Mangrove health index distribution on the restored post-tsunami mangrove area in Biak Island, Indonesia
I Wayan Eka Dharmawan
Abstract
Research Centre for Oceanography has launched and published a single metric for assessing mangrove health based on stand structure variables since October 2020. A spatial analysis study was conducted to implement the MHI formula in a post-tsunami area in a Pacific-edge island in Biak-Papua which has been rehabilitated since 2017, especially in Tanjung Barari lagoon. The study was aimed to analyze the recent MHI value based on field data collection and to interpolate the value in the entire mangrove area. We compared the MHI distribution along the study area in 2015 and 2020. Sentinel 2 imageries were used as primary data which were preprocessed for extracting the mangrove area in the lagoon area. A multiple vegetation indices relationship which was consisted of NBR, GCI, SIPI, and ARVI, was applied on each observation period for MHI distribution estimation. The interpretation of mangrove health was divided into three categories such as poor, moderate, and excellent. This study found that the mangroves area in the lagoon was declining at 33.53 ha during periods. Based on MHI value, mangrove was dominantly at the moderate level. In addition, moderate and excellent mangrove areas were increasing during observation. The poor mangrove area was decreased due to loss of the dieback mangrove, seedling natural settlement, and rehabilitation activities. We identified as many as 144.39 ha of the lagoon area in 2020's imagery which was potential for the future rehabilitation area. Even though, the area needed to be confirmed related to environmental setting and land tenure issue.