Assessment of global planted-to-natural mangroves biomass ratio and mangroves biomass carbon stocks by machine learning.

Despite the many ecological services and benefits provided by the mangrove ecosystem, deforestation of mangrove ecosystem for industrial and other development has caused irreversible damage in coastal regions throughout the world and in the Arabian Gulf. In 1980s, transplantation of mangrove in Qatar's coastal areas was approached as an effort to restore some of the lost mangrove. However the growth of the transplanted mangrove over three decades seems constrained where the plants are shorter (about 2–3 m less than natural mangroves) and less dense. Despite the fact that sources of inorganic nutrients (N, P) in Qatari coastal water are minimal, natural mangroves seem to grow efficiently in this arid environment. However, the growth of transplanted mangrove over three decades was not fully efficient. Factors limiting the growth of the transplanted mangrove, are not evaluated. The current study was funded by Qatar University (2015–2017) and it aims to quantify and compare sediment metabolism in natural and planted mangrove and to compare the function “role” of the benthic community (autotrophs and heterotrophs) using in situ measurements of fluxes of nutrients and carbon. Sediment-water exchange of dissolved oxygen and inorganic nutrients were measured in situ in natural and planted mangrove during the extreme summer (2015) and winter of 2016 in the central Arabian Gulf. Paired benthic chamber was used in sediments incubations for up to three hours in each location.Two locations were selected to represent the natural and planted mangroves, (Al Dakhira and Al Mafjar). Average salinity was 44 psu. Results showed that the concentrations of Chla and Chlb were significantly variable between mangrove locations (P < 0.01) with highest concentration in the natural mangrove exceeding 2. μg.cm-2 at some locations. On the other hand, there was significant difference in the fluxes of carbon and nutrients between the natural and planted mangrove. Oxygen production in the sediments of the natural mangrove was also significantly higher than those in the planted mangrove (P < 0.01). Percentage of the net O2 production measured at the planted mangroves ranged between 10% − 50% of the net production measured at the natural mangrove. The results indicated that remineralization of organic matter and cycling of carbon and nutrients are significantly more efficient in the natural mangrove which consequently affect the trophic conditions in these ecosystems.

Abstract. Matatula J, Afandi AY, Wirabuana PYAP. 2021. Short Communication: A comparison of stand structure, species diversity and aboveground biomass between natural and planted mangroves in Sikka, East Nusa Tenggara, Indonesia. Biodiversitas 22: 1098-1103. The effectiveness of mangroves reforestation can be evaluated by comparing the stand dynamics of planted mangroves with natural mangroves in similar site conditions. This study investigated stand structure, species diversity and aboveground biomass between natural and planted mangroves in Sikka, East Nusa Tenggara. A field survey was conducted using quadrat transect method for vegetation measurement, especially related to species composition and its size distribution. Several parameters were recorded in field observation, including number of species, diameter, height, volume, and aboveground biomass. The stand structure of both mangroves was demonstrated by the distribution of diameter class while the species diversity was described using three parameters, i.e., richness, heterogeneity, and evenness. Moreover, the IVI of each species recorded was also calculated to understand the contribution of species in the mangrove ecosystems. The comparison of stand characteristics between natural and planted mangroves was examined by Mann-Whitney test and Spearman Correlation was also applied to understand the relationship between IVI and aboveground biomass. The results showed that the diameter and height between the natural and planted mangroves significantly differed (P<0.05). In contrast, there was no significant difference in tree density, volume, and aboveground biomass (P<0.05). The stand structure of both mangrove stands followed the pattern of J-inverse in which the frequency of trees decreased with the increase in diameter class. Species diversity in both stands was statistically equal in richness, heterogeneity, and evenness (P>0.05) even though there were some specific species which only observed in the natural or planted mangroves. The most superior species in the planted mangroves was Rhizophora mucronata (IVI = 96.99) while the most important plant in the natural mangroves was Sonneratia alba (IVI = 82.49). Our study found there was a significant correlation between IVI and aboveground biomass in which species with higher IVI indicated greater aboveground biomass. Based on these findings, restoration efforts of degraded mangroves in Sikka have been effective. The restoration, which has been conducted for almost three decades, has not only brought back its vegetation cover but also the functional traits of the mangrove stand to mimic with natural mangroves in the area.

We report carbon stock in biomass, litter and soil estimated for six locations in natural Quercus ilex L. stands of the Middle and High Moroccan Atlas. Twenty trees at each location were selected according to their diameter classes and felled to measure the biomass of trunk, branches, twigs and leaves and determine allometric relationships. Soil was sampled in five depths (0 - 15, 15 - 30, 30 - 50, 50 - 70 and 70 - 100 cm) and litterfall production measured in all tree stands. The total carbon stock in above-ground biomass ranged between 17 Mg&#183ha&#451 in A&#239t Aamar stand (High Atlas) and 91 Mg&#183ha&#451 in Ksiba stand (Middle Atlas). Perennial organs (trunk, branches and twigs) stored over 95% of the tree carbon stock. Soil organic carbon concentrations ranged from 0.01% (in 70 - 100 cm in all stands) to 8.1% (in 0 - 15 cm in the Ajdir stand in Middle Atlas). The total organic carbon stock in the soil ranged between 141.4 t&#183ha&#451 in Ajdir and 24.6 t&#183ha&#451 in Asloul. The litter contained 0.2 Mg C ha&#451 in the clearing (C2) stand of High Atlas and 14.3 Mg C ha&#451 in (Ajdir) of carbon. The best fitted model for predicting carbon stock in tree biomass was obtained by applying the allometric equation Y = aXb for each biomass fraction and stand, where Y is the aboveground biomass (dry weight) and X is the DBH (Mean diameter at breast height, 1.30 m). These previous data obtained in the present study confirm the important function of these natural forests as longterm C sinks, in forest biomass, litter and soil. The potential long term C storage of these systems is moderately high, especially in less-intensively managed forests that include large trees. The established relationship between DBH and carbon stock in different tree organs can be used for forest carbon accounting, and also synthesize available information on oak forest as a sink for atmospheric CO2, and identify the management options that may enhance the capacity for C capture/ storage in forest soils.

Total carbon stocks in a tropical forest landscape of the Porce region, Colombia

Land use change is a huge threat for mangrove ecosystems,which are known for their high carbon sequestration and storage capacity.Vegetation restoration efforts are often undertaken, but fail to restore optimal ecosystem carbon sequestration. The mangrove forest of Perancak Estuary with a history of restoration project was made the subject of this research. The objectives include: (i) estimation of mangrove biomass and sediment carbon stock; (ii) comparison of restored, mixed and natural mangroves’ total carbon stock; (iii) correlational analysis between stand density and diversity indices with ecosystem carbon stock. Nine sampling points were determined within three mangrove categories (mixed, natural, restored). Stand characteristics and diameter at breast height (DBH) were measured to allometrically estimate biomass carbon. Sediment carbon was analyzed with Loss on Ignition (LOI) method. Correlational analysis was done with Pearson’s correlation coefficient. Total ecosystem carbon stock is 4472,93 tonnes ha-1 (biomass C: 4046,31 tonnes ha-1; sediment C: 426,62 tonnes ha-1). Highest carbon stock value was found on restored mangroves due to high contribution of sediment C offsetting its low biomass C. Lowest carbon stock value was found on natural mangroves due to decreased root biomass production and increased decomposition due to change in tidal regimes. There is a strong positive correlation between stand density and biomass carbon. Simpson index of diversity has a stronger (though non significant) correlation with biomass carbon than Shannon-Wiener index.

Improving mangrove above-ground biomass estimates using LiDAR

Mangrove forest ecosystems are distributed at the land–sea interface in tropical and subtropical regions and play an important role in carbon cycles and biodiversity. Accurately mapping global mangrove aboveground biomass (AGB) will help us understand how mangrove ecosystems are affected by the impacts of climatic change and human activities. Light detection and ranging (LiDAR) techniques have been proven to accurately capture the three-dimensional structure of mangroves and LiDAR can estimate forest AGB with high accuracy. In this study, we produced a global mangrove forest AGB map for 2004 at a 250-m resolution by combining ground inventory data, spaceborne LiDAR, optical imagery, climate surfaces, and topographic data with random forest, a machine learning method. From the published literature and free-access datasets of mangrove biomass, we selected 342 surface observations to train and validate the mangrove AGB estimation model. Our global mangrove AGB map showed that average global mangrove AGB density was 115.23 Mg/ha, with a standard deviation of 48.89 Mg/ha. Total global AGB storage within mangrove forests was 1.52 Pg. Cross-validation with observed data demonstrated that our mangrove AGB estimates were reliable. The adjusted coefficient of determination (R2) and root-mean-square error (RMSE) were 0.48 and 75.85 Mg/ha, respectively. Our estimated global mangrove AGB storage was similar to that predicted by previous remote sensing methods, and remote sensing approaches can overcome overestimates from climate-based models. This new biomass map provides information that can help us understand the global mangrove distribution, while also serving as a baseline to monitor trends in global mangrove biomass.

Above- and belowground carbon stocks are decoupled in secondary tropical forests and are positively related to forest age and soil nutrients respectively

Aboveground biomass and carbon stock estimation using UAV photogrammetry in Indonesian mangroves and other competing land uses

The biomass and carbon stocks of 2, 6 and 10 year planted mangroves were studied through destructive method of weighting each tree component. The objective was to establish new allometries and carbon production of R. apiculata. Two aboveground biomass allometries of R. apiculata have been developed based on D₃₀ (AGB_D = 0.1224 D₃₀^2.3380) and D₃₀²H (AGB_DH=0.1508 D₃₀²H^0.7793). Accuracy level of aboveground biomass estimation was 85.40% to the actual values of destructive calculation. Each biomass allometric equation can be applied accurately when the estimated mangrove ecosystem has similarity in species, age, tree-density, wood-density and growth factors of mangrove ecosystem where allometry is established. The allometric equation of above-ground carbon stock AGC_D=0.0368D₃₀^2.5996 (based on stem diamater) and AGC_DH=0.0422D₃₀²H^0.8730 (based on combined stem diameter and tree height) can be used to estimate the R. apiculata carbon stocks of non-destructive measurement. However, the accuracy level of AGC_D and AGC_DH allometries used to estimate non-destructive R. apiculata carbon stocks was 60.14% and 79.72% to the actual carbon value of destructive study. The average aboveground carbon stocks of 2 – 10 year R. apiculata were 37.2 MgC ha^-1 (destructive actual value), 30.2 MgC ha^-1 (D₃₀²H), and 29.9 MgC ha^-1 (D₃₀) respectively. It is concluded that the estimated allometric values of aboveground biomass and carbon productions of restored mangroves are closely related to the growth of stem diameter and tree height, but its values are lower than destructive actual value.

The paper focused on the estimation of aboveground biomass and its carbon stock in the vegetation cover on the territory of the High Tatras twelve years after a large-scale wind disturbance. Besides biomass quantification of main plant groups (i.e. trees and ground vegetation) we considered plant components with special regard to carbon rotation rate. The measurements were performed on two transects each containing 25 plots sized 4 × 4 m. Height and stem diameter of all trees on the plots were measured and used for biomass estimation. To quantify the biomass of ground vegetation, six subplots sized 20 × 20 cm were systematically placed on each plot and the aboveground biomass was harvested. The plant material was subjected to chemical analyses to quantify its carbon concentration. The study showed that while the wind disturbance caused dramatic decrease of carbon stock, young post-disturbance stands with abundant ground vegetation, represented large carbon flux via litter fall. Twelve years after the wind disturbance, the trees contributed to carbon stock more than the ground vegetation. However, the opposite situation was recorded for the carbon flux to litter that was related to the dominance of annual plants in the above-ground biomass of ground vegetation. The carbon stock in the biomass of young trees and ground vegetation represented about 8,000 kg per ha. The young stands manifested a dynamic growth, specifically the aboveground biomass increased annually by one third. The results confirmed different carbon regimes in the former old (pre-disturbance) and sparse young (post-disturbance) stands.

Impact of mangrove planting on forest biomass carbon and other structural attributes in the Rufiji Delta, Tanzania

Global climate change can increase carbon dioxide (CO2) emissions in the environment. The mangrove ecosystem is one of the main ecosystems that have a role in mitigating climate change as carbon sinks and stores. Mangroves absorb CO2 during photosynthesis, then convert it into carbohydrates by storing it in biomass. This study aims to determine the mangrove ecosystem’s total biomass, carbon stock, and CO2 sequestration in Anambas islands marine tourism park. The novelty of this research is conducted in conservation areas with minimal potential for land loss so that they can be used as monitoring in the following years. In addition, carbon stock assessment is carried out using allometric equations to obtain Above Ground Biomass (AGB) and Below Ground Biomass (BGB) values so as not to damage the existing mangrove ecosystem. The assessment of total biomass and carbon stock was carried out at 12 stations around Siantan and Jemaja islands using the line transect method. The species of mangrove and diameter breast high (DBH) were measured in each plot with a transect size of 10x10 m. The biomass calculation was carried out to provide information on carbon stock and converted it to get the data of Carbon stocks and estimates of CO2 sequestration. The results showed that the mangrove ecosystem in the Anambas Islands Marine Tourism Park has a biomass of 574.73 tons/ha, an estimated carbon stock of 270.12 ton/ha, and CO2 sequestration of 990.45 ton/ha. The mangrove ecosystem spread over the Anambas Islands Marine Tourism Park is 766.32 Ha, so that it can store carbon reserves of 206,998.39 Ton C. As a conservation area, it is necessary to be sustainably managed to protect the existence of the mangrove ecosystem and increase the carbon stock in the future. Climate change mitigation may be achieved by reducing carbon emission levels and maintaining the mangrove ecosystem services as carbon sinks and sequestration.

Kajian terkini mangrove di Mangrove Bontang Park terbatas pada kajian perubahan luasan area mangrove, namun belum menghitung nilai stok karbon. Penelitian ini bertujuan untuk mengetahui stok karbon yang tersimpan di biomassa mangrove di lokasi tersebut dan menganalisis hubungannya dengan sebaran tingkat kesehatan mangrove. Pengambilan data dilakukan di pada bulan Februari 2023. Sebaran zona penelitian berdasarkan model sebaran indeks kesehatan mangrove menggunakan data citra Sentinel-2A yang dibagi menjadi 3 zona yaitu Zona Excellent, Zona Moderate, dan Zona Poor. Data lapangan yang diambil antara lain jumlah tegakan, persentasi tutupan kanopi dan diameter batang pohon. Aplikasi MonMang 2.0 digunakan dalam mengukur tingkat kesehatan mangrove secara langsung di lapangan. Stok karbon pada biomassa mangrove dihitung menggunakan persamaan alometrik biomassa mangrove dan faktor konversi biomassa-karbon. Hasil validasi indeks kesehatan mangrove menggunakan MonMang 2.0 menunjukkan bahwa tingkat kesehatan mangrove di lokasi penelitian termasuk dalam kategori cukup baik. Stok karbon pada biomassa atas (AGB) diestimasi sebesar 180,74 MgC/ha dan stok karbon biomassa bawah memiliki rata-rata 102,29 MgC/ha dengan total 283,04 MgC/ha. Hasil analisis data menunjukkan tidak terdapat hubungan signigikan antara stok karbon pada biomassa mangrove dan indeks kesehatan mangrove. The recent study of mangroves in Bontang Mangrove Park was limited in studying changes in mangrove area, but the carbon stocks were not quantify. This research aimed to estimate the carbon stock stored in mangrove biomass and to analyze its relationship with the mangrove health distribution in there. The distribution of research zones were based on the mangrove health index distribution model by using Sentinel-2A image data. The model result divided into 3 zones that were Excellent Zone, Moderate Zone and Poor Zone. Field data collection was done in February 2023. Data collection included the number of stands, canopy cover and diameter at breast height. The MonMang 2.0 application was used to measure the health level of mangroves, directly in the field. Carbon stock in mangrove biomass was calculated by using the mangrove biomass allometric equation and the biomass-carbon conversion factor. The validation results of the mangrove health index using MonMang 2.0 showed that the level of mangrove health at the research location was moderate. Carbon stock in above-ground biomass (AGB) estimated at 180.74 MgC/ha and below-ground biomass was 102.29 MgC/ha with a total carbon stock was at 283.04 MgC/ha. No significant relationship was found between carbon stocks in mangrove biomass and the mangrove health index.

Blue carbon ecosystems in the Karimunjawa Islands may play a vital role in absorbing and storing the releasing carbon from the Java Sea. The present study investigated mangrove above-ground biomass (AGB) and carbon stock in the Karimunjawa-Kemujan Islands, the largest mangrove area in the Karimunjawa Islands. Taking the aerial photos from an Unmanned Aerial Vehicle combined with Global Navigation Satellite System (GNSS) measurements, we generated Digital Surface Model (DSM) and Digital Terrain Model (DTM) with high accuracy. We calculated mangrove canopy height by subtracting DSM from DTM and then converted it into Lorey’s height. The highest mangrove canopy is located along the coastline facing the sea, ranging from 8 m to 15 m. Stunted mangroves 1 m to 8 m in height are detected mainly in the inner areas. AGBs were calculated using an allometric equation destined for the Southeast and East Asia region. Above-ground carbon biomass is half of AGB. The AGB and carbon biomass of mangroves in the Karimunjawa-Kemujan Islands range from 8 Mg/ha to 328 Mg/ha, and from 4 MgC/ha to 164 MgC/ha, respectively. With a total area of 238.98 ha, the potential above-ground carbon stored in the study area is estimated as 16,555.46 Mg.