The application of Landsat imageries and mangrove vegetation index for monitoring mangrove community in Segara Anakan Lagoon, Cilacap, Central Java

The only place for estuarine-mangroves in Java Island, Segara Anakan Lagoon, experiences the vast decline of mangrove cover. Satellite remote sensing has a critical role in monitoring that change as it allows to record vast areas over time. However, most studies tend to utilize satellite data to investigate the change of mangrove areas into other land-use types rather than identify the mangrove community’s shifting. This study utilized the mangrove vegetation index (MVI) for monitoring the changes of mangrove communities at the life-form level using satellite data. The study used multi-temporal Landsat images as it has historical systematic archive data. The threshold value of the index for each class is defined by referring to the field data. The class referred to the life-form classification consisting of mangrove trees, Nypa, and understorey. The image analysis was conducted using Google Earth Engine (GEE), while R software was used for determining threshold values through statistical analysis. The result shows that the MVI can differentiate between some life forms of mangroves, with the overall accuracy reaching 78.79% and a kappa coefficient of 0.729. Further, the multi-temporal maps showed the decline of mangrove tree areas, which the understorey and Nypa community have replaced.

RESPONDENT ANALYSIS IN CONTEXT TO IMPACT OF CLIMATE CHANGE ON THE REGULATING SERVICES OF MANGROVE VEGETATION

The mangrove ecosystem in the lower Gangetic delta is noted for providing several regulatory services. The major regulatory services include erosion, natural disaster, Phytoremediation, carbon sequestration, siltation, and sea-level rise. Here, we have attempted to develop a mechanism of assessing and ranking the magnitude of regulatory services offered by Sundarban mangroves based on stakeholder’s views on the subject. The respondents were categorized into five major classes namely policy level worker, researcher, fisherman, agriculturist, and local inhabitant. About 295 respondents belonging to these 5 categories were asked about the types of regulatory services and their respective magnitude by ranking the services between 1 and 6. Finally, based on data generated, three separate Combined Mangrove Regulating Service Scale (CMRSS) were assessed for three sectors (western, central, and eastern) of Indian Sundarbans. The basic root for such assessment is contrasting variations between these three sectors based on geographical features, salinity, and biodiversity. The present approach of analysis can be a road map to identify and empirically score the regulatory services of mangroves.

LIMITATION ASSESSMENT AND WORKFLOW REFINEMENT OF THE MANGROVE VEGETATION INDEX (MVI)-BASED MAPPING METHODOLOGY USING SENTINEL-2 IMAGERY

The Mangrove Vegetation Index (MVI) was developed to map mangroves extent from remotely-sensed imageries accurately and quickly. MVI measures the probability of a pixel to be a ‘mangrove’ by extracting the greenness and moisture information from the green, NIR, and SWIR bands. The range of MVI values may vary depending on factors such as land cover classes, climatic conditions, or tidal conditions. Mapping the scope of mangrove sites involves setting a maximum and minimum MVI threshold to separate them from other land cover classes and vegetation. Although the MVI has a high index accuracy, its mapping performance is limited by some biophysical and environmental factors. Misclassification occurs in aquacultural areas, irrigated croplands, and sites with palm trees where mangrove and surrounding vegetation pixels have highly similar spectral signatures. There are scenes with complex environments, such as in aquaculture areas and along a network of rivers and streams, where an optimal threshold varies across the site, and setting a single MVI threshold may not yield excellent results. An automated threshold setting using the Otsu method was explored; however, the results were inaccurate due to a low intensity contrast between mangroves and other vegetation in the MVI raster layer. This study also looked into possible adjustments to improve the manual threshold setting workflow for a successful mapping of mangrove extent using MVI on Sentinel-2 imagery.

SPATIO-TEMPORAL MAPPING AND ANALYSIS OF MANGROVE EXTENTS AROUND MANILA BAY USING LANDSAT SATELLITE IMAGERY AND MANGROVE VEGETATION INDEX (MVI)

Mangroves are considered one of the most undervalued ecosystems in the world. It provides shelter to a wide range of species and protection from natural hazards to coastal communities. The Philippines, being a country with long coastlines, benefits greatly from mangroves. Historically, it had 400,000–500,000 hectares of mangroves forest in 1920, which declined to 120,000 hectares in 1994 due to rapid industrialization, particularly the conversion of these forests into aquaculture such as fishponds Mangrove forest in the Philippines saw a rapid decline between 1920 and 1994 due to aquaculture conversion and land reclamation Mangrove Vegetation Index (MVI), an established mangrove detection algorithm, was applied on Landsat satellite images of Manila Bay to map the extent of the mangrove forest from 1990 to 2020. Thirteen time-series maps were produced. Area computation showed that the coastline of Bulacan had the most mangroves, while the coastline of Metro Manila had the least throughout the years.

Local scale climate change mitigation through mangrove revegetation on the south coast of Lombok island

The mangrove vegetation in the coastal environment has a vital role, especially as a regulation for CO2 and O2 gas exchange. Mangrove revegetation has significant relevance for local-scale climate change mitigation. This study aims to assess and describe the success of mangrove revegetation in mitigating climate change at a local scale. Ecological data research methods are through surveys, observations and transect methods. Furthermore, the collection of social data through surveys, interviews, questionnaires, and Focus Group Discussions (FGD). Meanwhile, the research data were analyzed using descriptive statistical analysis, and analysis of the mangrove vegetation structure through frequency, density, cover, and essential value index analyses. The study results found seven types of mangroves, namely Sonneratia alba, Rhizophora stylosa, Rhizophora apiculata, Avicennia marina, Bruguira gymnoryzha, Lumnitzara racemosa, and Ceriops tagal. Sonneratia alba and Rizoporastylosaare species with the highest importance value of 194.04 where S. alba found Poton Bako and R. Stylosa found in Tanjung Luar. As for social data and knowledge, people in areas with a distance of 0-50 meters from mangrove forest have a better understanding than people living in areas with an average percentage value perspective of 52 %. Then, most respondents agreed that mangroves could prevent abrasion and reduce heat temperatures, with the percentage of respondents responding more than 41 % and 61 %, respectively in all locations. Based on the essential value index and respondents’ perceptions, it can be concluded that the Sonneratia alba and Rizopora Stylosa are species that have the highest ecological function because they have good adaptability in the coastal areas of South Lombok making them suitable as species for revegetation programs in South Lombok, and for the next revegetation program should be involving people who are close to mangrove forests because they are the ones who know and feel the benefits of mangrove forests.

Mapping the abrasion on Sederhana Beach, Muara Gembong, Bekasi, West Java province for the coastal mitigation purpose

Sederhana Beach is located in the waters of Muara Gembong, Bekasi Regency, West Java Province, northeast part of Jakarta Bay. The observation data in 2018 showed the morphology of the damaged coast and the massive fallen mangrove vegetation. Loss of land and mangrove populations has a major impact on the economic and environmental aspect. How to mitigate the impact of abrasion? This study aims to map the type of sediment, sediment distribution and its depositional environment, to obtain a correlation with the type and direction of currents causing abrasion. The results would become the base for determining the appropriate actions to overcome further abrasion, in an integrated coastal area planning program. Seabed sediments were taken using a grab sampler, megascopic descriptions and analysis of the depositional environment off sediments were held on site. The results are plotted onto a map, to determine the distribution of sediments. Sediment types found are: coarse sand, clay, sandy clay, medium-fine sand, and silt. 75% of the study area is: scattered sandy clay, mostly covering the coastline to the north. This is a common phenomenon because the mainland of research location is dominated by mangrove vegetation. The Coarse sand took 20% of the research location. An interesting phenomenon is: the coarse sand reaches the coast directly adjacent to the mangroves, where 5% of silt is found outside this coarse sand zone. The presence of coarse sand on the shoreline with mangrove vegetation indicates that the main current that triggers abrasion is longshore current, moving parallel to the coastline, namely northeast - southwest. So, the recommended steps that can be taken in mitigating further abrasion at Sederhana Beach is the construction of a current breaking structure that is perpendicular to the coast line

Production of Rhizophora Mangrove Leaf Litter in The Sungai Bersejarah Mangrove Ecosystem, Siak Regency

The mangrove ecosystem is one of the coastal ecosystems that has important ecological roles and functions in supporting marine and fishery resources. Marine and fisheries resources are largely determined by the contribution of mangrove litter. The aims of this study was to determine the production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem, and to determine the value of environmental parameters related to litter. The research was conducted in January until March 2021 in Sungai Bersejarah mangrove area Kayu Ara Permai, Siak Regency. Line transect plot were used to calculate the density of Rhizophora. Rhizophora litter production was measured using the trap net method placed at three sampling site. Three litter trap nets measuring 1 m x 1 m are placed at each station. Rhizophora tree density ranges from 316 - 444 ind./ha. The production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem was 0.82 – 1.39 g/m2/day (3.00 – 5.09 ton/ha/year), average was 4.11 ton/ha/year. Analysis of variance test showed that there was a significant difference in Rhizophora leaf litter production between sampling points with different Rhizophora tree densities (p<0.05). Mangrove vegetation density has a moderate relationship (r=0.43) to the production of Rhizophora mangrove leaf litter. Environmental parameters indicate that the condition of the Sungai Bersejarah mangrove ecosystem is still good and can support the life of mangrove vegetation.

Evaluasi Kesesuaian Peruntukan Lahan di Sempadan Sungai Krueng Lamnyong, Provinsi Aceh

Abstrak. Sempadan sungai merupakan kawasan penyangga antara ekosistem perairan (sungai) dan daratan. Sungai Krueng Lamnyong terletak di Kota Banda Aceh dan Kabupaten Aceh Besar yang merupakan daerah hilir dari sungai Krueng Aceh. Sempadan sungai Krueng Lamnyong telah dimanfaatkan oleh berbagai pihak untuk berbagai peruntukan. Penelitian ini bertujuan untuk mengevaluasi kesesuaian peruntukan lahan sempadan sungai Krueng Lamnyong berdasarkan peraturan perundang-undangan. Identifikasi serta evaluasi peruntukan lahan di sempadan sungai Krueng Lamnyong menggunakan perangkat lunak Sistem Informasi Geografis (SIG). Hasil penelitian menunjukkan bahwa penggunaan sempadan sungai Krueng Lamnyong diperoleh 10 jenis penggunaan lahan. Penggunaan sempadan sungai Krueng Lamnyong yang teridentifikasi sesuai dengan peruntukan yaitu sebesar 110,91 Ha atau 68,13% yang terdiri dari irigasi, jalan, sawah, rerumputan, tanaman palawija dan tanah kosong. Penggunaan yang tidak sesuai peruntukan sebesar 51,88 Ha atau 31,87% yang terdiri dari ruang terbangun, kebun, vegetasi mangrove dan kanopi pohon.Evaluation of Land Use Suitability in Aceh Province's Krueng Lamnyong River BorderAbstract. The river border is a buffer area between aquatic ecosystems (rivers) and land. The Krueng Lamnyong River is located in Banda Aceh City and Aceh Besar District which is the downstream area of the Krueng Aceh river. The Krueng Lamnyong river border has been used by various parties for various purposes. This study aims to evaluate the suitability of the land use of the Krueng Lamnyong river border based on the legislation. Identification and evaluation of land use in the Krueng Lamnyong river border using Geographic Information System (GIS) software. The results showed that the use of the Krueng Lamnyong river border obtain 10 types of land use. The use of the Krueng Lamnyong river border identified according to its designation is 110.91 Ha or 68.13% consisting of irrigation, roads, rice fields, grass, crops, and vacant land. The use that is not in accordance with the designation is 51.88 Ha or 31.87% consisting of build space, gardens, mangrove vegetation, and tree canopies.