Using a naturally occurring radioactive particle called Lead-210, researchers can also measure elevation changes in mangrove forests. Lead-210 travels from the atmosphere down to the Earth’s surface and breaks down in soil.
“Lead-210 allows us to analyze soil cores for the last 100 years and tells us a lot about mangrove forests. For instance, we know mangroves store 80 to 90 percent of carbon in their soil. Lead-210 has identified that this is due to high rates of carbon burial,” MacKenzie noted.
Unlike terrestrial forests, which have drier soil with air pockets, mangroves have water-logged soil with low oxygen levels. Fungi, bacteria, and other invertebrates can’t break down carbon in mangrove forests, because there’s not enough oxygen for them to breathe.
If left undisturbed, mangrove forests are bank accounts for carbon deposits, becoming increasingly rich over thousands of years. These storage vats of carbon mitigate climate change.
Along with powerhouses for carbon storage, mangroves are coastal guardians for communities. They serve as barriers during storm surges and tsunamis, safeguarding local communities and critical infrastructure. In Palau, mangrove roots create nurseries for young fish, which grow into larger species, and become a vital food source for Pacific Island communities. Along with fish, mangroves provide habitat for fruit bats and crocodiles. They also protect coral reefs from upland erosion and sediment build-up. Their contributions to the natural beauty of Palau draw tourists from around the world who contribute to the local economy.
“When you have healthy, resilient mangroves, you have healthy, resilient people. But when people deforest mangroves, they release tons of carbon back into the atmosphere. You lose all the other goods and services that benefit people. Conserving these trees is critical,” MacKenzie emphasized.
New technology offers hope to bolster mangrove conservation. MacKenzie and partners from the Rochester Institute of Technology and USGS are testing out LiDAR or 3D lasers from iPhones to gather key data about mangrove forests. Once tested and vetted, island foresters and conservation groups can use this technology to track the health of mangrove forests, locally and globally.
“I’m excited about this new technology and remain optimistic. I want to believe mangroves can sense sea level rise and kick underground productivity into high gear. They’ve withstood sea level rise for 65 million years. That gives me hope,” MacKenzie stated.