Effects of Road Decommissioning on Carbon Stocks, Losses, and Emissions in North Coastal California

Abstract

During the last 3 decades, many road removal projects have been implemented on public and private lands in the United States to reduce erosion and other impacts from abandoned or unmaintained forest roads. Although effective in decreasing sediment production from roads, such activities have a carbon (C) cost as well as representing a carbon savings for an ecosystem. We assessed the carbon budget implications of 30 years of road decommissioning in Redwood National Park in north coastal California. Road restoration techniques, which evolved during the program, were associated with various carbon costs and savings. Treatment of 425 km of logging roads from 1979 to 2009 saved 72,000 megagrams (Mg) C through on-site soil erosion prevention, revegetation, and soil development on formerly compacted roads. Carbon sequestration will increase in time as forests and soils develop more fully on the restored sites. The carbon cost for this road decommissioning work, based on heavy equipment and vehicle fuel emissions, short-term soil loss, and clearing of vegetation, was 23,000 Mg C, resulting in a net carbon savings of 49,000 Mg C to date. Nevertheless, the degree to which soil loss is a carbon sink or source in steep mountainous watersheds needs to be further examined. The ratio of carbon costs to savings will differ by ecosystem and road removal methodology, but the procedure outlined here to assess carbon budgets on restoration sites should be transferable to other systems.

An individual-based growth and competition model for coastal redwood forest restoration

“…While it is clear that reducing competition via thinning can increase the growth of residual trees, we are still uncertain what an optimal level of thinning might be, how thinning intensities should vary under different site conditions (e.g., stand slope, aspect, and age), how treatment effects may change as stands mature and, as noted above, how competitive processes might vary across the landscape. In some cases, it may be possible to thin stands a second time (second-entry thinning), but this is often difficult due to funding constraints and the removal of roads following restoration treatments (Madej et al 2013). Restoring young forests is a key component of coastal redwood forest conservation, not only to accelerate the development of old forest structure, but also to enhance forest resilience to disturbance.…”

Soil carbon storage following road removal and timber harvesting in redwood forests

“…() estimated that potential above‐ground storage of carbon on revegetated roads in the United States is 78–95 Mg/ha and that the above‐ground carbon storage potential after decommissioning and revegetating unneeded roads in the US national forests is 39.5–48.5 million metric tons. In RNP, carbon storage in 50 year old redwood forests is higher, at 165 Mg/ha (Madej et al ., ), so the potential for above‐ground carbon storage on treated roads in this region is greater than the national average. Studies quantifying the accumulation of biomass through time on treated roads in RNP are on‐going.…”

“…In recent years, public policy increasingly has focused on the effects of carbon cycling on global warming and on methods of carbon sequestration. Road removal, besides decreasing the erosion risk from roads (Madej, 2001), has implications for carbon budgets because various aspects of the work (fuel consumption, removal and regrowth of vegetation, soil development, and prevention of soil erosion) can represent carbon sources or sinks (Madej, 2010;Madej et al, 2013). Carbon storage on treated road prisms may increase as road surfaces become revegetated, litter accumulates, and fine roots decay in the soil column.…”

Soil-plant characteristics in an age sequence of coronilla varia l. plantations along embankments

“…Roads and the areas adjacent to road construction zones cover 15-20% of American land surfaces (Forman, 2000), and to accomplish road construction, heavy equipment, such as bulldozers, excavators, and dump trucks, is used to excavate buried stream channels and reshape disturbed hill slopes (Madej et al, 2012). Road construction exposes a substantial amount of bare land, and it impacts the physical and ecological properties of the landscape by changing the dynamics of plant and animal populations, altering the flow of materials, introducing exotic species, and changing the amount of available resources, such as light, water and nutrients (Angold, 1997;Coffin, 2007).…”