resources and a high risk of extinction on the island. That is, they grow slowly. The high functional diversity is mainly due to the species being widely distributed on nearby islands and landmasses,” explained Kreft.

“At the start of our study, we assumed that island plants would show fundamental differences and would be characterized by a somewhat limited diversity in terms of function due to their geographical isolation,” explains first author Dr Paola Barajas Barbosa. The results were part of his doctoral thesis, which he was working on at the University of Göttingen. He now conducts research at the German Center for Integrative Biodiversity Research in Leipzig (iDiv). “We were further surprised to find that Tenerife plants have a relatively high functional diversity.”

Original publication: Martha Paola Barajas Barbosa et al. Collection of functional diversity in oceanic island flora. Nature (2023). DOIs: 10.1038/s41586-023-06305-z

Contact:

Professor Holger Kreft

Göttingen University

Biodiversity, Macroecology and Biogeography Study Group

Büsgenweg 1, 37077 Göttingen, Germany

Tel: +49 (0)551 39-28757

Email: (email protected)

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