Mangrove replenishment a way to coastal resiliency

Report: Quadrant study to assess the feasibility of Mangrove species in coastal project village, Odisha

Project rationale:

A pilot project has been undertaken by IGSSS team to address the vulnerabilities through an understanding in the local community on coastal climate hazards, vulnerabilities & capacities. The project focuses to bring a positive change in knowledge, attitude and practice of the community to replenish coastal mangrove coverage. This will also add to atmospheric decarbonization and provide opportunities for alternative income to the local community which will incentivize the coastal mangrove coverage. The project targets replenishing a total of 25-hectare coastal mangrove coverage in the project villages. In the next three years this coverage could lead to decarbonize more than 1 million quintals.

Objective of the study:

To develop a quality knowledge document (report) which will give us an understanding on the surviving flora species in
the coastal forest patches and in the deforested embankment of the project villages. The study reveals,
1. The surviving flora species (including mangrove)
2. The species frequency in the surviving flora species (including mangrove)
3. The species density in the surviving flora species (including mangrove)
This knowledge document will help the team in identifying the primary or dominating mangrove species in the coastal forest patches neighbors to the project village embankments and accordingly will help in finalizing the mangrove species to plant in the deforested embankment of the project village.

Methodology of the study:

Quadrant methodology was used for data collection. The quadrant was used to enumerate the species frequency % and
species density. A quadrat is a sample plot of a specific size used for the study of species frequency and species density
in that plot. In the field 50 * 50 ft quadrant was taken for sampling and data collection. Measurement tape, thread, peg
etc were used for preparing sample quadrants.
The species frequency % and species density formula are given below;
1. Species frequency % (SF) = (Number of sample quadrant in which the species occurs)/(Total number of sample
quadrant employed for the study)*100
2. Species density (SD) = Total number of individuals of the species in all sample quadrats/ total number of sample
quadrats

Process of the study :

The process which was undertaken during the study is mentioned below,

1. Visited field for a basic understanding on the surviving flora in project village embankment. The height, girth at breast height, crown cover and ground cover of the trees was observed to understand the health status of the trees. This field visit was helped in formatting    the data collection tools for the study.
2. Prepared the tools for data collection of the study. Based on the field visit experiences and the classical formula for calculating species frequency and species density through a sample quadrant, the data collection tools were prepared.
3. A training with a field demonstration was imparted to the 8 volunteers and the project team on the data collection tools.
4. A data collection plan was developed by the participants and data was collected within a given deadline from the sample field.

Sampling:

10 sample quadrants, each of 50 * 50 ft was taken from the surviving forest patches and deforested embankments of the project village.

1. The sample quadrants from the forest patches were taken in the three different creeks of Balipantala project village. Both the species                 frequency and species density data were collected from the forest patches.
2. The sample quadrant from deforested embankment were taken in the four different creeks of Dakhinapantala project village. Only                      species frequency data was collected from the deforested embankment

Findings from the surviving forest patches of Balipantala project village:

Identified species with highest frequency and highest density in the sample quadrant:

Creek wise analysis:

The highest species frequency in creek I & II is Harakancha while the highest species frequency in creek III is Bani (Bada).
The highest species density i.e. the most dominating species in creek I is Sindhuka (Bada & Sana), in creek II the highest species density i.e. the most dominating species is Rai (Sana), in creek III the highest species density i.e. the most dominating species is Bani (Bada).

Species wise analysis:

1. Harakancha- It is frequently visible in the sample quadrants in all the three creeks. It is observed as moderately dense in creek II and low density in creek I
2. Sindhuka (Bada & sana)- In creek I, the species frequency is moderate while species density is highest. In creek II there is no trace of this species. In creek III it survives with low frequency and low density.
3. Bani (Sana)- The species frequency of Bani (Sana) is low while the species density is moderate in creek I. There is no trace of Bani (Sana) in creek II. In creek III the species frequency of Bani (Sana) is low while the species density is moderate.
4. Bani (Bada)- In creek I, the species frequency is moderate while with very low density. In creek II, low of this species frequency trace is visible. In creek III, this species survives with low species frequency and moderate species density.
5. Rai (Bada)- There is no Rai (Bada) in the sample quadrants of creek I & III. In creek II, this species survives with low density and moderate frequency.
6. Rai (Sana)- The species frequency of this species is moderate, and the species density of this species is highest in creek II. There is no trace of Rai (sana) in creek I. In creek III this species survives with low frequency and very low density, hence uncountable.
7. Kerua- This species has moderate species frequency only in creek III. The density of this species is very low, hence uncountable.

Details of Creek I:

1. The highest species density i.e. the most dominating species in creek I is Sindhuka (Bada & Sana) which is 130 in each sample quadrant and the species frequency is 70%.
2. Bani (sana) shows moderate species density which is 24 in each sample quadrant while with 60% frequency.
3. 15 Harakancha is visible in each sample quadrant with 80% frequency.

Details of Creek II:

1. The highest species density i.e. the most dominating species in creek II is Rai (Sana) which is 40 in each sample
   quadrant and the species frequency is 80%.
2. Harakancha shows moderate species density which is 37 in each sample quadrant while with 100% frequency.
3. Rai (Bada) is frequently visible in the sample quadrant; the frequency is 80% while the species density is 19 in each
   sample quadrant.

Details of Creek III:

1. The highest species density i.e. the most dominating species in creek II is Bani (Bada) which is 24 in each sample
   quadrant and the species frequency is 100%.
2. Bani (Sana) shows moderate species density which is 15 in each sample quadrant while with 30% frequency.
3. Sindhuka (Bada + Sana) is frequently visible in the sample quadrant, the frequency is 60% while the species density
   is 9.5 in each sample quadrant.

Findings from the deforested embankment of Dakhinapantala project village:

Harakancha is frequently visible in all the sample quadrants collected from the four creeks of Dakhinapantala village.
The species frequency of Sindhuka is 70% 20% and 10% in creek I, creek II & creek IV respectively. Bani (Sana) is 30%
frequent in creek II while 20% frequent in each of the creek I & III. No trace of Sindhuka reported in creek III and no
trace of Bani (Sana) reported in creek IV.

It also reveals that in creek I, the survivability rate is high in Harakancha and Sindhuka whereas in creek II, the surviving
rate of Bani(Sana), Harakancha and Sindhuka is almost same to each other. The surviving rate of Harakancha is high in
both the creek III & IV.

Recommendations from the study:

The quadrant study gives us a quality understanding on the mangrove biodiversity in the surviving forest patches of the coastal project village. Based on this understanding and quadrant data analysis the recommendations on the feasible/ suitable mangrove species for plantation in the deforested project village embankment is mentioned below.

Harakancha is the native shrub species which species frequency is highest in the forest patch creeks and as well as in the deforested embankment creeks of the project village. Apart from this, this species has extreme salt tolerance capacity, has adventitious root/ stilt-like root system which can hold the soil strongly, hence minimize flood risk. This is also termed as milky mangrove, as it secretes latex from stem. Suggestion is to propagate this species in the barren embankment. This can grow through vegetative reproduction from the root cuttings. This species can be accommodated as layer I, in the junction of the raised embankment and rivershore.

Sindhuka (Bada & Sana) both are visible in the deforested embankment of the project village. It is surviving densely in creek I and in low density at creek III of the forest patches. It has fused broom like stilt roots form buttresses on the trunk base. Due to this it has strong mechanical force to hold the embankment against cyclone hence it can minimize the risk of cyclone. It grows rapidly and native for the plantation site. Therefore, suggestion is to cultivate this species in the barren embankment through quadrant plantation. This species can serve the 2nd layer immediately after the layer of Harakancha. Out of all mangrove trees, Sindhuka (Bada & Sana) will be planted 50%

Bani (Bada & Sana)- Similar to Sindhuka (Bada & Sana), Bani(Bada & Sana) is surviving moderately dense in creek I & III of the forest patches. This species is frequently visible in all the creeks of the deforested embankment of the project village. This species has numerous pneumatophores like erect pencil, attain height up to 30cm. This helps the tree to stand straight on the land even in extreme current at high tide. Its mechanical strength minimizes the risk of flood and cyclone. It is a rapid growing species and native in the village embankment. Suggestion is to plant Bani (Bada & Sana) in layer II parallel to Sindhuka (Bada & Sana), in separate quadrant plantation. Out of all mangrove trees, Bani (Bada & Sana) will be planted 30%

Rai (Bada & Sana) is the mangrove with a unique feature of viviparous germination. It has prominent stilt roots from the trunk bases and has hanging aerial roots. This helps the tree in strongly holding the land. Due to this root system this tree become a habitat of several animals. Hence this tree can enhance the local biodiversity quality. This species can be accommodated as layer III, in a separate quadrant, in the junction of river and rivershore. Out of all mangrove trees, Rai (Bada & Sana) will be planted 20%

Note:

It has been proven from the data collected from the forest creeks, Rai (Bada & Sana) & Sindhuka (Bada & Sana) and Bani (Bada & Sana) & Sindhuka (Bada & Sana) are negatively corelated to each other i,e. the species are inversely proportionate to each other. This reveals that the mortality rate will be high if the species grow together. Hence suggestion is to plant each species in separate quadrants. There must be a gap of 20 to 30 feet between the two quadrants. This gap may serve as a trench for river water during drying and desiccation.

The plantation plan in the deforested embankment project village has been enclosed for the reference.

Appendix:

Local name & scientific name of the mangroves:
1. Sindhuka (Bada & Sana)- Kandelia candel(Rhizophoraceae)
2. Bani (Sana)- Avicennia marina (Avicenniaceae)
3. Bani (Bada)- )- Avicennia officinalis (Avicenniaceae)
4. Bandari- Bruguiera gymnorrhiza (Rhizophoraceae)
5. Rai (Sana) – Rhizophora stylosa (Rhizophoraceae)
6. Rai (Bada)- Rhizophora mucronate (Rhizophoraceae)

Contributed by: Proshin Ghosh & Pratishtha Parasher