Carbon Accounting in the Arboriculture Industry; Reduction of Greenhouse Gas Emissions from Tree Surgery

Abstract

Increasing atmospheric concentrations of greenhouse gases (GHG) have been directly attributed to human activity; burning fossil fuels, land use change e.g. deforestation and energy production. Current practices in arboriculture rely heavily on fossil fuel based equipment to maintain trees in urban areas; removing carbon sinks (trees) and emitting CO2 during management practices. Therefore, it has been suggested that the arboriculture industry may make a disproportionately large contribution to GHG emissions when compared to the size of the sector.

The study sought to identify the contribution of arboriculture to anthropogenic (GHG) emissions and provide recommendations for reduction. Assessment of the industry was achieved using a case study approach of a tree surgery company Down to Earth (DTE) based in Sevenoaks, Kent. The structure of CO2e (carbon dioxide equivalent) quantification methods followed the top-down approach - BS ISO 14064:2006; using secondary data to measure CO2e emissions and primary data for assessment of daily activity optimisation. The results, based on project boundaries included direct emissions from sources owned or controlled by the company – 101.2 tonnesCO2e yr-1, indirect emissions from energy use – 5.2 tonnesCO2e yr-1, and indirect emissions owned or controlled by other organisations – 98.9 tonnesCO2e yr-1. Results suggested that the arboriculture industry releases 7 times more CO2e emissions yr-1 than other similar-sized service sectors. This was mainly attributed to the use of plant and heavy-duty vehicles and the removal of carbon storing biomass. The study suggested that changing current practices could reduce GHG emissions from arboriculture by between 12% and 18%.

In 2011 DTE provided 719 tonnes of wood chip to a renewable electricity generation plant, substituting coal use avoiding the release of 1,062 tonnesCO2e. Therefore, although arboricultural activities emitted 235.50 tonnesCO2e, this figure was more than offset (825.58 tonnes CO2e) by the avoided emissions achieved in power generation. By providing a renewable feedstock for the generation of electricity it is suggested that the arboriculture industry may, in the future, achieve carbon positive status and its practices seen as the management of a renewable energy crop.