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Author: Baruah, Rashmi × End date: 2017 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Mapping of Carbon Stock in different Agro-Ecosystems of Jorhat District using Remote-sensing
    (AAU, 2015) Baruah, Rashmi; Medhi, B.K.
    Soil organic carbon mapping at larger scale to assess the carbon stock using remote-sensing is useful in predicting the need based strategies to be adopted in the context with land use change and different land management scenarios. The present study aims to develop data base for mapping carbon stock in different agro-ecosystem (AESs) for forest and agricultural lands of Jorhat district and to study the effectiveness of contiguously spaced spectral bands vis-a-vis other multispectral remote-sensing in carbon stock assessment. This study revealed that forest ecosystem had higher potential to sequester carbon than agricultural land. Among different agro-ecosystems (AESs), Humid Alluvial Flood Free (HAFF) situation have the highest biomass C stock followed by High Land (HL), Humid Alluvial Flood Prone (HAFP) and lowest in Char Area (CA). Soils of Jorhat district have high amount of organic carbon, especially in forest area of HL and CA. Among physical properties, bulk density ranged from 1.0-1.48 g/cc in HAFF, 1.19-1.61 g/cc in HAFP, 1.08-1.43 g/cc in HL and 1.15 g/cc to 1.51 g/cc in CA with increasing trend down the profile. In all the profiles under study, limit of variability in BD was within 11% of observed value with respect to mean. Sand content was dominant in all AESs followed by clay and silts content, baring for HL and CA. The extent of variability in relation to mean was found to be highest in silt fraction followed by clay and sand in HAFF and HL situations, while, highest variability was observed in case of clay followed by silt and sand fractions in HAFP and CA. Among different chemical properties, soil pH ranged 4.19-6.39 in HAFF, 5.26-7.22 in HAFP, 5.06-6.14 in HL and 5.35-6.88 in CA. Soil organic carbon ranged 0.90-20.40 g/kg in HAFF, 1.50-14.70 g/kg in HAFP, 1.20-17.40 g/kg in HL and 0.30 g/kg to 16.50 g/kg in CA. Cation exchange capacity (CEC) ranged from 1.80-9.80 cmol (p+) kg-1 in HAFF, 0.13-10.20 cmol (p+) kg-1 in HAFP, 5.0-17.40 cmol (p+) kg-1 in HL and 0.60-13.0 cmol (p+) kg-1 in CA. The maximum variations with respect to mean was found in case of EC followed by CEC and then pH in all AESs but in CA, soils showed highest variations in case of organic carbon (OC) followed by TN. Profiles under forest land use system exhibited relatively higher SOCD than paddy irrespective of AESs with an exception in one location of HAFF where land use under paddy showed higher value than forest land use system. Highest SOCD was recorded in HL followed by HAFF, HAFP and lowest in CA. Soil carbon stock (SCS) was highest for HAFF (56.24Tg) followed by HAFP (35.61 Tg), HL (12.29Tg) and lowest was recorded in CA (4.36Tg). Variations in SOCD of 94.20 per cent were found to be predictable from OC, depths, TN and clay content in forest soils, whereas, 89.40 per cent variations in SOCD were predicated from OC, depth and BD in case of paddy soil. Soil OC had signifiCAnt negative correlations with pH (r= -0.496**) and BD(r= -0.594**) while, it was correlated positively with Clay (r=0.447**), CEC(r=0.454**) and TN (r=0.496**). Similarly, SOCD showed negative and significant correlation with pH (r= -0.395**) and BD(r= -0.353**) and positive significant correlation with clay (r=0.443**), CEC (r=0.291**) and TN (r= 0.256*). Maximum efficiency to remove tones equivalent of CO2 from atmosphere as stable carbon was worked out to be highest in HAFF (2145.70 Tg) followed by HL (899.59 Tg), HAFP (616.85 Tg) and Char (16.0 Tg) which indicate potential efficiency of these zone in carbon sequestration and therefore, it is important in strategizing zones to plan for increasing efficiency accordingly in putting much thrust to conserve such situation in climate resilient perspective point of view. Moreover, spatial map prepared by kriging was found to be accurate with minimum error. Semivariogram generated by kriging showed higher autocorrelation of samples with minimum sampling error (Nugget value <1.0). Soil carbon stock could easily be calculated using krig map and could be recommended for precise data estimation. Considering total geographical area of Jorhat district (2852 sq.km), total potential for CO2 removal from atmosphere was worked to be 30.41 Tg as stable carbon over the Agro-Ecosystem.