ECR feature: Amazonian trees with Vitor Gomes

Vitor H. F. Gomes is a postdoc affiliated with the Federal University of Pará, Instituto Tecnológico Vale, and Centro Universitário do Pará. Vitor studies the response of Amazonian tree species to global change, and is particularly interested in the effects of climate change and deforestation on species diversity and distribution. His recent work investigates the diversity and distribution of all known Amazonian tree species — 10,071 in total.

Vitor in Mocambo Forest – Pará Brazil 2017: monitoring and measuring a 60 year old permanent plot in Amazonia.

Links: Personal page | Twitter | Instagram

Institution: Federal University of Pará – UFPA, Instituto Tecnológico Vale – ITV, and Centro Universitário do Pará – CESUPA

Current academic life stage: Postdoc

Research interests: I am interested in understanding how Amazonian tree species respond to global change, focusing on the effects caused by climate change and deforestation on species diversity and distribution.

Current study system: I currently study the diversity and distribution of all known Amazonian tree species, a total of 10,071 according to the most recent list. Half of those species may be threatened with extinction by 2050, since they are continually impacted by global change, especially by deforestation and climate change. Amazonia is the largest single block of rainforest on the planet and holds roughly half of all tree species in tropical areas. Understanding the impacts of global change on Amazonian tree species diversity and distribution is fundamental to predict the future of rainforest under human-induced changes, also to maintain and safeguard Amazonian biodiversity.

(left) Vitor in the National Forest of Caxiuanã – Pará/ Brazil 2016: research trip in Amazonia monitoring 11 ha of permanent plots and collecting samples for DNA Barcoding of over 400 species. Speedboat displacement to the permanent monitoring plots, (right) National Forest of Caxiuanã – Pará/ Brazil 2017.

Recent paper in Journal of Biogeography: Gomes, V. H. F., Mayle, F. E., Gosling, W. D., Vieira, I. C., Salomão, R. P., & ter Steege, H. (2020). Modelling the distribution of Amazonian tree species in response to long‐term climate change during the Mid‐Late Holocene. Journal of Biogeography, 47(7): 1530-1540.

Motivation for the paper: Previously published pollen records of rainforest tree species extracted from lake sediments in the southern margin of Amazonia showed that eastern Bolivia rainforests expanded southward over Cerrado savannas between the Mid and Late Holocene (past 3000 years). The concentration of rainforest tree pollen increased in two lakes (sites), Laguna Bella Vista (northern) and Laguna Chaplin (southern), which are 100 km away from each other. The rainforest communities surrounding Laguna Chaplin are younger than those around Laguna Bella Vista, indicating that species have expanded their distribution southward between those lakes in very recent times. This expansion is attributed to the increased seasonal latitudinal migration of the Inter Tropical Convergence Zone. Based on that, we wondered if species’ climate-based environmental suitability also increased during the Mid-Late Holocene in Amazonia, especially in the southern part, contributing to the rainforest expansion. We also wanted to confirm how pollen records from the topmost sediments (surface) correlate to the relative abundance of current plant species. We can use this information in our future research to simulate the abundance distribution of tree species in the past based on fossil pollen data.

Key methodologies: We used models based on machine learning and inverse distance weighting interpolation to produce maps of environmental suitability and relative abundance for tree species of Moraceae and Urticaceae, based on natural history collections and a large plot dataset. We used environmental suitability to test the response of the Amazonian rainforest to long-term climate change. Then, we quantified the increase in suitable areas for tree species in the past 6,000 years. We also used species relative abundance maps to test the correlation between species abundance in the current vegetation versus modern pollen assemblages. Our methods demonstrate how Amazonian rainforest responds to long-term climate change, and addresses questions about tree species distribution under past climate conditions. Also, our methods clarify the relationship between pollen and plant species abundance, connecting evidence of past rainforests from pollen records to species abundance plot data in the present.

(left) Vitor in the National Forest of Saracá-Taquera – Pará/Brazil 2009: research trip in Amazonia monitoring a permanent plot close to the edge of a 200 meter plateau, (right) National Forest of Saracá-Taquera – Pará/Brazil 2009: research trip in Amazonia monitoring and measuring permanent plots on a reforested area. Rest time. Left to right: Mario Rosa (Goeldi Museum), Mr. Bieco (Coopertec), Nelson Rosa (Goeldi Museum), Vitor Gomes.

Unexpected challenges: We found that the suitable areas and species richness for the species studied were higher in a narrow band in the Guiana Shield. Despite that, the abundance of species was very low in this area. Our understanding was that other factors besides environmental conditions might drive species distribution, such as biotic interactions, dissociating potential species distribution from observed species distribution. This outcome may lead the way to new questions and propositions regarding contrasting north-south patterns between species abundance (lower-north/higher-south) and environmental suitability (higher-north/lower-south). Perhaps we can expect lower plant abundance in areas with higher environmental suitability, since competition between species increases with optimal environmental conditions.

Mocambo Forest – Pará Brazil 2017: Research trip in Amazonia monitoring and measuring a 60 year old permanent plot. Collecting leaves. Vitor Gomes and Nelson Rosa (Goeldi Museum).

Major result and contribution to the field: We found that the mean environmental suitability of Moraceae and Urticaceae increased over the past 6,000 years, with southern ecotonal Amazonia showing the highest increase. The accompanied modelled mean species richness increased by as much as 120% throughout Amazonia. However, we found that under a future warmer and drier Amazonia, it is likely that the Holocene range expansion will be reversed over the 21st century. We predict that increased moisture stress will lead to forest and diversity losses, especially in ecotonal areas of Amazonia. Furthermore, we found that the current mean relative abundance of Moraceae and Urticaceae correlated significantly with the modern pollen assemblages for these families. This correlation implies that pollen records can be used to reconstruct the relative abundance of the species in the past.

What are the next steps? The crossover between pollen records, abundance data and environmental suitability models looks promising. The first step is modelling all Amazonian tree species distributions in the past, and looking deeper into the past, reaching the Last Glacial Maximum (~21 kyr before present) and the Last Interglacial (~100 ky before present). Second, I’ll expand our pollen analysis to all tree species with available records. These analyses may connect many pieces of the Amazonian rainforest history. I’m starting a postdoc focusing on the future of Amazonia based on the Paris Agreement goals, which aim to understand how past changes may help us to figure out the possible outcomes of current and future human-induced changes.

If you could study any organism on Earth, what would it be and why?
I would like to understand the relationship between tree species and their pollinators and dispersers. That would help to understand processes related to tree species distribution. Bees would be a good start, since many tree species in Amazonia are pollinated by them, and bees are as threatened as tree species due to human-induced changes.

Any other little gems you would like to share? Researching is pretty far from easiness; it is about passion, which makes us surpass distance, cultural differences, economic crises, budget issues and many other challenges present in the daily life of researchers. I should say a big thanks to the coauthors Hans ter Steege, Willian Gosling, Frank Mayle, Ima Vieira and Rafael Salomão, who are all passionate about Amazonia and supported this project.

National Forest of Caxiuanã – Pará/ Brazil 2016: monitoring 11 ha of permanent plots and collecting samples for DNA Barcoding of over 400 species. Rest time and lunch. Left to right: Vitor Gomes, Arua ter Steege, Hans ter Steege (Naturalist), Mr. Joca (Ferreira Pena Station), Nelson Rosa (Museum Goeldi).

Published by jbiogeography

Contributing to the growth and societal relevance of the discipline of biogeography through dissemination of biogeographical research.

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