The inspiration for this project is the deep rooted significance of the Ohi’a tree to Hawaiian spirituality and native culture. The birth of children is often celebrated with the planting of a new Ohi’a tree along with umbilical cords, and the trees are considered sacred to locals. This tree is the most abundant native tree and its environmental importance for other organisms and the local ecosystem cannot be overstated.Today, the very existence of the Ohi’a tree is threatened by a Rapid Ohi’a Death (ROD), caused by a fungal pathogen which is new to science and for which no cure exists. The method of transmission is not yet known, but sawdust from beetle boring, open tree wounds, water or soil are suspected vectors. In this Earth Hack, we sought to find a way to identify ways to detect high risk disease areas and rapidly treat them on a large scale.

What it does

We have identified that the fungal pathogen killing the Ohi’a and those similar to it are more effective at binding to plant cells under acidic soil conditions. By mapping existing soil pH data with existing Ohi’a tree death maps, we can predict what unaffected areas are at risk for being infected in the future. These areas would be investigated and quarantined in order to prevent future outbreaks. Investigation would consist of soil and tree sample collection collected by citizen scientists through existing programs such as The Green Program, Kubu, and BioBlitz. These programs could also leverage existing technologies such as iNaturalist, which allow for real time mapping of environmental conditions.

How we built it

We began by educating ourselves on the subject and its significance.

Evaluating existing data maps, and searching what vectors have already been looked at, and which have not. Research papers from similar fungal parasites in sweet potatoes were used it as supporting data for the conclusion that a pH of 5.5 creates favorable conditions for Ceratocystis fungus. Soil pH data on GIS from the US Department of Agriculture in conjunction with Ohi’a tree death data from the University of Hawaii at Manoa were used to develop the correlation between tree death and acidic soil conditions.

Challenges we ran into

From what we could find, pH data has not been published in the last 32 years. This makes it difficult to predict current soil acidity and how it may affect this problem.

Understanding the cultural value of these trees impacts how we look at providing solutions. Avenues regarding genetic engineering, introduction of invasive species or chemicals, and other unnatural methods would not be accepted in the Hawaiian community.

Accomplishments that we're proud of

When we first selected this topic, we knew it would be challenging because it was a subject we had minimal familiarity with besides that it was devastating and current. However, we were compelled by its spiritual implication as well as by its environmental impact to endemic species.

We are proud to have found a vector that was not previously discussed in depth concerning this epidemic. We overlaid an existing pH data map with a recent publication of infected ohia trees to suggest a correlation among acidic environments. We also learned about several viable organizations and tools we could implement in our solution strategies.

What we learned

We discovered a published article that shows the Ohi’a tree has been found to be more susceptible to the uptake of the pathogens when stressed, so acidic soil ( pH < 5.5) creates more favorable conditions for the Ceratocystis to infect ohia tree roots. This hypothesis is supported by published pH mapping. Most importantly, we learned how valuable environmental preservation is and that we as citizens have the power to make an impact in our global communities.

What's next for ʻŌhiʻa ʻOhana (our project)

In order to confirm that pH is indeed a vector that affects Ohi’a susceptibility, low cost and small scale experiments should be conducted comparing trees exposed to infection in acidic soil as compared to neutral and basic soil. If it is found that pH is not a factor, it at the very least can be eliminated as a factor that affects proliferation as it has not yet been considered in current research.

As part of our deployment strategy, we would like to leverage programs and “citizen science” tools such as Inaturalist, The Green Program, Bioblitz, and Kupu Hawaii to collect pH and soil data. These programs could also be used to implement strategies to reduce environmental stress on trees that makes them susceptible to infection. These strategies include providing crucial nutrients to the trees and ammending soil pH to be less acidic. Other strategies such as quarantine would also be implemented as needed.

Related links

Presentation: link The Story of Hawaii’s Tree: link

Conservation X Lab Problem proposal: link

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