International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 28 Carbon sequestration Potential and Chemical Characteristics of Soil along an Elevation transect in Southern Himalayas, NepalTripathee Lekhendra1*, Rupakheti Dipesh, Sharma Prakriti, Aryal Ranjan and Sigdel Shalik Ram2 Himalayan Environment Research Institute, Kathmandu, NEPAL Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Himalayan Environment Research Institute, Kathmandu, NEPALAvailable online at: www.isca.in, www.isca.me Received 22nd January 2015, revised 28th February 2015, accepted 14th March 2015 AbstractThe study was aimed at quantifying and comparing the amount of carbon stored in soil and chemical parameters of soil at different elevations under different land uses. Soil samples were collected from the surface (0–10 cm) and subsurface (10–20 cm) soil layers at Dhunche and from five other sites samples were randomly chosen at four different locations at each site. Samples were collected during May at different elevation (approximately 500m change in elevation) in forest land uses and grassland use. Soil of the study area was slightly acidic to alkaline in nature. The dominant textures were sandy loam and loamy sand. Biomass was gradually increased at north with increasing altitude whereas at south aspect biomass was increased up to 3650m and then gradually decreased. SOC stock was high at the highest elevation and similar trend was seen at other sites. SOC was gradually decreased with increasing soil depth. Soil nutrients (NPK) were found to decrease with increase in altitude. The results from the present study also suggest that the Himalayan soil have a great potential to store the carbon. The present study provides the dataset on soil physical and chemical properties and paves a way for further study in the region. Keywords: Carbon sequestration, altitude, SOC, soil nutrients, Himalayas, Nepal. Introduction Soil Organic Carbon (SOC) makes up a huge amount of the terrestrial carbon pool which is regarded as part of the global carbon cycle. It plays an important role in mitigating climate change and guaranteeing food security worldwide. Soil carbon sequestration has much to recommend climate change mitigation, land as well as livelihood protection including resilience to climate change. Moreover, soil also plays a important role in the global carbon budget and greenhouse effect. Soil Organic Matter (SOM) can act both as a sink and a source of carbon in response to climate, different land use changes, and to the rising CO levels in the atmospheric1,2. Small changes in SOM could influence long-term ecosystem sustainability, the global carbon budget and the atmospheric CO concentration. High altitude terrestrial ecosystems are considered as important components in the global carbon cycle and stores large reservoirs of soil organic carbon (SOC). SOM includes all living and non-living organic material in the soil. In general, about two-thirds of earths carbon is sequestered in the standing forests, leaf and forest debris, and in forest soils. Forest vegetation and soils share upto 60% of the world’s terrestrial carbon in common. Vegetation and soils may significantly add to mitigation of global climate change as they are natural sinks for atmospheric carbon (C)7-10. Moreover, soil organic matter can also increase or decrease that depends on various factors including: climate, vegetation type, nutrient availability, disturbance, and land use and management practices11,12. In addition, physical soil properties, for example soil structure, particle size, and composition, has significant impact on soil carbon (C). Further, soil particle size also has a strong influence on the rate of decomposition of soil organic carbon. The macronutrients: nitrogen (N), phosphorus (P) and potassium (K) are deficient in the soil as plants require them in the largest quantities. These soil nutrients are considered to have a close relation with the soil organic matter as a significant proportion of N and P are released through decomposition of organic residues in soil. They often serve as good chemical indicators of the status or quality of the soil. Moreover, terrestrial carbon and nitrogen coupling has increasingly received research interest over the decades because of the progressive nitrogen limitation on future carbon sequestration in terrestrial ecosystems13. Nepal is a Himalayan country which is one of the remote and isolated regions with complex terrain14. Due to remoteness, high altitude and harsh climate conditions; sampling and monitoring is very difficult in the region15,16. Till date there is limited published data on soil physical and chemical composition in the Nepal Himalayas. Thus, there is a need for understanding the carbon stocks and soil properties varying at different land use with change in elevation. Therefore, we selected different locations at different elevation International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 29 transect (1900 to 4410 m a.s.l) for evaluating soil carbon stocks. In this study we aim to quantify and compare the amount of carbon stored in soil at different elevations and under different land uses in the central Himalayas, Nepal. Moreover, we also access the physical properties (bulk density, soil texture) and Chemical properties (pH, macronutrients – N, P, K) in the Himalayan soil at different altitude. Material and Methods Study area: The study was carried out in six different elevation transect in forests and grasslands in Langtang National Park, Nepal from (1930-4410 m.a.s.l). The higher elevation gradients coupled with complex topography and geology has enriched a rich biodiversity, vegetation belts and different soil features in the study area. Langtang National Park is the nearest national park of the capital city Kathmandu in the Central Himalayan Region. The study was done from 85° 18.503’ - 85° 24.90’ E longitude and 28° 06’ - 28° 04.91’ N latitude from Dhunche to Goshainkunda. Details on sampling sites have been presented in figure-1 and table-1. Table-1 Sampling sites description Sites Elevation (m) Land-Use Dhunche 1935 Forest / Agriculture Deurali 2795 Forest/ Agriculture Chandanbari 3184 Forest Cholangpati 3617 Forest Lauribinayak 3973 Shrub land Gosainkunda 4404 Alpine meadows Figure- 1 Map showing the sampling locations of soil Soil Sampling: Top soil samples were collected from the surface (0–10 cm) soil layers 5 sites and (0-10 and 10-20cm) at lowest elevation site Dhunche. At each location four soil sampling sites were randomly chosen from about 50 meters distance to make a replicate sample representative of each location. Sample collection was done during May, 2011 at different elevation (approximately 500m change in elevation) in forest land uses and grassland use. Soil samples for bulk density (BD) analysis for each depth were found with core samplers (which was 5 cm in diameter and 6 cm high). Bulk soil samples to measure and compute average soil parameters were collected randomly from four different points at each sampling locations, and transferred to zip-lock plastic bags. A total of 28 samples were collected and analyzed in the Aquatic Ecology Centre, Kathmandu University. Laboratory analysis: The details on laboratory methods used are presented in the table-2. Table-2 Methods used for Laboratory analysis Parameters analyzed Methods used Bulk density core method Soil organic matter (SOC)dry combustion method Soil texturesoil hydrometer method soil pHpH probe Total NKjeldahl digestion–distillation method Total PModified version of Olsen’s method Total KFlame photometer emission method Results and Discussion Soil physical parameters: The physical characteristics of soil from our sampling locations were analyzed and shown infigure-2. The bulk density of the soil reflects the level of compaction and amount of pore space in the soil. There was no significant change observed in bulk density value at varying altitude at our study sites. However, SOC% was found to be lowest in the Dhunche, lowest elevation soil sampled. Soil organic matter can also increase or decrease due to nutrient availability, disturbance, and land use and management practices. This is due to the human disturbance in the site as it was close to the human settlement. However, other sites had comparatively similar trend in the SOC% and slightly higher at the highest elevation. Previous studies have suggested that decrease in temperature and increase in precipitation with increasing altitude changes in climate along altitudinal gradients can influence the composition and productivity of vegetation and, as a result of these can affect the quantity and turnover of SOM17,18,19. Similarly, study done by Sims Z.R. and Nielsen G.A.20 indicated that the relationship between SOM and altitude has positive correlations. Similar, results was observed in this study. Another important physical factor in the soil is pH, which determines the acidity and alkalinity of the soil. From, figure-2 International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 30 we can see that the soil in the regions are slightly acidic to alkaline but no clear trend with altitude. Texture is the distribution of different size fractions of particles. Texture is an expression that characterizes the relative amounts of sand, silt and clay in the soil. The soil texture in the study region has been presented in table-3. The results showed that the central Himalayas soils falls in the 3 categories of USDA defined textural classes such as Silt Loam, Sandy Loam and Loamy Sand. The two low altitude sites had a Silt Loam and another consecutive sites and highest altitude site fell on Sandy Loam. Only one site fell on Loamy Sand category. This explains that the silt and sand percentage are higher in the soil sampled at different sites. Carbon stock density at the sampling sites: The carbon stock density of soil organic carbon was calculated as described earlier by Pearson T.R. et.al.21: SOC stock= d SOC%, Where: SOC stock = soil organic carbon stock per unit area [t ha-1], = soil bulk density [g cm-3], d=Total depth at which sample was taken [cm], and SOC= carbon concentration [%]. The soil carbon stock density was calculated for all 4 samples collected from each sites. This gives the measure of tons carbon sequestered per hectare of soil in the region. The average calculated value of soil carbon stock has been presented in figure-3. It is clear from the figure-3 that SOC stock density (tHa-1) was found to be consistent at different elevation at 5 sites. However, the highest SOC stock was observed at Gosainkunda at the highest altitude (4404m) sampled. The consistency of SOC stock at 5 sites may be due to the samples collected from the forest soils. In case of the last sampling point the sample was collected from the alpine meadows. The lowest SOC stock was found to be at Dhunche, lowest elevation site which is because of the disturbed land use due its closeness to the human settlements that enhance the disturbances in the soil due to cattle and horses and over grazing. These results clearly revels that the soil carbon sequestration rate is higher in the less disturbed high altitude soil which have already been discussed in the above section. Table-3 Sand, silt and clay percent and USDA textural class of soil in Nepal Himalayas Sites sample no. Clay% Sand% Silt% USDA textural class Dhunche 1 6 37.86 56.14 Silt Loam 2 9 37.67 53.33 Silt Loam 3 8 38.14 53.86 Silt Loam 4 7 37.76 55.24 Silt Loam Mean ± SD 7.5 ±1.29 37.85 ±0.203 54.64 ±1.282 Deurali 1 8 40.56 51.44 Silt Loam 2 9 41.36 49.64 Silt Loam 3 10 40.68 49.32 Silt Loam 4 8 41.08 50.92 Silt Loam Mean ± SD 8.75 ±0.957 40.92 ±0.368 50.33 ±1.01 2 Chandanbari 1 6 62.26 31.74 Sandy Loam 2 7 60.16 32.84 Sandy Loam 3 5 60.98 34.02 Sandy Loam 4 8 61.36 30.64 Sandy Loam Mean ± SD 6.5 ±1.290 61.19 ±0.871 32.31 ±1.451 Cholangpati 1 8 69.74 22.26 Sandy Loam 2 7 69.04 23.96 Sandy Loam 3 9 6 8.78 22.22 Sandy Loam 4 7 69.34 23.66 Sandy Loam Mean ± SD 7.75 ±0.957 69.225 ±0.41 23.025 ±0.41 Lauribinayak 1 6 80.64 13.36 Loamy Sand 2 9 78.88 12.12 Loamy Sand 3 7 79.22 13.78 Loamy Sand 4 10 80.06 9.94 Loamy Sand Mean ± SD 8 ±1.825 79.7 ±0.799 12.3 ±0.799 Gosainkunda 1 6 68.98 25.02 Sandy Loam 2 8 69.07 22.93 Sandy Loam 3 6 67.93 26.07 Sandy Loam 4 7 68.05 24.95 Sandy Loam International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 31 Mean ± SD 6.75 ±o.957 68.507 ±0.60 24.74 ±0.600 Figure- 2 Soil physical characteristics at different altitude Figure-3 Average soil organic carbon stock at different elevation in the study area International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 32 Figure-4 Bar graph of soil organic carbon at different depthSoil organic carbon at (0-10 and 10-20 cm) depths at Dhunche: The soil organic carbon percentage at different soil depths (0-10 and 10-20 cm) were analyzed and presented in the figure-4. The results showed that the SOC% decreases as depth increases. SOC gradually decreased with increasing soil depth. As there are higher organic matter in the top layer soil, the percent of organic carbon is higher in top soil. The higher concentration of soil organic carbon in top layer than in lower layer has also been reported by various authors22,23 in the past and our results also showed the similar trend. Chemical characteristics of the Soil: The concentrations of soil nutrients Nitrogen (N), Phosphorous (P) and Potassium (K) in soil samples at different altitude are shown in figure-5. It is clear that the N, P and K concentration has a negative or inverse relation with altitude i.e. with increase in altitude decrease in concentrations was observed in this study. The highest concentrations of nutrients were found in the lowest altitude and lowest concentrations in the highest altitude explaining the loss of nutrients in the higher elevations. The highest concentrations of NPK in soil are due to the inorganic fertilizer availability in the lower altitude soil24 close to the agricultural areas and human settlements. Our results showed the good nutrients in the sampled soil and when compared to the agricultural soil in the India25. Conclusion Physiochemical properties of soil at different elevation transect from Nepal were investigated. The results showed that Himalayan soil had huge potential to store carbon and may be useful to combat climate change. SOC% gradually decreased with increasing soil depth. The central Himalayas soils falls in the 3 categories of USDA defined textural classes such as Silt Loam, Sandy Loam and Loamy Sand. The soil in the regions is slightly acidic to alkaline but no clear trend with altitude. Figure-5 N, P and K concentrations in soil at different elevations in ppm International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 33 The soil properties were found to change randomly with altitude along all studied areas. Sampled soils were found to be richer in organic matter, slightly acidic, and less fertile which was indicated by decreasing nutrient concentrations with increasing altitude in the study area. However, even at relatively alike altitude soils properties were found to be highly heterogeneous as a consequence of the heterogeneous substrates for soil formation including the varying hydrologic conditions, element redistribution on a landscape level as a result of the steep and uneven morphology, and potentially also due to drawbacks of the huge diversity of plant species. Further, soil of the Himalaya appears to have potential for significant carbon accumulation, especially in the high elevations (beyond 2500m). Hence, such areas need to be conserved under forest and natural vegetation to enhance C stocks and sequestration for mitigation of climate change. Acknowledgement We would like to acknowledge Aquatic Ecology Centre, Kathmandu University for lab analysis. Himalayan Environment Research Institute, team for helping in the field work. References 1.Jobbagy E.G. and Jackson R. B., The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecol. Appl.,10, 423–436 (2000) 2.Kirschbaum M.U.F., Will changes in soil organic carbon act as a positive or negative feedback on global warming?, Biogeochemistry, 48, 21– 51 (2000) 3.Amundson R., The carbon budget in soils, Annual Review of Earth and Planetary Sciences, 29, 535– 562 (2001) 4.Baldock JA and Skjemstad JO, Organic soil carbon/soil organic matter, In 'Soil analysis: An interpretation manual', (Eds KI Peverill, LA Sparrow, DJ Reuter), 159-170 (1999) 5.Sedjo R.A., Sohngen B. and Jagger, P., Carbon Sinks in the Post-Kyoto World, RFF Climate Issue Brief No, 13, Internet Edition, (1998) 6.Winjum J.K., Dixon R.K. and Schroeder P.E., Estimating the global potential of forest and agro forest management practices to sequester carbon, Water Air Soil Pollution,64(1–2), 213–227 (1992) 7.Bajracharya R.M, Lal R. and Kimble J.M., Soil organic carbon distribution in aggregates and primary particle fractions as influenced by erosion phases and landscape position, In: Lal R, Kimble JM, Follett RF, Stewart BA (eds) Soil processes and the carbon cycle, 353–367 (1998) 8.Phillips O.L, Malhi Y., Higuchi N., Laurance W.F., Nunez P.V., Vasquez R.M., Laurance S.G., Ferreira L.V., Stern M., Brown S. and Grace J., Changes in the carbon balance of tropical forests: evidence from long-term plots, Science,282(5388), 439–442 (1998) 9.Lal R., Soil carbon sequestration to mitigate climate change, Geoderma, 123(1–2), 1–22 (2004) 10.Smith P., Carbon sequestration in croplands: the potential in Europe and the global context, Eur J Agron20(3), 229–236 (2004) 11.Six J., and Jastrow J.D., Organic matter turnover, 936-942 (2002) 12.Barker J.R., Baumgardner G.A., Turner D.P. and Lee J.J., Carbon dynamics of the conservation and wetland reserve programs, Journal of Soil and Water Conservation, 51, 340–346 (1996)13.Reich P.B., Hobbie S. E., Lee T., Ellsworth D.S., West J.B., Tilman D., Knops J.M.H., Naeem, S. and Trost, J., Nitrogen limitation constrains sustainability of ecosystem response to CO, Nature,440, 922–925 (2006) 14.Neupane B. and Thapa P., Assessment of Pesticide Use and Heavy Metal Analysis of Well Water in JhikuKhola Watershed, Kavrepalanchowk, Nepal, Int. Res. J. Environment Sci, 3(10), 79-83 (2014) 15.Tripathee L., Kang S., Huang J., Sillanpää M., Sharma C.M., Lüthi Z.L., Guo J. and Paudyal R., Ionic composition of wet precipitation over the southern slope of central Himalayas, Nepal, Environ. Sci. Pollut. Res., 21, 2677–2687 (2014a) 16.Tripathee L., Kang S., Huang J., Sharma,C.M., Sillanpää M., Guo J. and Paudyal R., Concentrations of trace elements in wet deposition over the Central Himalayas, Nepal, Atmos. Environ., 95, 231–238 (2014b) 17.Garten C.T., Post W.M., Hanson P.J. and Cooper L.W., Forest soil carbon inventories and dynamics along an elevation gradient in the southern Appalachian Mountains, Biogeochemistry,45, 115–145 (1999) 18.Hontoria C., Rodriguez-Murillo J.C. and Saa A., Relationships between soil organic carbon and site characteristics in peninsular Spain, Soil Science Society of America Journal, 63, 614–621 (1999) 19.Quideau S.A., Chadwick Q.A., Benesi A., Graham R.C.and Anderson M.A., A direct link between forest vegetation type and soil organic matter composition, Geoderma,104, 41–60 (2001) 20.Sims Z.R. and Nielsen G.A., Organic carbon in Montana soils as related to clay content and climate, Soil Science Society of America Journal, 50, 1269–1271 (1986) 21.Pearson T.R., Brown S.L. and Birdsey R.A., Measurement guidelines for the sequestration of forest carbon, U.S.: Northern research Station, Department of Agriculture, (2007) International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 28-34, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 34 22.Dinakaran J and Krishnayya N.S.R., Variation in type of vegetal cover and heterogeneity of soil organic carbon in affecting sink capacity of tropical soils, Current Science, 94, 9 (2008) 23.Alamgir M. and Amin M.A., Storage of organic carbon in forest undergrowth, litter and soil within geoposition of Chittagong (south) forest division, Bangladesh, International Journal of Usufruct Management,9(1), 75-91 (2008) 24.Singh R., Soil Major (N,P,K) and Micro (Cu, Mn, Zn and Fe) Nutrients as Influenced by Different Herbicides in Presence of Fertilizer (NPK) in Field Condition of Aligarh Soil under Wheat Cultivation, Int. Res. J. Environment Sci.,(2014)25.Ladwani K.D., Ladwani K.D., Manik V.S. and Ramteke D.S., Impact of Industrial Effluent Discharge on Physico-Chemical Characteristics of Agricultural Soil, Int. Res. J. Environment Sci., 1(3), 32-36 (2012)