Develop a global distribution map of mangrove forests

" Watching scenes of devastating tsunamis on TV, I realized that mangroves play a role as a protective barrier against some natural disasters ," said Chandra Giri, a transformational scientist. Land, work at the US Geological Survey.

Countless people have survived by hiding forests near the coast, when the 2004 tsunami killed more than 230,000 people in Indonesia, India, Thailand and Sri Lanka.

In the aftermath of natural disasters, Chandra Giri, a land conversion scientist working at the US Geological Survey, decided to understand how these species are characterized by mangrove areas, creating a valuable forest ecosystem. The so-called mangrove forest has the ability to hold well, helping protect the lives and property of people and beaches during storms, floods and tsunamis. In the process, he and his colleagues produced the first complete distribution map of the mangrove forest on Earth.

1. Why are mangroves important?

Mangroves are extremely valuable as a solid refuge, a habitat and food source for hundreds of wildlife species as well as humans. Mangroves are important when it comes to biodiversity, and store a larger disproportionate amount of terrestrial carbon than many other ecosystems.

2. How did you identify the research topic?

Six years ago, I witnessed a mystery of mangroves, watching scenes of devastating tsunamis on TV, I realized that mangroves also have a role as a protective barrier against a number of natural disasters. I think that perhaps to some extent, mangroves have a protective role that can be viewed in many different ways.

3. So what did your research come up with?

To date, no one has a system to collect hard data on mangroves on a larger scale. Therefore, we raised the issue of building the first accurate mangrove forest map, originating from global satellites. What the map showed us is that mangrove forests account for 12% (about 53,190 square miles) of Earth's surface area much less than before.

This is troubling when you combine it with increasing interest that, according to the International Union for Nature Conservation, 16% of mangrove species are in danger of extinction, and, according to the assessment of the Millennium Ecosystem Assessment, an unusually large number of 35% of mangrove ecosystems disappeared between 1980 and 2000. It was a major decline due to agricultural expansion and distribution. urban development and shrimp farming.

4. How to make a map?

We use more than 1,000 high resolution images from Landsat satellites (jointly managed by NASA and The US Geological Survey). Mangroves are mainly seen in color assumptions from satellite imagery, they appear as a red shadow near the coast or adjacent to the water surface, so that the mangrove forest can be distinguished. Different types of soil surfaces.

Satellite photography of the earth with different levels of resolution, similar to pixels on a television screen size. Over the years, scientists often view global land in personal pixels, or snapshots, extending in the 1km ² area, so there is not enough detail displayed in low resolution, to play present mangrove forest. Our technique involves using data at a better resolution, each image is only 30m ^{2 in size} and makes the image easy to observe to classify mangroves that are often found in the small cluster.

We have invited scientists from South America, Africa, India, and Asia to help us slowly transplant each piece of mangrove maps together. To make sure we actually saw the mangrove forest and not something else, we also used field data, newsletters, scientific publications, and Google images of each region.

5. The next case?

This map has given us a step that can begin to answer our original question, does mangrove planting provide coastal protection? First of all, we have to learn more about where mangroves are located, the density of mangroves, as well as the growth and development of mangroves.

We know that the Asia-Pacific region, Indonesia in particular, has the largest area of ​​mangrove forests. From UN sources and other reports, we also know that Asia is the region most at risk from natural disasters such as deadly tsunamis. So, with our map will help to accurately locate to investigate " value like armor against natural disasters, and to help demonstrate conservation efforts in the area to prevent mangrove forest decline . "

We also expect satellite-based scientists with remote sensing measurements, so that they can estimate the height and biomass of mangroves to make more accurate estimates in forest conditions. mangrove.