Mangrove ecosystems are vital to coastal communities by providing a variety of crucial ecosystem services including the providing of fish stocks, building materials and firewood; the storing of large amounts of carbon; and the sheltering of coastal communities from tropical storms. For many decades, human activities have led to the degradation of these mangrove ecosystems. There are further concerns that increases in the severity of hurricanes caused by climate change may have severe negative impacts on the health of these important ecosystems. This study aims to determine whether mangroves degraded by humans will be more damaged by hurricanes than healthy, undisturbed mangroves. The impact of Hurricane Rai was measured on two different mangrove forests, found on Siargao Island in the Philippines: one in a protected national park and the other degraded by human activities for decades. The impact of the hurricane was compared using normalized vegetation index (NDVI) time-series analysis before and after the passing of the hurricane. The time series measured an NDVI decline of 0.0468 at the control site and a decline of 0.0539 at the impacted site. Furthermore, 16.3% of the total area at the control site showed a significant decrease in NDVI, while only 1.8% of the area at the impacted site showed a significant decline. Based on the results of this study, it could not be confirmed whether human degradation of mangroves has a negative impact on their resilience to hurricanes.

This map illustrates damaged structures in Calbayog City, Samar Island, Philippines. Using a satellite image acquired 09 December 2014 and compared to an image collected 27 May 2014, UNOSAT reviewed the City of Calbayog and identified a total of 526 damaged structures in the area. 88 structures were identified as destroyed, 180 as severely damaged and 258 as moderately damaged. This is a preliminary analysis & has not yet been validated in the field. Please send ground feedback to UNITAR / UNOSAT.