Application of Google earth in carbon assessment and monitoring in agroforestry: a study from Ratanpur, Nepal

Abstract

The carbon assessment and monitoring in small scale forests like agroforests are difficult tasks but it creates enormous opportunity as carbon credit. This study aims to assess carbon sequestration potential in agroforestry including soil carbon using google earth imageries. Agroforestry of Ratanpur village in Tanahun district Nepal was selected as the study site. Total agroforests of 19 farmers were selected as the experimental and no agroforests area of 4 farmers were selected as the control site. The high resolution imageries of 2020 and 2015 were acquired from Google earth pro. The digitization was done to classify the image into agriculture, agroforestry, natural trees, settlement areas and others. Total enumeration was done to measure the diameter and height of the plants (tree species) planted in the agro-forest. Moreover, total 69 soil samples were collected from 0-10, 10-20 and 20-30 cm depth. The biomass was calculated using Chave et al. equation while soil carbon was analyzed using Walkley Black method. The biomass was converted into carbon which was used to calculate mean annual carbon increment. The result showed the highest carbon stock was 17.6 kg/ stand of Paulownia tomentosa. Total carbon sequestration potential was 2057.689 kg and its monetary value was US$ 30.863. The mean soil carbon stock of agro-forest was higher 52.92 ton/ha than this of 50.3 ton/ha in agriculture site. The map showed it was 7.63 ha agroforest in map of 2020. The overall accuracy of map of 2015 was 90.91% with Kappa coefficient 0.86 but these values were 80.65% and 0.74 respectively of map of 2020. One-way ANOVA and Post hoc test showed that there was significant difference in species wise carbon stock per stand at 95% confidence level. The research will be useful to understand the carbon stock in agroforestry practices.