Spatial Assessment of Soil Organic Carbon Density Through Random Forests Based Imputation
- PDF / 477,738 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 24 Downloads / 189 Views
RESEARCH ARTICLE
Spatial Assessment of Soil Organic Carbon Density Through Random Forests Based Imputation K. Sreenivas & G. Sujatha & K. Sudhir & D. Vamsi Kiran & M. A. Fyzee & T. Ravisankar & V. K. Dadhwal
Received: 11 March 2013 / Accepted: 14 October 2013 # Indian Society of Remote Sensing 2014
Abstract Regional estimates of soil carbon pool have been made using various approaches that combine soil maps with sample databases. The point soil organic carbon (SOC) densities are spatialized employing approaches like regression, spatial interpolation, polygon based summation, etc. The present work investigates a data mining based spatial imputation for spatial assessment of soil organic carbon density. The study area covers Andhra Pradesh and Karnataka states of India. Field sampling was done using stratified random sampling method with land cover/use, soil type, agro-ecological regions for defining strata. The spatial data at 1 km resolution on climate, NDVI, land cover, soil type, topography was used as input for modeling the top 30 cm Soil Organic Carbon (SOC) density. To model the SOC density, a Random Forest (RF) based model with optimal parameters and input variables has been adopted. Experiment results indicate that 500 number of trees with 5 variables at each split could explain the maximum variability of soil organic carbon density of the study area. Out of various input variables used to model SOC density, land use / cover was found to be the most significant factor that influences SOC density with a distinct importance score of 34.7 followed by NDVI with a score of 12.9. The predicted mean SOC K. Sreenivas (*) : G. Sujatha : M. A. Fyzee : T. Ravisankar : V. K. Dadhwal Department of Space, National Remote Sensing Centre, Balanagar, Hyderabad, Andhra Pradesh, India e-mail: [email protected] K. Sreenivas e-mail: [email protected] D. V. Kiran Environmental Geomatics division, JNTU, Hyderabad, India K. Sudhir University of Agricultural Sciences, Hebbal, Karnataka, India
densities range between 2.22 and 13.2 Kg m−2 and the estimated pool size of SOC in top 30 cm depth is 923 Tg for Andhra Pradesh and 1,029 Tg for Karnataka. The predicted SOC densities using this model were in good agreement with the measured observations (R =0.86). Keywords Soilcarbon . Randomforests . Spatialimputation . SOC density
Introduction Soil organic carbon (SOC) plays an important role in soil health and its rejuvenation. It is one of the important parameters that determine soil quality. Soil organic carbon pool plays a vital role in global carbon cycle. It determines the functioning of various ecosystems and besides influencing soil productivity to a large extent. Several studies and assessments were made to find the global and regional carbon stocks using various approaches. Soil is the largest pool of terrestrial organic carbon in the biosphere (Schlesinger 1997) storing approximately 1,500 Pg in the top 100 cm depth layer (IPCC 2001; Xu et al. 2011). To find the carbon sequestering capacity of soil, it is essential to
Data Loading...
