Carbon dioxide emissions from forest operations in Portuguese eucalypt and maritime pine stands

A methodology for assessing fossil fuel-related carbon dioxide (CO2) emissions from operations performed in eucalypt and maritime pine stands was developed and applied to Portugal. This methodology includes all the operations carried out during site preparation, stand establishment, stand tending, logging and infrastructure establishment. For the year 2000, CO2 emissions for the entire area of maritime pine and eucalypt stands in Portugal were estimated to be 51 and 67 Gg CO2 year(-1), respectively. These results demonstrate the more intensive nature of the management activities used in eucalypt stands, as these stands occupied an area approximately 30% smaller than maritime pine stands and produced only 5% more harvested wood than maritime pine stands. Wood logging accounted for approximately 40% of the total annual CO2 emissions in both stands. The results obtained from a sensitivity analysis suggest that annual CO2 emissions from eucalypt and maritime pine stands could be decreased by nearly 20% if, simultaneously, mowing is used instead of disking in clearing/cleaning operations, soil scarification is made by furrowing and ridging instead of ripping followed by subsoiling, and forwarders are used instead of modified farm tractors in wood extraction. A reduction of approximately 30% could be obtained for maritime pine stands if, in addition, natural regeneration is used instead of planting.