TRI discussed research and rain forests with with 2019 TRI Fellow and recent Yale College graduate Jasmine Liu to learn more about her research in Ecuador.
1. Where did you go for your fellowship?
I spent the summer in Yasuní National Park, a lowland tropical rain forest in the western Amazon but on the Eastern side of Ecuador. The Pontificia Universidad Católica del Ecuador (PUCE) in Quito has a research station there. I was living in the research station, which is a short walk to the forest site.
2. Why did you choose to go there?
I work with Simon Queenborough (Musser Director of Tropical Resources Institute and Senior Lecturer and Research Scientist at Yale University) and Margaret Metz (Assistant Professor of Biology at Lewis and Clark University). I have been working in Simon’s lab for the last two years and he is my senior thesis advisor; Margaret is a long-term collaborator of Simon’s and has been monitoring seedlings in a network of plots for 17 years. Yasuní made the most sense because I was able to work with her seedling plots.
Renato Valencia (Professor of Biology at the Pontifica Universidad Católica de Ecuador) is the principal investigator of the Yasuni Forest Dynamics Plot in which Margaret’s seedling plots are located. The Forest Dynamics Plot is a 50-ha area of forest were all the trees >1 cm diameter at 1.3m are mapped, identified, and measured every 5 years, and is part of a global network of large plots.
3. What problem or question are you investigating?
In a broad sense, I want to know how a place Yasuni, with its incredible biodiversity, can exist. My TRI field research examined how herbivory damage to plants is distributed across different topographic habitats and among plants with different defense mechanisms. I want to know whether herbivory is different for a plant on a dry ridge versus a wet valley, which have different herbivore communities.
The two defense traits I collected data on were the color of new leaves and extra-floral nectaries (EFNs). EFNs are considered a form of indirect defense for plants. For example, mutualists such as ants attracted to nectar secreted from the EFNs will also protect the plant. I want to know whether these defenses translate to a reduction in herbivory.
This research is also related to broader questions about rarity and biodiversity. Current hypotheses suggest that rare species have an advantage over species that tend to clump together—host-specific pests and pathogens can move through a stand of conspecific trees or herbaceous plants, while rarer species are harder to find. Researchers are interested in the relationship between density of same-species individuals and herbivory.
4. Why does this question matter to you? Or to the people you were working with and studying with?
There is a not a lot of data about the herbivory experienced by seedlings in tropical forests. Herbivory in seedlings is particularly important because seedlings may stay small for decades. You can imagine that damage to a few leaves on a small seedling will have a disproportionate effect on mortality compared to damage on a mature tree with countless leaves. I hope to use Margaret Metz’s long-term seedling plot data to connect damage from herbivory to future growth and mortality.
5. What experiences can you share that help illuminate this problem and place better?
On the topic of illumination, the forest is remarkably dark! I remember reading that only maybe 1-2% of solar radiation will reach the forest floor in a tropical forest. I thought, “OK, I get it.” But Yasuni is really dark. Also it’s loud—you can feel and hear the life around you. It’s kind of eerie in that way … you hardly ever see things you are hearing, but it’s all around you
6. What do you think is needed to understand the situation better? Or to improve the situation?
Long-term data is essential to understand complex ecosystems such as tropical forests. At the moment, the 2019 seedling census data is being cleaned. Future census data will allow us to look at how herbivory up to 2019 affects future growth and survival of these seedlings.
7. How do you want to use your research?
As far as I know, a survey of this scale has not been conducted since the 1980s! I hope my research will contribute general knowledge about herbivory on seedlings in tropical forests. Specifically, I’d like to look at density-dependent patterns in herbivory using both data on the seedling communities and the surrounding adult trees. I’ll have to wait and see what my actual results are going to be, though.
8. What challenges did you experience in your research?
I decided to use old-fashioned urinalysis strips, called Diastix, to detect whether plant nectaries were excreting any actual nectar. I tested them in a greenhouse at Yale’s Marsh Botanical Gardens and they worked great. When I got to Yasuni, I realized that many of the EFNs were too small to use the strips. Also, even when I could see the nectar glands, I had no idea what species the plant was.
Luckily, I met Nancy Garwood from Southern Illinois University. She maintains a seedling herbarium and she graciously allowed me to examine her dried herbarium species with a hand lens. So even though my original plan was to look at each individual seedling in the field, I was still able to collect data on which species have extra-floral nectaries.
9. What are the critical challenges facing your research site and the communities who are involved?
The socio-political situation in Yasuni is very complex, with many stakeholders, including biologists, anthropologists, local people, indigenous people, and oil companies. Resolving the tensions among these communities will be key to the long-term persistence of the forest and the people that live and work there.
10. Is there anything else you want to tell us?
I was really fortunate to have two field assistants, Sofia and Leticia, who were both tremendous. It’s great to work with others who are excited to be at Yasuni and talk about ecology. Sofia is actually one of Renato’s students from Quito, and I loved hearing about what it’s like to live and study ecology in Ecuador.