Above-ground Carbon Stocks of Tectona grandis and Gmelina arborea Plantations in Njala University, Southern Sierra Leone

Aboveground biomass and carbon stock in tropical forest play an important role in global carbon cycle. Assessment of biomass and carbon pool in different forest stands may provide information in making decisions about the carbon management within the forest. Gmelina arborea , a fast growing species that is widely distributed and an important timber species of Mizoram has been chosen to assess its biomass and carbon stock. The present study was carried out to estimate the aboveground biomass and carbon stock in G. arborea in different forest stands of Mamit District, Mizoram, north-east India. The result shows that the total aboveground biomass ranged between 66-108 Mg ha -1 and carbon stock (30.00-53.20 mg C ha -1 ). The aboveground biomass and carbon stock was maximum in forest stands (site-III) with highest tree density and diameter class of 30-40cm and 40-50cm indicating the forest site was mature and undisturbed. The result demonstrates that G. arborea contribute in carbon sequestration and helps in mitigating global warming. Further, the aboveground biomass and carbon sequestration potential was greatly affected by the tree composition, population pressure and anthropogenic activities. Keywords: Aboveground biomass, carbon stock, diameter class,Gmelina arborea, tropical forest.

Human activities have been severely affecting forest structure and functions in humid tropics across the globe. In present study, we estimated aboveground biomass and carbon stocks along a disturbance gradient in wet tropical forests of southern Assam, India, using non-destructive sampling method. A total of 26 forest stands were surveyed and based on a disturbance index grouped into 4 categories, viz. undisturbed (UD), mildly disturbed (MLD), moderately disturbed (MD) and highly disturbed (HD) forests. Mean aboveground carbon (AGC) stocks and basal area decreased with increased disturbance index. Though phytosociological parameters such as species richness, Shannon-Wiener diversity index, tree density, basal area and AGC stocks showed a significant negative correlation with disturbance index, tree density (693 ± 11.6 trees ha−1) and Shannon-Wiener diversity index (1.98 ± 0.07) were highest in mildly disturbed forests. Aboveground carbon stocks were positively correlated with basal area (p < 0.01) and diversity indices (p < 0.01) across disturbance regimes. Tree species such as Cynometra polyandra, Mesua ferrea, Palaquium polyanthum, Mesua floribunda, Artocarpus chama and Stereospermum personatum together contributed 41.3 ± 6.2 % and 42.4 ± 6.7% of the total AGC stocks in undisturbed and mildly disturbed forests, respectively, while Artocarpu schama, Holarrhena pubescens, Mitragyna rotundifolia, Sapium baccatum, Schima wallichii and Toona ciliata contributed 47.2 ± 3.5% in moderately and 55.4 ± 4.0% in highly disturbed forests.

Abstract. Bao TQ, Ha NT, Nguyet BTM, Hoan VM, Viet LH, Hung DV. 2021. Aboveground biomass and carbon stock of Rhizophora apiculata forest in Ca Mau, Vietnam. Biodiversitas 23: 403-414. Despite the small proportion of mangrove forests globally, they contribute significantly in carbon storage. Yet, biomass and carbon stock in mangrove forests might vary depending on various factors including the dominant species that occurred. This study was conducted to determine the biomass and carbon stock of a mangrove forest dominated by Rhizophora apiculata Blume in Ca Mau, Vietnam. Data were collected from 56 representative sample plots (50m x 50m), and 46 sample trees with different age classes and diameter sizes were cut down to measure the fresh biomass. The dry biomass and carbon content were analyzed in the laboratory. The average aboveground biomass and carbon stock of the individual tree and the R. apiculata forest at different diameter sizes had a significant difference and were mostly found in the stem (74.5%-79.5%). The conversion factor from fresh biomass to dry biomass was 0.56; the conversion factor from dry biomass to carbon was 0.46. The total biomass of the individual trees had a close relationship with two variables diameter at breast height (DBH) and height (Hvn) in the form of the logarithmic function: ln(Wtk) = -1,86412 - 1,95419*ln(Hvn) + 2,26798*ln(DBH*Hvn). The total biomass and carbon stock of the entire forest stand increased in accordance with the diameter size and age classes. The R. apiculata stand had a density of 1,040-15,800 trees/ha and a timber volume of 27.2 to 365.6 m3/ha. The average biomass of the R. apiculata stand was 191.1 tons/ha with a range from 49.6 to 357.4 tons/ha. The carbon stock in forest biomass ranged from 23.8 to 188.7 tons C/ha, with an average of 117.4 tons C/ha. The forest’s CO2 absorption ranged from 60.0 to 691.7 tons CO2/ha, with an average of 415.9 tons/ha. The carbon stocks of trees of age class I to age class VI were 41.6 tons C/ha, 79.4 tons C/ha, 101.4 tons C/ha, 132.9 tons C/ha, 154.0 tons C/ha, and 167.4 tons C/ha, respectively.

&#x0D; &#x0D; &#x0D; Homegardens are one of the most significant and oldest types of land use systems in Sri Lanka which have been recognized as an essential component in providing a variety of ecosystem services. In these systems, trees and shrubs are grown together with food crops under family labor, creating a multitude of biological interactions. Due to rich tree diversity and density, homegarden agroforestry systems are known to have a great capacity to capture and store carbon in their biomass and soil, and thus greatly contribute to mitigation of climate change. Even though the importance of homegardens with regard to the above is highlighted significantly, large knowledge gaps remain on their total carbon storage potential, particularly in low country wet zone homegardens of Sri Lanka. Therefore, the current study aims to estimate the total aboveground and belowground carbon stocks of homegardens in Kalutara district. The study was conducted in ten homegardens ranging from 0.15 Ha to 0.43 Ha. The study focused on all perennial woody trees present in the homegardens. Heights and diameters at breast height (DBH) were measured in a total of 966 woody trees. Aboveground biomass of each tree was calculated nondestructively, using allometric equations which incorporated wood density, DBH and tree height. Belowground biomass was calculated using root: shoot ratios of trees. Total biomass of each tree was converted to total carbon stocks using a conversion factor of 0.5 extracted from literature, considering that total carbon stock of a tree is equivalent to half of its biomass. In order to get the total carbon stock, soil organic carbon (SOC) content of each home garden was analyzed in the laboratory from collected soil samples using the Loss-on-ignition method. Belowground biomass carbon stock and the SOC stock together were taken as the total belowground carbon stock of each homegarden. Estimated mean aboveground carbon stock was 91.4±11.4 Mg ha-1, while the mean belowground carbon stock was determined as 134.3±12.3 Mg ha-1 in low country wet zone home gardens. Aboveground carbon stock, together with the belowground carbon stock, was taken as the total carbon stock of the homegardens. Calculated total carbon stock per unit area for low country wet zone homegardens ranged between 179.873 Mg ha-1 and 286.606 Mg ha-1 with a mean value of 225.7±11.9 Mg ha-1. Above findings of the study present evidence for significant carbon storage capacity of low country wet zone homegardens.&#x0D; Keywords: Homegarden, Low country, Wet zone, Carbon stock, Climate change&#x0D; &#x0D; &#x0D;

This study assessed the growth performance and Carbon sequestration potential of 21-year-old Albizia versicolor Welw ex. Oliver. (Av) and Albizia harveyi Fourn (Ah) planted in 2003 at Maseyu village, Morogoro, Tanzania. These species are among the species preferred for wood fuel in Tanzania and other countries within African savanna ecosystems. Seedlings of the two species were planted at a spacing of 2 x 2 m with 25 trees per plot (8 x 8 m) using a completely randomized block design with three replications. In 2024, measurements were taken for diameter at breast height (Dbh) and height. Data was analyzed to get means for Dbh, height, volume, annual increment (MAI), above-ground biomass (AGB) and above-ground Carbon stock (AGC). An independent t-test was used to analyze differences in species parameters using R-studio. Results showed significant differences in stocking density (p &lt; 0.001), Dbh (p &lt; 0.001) and height (p &lt; 0.001) between species, with Albizia versicolor exhibiting larger mean Dbh (8.82 ± 1.36 cm) and height (7.46 ± 1.47 m) but relatively lower stocking density (1,188 ± 407 stems/ha) compared to Albizia harveyi (7.33 ± 1.16 cm,6.63 ± 2.28 m and 2,230 ± 1046 stems/ha respectively). However, no significant differences were found in volume, AGB, and AGC. Volume increments were 2.41 m³/ha/yr for Albizia versicolor and 2.58 m³/ha/yr for Albizia harveyi, while AGB increments were 1.23 and 1.17 t/ha/year for Albizia versicolor and Albizia harveyi respectively. Above-ground Carbon (AGC) stock increments (0.58 and 0.62 tC ha⁻¹ year⁻¹) for Albizia versicolor and Albizia harveyi respectively under monoculture were consistent with studies on mature Miombo woodlands. These findings suggest that both Albizia species perform well in monoculture growth, demonstrating their potential for sustainable Miombo woodland management and Carbon sequestration, despite lower biomass accumulation rates compared to natural Miombo ecosystems.

The impact of integrating WorldView-2 sensor and environmental variables in estimating plantation forest species aboveground biomass and carbon stocks in uMgeni Catchment, South Africa

Structural development and carbon dynamics of Moso bamboo forests in Zhejiang Province, China

Bark beetle outbreaks kill billions of trees in western North America, and the resulting tree mortality can significantly impact local and regional carbon cycling. However, substantial variability in mortality occurs within outbreak areas. Our objective was to quantify landscape-scale effects of beetle infestations on aboveground carbon (AGC) stocks using field observations and remotely sensed data across a 5054 ha study area that had experienced a mountain pine beetle outbreak. Tree mortality was classified using multispectral imagery that separated green, red, and gray trees, and models relating field observations of AGC to LiDAR data were used to map AGC. We combined mortality and AGC maps to quantify AGC in beetle-killed trees. Thirty-nine per cent of the forested area was killed by beetles, with large spatial variability in mortality severity. For the entire study area, 40–50% of AGC was contained in beetle-killed trees. When considered on a per-hectare basis, 75–89% of the study area had >25% AGC in killed trees and 3–6% of the study area had >75% of the AGC in killed trees. Our results show that despite high variability in tree mortality within an outbreak area, bark beetle epidemics can have a large impact on AGC stocks at the landscape scale.

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.

Mangrove forests are considered potential carbon sinks in the atmosphere, surpassing other terrestrial ecosystems and playing a crucial role in the global carbon cycle. As the world strives towards climate neutrality and zero greenhouse gas emissions, the importance of mangrove forests is becoming increasingly evident. The application of technology and science to measure, monitor, and manage mangrove forests for enhanced efficiency, accuracy, and cost reduction is paramount. The study was conducted in mangrove forests in southern Vietnam, a total of 96 trees from various species were measured in the field to validate the accuracy of the UAV method using statistical indices such as Root Mean Square Error (RMSE) and Coefficient of Determination (R2). We constructed a correlation model between canopy height and diameter at breast height (DBH), where canopy height was the independent variable and DBH was the dependent variable. The ground-based biomass model based on height variables was used to estimate mangrove forests biomass and above-ground carbon stocks. We estimated mangrove species using an object-oriented classification method to determine mangrove species boundaries. The estimated heights from UAV correlated closely with ground-truth heights, with R2 = 0.99 and RMSE = 0.2 m. There was a strong correlation between canopy height from UAV (CHMuav) and DBH, with R2 = 0.95 and RMSE = 0.40 cm. The estimated canopy height (CHMuav) ranged from 1 m to 21.5 m. The object-oriented classification model for mangrove forests achieved an overall classification accuracy (OA) of 89% and a Kappa coefficient of 0.85. Above-ground biomass of Rhizophora apiculata forest with an average of 45 Mg ha−1; Avicennia alba species with an average of 22 Mg ha−1; Above-ground biomass of mixed-species with an average of 25 Mg ha−1. The above-ground carbon stocks of Rhizophora apiculata, Avicennia alba, and mixed-species have been estimated. Using the Unmanned Aerial Vehicle (UAV) and Real-Time Kinematic (RTK) methods reduced the uncertainty in estimating above-ground biomass and carbon stocks of mangrove forest.

Mangrove forests are important sinks of atmospheric carbon, and the internal deposits and fluxes of organic matter can reflect how these ecosystems respond to disturbances and environmental changes. Data on carbon content of mangrove forests vary geographically due to differences in abiotic (climate, geomorphic settings, tides) and biotic (diversity, herbivory, bioturbation) conditions. Mangroves have been degraded worldwide and ecological restoration is an alternative to recover these ecosystems and their functionality. However, although growing and biomass after disturbances have been addressed, studies on the recovery of faunal groups are rare. The brachyuran crab assemblage is strongly integrated to carbon recycling and ecosystem functioning, since propagule consumption and fossorial activity can affect the diversity and biomass of mangroves. We assessed the aboveground biomass and carbon stock of differently managed mangrove areas in northeastern Brazil, after being deforested for shrimp culture and then abandoned, and compared data with other forests worldwide. After a decade, the area restored with Rhizophora mangle showed higher carbon stock than the self-recovered forest and similar amount as an older forest. We discuss the applied rehabilitation measures regarding the effects of management and brachyuran crabs on forest aboveground carbon storage. The effects of herbivory and bioturbation of brachyurans on the low recruitment of Laguncularia racemosa propagules, contributed to higher biomass levels in the restored forest through reinforcing the predominance of R. mangle, which stocks more aboveground carbon with respect to Laguncularia. This suggests that the particularities of target tree species and brachyuran assemblage need to be considered in mangrove restoration, since they are related to function recovering and carbon cycling in the ecosystem.

Aboveground biomass and carbon stock in the largest sacred grove of Manipur was estimated for trees with diameter >10 cm at 1.37 m height. The aboveground biomass, carbon stock, tree density and basal area of the sacred grove ranged from 962.94 to 1130.79 Mg ha−1, 481.47 to 565.40 Mg ha−1 C, 1240 to 1320 stem ha−1 and 79.43 to 90.64 m2 ha−1, respectively. Trees in diameter class of 30–40 cm contributed the highest proportion of aboveground biomass (22.50–33.73%). The aboveground biomass and carbon stock in research area were higher than reported for many tropical and temperate forests, suggesting a role of spiritual forest conservation for carbon sink management.

The importance of terrestrial ecosystems for carbon sequestration and climate regulation is acknowledged globally. However, the underlying structural drivers are still not well understood, particularly across distinct tropical forest ecosystems where trees species have different growth habits and potential to reach different maximal size. In particular, how important are different tree size classes in contributing to stand aboveground carbon (AGC) remains unclear across forest ecosystems. Here, we hypothesized that (i) tree size classes would contribute differently to stand AGC across forest ecosystems; and (ii) few species, possibly dominant, would determine most of stand AGC. We tested these hypotheses using a 17-ha sampled inventory data from gallery forests, woodlands and savannahs in the Republic of Benin. We examined (i) how AGC stocks vary among small- (<20 cm), medium- (20–40 cm) and large-size (>40 cm diameter at breast height - dbh) trees; (ii) how the large size class and its individual species contribute to AGC; and (iii) how size class-based taxonomic and structural variables influence AGC?Stand AGC was 23 ± 5, 30 ± 8 and 42 ± 12 MgC ha−1 in savannah, woodland and gallery forest, respectively. There were significant main and interaction effects of vegetation types and size classes. As expected, medium and large-size classes contained more of the AGC, irrespective of the vegetation type. However, gallery forests had the lowest AGC in the <20 cm dbh class, but higher values in medium- and large-size classes as compared to woodlands and savannahs. The top 10 species contributed 82%, 89% and 91% of AGC in gallery forests, woodlands and savannahs, respectively. In addition, five of the top 10 dominant species were shared by the three vegetation types and alone contributed 70–76% of AGC. Tree basal area was the most constant structural attribute influencing AGC; however, its influence shifted with vegetation type and size class, with greater effects of large-size tree basal area in gallery forests, and of medium trees and small trees’ basal area in woodlands and savannahs, respectively. The study shows that (i) AGC allocation to size class varied across vegetation types, and (ii) small and medium trees are also important in predicting AGC, especially in semi-arid environments dominated by high densities of small-size trees (e.g. woodlands and savannahs). It also highlights the importance of few dominant species in contributing a large proportion of AGC stocks. The conservation of these dominant species is essential to avoid substantial decline of AGC stock.

ABSTRACTUrban vegetation can help to offset carbon emissions. However, urban vegetation cover is vulnerable to urbanization. This study attempts to detect the change in vegetation cover and to quantify its impact on aboveground carbon (AGC) stocks in Auckland, New Zealand, between 1989 and 2014. Field-measured vegetation parameters were used to calculate the amount of carbon stored in plants at the plot-level. Plot-level AGC stocks were linked with vegetation spectral/structural features derived from Landsat images and Light Detection and Ranging (LiDAR) data. These data were also used to map vegetation cover and to estimate AGC stock. Vegetation cover decreased from 394.0 km2 in 1989 to 379.4 km2 in 2014. AGC stock in 1989 was estimated at 1,001,184 Mg C from Landsat 4 data. The total AGC in 2014 was estimated at 1,459,530 Mg C from Landsat 8 data. Thus, total AGC stock increased by 458,346 Mg C (45.8%) in spite of a 3.7% decrease in vegetation cover (14.6 km2) during the same period. The increase in AGC stock was derived partly from tree growth and tree plantings. Vegetation growth contributed more to the increase in AGC stock than its gain from non-vegetation to vegetation changes. The AGC stored in trees and shrubs estimated at 1,333,011 Mg C from the 2014 Landsat data is 5.7% lower than 1,414,607 Mg C estimated from the 2013 LiDAR data, due to the inability of optical imagery to capture the sub-canopy structure of forests and the saturation effect. Thus, LiDAR data provided a more accurate estimate of AGC stock, especially when the stock density is high (e.g. >97.9 Mg C ha–1).

Allometric models to estimate above-ground biomass and carbon stocks in Rhizophora apiculata tropical managed mangrove forests (Southern Viet Nam)