Carbon Sequestration Potentiality in Three Agro-ecological Zones of Bangladesh under Different Agroforestry Systems

Abstract

A field study was conducted to evaluate the carbon sequestration potentiality in different agroforestry systems in the northern part of Bangladesh, Dinajpur districts during October, 2018 to March, 2019. The experiment was laid out in three agro-ecological zones; AEZ 1-Old Himalayan piedmont plain (Birganj), AEZ 3-Tista meander flood plain (Parbotipur) and AEZ 25-Level barind tract (Dinajpur sadar). The Experimental plot was selected randomly in different locations from each experimental unit (AEZ), in a randomized complete block design (RCBD) with four replications. The treatments were: Factor A- five agroforestry systems like homestead, eucalyptus and mahogany cropland based, mango and litchi orchards based agroforestry system and Factor B- three AEZs like AEZ 1, AEZ 3 and AEZ 25. Data were recorded from tree growing parameters (height, diameter at breast height) and under storied vegetation (herbs, shrubs and crops) to estimate the total biomass accumulation and also soil carbon was estimated. In case of the main effect of different agroforestry system on carbon sequestrations, it was observed that there was significantly difference in respect of tree height (m), DBH (cm), no of tree per hectare, under storey vegetation and soil carbon stock (t/ha). The highest total carbon sequestrations (563.12 t/ha) was recorded from homestead agroforestry systems and the lowest (64.66 t/ha) was obtained from mahogany cropland based agroforestry system. In case of soil carbon sequestration, eucalyptus based cropland agroforestry system sequestrated the highest amount (29.92 t/ha) of carbon and mango based orchard agroforestry sequestrated the lowest amount (25.67 t/ha) of carbon. The main effect of agro-ecological zones (AEZ) on carbon sequestrations also significantly varied. The highest amount of carbon (307.56 t/ha) was sequestrated by AEZ 25 and the lowest (159.68 t/ha) was from AEZ 3. Again, in the interaction effect of AEZ and agroforestry systems on carbon sequestrations, the highest carbon sequestration capacity (676.27 t/ha) was found in S1T1 (AEZ 1 + homestead agroforestry system) and the lowest (43.87 t/ha) was found in S2T3 (AEZ 3 + mahogany based cropland agroforestry system). The findings of this study concluded that among the five agroforestry systems, homestead agroforestry system sequestrated more carbon and a better option for reducing atmospheric carbon. Again, among the three AEZs, AEZ 25 gave the maximum carbon sequestration potentiality. In case of economic value of carbon sequestration, homestead agroforestry system also gave the maximum (29558.5 $/ha) monetary return. Therefore, emphasis should be given in homestead agroforestry systems to get better ecological impact in the northern region of Bangladesh. Moreover, judicious tree plantation program should be done in AEZ3 and AEZ 1 for the equilibrium carbon sequestration capacity among different AEZs.