Effects of Pear Orchards on Carbon Reduction

Abstract

This study quantified storage and annual uptake of carbon from pear trees through a direct harvesting method, and calculated annual carbon emissions from pear cultivation. Individual trees in three study orchards were sampled to include the range of stem diameter sizes. The study measured biomass for each part including the roots of sample trees to compute total carbon storage per tree. Annual carbon uptake per tree was quantified by analyzing the radial growth rates of stem samples at ground level. Annual carbon emissions from management practices such as pruning, mowing, irrigation, fertilization, and pesticide and fungicide use were estimated based on maintenance data, interviews with managers, and actual measurements. Regression models were developed using stem diameter at ground level (D) as an independent variable to easily estimate storage and annual uptake of the carbon. Storage and annual uptake of carbon per tree increased as D sizes got larger. Pear trees with D sizes of 10 and 20 cm stored 7.5 and 46.5 kg of carbon and annually sequestered 0.6 and 3.0 kg, respectively. Storage and annual uptake of carbon per unit area in study orchards were 8.75 t/ha and 0.61 t/ha/yr, respectively, and annual carbon emissions were 3.86 t/ha/yr. Thus, the carbon emissions were 6.3 times greater than the annual carbon uptake. The study explored useful strategies for low-carbon orchard management to improve carbon reduction effects, including efficient uses of water, pesticides, fungicides, and fertilizers. This study breaks new ground by including measured root biomass of pear trees and a detailed inventory of carbon emissions from their maintenance.