Mangrove condition at Selayar Island based on field data and NDVI

Abstract

Mangrove monitoring in Selayar is part of Reef Health Monitoring which starts from 2015 to 2019 as a result of collaboration between Coremap CTI and Hasanuddin University. The results of satellite image analysis show that the estimated mangrove area in Selayar is 695 hectares, spatially distributed over 9 islands and 24 villages. This study aims to map the condition of mangroves in Selayar and Pasi Island based on canopy cover and NDVI. There were six mangrove locations visited on the field, four locations at Selayar Island, and two locations at Pasi Island. Each station was divided into three observation plots where positions are determined as detail as possible using GNSS, laser distance meter, and compass. There were 18 observed plots. The canopy cover was measure using the hemispherical photo method. Sentinel 2A satellite image was use to mapping NDVI and mangrove condition based on its canopy cover. The correlation between canopy cover and NDVI was 0.96. The coefficient of determination of the regression was 91.3%, and the RMSE value was 5.3%. Referring to KLH standards, mangroves in Selayar and Pasi Island classified as dense, moderate and sparse was 34%, 39%, and 27% recpectively of the total 274 hectares. Mangroves in damaged condition are about 75 hectares scattered on Selayar Island. These results are expected to become a benchmark to monitor mangrove conditions in the Selayar Islands and its vicinity.