The distribution of mangrove area, mangrove density, and species diversity on the North Coast of Jakarta

The distribution of mangrove area, density, and species diversity on the North Coast of Jakarta indicate the mangrove adaptation to live and grow in permanent water inundation areas. Therefore, this research aimed to analyze the distribution and mapping of the mangrove ecosystem in permanent water inundation area using the index of mangrove density, diversity, and geographical information system. The results showed that soil water salinity ranged from 5.6 to 7.0 ppt, water salinity ranged from 0.1 to 9.8 ppt, soil water pH ranged from 6.25 to 7,0, water pH ranged from 5.83 to 6.5, soil nitrate ranged from 12.2 to 22.8 mg/L, soil phosphate ranged from 1.7 to 14.8 mg/L, soil pyrite ranged from 0.12 to 0.3 mg/L, and soil texture varied from silt loam to silty clay loam. The mangrove ecosystem on the North Jakarta was dominated by a very rare density and low–moderate diversity, with a density between 440–1,250 trees/ha. The distribution of mangrove area also showed a very rare density from 0.18 ha (2000) to 166.95 ha (2020), a rare from 197.03 ha (2000) to 359,72 ha (2020), the moderate from 263.65 ha (2000) to 351.09 ha (2020), the dense from 591.78 (2000) to 273.92 ha (2020), and the very dense from 486.35 ha (2000) to 98.91 ha (2020). The mangrove ecosystem in the North Coast Jakarta was dominated by Avicennia marina, Rhizophora mucronata, Rhizophora apiculata, Rhizophora stylosa, Nypa frutican, Sonneratia alba and Sonneratia caseolaris . The conclusions of this research showed that the mangrove ecosystem inJakarta is degraded because it is dominated by rare-very rare of mangrove density.


Introduction
Jakarta has many type of ecosystem, including the mangrove ecosystem, brackish water ecosystem, beach, seagrass, and coral ecosystems (Onrizal et al. 2005;Yanuartanti et al. 2015;Hilmi et al. 2021dHilmi et al. , 2022b)).In Jakarta, the mangrove ecosystem is a main ecosystem that has many functions to reduce risk of tidal flooding, seawater intrusion and abrasion.Beside that, mangrove ecosystem in Jakarta has fuction to support activity of fishing activity, ecotourism and aquaculture activity.As a coastal ecosystem, the mangrove ecosystem also is influenced by freshwater from Ciliwung and Angke River (Hilmi et al. 2021d(Hilmi et al. , 2022a) ) and seawater from the Java Sea (Yanuartanti et al. 2015;Hilmi et al. 2017a), permanent tidal inundation (Hilmi et al. 2021d(Hilmi et al. , 2022b)), seawater intrusion (Hilmi et al. 2017a), water and heavy metal pollution (Hilmi et al. 2017c) and anthropological factors (Ariani et al. 2016).
Jakarta city as coastal area also is influenced by many disasters (Hilmi 2018;Nur and Hilmi 2021) like as the tidal flooding (Bomer et al. 2020;Hilmi et al. 2022a), and permanent water inundation (Hilmi et al. 2021d(Hilmi et al. , 2022b)).Base on coastal disasters, the existence of mangrove ecosystem plays important role and function to reduce coastal disasters.
The distribution of mangrove ecosystems using indicators of mangrove area, mangrove and species density, and species diversity (Ismail et al. 2018;Hilmi et al. 2021b, d) are used to analyze species adaptation to live and grow in the coastal area.The potential of mangrove area, density and diversity are needed to reduce the impact of the permanent water inundation area (Hilmi et al. 2022b), sea water intrusion, tidal flooding and support the ecosystem services.
The distribution of density, diversity, and area in many coastal areas also show the mangrove adaptation to live and grow in area with heavy metal and water pollution (Zhang et al. 2019a;Chai et al. 2020), tidal inundation (Bullock et al. 2017;Ahmed et al. 2021;Hilmi et al. 2022b), poor water quality (De Valck and Rolfe 2018;Hilmi et al. 2021e), soil conditions (Domínguez-domínguez et al. 2019), and anthropological factors (Markle and Chow-Fraser 2016; Cheng et al. 2018).The adaptation and ability of mangrove ecosystem support the sustainability and stability of the mangrove ecosystem which have correlation with many functions and aspects including the economy, ecology, social, and cultural.
Basically the ecosystem services of mangrove ecosystem give reflection of human beings, welfare, and nature (Comberti et al. 2015;Elmqvist et al. 2015).Müller et al. (2020), Zhou et al. (2020) and Hugé et al. (2020) also stated that the mangrove functions also directly or indirectly contribute to human wellbeing through the ecological, social economic, fresh water and food, regulating services, groundwater recharge, flood storage, water quality, carbon storage, wildlife habitat, organic waste reduction, fisheries, ecotourism, cultural and education resources (Matthews 2016;Yan et al. 2016).Mangrove ecosystem also has positive contribution to climate regulation, and nutrient cycling (Ramyar 2019;Tost et al. 2019;Sharafatmandrad and Mashizi 2020;Wang et al. 2020).
Moreover, the distribution of mangrove density, diversity, and area on the coast of Jakarta must be developed to analyze the condition of mangrove ecosystem.The data of mangrove distribution is used to maintain the functions and ecosystem services of mangrove ecosystem (Dijk et al. 2016;Duncan et al. 2016;Hilmi et al. 2017b;Hu et al. 2020).Basically, Jakarta has many type of mangrove ecosystems that are protected forest, greenbelt, arboretum, and wildlife reserve area (Hilmi et al. 2021b(Hilmi et al. , 2022b)).Due to unfavorable conditions, mangrove ecosystems must have high adaptation to reduce the impact of permanent water inundation (Yanuartanti et al. 2015;Hilmi et al. 2022b), tidal flooding (Hilmi et al. 2022a), seawater intrusion (Hilmi et al. 2017a), supporting of mangrove ecotourism (Dijk et al. 2016;Soares et al. 2018), fishing activity, and buffering of settlement.This research aimed to analyze the distribution and mapping of mangrove ecosystem in permanent water inundation area using index of mangrove density, diversity, and geographical information system.

Time and Research Site
This research was conducted in two stage activities that were (1) the mapping analysis using the satellite imagery 2000, 2010 and 2020, (2) the vegetation and environment analysis were conducted from January to July 2022 The research location was focused in the North Coast of Jakarta which was divided into 9 stations, namely Protected Forest of Muara Angke, Rehabilitation area (Elang of Muara Angke), Greenbelt area (Galatama of Muara Angke), Ecotourism of Muara Angke, Greenbelt area of Tol Sediyatmo, and Arboretum of Muara Angke, as shown in Fig. 1 and Table 1.
The data used 10 sampling plots for each station, from 9 stations and the size of the sampling plot of mangrove trees was 10 m × 10 m (Kantharajan et al. 2018;Hilmi et al. 2020Hilmi et al. , 2021d)).The sampling plots were used to collect the mangrove density, mangrove species and environmental properties.

Research Variable
The research variables were mangrove density, diversity, area and environmental properties (including water quality, and soil properties).These variables were used to analyze the distribution and mapping analysis of the mangrove ecosystem in North Coast of Jakarta.

Research procedures 2.3.1. Mangrove sampling
The mangrove sampling used a one-stage cluster sample with the transect method (Kusmana 1997;Hilmi et al. 2019Hilmi et al. , 2021c) ) to analyze tree density and the physical-chemical environmental factors based on the potential of permanent water inundation.To analyze mangrove tree density, a total of 90 sampling plots were obtained from 9 stations.The mangrove plot had a size of 10 m × 10 m, which was used to evaluate tree density with a diameter > 4 cm.

Environment sampling
The environment sampling was conducted through a clustering method, including (1) soil texture and (2) water quality with the related salinity, pH, phosphate, nitrate, and pyrite (Nusantara et al. 2015;Xiong et al. 2018;Xiao et al. 2019).The environmental sampling was taken based on the mangrove samples, with 20 sampling plots to analyze the environmental variables.

Data analysis 2.4.1. The density and diversity Indicators of mangrove vegetation
The density and diversity were conducted using the equations expressed by (Hilmi et al. 2017b(Hilmi et al. , 2019(Hilmi et al. , 2021d)), which include: (a) Mangrove density.The analysis density used the vegetation analysis using the equation (Xiong et al. 2018;Hilmi et al. 2021d;Cooray et al. 2021): To analyze the mangrove density classification, the formulation of (Hilmi et al. 2019) was used as shown in Table 2. (b) Dominance index.Dominance index used important value of mangrove, which can be divided into frequency, dominance, and relative density (Kusmana 1997;Hilmi et al. 2015Hilmi et al. , 2017bHilmi et al. , 2021d)).
Where i = species-i (c) Diversity Index.The diversity index only used the Shannon wiener analysis (Magurran 1996;Hilmi et al. 2015) with the equation stated below: where H' is Shanon wiener index, Pi is proportion of mangrove trees -i, and s is number of species.
Previous research showed that mangroves can be grown in an environment with different properties, which include soil textures of coarse, sandy and clay, salinities between 2 and 30‰, and pH values of 4-8 (Krauss et al. 2008;Yanuartanti et al. 2015;Hilmi et al. 2021d).Hilmi et al. (2021e) and Hilmi et al. (2019) also reported that the mangrove ecosystem in Segara Anakan Lagoon is divided into two ecosystems, where the first area is dominated by phosphate of 9.56-19.72%,Corganic of 1.161-0.49%and pyrite of 0.03-2.88%.Meanwhile, the second area is dominated by water salinity between 13.5-32.33ppt, pH of 5.73-7.53,soil texture was clay and , and C-organic ranging from 1.16 to 1.47%.Mangrove also can be grown on water inundation with physical and chemical parameters, which include water temperature of 25.0-30.5oC,water salinity of 6.0-7.5 ppt, water pH of 5.0-6.4,soil pH 6.0-7.0 with a muddy clay texture, soil nitrate of 11.5-14.5 mg/l, soil phosphate between 8.2-16.0mg/l and soil pyrite of 1.0-3.0%(Hilmi et al. 2022b).Onrizal and Kusmana (2008) stated that in North of Sumatra, mangrove environmental characteristics are temperature of 31oC, pH 6-7, and salinity at 30 ppt.

Trees Density and Diversity of Mangrove ecosystem
The density and diversity of the mangrove ecosystem on the North Coast of Jakarta are presented in Table 4.The data showed that the ecosystem in North Jakarta was dominated by as associate mangroves.The domination of Avicennia spp, Sonneratia spp, Rhizophora spp and Nypa frutican are caused by the good adaptation pattern of these species to life and grow in permanent of water inundation, the water pollution, and muddy clay texture.The data also described that the mangrove had only two categories that were rare and very rare density.The rare density was discovered in the Mangrove ecotourism area, Angke Kapuk Preservation Forest, Mangrove Arboretum, while the very rare categories were found in Galatama Mangrove Area, Elang Mangrove Greenbelt, and Suaka Marga Satwa Muara Angke.
Based on the mangrove density and diversity, the ecosystem in North Jakarta was dominated by very rare density and lowmoderate diversity.The rare density was discovered in the mangrove ecotourism area, preservation area, and arboretum area with a value of 1060-1250 trees/ha.Meanwhile, the very rare density is dominated in Galatama, Elang Greenbelt, and Suaka Margaswatwa   The data showed that the mangrove ecosystem was degraded because it had increasing moderate-very rare density and decreasing dense and very dense density.The factors of degradation were permanent water inundation (Hilmi et al. 2021d(Hilmi et al. , 2022b)), tidal flooding (Hilmi et al. 2022a), anthropology effect (Onrizal et al. 2005;Yanuartanti et al. 2015;Kuvaini et al. 2017), garbage, micro and macro plastic (Syakti et al. 2013;Dangan-Galon et al. 2016), sweater tide, and oceanography (Yanuartanti et al. 2015;Hilmi et al. 2022a, b).Fig. 3 also described that the mangrove area on the North Coast of Jakarta tends to decrease from 1538.99 ha (2000) to 1250.59 ha (2020).The degradation of mangrove ecosystem in Jakarta is caused by the conversion of mangrove ecosystem to settlement, market buiding, and others activities.The other factors are permanent water inundation, garbage and water pollution Similarly, Sari et al. (2016) stated that the lagoon area in Segara Anakan Lagoon has an increasing trend from 1.199 ha (2003) to 1.043 ha (2016) or 156 ha/13 year, with 12 ha/year.A different result was obtained in Iswahyudi et al. (2020) stating that the ecosystem in Langsa, Aceh has a mangrove area from 4188.50 ha (2007) to 4512.78 ha (2013).

The mapping analysis of mangrove area distribution on the North Coast of Jakarta
The mapping analysis of mangrove area distribution on the North Coast of Jakarta was developed using the data from 2000, 2010, and 2020.Fig. 4-6 showed the degradation area of the mangrove ecosystem, the increasing area of very rare density, and the rare density of the mangrove ecosystem.
2.4.2.Mapping analysis of mangrove density and area on the North Coast of Jakarta The mapping analysis of mangrove density and area was conducted using Landsat 2000, 2010, and 2020.The analysis used ENVI and Arc GIS program with stages were radiometric correctionsand Normalized Difference Vegetation Index (NDVI) to analyze mangrove density using the red band and electromagnetic spectrum based on equation  = (−) (+), where NIR = NIR: band nearinfrared and RED: band red.The mangrove density following the calculation of NDVI with categories are pixel score 0.43 ≤ NDVI ≤ 1.00 = high density, 0.33 ≤ NDVI ≤ 0.42 = moderate density, and -1.0 ≤ NDVI ≤ 0.32 = lower density.

Figure 3 .
Figure 3.The total distribution of mangrove area in the North Coast of Jakarta.

Figure 2 .
Figure 2. The total of mangrove density classification in the North of Coast Jakarta

Figure 4 .
Figure 4.The mapping of mangrove ecosystem in the North Coast of Jakarta in 2000.

Figure 5 .
Figure 5.The mapping of mangrove ecosystem in the North Coast of Jakarta in 2010.

Figure 6 .
Figure 6.The mapping of mangrove ecosystem in the North Coast of Jakarta in 2020.

Table 2 .
The mangrove density classification Mangrove density Class Mangrove density (trees/ha)

Table 3 .
The environmental factors of mangrove ecosystem in North Coast of Jakarta

Table 5 .
The distribution of mangrove area in The North Coast of Jakarta value of 440-820 trees/ha.The mangrove diversity was dominated by low diversity spread over the Ecotourism, Preservation, Elang Greenbelt, and Suaka Margaswatwa area, while the moderate diversity was in the Arboretum and Galatama