Mangroves – seen from space and taller than you might think!

We may not always think about mangroves on the International Day of Forests, but we should. Mangroves are most definitely trees…with 80 different species of mangroves trees around the world. The benefits of mangroves are unmatched—home to thousands of aquatic and terrestrial species, mangroves provide food, fish and carbon sequestration. They also provide flood protection that is rivaled only by the most expensive human-made infrastructure.

Despite their mighty abilities, mangroves occupy only 0.1% of the Earth’s surface. This makes analyzing and monitoring global mangrove forests very difficult. However, technology can help answer the questions we need to ask to ensure mangroves continue to provide the services on which people depend. What is the current state of mangroves today; where are mangroves at risk; where would mangrove conservation be most effective?

Mangroves

A recent study looking at the relationship between mangrove height and climate conditions has revealed some interesting facts about mangrove forests. We often think of mangroves as short shrub-like trees that fringe the shoreline. Yet, in West Africa mangroves trees can reach heights of nearly 63 meters, that’s over 200 feet. That’s comparable to many upland tropical tree species. South and Central America also boast some very tall mangrove trees.

The tallest mangrove trees in Columbia, Venezuela, and Panama reach above 50 meters and their average canopy height is around 30 meters. In comparison, temperate broadleaf forests that dominate much of Europe and the United States have an average canopy height of about 25 meters (NASA Earth Observatory/ based on data from Michael Lefsky).

Of course, these super mangrove trees live where you might expect – in areas of little development pressure, sheltered from tropical cyclones, and with the hottest and wettest climate conditions. Researchers have used spaceborne radar and laser instruments to create global coverage of the relative canopy height of mangrove forests around the world. It’s now at a resolution accurate enough for national level monitoring and carbon accounting. Why do we care? Knowing mangrove canopy height is crucial to calculate above-ground stored carbon.

In turn this will allow countries to use a more reliable baseline when estimating carbon storage from intact mangroves and the subsequent loss that may occur from degradation as countries develop national carbon accounting schemes. Understanding our forests is critical if we want to protect them and help stabilize the climate.

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