Mangrove trees, Walakiri Beach, Sumba Island, Indonesia

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The dancing trees of Sumba Island

On the northern coast of Indonesia's Sumba Island, a stand of mangrove trees appears to dip and sway to summon another sunrise. Walakiri Beach is gently sloped, so it's easy for a visitor to walk out into the knee-deep water to examine the transitional zone - where land meets the sea - of a mangrove ecosystem. Mangroves thrive here, growing in coastal salt water and low-oxygen conditions where other trees would quickly die. Their complex root systems filter out the salt and form a strong natural defence against storm surges, rising sea levels and coastal erosion. They are also home to a huge range of juvenile fish and crustaceans.

But mangroves are disappearing fast, several times faster than forests on land. The United Nations estimates that the world has lost half its mangrove coverage in just the last 40 years. To raise awareness of their importance and the need to find ways to protect them, the UN has declared that 26 July is International Day for the Conservation of the Mangrove Ecosystem. We'll dance to that.