Presented by Rupesh Bhomia (CIFOR-ICRAF) at MMM6 on 25 July 2023 in Cartagena

1. Carbon Dynamics in Mangrove
Ecosystems of Andaman Islands:
A living laboratory for studying natural disturbance and
ecological succession Rupesh Bhomia
25 July, 2023

2. Outline
• Context – What, Where
• Motivation – Why
• Process – How, When
• Outputs – Preliminary Results
• Status – Ongoing and Next Steps
Acknowledgements: Wildlife Institute of India,
US Forest Service, and funding support from
USAID.

3. CONTEXT
• Indian Coastline ~ 7500 km, but
mangroves exist in few areas.
• Indian mangroves extent = 4,975
km2, which is ~ 3.6% of global
mangrove vegetation and 0.15% of
country’s geographical area.
• Mangroves in Andaman (614 km2)
and Nicobar (2 km2) Islands (ANI)
cover an area of 616 km2.
• ANI have a tropical to subtropical
climate - temp range –summer (27–
33oC) and winter (21–25oC), annual
rainfall ~ 3000–3500 mm. https://www.globalmangrovewatch.org/country/IND

4. CONTEXT
• Mangroves in Andaman and Nicobar
are best in terms of density and growth
in the country.
• Different from other areas in India, and
therefore experience different set of
pressures, drivers, and bio geomorphic
influences.
• Unique biodiversity value due to
endemic flora and fauna.
• High levels of Vegetation C stock
estimated for ANI (Ragavan et al, 2021).

5. In 2004 coastal geomorphology of ANI
changed drastically due to an Earthquake and
resulted in subsidence (~ 2.85 m) and uplift
(~ 1.35 m) in different parts of the island.
WHY
Porwal et al. 2012
https://www.usgs.gov/media/images/vertical-movement-
seafloor-2004-sumatra-andaman-earthquake
Uplift (U)
Subsided (S)
Control (C)

6. • Sudden change in elevation impacted tidal regime
causing vast mangrove mortality (sudden and gradual).
• Ecosystem response and vegetation shift over time-
Succession trajectories.
• Impact on above and below ground carbon stocks.
WHY
Photo:
Nehru
Prabakaran
Source : Kayanne et al, 2007

7. • Coastal Vulnerability and Resilience by
developing vulnerability indices (CVI and MVI).
• Ecosystem Carbon Stocks assessment across
the uplift and subsidence gradients – CIFOR’s
mangrove protocol (Kauffman and Donato, 2012).
• Understanding sediment accretion rates to
predict future vulnerability (rSETS).
• Determination of local hydrodynamics – Water
depth and salinity at high resolution.
HOW

8. WHERE and WHEN

9. 9

11. RESULTS
• Mean Tree density was highest in control sites (1288 ± 218/ha) followed by subsided (937 ±
155/ha) and uplifted sites (777 ± 149/ha).
• Vegetation species richness per site in tree cohort was mostly comparable across three
categories. Highest in Subsided (4.38 ± 0.15), Uplifter (4.20 ± 0.23), and Control (3.63 ±
0.07).
Tree Density Species Richness

12. RESULTS

13. The above ground carbon stocks in control sites (116.6 ± 31.4 MgC/ha) were higher
than uplifted sites (103.6 ± 38.8 MgC/ha) and subsided sites (78.5 ± 44 MgC/ha.
RESULTS
Vegetation Carbon Stocks

14. RESULTS
Relative contribution of live and dead trees, woody debris and saplings show some
pattern across uplift and subsided categories.

15. Ongoing and Next Steps

16. Data Logger (Outputs)
DL1 – close to creek, High flooding
Rhizophora patch
DL3 – farther from creek, higher ground
Avicennia patch
Ongoing and Next Steps

17. Ongoing and Next Steps
17 rSETs
Across the Island

18. Ongoing and Next Steps
• Measurement of sediment accretion rates (rSETs)
• Lead 210 radionuclide tracer from soil cores at these
locations
• Total Carbon stocks estimates (belowground veg + Soils)
• Water Depth and Salinity (high temporal resolution) data to
pair with vegetation characteristics
• Soil microbial community assessment (uplifted sites).
• Vulnerability assessment and other modelling products
• Training and capacity building (Local institutions, Forest Dept,
Young Researchers

19. cifor-icraf.org | globallandscapesforum.org | resilient-landscapes.org
The Center for International Forestry Research (CIFOR) and World Agroforestry (ICRAF) envision a more equitable
world where trees in all landscapes, from drylands to the humid tropics, enhance the environment and well-being for
all. CIFOR and ICRAF are CGIAR Research Centers.
Thank you!