Mangroves is highly valuable green vegetation that enhance ecological diversity in costal environment and support socio-economic activities (Nagelkerken et al., 2008).
Mangroves can be defined as “an association of trees and shrubs forming the dominant vegetation in tidal, saline wetlands, along equatorial, tropical and subtropical coasts” (Tomlinson, 1994). Mangroves serves as trophic chain, which directly linked to coastal fisheries and protect shorelines and sequester carbon of the ecosystem (Odum & Heald, 1975). The values that provided by mangroves to the ecosystem are social, cultural and economic that demonstrated by numerous Authors and international organization (Field, 1998). Scientific community state that CO2 in the atmosphere increase mainly as a result of fossil fuels burning and land use change that causes carbon emission due to clearance of natural vegetation, forest fire, agricultural activities and as well deterioration of ecosystem that serve as carbon sink (Solomon & Qin, 2013). To bound the incremental global mean temperature to not more than 2% at 2050 global carbon emissions must be reduced by 85% from 2000 trend (Bernstein et al., 2007).
To do this, dominant vegetation at coastal ecosystems such as mangroves, salt marshes, and seagrasses take a lion share in the global carbon sequestration that would nevertheless remain as atmospheric CO2 and aggravate climate change (Chmura, Anisfeld, Cahoon, & Lynch, 2003; Bouillon et al., 2008; Kennedy & Björk, 2009). The potential of mangroves in sequestering greenhouse gas is four times higher per unit area than terrestrial forest ecosystem which indicate that deforestation of coastal wetland like mangrove has significant contribution on greenhouse gas emission (Hamilton, 2013). The assessments conducted by Duarte, Middelburg, & Caraco (2004) also indicate that about one-third of mangrove, seagrass, and salt marsh areas have already been lost over the past several decades because of reclamation, engineering and urbanization, deforestation and transformation to aquaculture ponds.Mangroves, those predominantly tropical trees and shrubs growing in sheltered coastline, mudflats and riverbanks in many part of the world belongs to variety of plant families, which all has a common characteristic to tolerate salt water (Field, 1998).
However, the largest world area coverage of mangroves is found in Indonesia and home to large species growth in the world, Over 22.6% of the world’s mangroves originated in Indonesia (Giri et al., 2011). The fate of these mangroves suddenly changed during the early nineties with the beginning of the conversion of wetlands to shrimp farms. By 1999, over half of the mangrove forests of the delta were clear felled or already converted to shrimp ponds and degradation of this ecosystem contribute to the atmosphere (N. Bosma ; Stam, 2012).
The issue of coastal wetlands carbon has recently been placed on the international policy agenda through the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement (UNFCC, 2015)An extremely rapid and chaotic degradation of mangroves occurred without any governmental control in the Mahakam Delta and such degradation was also simultaneously recorded in south Sumatra and on other Indonesian islands(Persoon ; Simarmata, 2014). By 2001, the total mangroves area was about 75,000 ha, which represent 80% of the total surface of the delta. This ecological disturbance reached its peak during Asian economic crisis (1997- 2000) when shrimp price on the global market inflated to 4 – 5 times the normal level due to devaluation of Indonesian rupiah against international currency.Mangroves ecosystem are very dynamic and their growth and decline often reflect the changing conditions of the coastal environment in which they grow. Mangroves in Mahakam delta region which belongs to Indonesian Ministry of Forestry classified to as a production forest, however three other different government sectors claim to the management of the Mahakam delta: The Fishery Department, Interior Affairs Department, and the Environment Department (R. Bosma, Sidik, van Zwieten, Aditya, ; Visser, 2012).
Due to unclear management, laws and regulations the area imposed to massive degradation of mangrove ecosystems and need attention of all stakeholders to plant new areas of mangroves (Field, 1998). However, Mangrove rehabilitation has often been carried out simply by planting mangrove seedlings, without adequate site assessment, or subsequent evaluation of the success of planting at the ecosystem level (Bosire et al., 2008)). Study conducted on Mahakam Delta by Susilo et al.(2017) indicate that out of 364, 90 % of the respondent agreed and willing to protect mangroves ecosystem as his/her own responsibility. As a result, mangroves in the study area are replanted/rehabilitated from environmental stress naturally or by the community.
According to Farnsworth ; Ellison (1997) local community must well informed and educated about the conservation of mangroves to address the problem very well. While the community doing this, mangroves ameliorate microclimate of the ecosystem through carbon sequestration which is vital and most important to mitigate climate change. Therefore, quantifying the carbon stock is important and need attention of all stake holders as a key part of the carbon cycle and productive ecosystem (Jennerjahn ; Ittekkot, 2002). Previous study done by Feliciano et al. (2014) showed the advantage and robustness of using TLS in calculate AGB which is not easy by traditional destructive sampling method that harvest to create allometric equations.To get the complete picture of the mangrove in relation to Above Ground Biomass (AGB) / carbon stock, the research under consideration will use unmanned aerial vehicle (UAV) and Terrestrial laser scanner (TLS) which is the first in using UAV and TLS together in this ecosystem. Therefore, the intention of this paper is to measure AGB using TLS and UAV to acquire the full canopy structure which shows accurately the potential of mangrove in capturing and sequestrating carbon and to compare TLS and UAV derived estimate with published estimated AGB using traditional allometric equation which is not done yet using TLS and UAV on mangrove.
