Can Harvesting Flowers Reduce the Amount of Atmospheric Carbon Dioxide? : The Case of Cherry Blossoms

Abstract

Cherry blossoms are popular as street trees in East Asia, providing an attractive backdrop to urban architecture, however their fallen petals can create a waste problem. These petals are likely to contain a significant proportion of fixed carbon so it is suggested that harvesting them may be a solution to both the waste problem and a means of quenching atmospheric CO2 concomitantly. This study investigated the feasibility of flower harvesting for reducing atmospheric CO2. In particular, the total carbon (TC) stored in all cherry blossoms on streets was quantified in the geographic area of South Korea and compared to various CO2 emission rates or amounts quenched by other methods. Branches with flowers were collected from different locations; the TC stored in them ranged between 41.5% - 44.8% of flower dry weights, resulting a mean flower TC per a metre of branch as 0.851{+/-}0.070 gC/m. A functional relationship of the sum of the two most apical branch lengths against crown diameter was developed to obtain an estimate of total flowering branch length from the crown diameter of a typical tree on street. The product of flowering branch length and flower TC per a metre of branch indicated that TC stored in all flowers of a tree summed to 336{+/-}163 g of carbon, equivalent to 1.23{+/-}0.60 kg CO2 per tree, on average. The nationwide flower TC in each spring was calculated to be 1,900{+/-}920 tonnes of CO2, equivalent to the yearly carbon capture of 176 hectares of mature pine trees and carbon emissions from 0.24 million car operations each day. As compounds from cherry blossoms can be used extensively for pharmaceutical and cosmetic products, harvesting can be cost effective. Yet, its environmental costs and disposal after component extraction need to be considered altogether in a more complete life cycle analysis of diverting this product from landfill or decomposition.