Development of a Rapid Mangrove Zonation Mapping Workflow Using Sentinel 2-Derived Indices and Biophysical Dataset

Moderate to high resolution satellite imageries are commonly used in mapping mangrove cover from local to global scales. In addition to extent information, studies such as mangrove composition, ecology, and distribution analysis require further information on mangrove zonation. Mangrove zonation refers to unique sections within a mangrove forest being dominated by a similar family, genus, or species. This can be observed both in natural and planted mangrove forests. In this study, a mapping workflow was developed to detect zonation in test mangrove forest sites in Katunggan-It Ibajay (KII) Ecopark (Aklan), Bintuan (Coron), Bogtong, and Sagrada (Busuanga) in the Philippines and Fukido Mangrove Park (Ishigaki, Japan) using Sentinel-2 imagery. The methodology was then applied to generate a nationwide mangrove zonation map of the Philippines for year 2020. Combination of biophysical products, water, and vegetation indices were used as classification inputs including leaf area index (LAI), fractional vegetation cover (FVC), fraction of photosynthetically-active radiation (FAPAR), Canopy chlorophyll content (Cab), canopy water content (Cw), Normalized Difference Vegetation Index (NDVI), modified normalized difference water index (MNDWI), modified chlorophyll absorption in reflectance index (MCARI), and red-edge inflection point (REIP). Mangrove extents were first mapped using either the Maximum Likelihood Classification (MLC) algorithm or the Mangrove Vegetation Index (MVI)-based methodology. The biophysical and vegetation indices within these areas were stacked and transformed through Principal Component Analysis (PCA). Regions of Interest (ROIs) were selected on the PCA bands as training input to the MLC. Results show that mangrove zonation maps can highlight the major mangrove zones in the study sites, commonly limited up to genera level only except for genera with only one known species thriving in the area. Four zones were detected in KII Ecopark: Avicennia zone, Nypa zone, Avicennia mixed with Nypa zone, and mixed mangroves zones. For Coron and Busuanga, the mapped mangrove zones are mixed mangroves, Rhizophora zone and sparse/damaged zones. Three zones were detected in Fukido site: Rhizophora stylosa-dominant zone, Bruguiera gymnorrhiza-dominant zone, and mixed mangrove zones. The zonation maps were validated using field plot data and orthophotos generated from Unmanned Aerial System (UAS) surveys, with accuracies ranging from 75 to 100%.

Spatiotemporal Heterogeneity of Mangrove Root Sphere under a Tropical Monsoon Climate in Eastern Thailand

Mangrove ecosystems under tropical monsoon climates experience changes in environmental factors, especially seasonal variations in salinity. These changes might have direct influences on the mangrove root sphere, which plays an important role in carbon dynamics and supports mangrove growth. We aimed to elucidate how the soil properties including salinity and nutrient budget affect the mangrove roots in the wet and dry seasons across the mangrove zonation (Avicennia, Rhizophora, and Xylocarpus zones). This area is in a secondary forest at the Trat River estuary, eastern Thailand. Root mass was observed at 0–10 and 10–20 cm depths across all zones and the living roots were separated into diameter classes. The soil water salinity was measured at a 10 cm depth. We analyzed the nitrogen, phosphorus, and carbon contents in the roots and soil. Spatiotemporal changes occurred due to the vegetation zonation and the variations in salinity and the content of soil available phosphorus that caused different root sphere conditions along the distance from the river. The highest root biomass was found in the riverward Avicennia zone, which was 4.8 times higher than that of the inland Xylocarpus zone in the wet season. The root necromass distribution along the zonation showed an opposite trend to that of biomass. Among seasons, the root size-class proportion differed, with high fine roots observed during the wet season. We confirmed that the root sphere showed both spatial and temporal heterogeneity. Mangrove roots, especially fine roots, interacted with changing salinity, inundation regime, and biological processes evoked by microtopographic gradients as a consequence of mangrove zonation and seasonal rainfall. Our findings indicate how the root sphere differed by specific vegetation structure in this mangrove forest. Therefore, these might provide an ecological perspective for the mangrove rehabilitation plans to facilitate below-ground carbon stock.

Mapping Mangrove Zonation Changes in Senegal with Landsat Imagery Using an OBIA Approach Combined with Linear Spectral Unmixing

The mangrove areas in Senegal have fluctuated considerably over the last few decades, and it is therefore important to monitor the evolution of forest cover in order to orient and optimise forestry policies. This study presents a method for mapping plant formations to monitor and study changes in zonation within the mangroves of Senegal. Using Landsat ETM+ and Landsat 8 OLI images merged to a 15-m resolution with a pansharpening method, a processing chain that combines an OBIA approach and linear spectral unmixing was developed to detect changes in mangrove zonation through a diachronic analysis. The accuracy of the discriminations was evaluated with kappa indices, which were 0.8 for the Saloum delta and 0.83 for the Casamance estuary. Over the last 20 years, the mangroves of Senegal have increased in surface area. However, the dynamics of zonation differ between the two main mangrove hydrosystems of Senegal. In Casamance, a colonisation process is underway. In the Saloum, Rhizophora mangle is undergoing a process of densification in mangroves and appears to reproduce well in both regions. Furthermore, this study confirms, on a regional scale, observations in the literature noting the lack of Avicennia germinans reproduction on a local scale. In the long term, these regeneration gaps may prevent the mangrove from colonising the upper tidal zones in the Saloum. Therefore, it would be appropriate to redirect conservation policies towards reforestation efforts in the Saloum rather than in Casamance and to focus these actions on the perpetuation of Avicennia germinans rather than Rhizophora mangle, which has no difficulty in reproducing. From this perspective, it is necessary to gain a more in-depth understanding of the specific factors that promote the success of Avicennia germinans seeding.

STRUKTUR KOMUNITAS DAN ZONASI VEGETASI MANGROVE DESA DARUNU KECAMATAN WORI KABUPATEN MINAHASA UTARA

Mangrove ecosystem is a collection of distinctive plant types that contained in tropical and subtropical coastal region. The purpose of research was to find out the community structure and mangrove zonation at Darunu Village, Wori District, North Minahasa Regency. The research was conducted by the quadrant transect line method. It was done by pulling a straight line, perpendicular from the outermost mangrove area to the land direction, along 100 m by determining three data retrieval Station. To determine the condition of mangrove then density, species frequency, species coverage, important value index, diversity index and equality types were analyzed. The result found 5 mangroves species, namely: Rhizophora apiculata, R. mucronata, Sonneratia alba, Bruguiera gymnorrhiza and Avicennia officinalis. The highest density value was R.apiculata, as well as species frequency, while the species coverage value found in S. alba. The diversity value found at Station 2. The zonation of mangrove vegetation in Darunu village respectively, at Station 1 and 2 in the front was overgrown by R.apiculata species with sandy mud substrate. The Station 3 was overgrown by S.alba species with sandy mud. Generalyl, this location substrate contains of sandy mud and mud.Keywords : Mangrove, community structure, zonation.

Differential analysis of prokaryotic communities from pristine mangrove tidal zone sediments reveal distinct structures and functional profiles

Mangrove forests are intertidal ecosystems that constitute a large portion of the world's coastline, as such, they are composed of, and reliant upon, microhabitats defined by the tides. However, we are only beginning to understand tidal microhabitat biodiversity and their role in nutrient cycling. The majority of metagenomic studies have so far been conducted on anthropogenically impacted areas. As even mild disruption can severely alter ecosystems and lead to decreased biodiversity and local extinctions, this is a critical issue. Here, we characterize prokaryotic populations and their involvement in nutrient cycling across the tidal zones of a pristine mangrove forest within a Brazilian Environmental Protection Area of the Atlantic Forest. We hypothesize that tidal zones in pristine mangroves constitute distinct microhabitats, are composed of different prokaryotic communities and, consequently, distinct functional profiles. Samples were collected in triplicate from zones below, between, and above the tidal waterline. Using 16S amplicon sequencing, we find significantly different prokaryotic communities with diverse nutrient cycling related functions, as well specific taxa with varying contribution to functional abundances between zones. Our findings contrast those observed in anthropogenically impacted mangroves and suggest that some aspects of mangrove zonation may be compromised by human activity.

Propagule Dispersal Determines Mangrove Zonation at Intertidal and Estuarine Scales

Propagule dispersal has generally been recognized as a vital factor affecting the spatial structure of tropical forest plants. However, available research shows that this hypothesis does not apply to mangrove species the propagules of which are dispersed by water. Due to the lack of comprehensive and quantitative information as well as the high spatio-temporal heterogeneity of the mangrove environment, the exact factors affecting the spatial structure of mangrove forests are poorly understood. To assess this, we selected a mangrove estuary with high mangrove species richness that experiences great changes in water salinity. After investigating the zonation of mature mangrove individuals across tides and the estuary, we measured the size and initial specific gravity of the propagules and then selected the eight most common species from which to observe the changes in specific gravity, buoyancy, and root initiation during dispersal at different sites with different water salinity regimes. The relationships among distribution patterns, propagule establishment, and dispersal behavior were investigated. We found that mangrove propagule dispersal is not a passively buoyant process controlled by water currents. During dispersal, mangrove propagules can actively adjust their specific gravity and root initiation. The dynamic specific gravity of the propagules was negatively related to propagule buoyancy and surface elevation. The differences in propagule specific gravity corroborated the distribution patterns of the species across the intertidal zone and estuary. Mangrove zonation on both the intertidal and estuarine scale can be explained by the tidal sorting hypothesis, as zonation is controlled by the tidal sorting of the propagules according to buoyancy and by the differential ability of the propagules to establish in the intertidal zones. The results add new understanding of observed mangrove species zonation and should inform conservation managers when restoring mangroves or evaluating the potential impacts of global change and anthropogenic disturbances that might alter the hydrology, including the water salinity regime.

Diversity of Mangrove Plant for Support Ecotourism Activities in Nature Conservation Forum Putri Menjangan, Pejarakan Buleleng-Bali

This study aims to identify the species of mangrove constituents and determine the zonation of the growing community of mangrove plants from the seaward to the landward zone, of the Nature Conservation Forum (NCF) Putri Menjangan coastal Pejarakan village Buleleng from July to October 2017. Identification of mangrove plant species based on the following characteristics: habitus, root type, fruit shape, inflorescence, leaf shape and leaf arangement. Zoning of mangrove grown is determined from vegetation analysis conducted in 3 zones (front zone, middle zone and back zone) with quadrat method, the area of each square is 20 m x 20 m. Parameters specified in each kwadrat are the density, dominance and frequency of presence of each species. Zoning of mangrove community is determined based on the important value of mangrove plant species. The diversity of the mangrove community is calculated by the Shanon-Wiener Diversity Index. The results of the study identified 13 species of true mangrove plants (mangrove) and 14 mangrove mangrove associates. The dominant species are Sonneratia alba (important value / iv is 98.19), Lumnitzera racemosa (iv. is 40.75), Rhizophora apiculata (iv.is 35.53), Rhizophora mucronata (iv. 33.02), Ceriops decandra (iv.23.61) and Avicennia marina (iv. 22.22). The diversity index of mangrove species (H) is 2.07, then it is considered good. The pattern of growing mangrove plants in coastal Pejarakan Buleleng, in general follow the natural pattern of mangrove zonation. Typical characteristics and patterns of growing mangrove zonation become interesting attractions and reference for mangrove area managers in ecotourism development and efforts to conserve mangrove forests.

Vegetation structure, species diversity, and mangrove zonation patterns in the Tanjung Panjang Nature Reserve Area, Gorontalo, Indonesia

This study aimed to analyze the structure of vegetation, diversity and patterns of mangrove zonation in the Tanjung Panjang Nature Reserve area. Data collection of mangrove vegetation structure was carried out by using the line transect method (plot measuring 20 m x 20 m), measurement of environmental parameters that supported mangrove life, and 12 soil samples carried out by laboratory tests. The sample distribution was 18 research sample points. The results showed that mangrove vegetation density both at the level of trees, saplings and seedlings was in the category of total damage with density values at tree level 0.04-0.22 ind/ha), sapling 0- 0.07ind/ha), and seedlings 0.02-0.08 ind/Ha). The percentage of closure types ranged from 0% - 38%, meaning that the criteria of damage was rare, which was <50%, and some were included in the criteria of total damage, which was 0%. The index of mangrove species diversity was sequential starting from the level of trees, saplings and seedlings, which were 0.37-1.53, 0.00-0.31, and 0.00, where the tree level diversity index was in the medium category, and the sapling and seedling levels were in the low category.