Sea-level rise will eventually flood and kill many coastal mangrove trees. The loss of mangrove forests will strongly affect human populations on isolated western Pacific islands as they rely heavily on mangroves for food, such as fish, shrimp, and crabs; building materials; and fire wood. Mangroves also shelter coastal communities from the impacts of tsunamis and cyclones, are home to endangered species such as the Yapese monarch and flying fox, and remove and store CO2 from the atmosphere. In the past, mangroves have adjusted to sea-level rise through tree root growth and the accumulation of sediments from rivers and oceans, processes which allow them to maintain their forest floor elevation relative to sea level. However, in light [...]
Summary
Sea-level rise will eventually flood and kill many coastal mangrove trees. The loss of mangrove forests will strongly affect human populations on isolated western Pacific islands as they rely heavily on mangroves for food, such as fish, shrimp, and crabs; building materials; and fire wood. Mangroves also shelter coastal communities from the impacts of tsunamis and cyclones, are home to endangered species such as the Yapese monarch and flying fox, and remove and store CO2 from the atmosphere. In the past, mangroves have adjusted to sea-level rise through tree root growth and the accumulation of sediments from rivers and oceans, processes which allow them to maintain their forest floor elevation relative to sea level. However, in light of the projected acceleration of the rate of sea-level rise, as well as modifications made to coastal environments that impede their ability to respond, it is unclear how mangrove forests will respond to future conditions.
Identifying which mangrove forests are most affected by sea-level rise allows us to determine how to protect them today so that they can continue to support humans and wildlife tomorrow. Mangroves in the western Pacific contain some of the most pristine and productive ecosystems in the world, but very little data is available in this region to predict mangrove vulnerability or resilience. This project is building on an existing mangrove monitoring network created by the U.S. Forest Service, the USGS, and the Micronesia Conservation Trust in the Federated States of Micronesia to assess the vulnerability of mangrove forests to sea-level rise to inform management planning. Focusing on the islands of Kosrae and Pohnpei in the Federated States of Micronesia, researchers will identify which mangroves are keeping up with sea-level rise and which are not, and then model potential changes in the ecosystems that could occur.
This information will then be shared with state management agencies and local conservation organizations on both islands, including the Conservation Society of Pohnpei and the Kosrae Island Resource Management Authority, so that managers can identify what can be done to increase the ability of mangroves to keep up with sea-level rise. For example, moving roads or bridges so that mangroves can migrate inland or restoring connections to streams so that sediments can be deposited onto the mangrove forest floor could both support mangrove resiliency. Meanwhile, mangroves that are building elevation and adapting to sea-level rise should be protected from deforestation and maintained in that state for as long as possible. Increasing or protecting the ability of mangroves to keep up with sea-level rise will mean that these ecosystems can continue their role of supporting subsistence economies and diverse ecological communities in the Pacific Islands.
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Mangrove_MikeOsland_USGS.JPG “Mangroves. Credit: Mike Osland - USGS”
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Purpose
Sea level rise (SLR) will eventually flood and kill many coastal mangrove trees. The loss of mangrove forests will strongly affect human populations on isolated Western Pacific islands as they rely heavily on mangroves for food (fish, shrimp, and crabs), building materials, and fire wood. Mangroves also protect humans from tsunamis and cyclones. Mangroves have kept up with SLR in the past by maintaining their forest floor elevation relative to sea level through tree root growth and accumulation of sediments delivered every day to the mangroves by adjacent rivers or oceans. It is not clear if mangroves will be able to survive current or future rates of SLR, not only because of projected acceleration of SLR rates, but also because of the many coastal modifications made to coastal environments that influence the natural response of mangroves to SLR. Identifying mangroves most affected by SLR allows us to determine how to protect them today so that they can continue to support humans tomorrow. The main goal of this project is to continue to collect and compile data from mangrove forests around the islands of Kosrae and Pohnpei and use those data in a model that will identify which mangroves are not keeping up with SLR, identify those stands that are, and determine projected pathways of inland migration that may be influenced positively by management action. This information will then be shared with various organizations on both islands so that they can identify what can be done to increase the ability of mangroves to keep up with SLR. For example, moving roads or bridges so that mangroves can migrate inland or restoring connections to streams so that sediments can be deposited onto the mangrove forest floor. Mangroves that are building elevation during SLR should be protected from deforestation and maintained in that state as long as possible. Increasing or protecting the ability of mangroves to keep up with SLR means that they can continue to support subsistence economies and well-being of Pacific Islands through the provision of food, wood, fuel and protection from storms. Healthy, productive mangroves mean that CO2 is being removed from the atmosphere and buried in their sediments, and that mangroves continue to keep up with SLR and provide important means for climate change adaptation and mitigation.
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Technical Summary
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Our objective is to develop a national assessment of mangrove vulnerability to future sea level scenarios in the Federated States of Micronesia (FSM). This information is essential to develop management strategies to conserve mangroves for the continual provision of their many benefits as well as to support climate change adaptation strategies for individual island states and their communities. Sea level rise (SLR) is one of the greatest future threats to mangroves and the many ecosystem services that support human communities in the Federated States of Micronesia (FSM). Mangroves have survived increased rates of SLR in the past by: 1) maintaining their vertical elevation through belowground root growth and sedimentation and 2) migrating inland. This proposed research will focus on synthesis of empirical data collected across multiple mangrove forest plots that will be used to develop a spatially explicit model for two island states (Pohnpei, Kosrae) to inform stakeholder planning. The model will predict which mangroves are most vulnerable to future SLR scenarios; SLR is predicted to become more extreme over the next century. Identifying mangroves vulnerable to SLR vs those that are resilient will allow resource managers to develop strategies to increase or maintain that resilience to SLR, protecting areas that are the main source of food, fiber, and fuel for many island communities. Furthermore, if these habitats are lost, coastal areas will be at a much higher risk of flooding as well as have a reduced capacity for climate change adaptation and mitigation will be lost. Personnel (Thorne, MacKenzie, Krauss, Buffington) and Cooperators (Eperiam, Nithan) will be responsible for collecting and analyzing data, while Partners (Obispo, Nithan) will engage end-users so that the products developed can be used to develop climate change adaptation strategies to mitigate future impacts. This work will be transferable to other island communities with mangroves.