The presence of forest vegetation in the Lesan River Protection Forest (HLSL) at various levels, from understorey vegetation, seedlings, saplings, poles, to trees are contributes to forest carbon storage. The photosynthesis process carried out by various groups and classes of plants has made a very significant contribution in absorbing CO2 and then making carbohydrates stored by plants. Over time, the amount of carbon stored in various types of plants in HLSL also increases.
To find out how much carbon has been stored in the HLSL, OWT Foundation has plotted carbon measurements scattered in various HLSL vegetation cover classes. The parameters used for carbon calculation are tree diameter, litter weight, understorey weight, and soil organic C content at several depths (0-5 cm, 5-10 cm, 10-20 cm, and 20-30 cm). With this calculation we can find out how much the ability of forests in HLSL to absorb and store carbon stocks. If there is no forest disturbance, then over time, tree growth will further increase forest carbon sequestration and storage. There is a combination of two plot models used for carbon calculations, namely rectangular and circular plots from the Forest Health Monitoring (FHM) plot model.
The reference for plot development and carbon stock calculation in HLSL is based on the Forestry Research and Development guidelines, namely SNI 7724:2011 concerning Measurement and Calculation of Carbon Stocks – Field measurements for estimating forest carbon stocks (ground-based forest carbon accounting). Survey activities were conducted by OWT field staff involving local communities. Permanent Sampling Plots (PSP) that have been made with sampling errors 20 % are 34 PSP with a 0.1 Ha plot area.
Distribution of placement of 14 plot made before Opwall seasons are as follow
Stand density in each canopy closure class
| Class of Tree | Amount/ ha , each Land Cover Class | |||
| Dense | Medium | Light | Mixed shrubs | |
| PancangH> 1.5 m, DBH < 10 cm | 7.200 | 6.667 | 6.533 | 10.400 |
| TiangDBH:10-20 cm | 400 | 633 | 700 | 525 |
| Pohon DBH 20-30 cm | 115 | 142 | 83 | 63 |
| Pohon DBH > 30 cm | 110 | 70 | 63 | 43 |
The result of 5 carbon pool calculation in HLSL in 2019 are presented as follows
| Carbon Pool | Classes of vegetation cover | |||
| High | Medium | Low | Shrubs | |
| Carbon stock from Above ground biomass (ton/ha) | 155,53 | 93,98 | 112,40 | 88,39 |
| Carbon stock from Bellow ground biomass (ton/ha) | 57,54 | 34,77 | 41,59 | 32,71 |
| Carbon stock from litter(ton/ha) | 0,98 | 0,91 | 1,09 | 0,76 |
| Carbon stock from from necromass (ton/ha) | 22,53 | 19,66 | 7,26 | 38,14 |
| Carbon stock from soil (ton/ha) | 14,29 | 22,71 | 16,42 | 11,40 |
| Total carbon stock from 5 carbon pool (ton/ha) | 250,87 | 172,03 | 178,76 | 171,39 |
| Area represented (ha) | 6,735,15 | 1.708,44 | 738,23 | 1.056,36 |
| Total carbon stock from 5 carbon pool in every classes of vegetation cover (ton) | 1.698.635,30 | 293.905,59 | 131.965,86 | 181.051,78 |
| Total Carbon stock in HLSL (ton) | 2.296.558,53 | |||
| CO2 Equivalen (ton) | 8.420.714,61 | |||
In estimating above ground biomass calculations are performed using the equation Basuki et al (2009) with a single parameter DBH-Diameter Breast Height. Estimation of under-tree biomass was approached by the formula of the shoot and root ratio with a default value of 0.37. The default Carbon Fraction (CF) value used is 0.47.
Estimated carbon stock from 5 carbon pools in HLSL in various classes of vegetation cover are high density is 250.87 tons C / Ha, medium density 172.03 tons C / Ha, low density 178.76 tons C / Ha and Shrub 171.39 tons C / Ha. Estimation of the total carbon stock in the HLSL in 5 carbon pools is obtained by multiplying the area of each land cover class (stratum) by the carbon density of each stratum. Through this calculation, the results show that carbon stock is 2,296,558.53 tons C or CO2 equivalent is 8,420,714.61. The largest carbon stock is 1,698,635. 30 ton C is stored at high density, equivalent to 73.5 7% of the total carbon stock in HLSL.