Journal of Resources and Ecology >
Contribution of Urban Trees to Offset Carbon Dioxide Emissions from the Transportation Sector in the Ring Road Area of Kathmandu Valley, Central Himalaya
JOSHI Nabin Raj, E-mail: nabin2001@gmail.com |
Received date: 2022-08-06
Accepted date: 2023-02-10
Online published: 2023-10-23
Urban trees are valuable resources for urban areas as they have the capacity to reduce ambient temperatures, mitigate urban heat island effects and reduce runoff of rainwater playing an important role in mitigating the impacts of climate change by reducing atmospheric carbon dioxide (CO2). It also helps to reduce aerial suspended particulate matter, add visual appeal to the urban landscape sequestrating a significant amount of carbon from ambient atmospheric CO2. Carbon storage by urban trees in the ring road area of the Kathmandu Valley was quantified to assess the magnitude and role of urban forests in relation to mitigate the impact of global climate change. A total of 40 sample plots were placed randomly for the detailed carbon assessment. Aboveground and belowground carbon pools were considered in the detailed assessment. Furthermore, quality assurance (QA) and quality control (QC) were maintained through regular monitoring and capacity building of the field crews while collecting the bio-physical data. The assessment recorded a total of 33 different species of plants in the avenue’s plantation sites in ring road. The mean seedling, sapling, and tree density was found to be 2149585 and 185 per hectare. The mean carbon stock per hectare in the avenue plantation of the ring road area was 24.03 tC ha-1 and the existing total carbon stock was 7785.72 tC in 2021. Likewise, the total baseline carbon dioxide equivalent (tCO2e) in the avenue plantation was found to be 28573.60 tCO2e. The carbon dioxide emission from the transport sector in the ring road area in a full movement scenario was 312888.00 tCO2e per annum, while the net emissions was 42547 tCO2e. There was a deficit of carbon dioxide in terms of stock by avenue plantations of 14000.8 tCO2e. This study indicates that the existing urban forest plantation is unable to sequestrate or offset the carbon dioxide that is emitted through the transportation sector. Consequently, open spaces like riverbanks and any other public lands, in which urban forests could be developed has to be planned for the green infrastructure and plantation of the multipurpose trees. The distinct values of forests in and around urban areas have to be recognized in the specific policies and plans for the sustainable management of urban and peri-urban forests to meet the adverse impact of global climate change. In addition, this study provides insights for decision-makers to better understand the role of urban forests and make sustainable management plans for urban forests in the cities like in Kathmandu Valley.
JOSHI Nabin Raj , JOSHI Rajeev , MISHRA Jay Raj . Contribution of Urban Trees to Offset Carbon Dioxide Emissions from the Transportation Sector in the Ring Road Area of Kathmandu Valley, Central Himalaya[J]. Journal of Resources and Ecology, 2023 , 14(6) : 1272 -1281 . DOI: 10.5814/j.issn.1674-764x.2023.06.015
Fig. 1 Map of the study site |
Table 1 Methods adopted for the estimation of forest carbon |
Measured carbon pool | Equations | Description of the equation | References |
---|---|---|---|
Above ground tree biomass (AGTB) | $AGTB=0.0509\times \rho \times \ {{D}^{2}}\times H$ | $\rho $: wood specific gravity (kg m-3), D: tree DBH, H: tree height (m) | Chave et al. (2005) |
Below ground biomass (BGB) | BGB=AGTB×20% | The total below ground biomass is equivalent to 20% of the above ground biomass (t ha-1) | MacDicken (1997) |
Above ground sapling biomass (AGSB) | ln(AGSB)=a+b lnD | a: intercept of allometric relationship for sapling, b: slope allometric relationship for saplings, D: over bark at DBH | Tamrakar (2000) |
Herbs & grasses (HG) | $HG=\frac{{{w}_{\text{field}}}}{A}\times \frac{{{w}_{\text{subsample},\text{dry}}}}{{{w}_{\text{subsample},\text{wet}}}}\times 10$ | wfield: weight of the fresh field sample of HG, destructively sampled within an area of size A (kg); A: size of the area in which HG were collected (m2); wsubsample, dry,: weight of the oven-dry sub-sample of HG taken to the laboratory to determine moisture content (g); and wsubsample, wet: weight of the fresh sub-sample of HG taken to the laboratory to determine moisture content (g) | Subedi et al. (2010) |
Total biomass (TB) | TB=AGTB+BGB+AGSB+HG | Sum of all measured carbon pools i.e trees, below ground, saplings and herbs & grasses | Subedi et al. (2010) |
Fig. 2 Scattered plot between tree diameter and height |
Table 2 Seedling, sapling, tree density in the ring road area of Kathmandu Valley |
S.N. | Variables | Seedling density (plant ha-1) | Sapling density (plant ha-1) | Tree density (plant ha-1) |
---|---|---|---|---|
1 | Mean | 2149 | 585 | 194 |
2 | Std. Deviation | 1962 | 536 | 165 |
Fig. 3 Box and whisker plot for tree, saplings and herbs & grasses carbon stock |
Table 3 Total and mean carbon in all the pools in the plantation site |
S.N. | Plot | Tree carbon stock (tC ha-1) | Sapling carbon stock (tC ha-1) | Herb carbon stock (tC ha-1) | Total carbon stock (tC ha-1) | Total (tCO2e) |
---|---|---|---|---|---|---|
1 | Mean | 22.98 | 0.82 | 0.22 | 24.03 | 88.18 |
2 | Std. Deviation | 2.21 | 0.10 | 0.20 | 4.52 | 65.90 |
Note: In last two columns, one is total carbon stock and another value is carbon dioxide equivalent. |
Table 4 Total CO2 emissions in ring-roads per unit time |
Vehicle type | Total tCO2e emissions in ring-road (per year) by all vehicle type | Total tCO2e emissions full way vehicle movement1 | Total tCO2e emissions of half way vehicle movement2 | Total tCO2e emissions of one third way vehicle movement3 | Total tCO2e emissions one fourth way vehicle movement4 |
---|---|---|---|---|---|
Motorbike | 123987 | 1240 | 2480 | 3720 | 6199 |
Scooter/Moped | 50076 | 501 | 1002 | 1502 | 2504 |
Car | 22280 | 223 | 446 | 668 | 1114 |
Van | 9732 | 195 | 195 | 292 | 487 |
Bus | 8361 | 167 | 167 | 418 | 836 |
Mini-truck | 49891 | 998 | 998 | 2495 | 4989 |
Heavy truck | 48561 | 486 | 971 | 2428 | 4856 |
Total | 312888 | 3809 | 6258 | 11523 | 20985 |
Grand total emissions (tCO2e yr-1) in ring-road (1+2+3+4) | 42574.40 | ||||
Per month | 3547.86 | ||||
Per day | 118.26 | ||||
Per hour | 4.93 | ||||
Per minute | 0.08 |
Table 5 Carbon removals and emission scenario in Kathmandu Valley |
Carbon removal (tCO2e) by avenues plantations in ring road | Carbon emissions (tCO2e) by vehicles in ring road | ||
---|---|---|---|
Total carbon stock (tC yr-1) | Total carbon-dioxide equivalent (tCO2e yr-1) | Total emission by vehicles (tCO2e monthly) | Total emission by vehicles (tCO2e yr-1) |
7785.72 | 28573.60 | 3547.83 | 42574.40 |
Carbon surplus/deficit | Total tCO2e emissions by transport sector (E)-Total tCO2e sequestration by urban trees (R) | (E-R) 42574.40-28573.60 | 14000.80 tCO2e |
[1] |
|
[2] |
|
[3] |
|
[4] |
|
[5] |
|
[6] |
|
[7] |
|
[8] |
|
[9] |
DFRS. 2015. Forest resource assessment (FRA). Kathmandu, Nepal: Department of Forest Research and Survey (DFRS).
|
[10] |
FAO. 2011. State of the world’s forests. Rome, Italy: FAO.
|
[11] |
|
[12] |
FRA. 2005. The global forest resource assessment. http://www.fao.org/forestry/fra. Viewed on 2022-07-20.
|
[13] |
FRA. 2015. State of Nepal’s forests. Kathmandu, Nepal: Forest Resource Assessment (FRA).
|
[14] |
IPCC. 2000. Land use, land-use change and forestry. Geneva, Switzerland: Intergovernmental Panel on Climate Change.
|
[15] |
IPCC. 2006. Good practice guidance for national greenhouse gas inventories. Geneva, Switzerland: Intergovernmental Panel on Climate Change.
|
[16] |
|
[17] |
|
[18] |
|
[19] |
|
[20] |
|
[21] |
|
[22] |
|
[23] |
|
[24] |
|
[25] |
|
[26] |
|
[27] |
|
[28] |
|
[29] |
|
[30] |
R Development Core Team. 2009. R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing.
|
[31] |
|
[32] |
|
[33] |
|
[34] |
|
[35] |
|
[36] |
|
[37] |
|
[38] |
|
[39] |
|
[40] |
|
[41] |
|
[42] |
|
[43] |
|
[44] |
|
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〈 |
|
〉 |