Soil carbon stock in different of mangrove ecosystem in Mahakam Delta, East Kalimantan, Indonesia

Mangrove forests serve as a buffer against sedimentation from the mainland into the sea, protect the area from coastal erosion, and prevent seawater intrusion in some ecological types of coastal environments. Additionally, because soil and below-ground biomass retain a significant quantity of carbon, they are essential for carbon sequestration. The current study seeks to estimate the soil organic carbon stock of mangroves associated with natural regeneration, mangrove rehabilitation areas and abandoned shrimp ponds, in Mahakam Delta, East Kalimantan, Indonesia. A 125-meter-long transect line was used to collect data, with three sampling points representing the length of the transect line. Each soil sample was taken at three different depths: 0-50 cm, 50-100 cm, and 100-150 cm. After that, the samples were taken to the laboratory for carbon analysis. The mangrove rehabilitation area had the highest bulk density at 8.64 gr/cm3, followed by natural mangroves along the river border at 7.67 gr/cm3, and abandoned ponds had the lowest at 7.16 gr/cm3. The rehabilitation area had the highest soil carbon stock at 1120 tons/ha, followed by natural mangroves along the riverside at 686 tons/ha and abandoned ponds at 383 tons/ha. In accordance with the study, mangrove rehabilitation regions had larger soil carbon stocks than natural regeneration along the riverside and abandoned ponds. In order to protect the ecologically significant mangrove ecosystem and minimize the effects of climate change, mangrove restoration and rehabilitation are necessary

BIOCHAR YANG DIPRODUKSI DENGAN TUNGKU DRUM TERTUTUP RETORT MEMBERIKAN PERTUMBUHAN TANAMAN YANG LEBIH TINGGI (BIOCHAR PRODUCED BY RETORT CLOSED DRUM KILN PROMOTES HIGHER PLANT GROWTH RATE)

ABSTRACTInterests on biochar application for the improvement of soil properties and fertily are increasing worldwide nowadays and numerous of production techniques are now available. This research was aimed at the investigation (a) on the characteristics biochar produced by 3 (three) different techniques, i.e: (1) traditional soil pit, (2) retort closed drum and (3) open drum kilns, as well as (b) on growth (height, leaf number and survival) response of Shorea leprosula seedling to 20%v biochar application on bioassay trial in the nursery. Bioassay trial was carried out in nursery of Forestry Faculty of Mulawarman University, Samarinda, Indonesia and was in accordance with Completely Randomized Design (CRD) applying 4 treatments and 3 replications.Of those 3 production techniques, retort closed drum kiln production technique was the most promising for further development and adoption providing not only that the biochar produced gave better properties and soil improvement capacity but also higher production recovery and less time and labour involvement. Furthermore, eventhough it was not statistically significant, biochar produced by retort closed drum gave better growth (height and leaf number) rate to S. leprosula seedlings in bioassay trial compared to those given by biochar produced by other techniques and without biochar treatments

Soil carbon balance following conversion of grassland to oil palm

Oil palm (Elaeis guineensis Jacq.) crops are expanding rapidly in the tropics, with implications for the global carbon cycle. Little is currently known about soil organic carbon (SOC) dynamics following conversion to oil palm and virtually nothing for conversion of grassland. We measured changes in SOC stocks following conversion of tropical grassland to oil palm plantations in Papua New Guinea using a chronosequence of plantations planted over a 25-year period. We further used carbon isotopes to quantify the loss of grassland-derived and gain in oil palm-derived SOC over this period. The grassland and oil palm soils had average SOC stocks of 10.7 and 12.0 kg m⁻², respectively, across all the study sites, to a depth of 1.5 m. In the 0–0.05 m depth interval, 0.79 kg m⁻² of SOC was gained from oil palm inputs over 25 years and approximately the same amount of the original grass-derived SOC was lost. For the whole soil profile (0–1.5 m), 3.4 kg m⁻² of SOC was gained from oil palm inputs with no significant losses of grass-derived SOC. The grass-derived SOC stocks were more resistant to decrease than SOC reported in other studies. Black carbon produced in grassfires could partially but not fully account for the persistence of the original SOC stocks. Oil palm-derived SOC accumulated more slowly where soil nitrogen contents where high. Forest soils in the same region had smaller carbon stocks than the grasslands. In the majority of cases, conversion of grassland to oil palm plantations in this region resulted in net sequestration of soil organic carbon

Carbon outcomes of major land-cover transitions in SE Asia: Great uncertainties and REDD+ policy implications

Policy makers across the tropics propose that carbon finance could provide incentives for forest frontier communities to transition away from swidden agriculture (slash-and-burn or shifting cultivation) to other systems that potentially reduce emissions and/or increase carbon sequestration. However, there is little certainty regarding the carbon outcomes of many key land-use transitions at the center of current policy debates. Our meta-analysis of over 250 studies reporting above- and below-ground carbon estimates for different land-use types indicates great uncertainty in the net total ecosystem carbon changes that can be expected from many transitions, including the replacement of various types of swidden agriculture with oil palm, rubber, or some other types of agroforestry systems. These transitions are underway throughout Southeast Asia, and are at the heart of REDD+ debates. Exceptions of unambiguous carbon outcomes are the abandonment of any type of agriculture to allow forest regeneration (a certain positive carbon outcome) and expansion of agriculture into mature forest (a certain negative carbon outcome). With respect to swiddening, our meta-analysis supports a reassessment of policies that encourage land-cover conversion away from these [especially long-fallow] systems to other more cash-crop-oriented systems producing ambiguous carbon stock changes - including oil palm and rubber. In some instances, lengthening fallow periods of an existing swidden system may produce substantial carbon benefits, as would conversion from intensely cultivated lands to high-biomass plantations and some other types of agroforestry. More field studies are needed to provide better data of above- and below-ground carbon stocks before informed recommendations or policy decisions can be made regarding which land-use regimes optimize or increase carbon sequestration. As some transitions may negatively impact other ecosystem services, food security, and local livelihoods, the entire carbon and noncarbon benefit stream should also be taken into account before prescribing transitions with ambiguous carbon benefits.Alan D. Ziegler, Jacob Phelps, J I A Qi Yuen, Edward L. Webb, Deborah Lawrence, Jeff M. Fox, Thilde B. Bruun, Stephen J. Lei Szk, Casey M. Ryan, Wolfram Dressler, Ole Mertz, Unai Pascual, Christine Padochkk, and Lian Pin Ko