Identification of species composing the Bagik Batu mangrove ecosystem, Jerowaru, Indonesia

Preserving mangrove ecosystems is an important part of several global warming mitigation efforts. The latest information about the existence of mangrove ecosystems is important information for evaluating the current condition of mangrove forests. This research aims to examine the species that make up the Bagik Batu mangrove ecosystem in Jerowaru, Indonesia. Information related to the condition of the Bagik Batu mangrove ecosystem can be initial information for policy decisions by policymakers in formulating policies related to global warming mitigation. This research is descriptive (Survey). Area samples were taken using purposive sampling and the plot sampling method (random), and then many mangrove individuals were identified based on their morphological characteristics, starting from leaves, flowers, fruit, seeds, stems, and roots. In addition, the data used in this study are data on the number of individuals per species and environmental parameter data such as pH, temperature, salinity, and substrate type. The research results show that the Bagik Batu mangrove ecosystem consists of several types of mangrove species, namely Avicennia alba, Calotropis gigantea, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora stylosa, and Sonneratia alba.


Introduction
The phenomenon of global warming is a problem that has currently been the focus of various parties, including government, academics, and several non-governmental organizations.The focus in question is studies on how to prevent and reduce the direct impact of global warming.Global warming is a term that describes the condition of increasing the average temperature of the earth's climate in a certain period [1].One of the causes of global warming is the greenhouse effect.The greenhouse effect is a condition where geothermal heat is trapped and blocked by carbon dioxide gas in the atmosphere.Carbon dioxide is a type of gas in the atmosphere that comes from the remains of burning fossil fuels and the remains of the respiratory process in living things [2].
One of the mitigation efforts to reduce the effects of global warming is to use several approaches, the approaches in question can be in the form of a policy approach or an action approach.The policy approach is an action taken by creating policies that lead to steps to prevent environmental damage, and the action approach is by taking direct action to prevent environmental damage.
Apart from that, efforts that can be made to prevent and reduce the effects of the global warming phenomenon are by utilizing natural resources, especially plants as protective agents from the risks of global warming.Plants play an important role in absorbing carbon dioxide, where plants utilize carbon dioxide as a material used in their photosynthesis process.The process that occurs in photosynthesis uses water and carbon dioxide as basic ingredients.So it can be concluded that plants play an important role in reducing pollutants and the effects of global warming [2].One plant that can play an important role in preventing further effects of global warming is mangroves.Mangroves are a type of plant that can live and grow in extreme physical conditions, including habitats with salty water and muddy soil [3].Apart from that, mangroves also have other roles that are no less important, such as protecting land from crashing waves or what is usually called a wave breaker [4].
East Lombok is an area that has mangrove forests spread across several sub-districts, one of which is Jerowaru sub-district [5].Previous research conducted by the author in Teluk Jor and Ekas Buana showed that Jerowaru District has a diversity of mangrove species [6,7], however, further research in other areas in Jerowaru still requires exploration.Apart from that, one of the areas in Jerowaru District that has a mangrove ecosystem is Bagik Batu Hamlet, which is one of the areas in the Pandan Wangi Village area.
Research that reveals the current condition of mangroves in other areas in Jerowaru District is still relatively limited, including in Bagik Batu Hamlet, Pandan Wangi Village, so this research aims to examine the species that make up the Bagik Batu mangrove ecosystem, Pandan Wangi Village, in Jerowaru, Indonesia.Information related to the condition of the Bagik Batu mangrove ecosystem can be initial information for policy making by policymakers in formulating policies related to global warming mitigation.

Material and Methods
This research is descriptive (Survey).Area samples were taken using purposive sampling and the plot sampling method (random), and then many mangrove individuals were identified based on their morphological characteristics starting from leaves, flowers, fruit, seeds, stems, and roots.

Research Sampling
Research sampling was based on certain considerations, this research used a purposive sampling technique.In this study, the number of observation stations was 5 observation stations and consisted of 6 sample plots.Determination of the research sample plot size was based on Kitamura et.al. with the sub-plot sizes used as follows: a).Plot with dimensions of 10 m x 10 m for tree level with diameter (20 ≤ DBH < 35 cm); b).Plot with dimensions of 5 m x 5 m for stake level with diameter (2 ≤ DBH < 20 cm); and c).Plot with dimensions of 2 m x 2 m for seedling level with diameter (DBH < 2 cm) [8].Apart from that, other data was taken in the research in the form of environmental factors in each research sample plot in the form of pH, Salinity, Temperature and Substrate Analysis.Apart from that, identification of the types of mangrove species found in the Bagik Batu mangrove ecosystem refers to Noor, et al [9].

Data analysis
Data analysis of density, relative density, frequency, relative frequency, frequency, relative frequency, coverage, relative coverage and Importance Value Index refers to Indriyanto [10], with each of the following formulas

General description
Based on the research results, several mangrove species were found that make up the Bagik Batu mangrove forest.There were 6 mangrove species found, namely mangroves of the type Avicenia alba (Figure 2), Calotropis gigantea (Figure 3), Lumnitzera racemosa (Figure 4), Rhizophora apiculata (Figure 5), Rhizophora stylosa (Figure 6), and Sonneratia alba (Figure 7).The mangroves found in Bagik Batu are still similar to the mangroves found in other areas in the Jerowaru region.Compared with research conducted by Hadi, et.al. [6], there were similar findings of mangrove species with the species, Rhizophora apiculata, Rhizophora stylosa, and Sonneratia alba, but the species Avicennia alba, Calotropis gigantea and Lumnitzera racemosa were not found as found in the Bagik Batu mangrove ecosystem.If we look further, the Avicennia alba type of mangrove is the type with the most mangrove samples found from observation stations 1-5.This is because mangroves of this type in the Bagik Batu mangrove are still found in small stands and are mostly found in the sapling and seedling categories (Table 1).Apart from that, the second position was taken by the mangrove type Sonneratia alba with a total of 31 individuals found from all observation stations.Next, Rhizophora stylosa is the third largest type of mangrove found in the Bagik Batu mangrove ecosystem with 25 individuals.
On the other hand, mangroves with the types Lumnitzera racemosa and Rhizophora apiculata were found in 24 and 17 individuals respectively.observation stations 1, 4 and 5, while Rhizophora apiculata was only found at observation stations 1, 2, 4 and 5.One of the interesting findings in the Bagik Batu mangrove ecosystem is the discovery of Calotropis gigantea mangroves which are only found at observation stations 1 and 4.This finding is unique in itself, because other parts of the observation station do not contain Calotropis gigantea mangrove species.This type is an accompanying type of mangrove.Calotropis gigantea is a type of coastal plant which has the characteristic that it can grow up to 3 meters high and has a lot of sap.It usually lives in arid areas and is usually found in coastal areas [9].On the other hand, the Sonneratia alba type of mangrove is the dominant type of mangrove in the Bagik Batu mangrove ecosystem.This type of mangrove is found with the characteristics of stems that are quite large and quite dominate compared to other types found, this is due to the condition of the Bagik Batu mangrove ecosystem which tends to be sandy.This is in line with the explanation from Noor et al. who explains that Sonneratia alba is a type of mangrove with the characteristic that it can live on sandy beaches, and is always flooded [9].

Bagik Batu mangrove community structure
Based on the results of observations carried out on the Bagik Batu mangrove, Pandan Wangi, Jerowaru District, 3 categories of mangrove stands were found, namely the Tree, Sapling and Seedling categories.In the tree category there are 2 types of mangroves, namely Rhizophora stylosa and Sonneratia alba (Table 2).This type of mangrove is a mangrove that has relatively large stands and is quite dominant in several observation sample plots.Apart from that, Sonneratia alba is the mangrove with the highest IVI, namely 170.72, followed by Rhizophora stylosa with an IVI of 129.28 (Table 2), which means, in this condition, mangroves of this type, in the Sonneratia alba tree category, are the most numerous mangroves and can live well.Habitat conditions found are sandy and rocky.Meanwhile, other types of mangroves in the Bagik Batu mangrove ecosystem are temporarily found in the sapling category.On the other hand, mangroves in the sapling category are found with a stem diameter at breast height (DBH) between 2-20 cm found in the Bagik Batu mangrove ecosystem consisting of 5 types, namely Avicenia alba, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora stylosa and Sonneratia alba (Table 3).Avicennia alba is the mangrove type with the largest IVI, namely 66.61, followed by Lumnitzera racemosa, Rhizophora apiculata with IVI of 65.39 and 64.55 respectively.In addition, mangroves with the types Rhizophora stylosa and Sonneratia alba were found with IVI of 57.67 and 45.98 respectively.This gives an idea that, in mangrove stands with the sapling category dominated by IOP Publishing doi:10.1088/1755-1315/1317/1/0120076 Avicennia alba, however in this category, Sonneratia alba and Rhizophora Stylosa still exist and grow and are in this category, this is due to the ability of mangroves with the Sonneratia alba type which are able to live in the place.which is classified as extreme, apart from that, with lots of fruit, this type of mangrove can still dominate among other types of mangroves.In the seedling category, mangroves in Bagik Batu were found in a total of 6 types, namely Avicennia alba, Calotropis gigantea, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora stylosa and Sonneratia alba.The Avicennia alba type is the most dominant type among the other species with a fairly large IVI, namely 57.07, and Calotropis gigantea is the type with the lowest IVI, namely with an IVI of 21.40 (Table 4), this is of course closely related to the number of individuals found during the period.observation.Calotropis gigantea is a type of mangrove with the lowest number of individuals, namely 8 individuals and is only found at 2 observation stations, namely stations 1 and 4 (Table 1).Based on the data above, even though the substrate is sandy and slightly rocky, the Rhizophora type is a type of mangrove that is almost always found in every plant category, both in the Tree, Sapling, and Seedling categories.This is due to the ability of Rhizophora mangroves to live in various substrate conditions [11], unlike other types of mangroves.

Environmental Parameters
Based on observations, several environmental parameters were obtained in the research sample plot, station 5 being the station whose substrate consists of sandy mud (Table 5) and salinity with the lowest percentage, namely 4.2 because of its location close to rivers/fresh water.
If we look at environmental factors (Table 5), the dominance of several species such as Avicennia alba, Rhizophora Rhizophora apiculata, Rhizophora stylosa and Sonneratia alba is closely related to these environmental parameters.Especially in the Rhizophora family.Apart from that, the diversity in the number of individuals of each type of mangrove based on station is greatly influenced by environmental parameters, this is in line with Ball & Pidsley [12] who stated that the structure of each type of mangrove is very dependent on its ability to adapt to the environment in which it grows and develops.Apart from that, if seen from the temperature side, the Bagik Batu mangrove ecosystem ranges between 29-30 o C, the condition of these environmental parameters is quite good and has an impact on the growth and development of mangroves in Bagik Batu, where, according to Efriyeldi et al [13] the temperature is 30 o C This is the right temperature for mangrove growth.

Conclusion
The Bagik Batu mangrove ecosystem located in Bagik Batu Hamlet, Pandan Wangi Village, Jerowaru District consists of six species, namely Avicennia alba, Calotropis gigantea, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora stylosa and Sonneratia alba.One thing that is unique about the results of this research compared to previous research conducted by the author on the mangrove ecosystems of Teluk Jor and Ekas Buana is the presence of mangroves including the Calotropis gigantea and Lumnitzera racemosa types, while the mangrove types Rhizophora apiculata, Rhizophora stylosa and Sonneratia alba were found by the author in the Teluk Jor and Ekas Buana mangroves ecosystem.In closing, this research is initial research that still requires further research, both in terms of evaluating mangrove carbon storage and uptake, evaluating mangrove ecosystem management and developing strategies for managing the Bagik Batu mangrove forest as a tourist and educational destination.

Table 1 .
Number of individuals found

Table 2 .
Tree level importance index

Table 3 .
Sapling level importance value index

Table 4 .
Importance value index seedling level

Table 5 .
Environmental parameters