Future forests will depend on the effect of climate change and a future land use regime. A land-use regime, defined as the frequency, intensity and spatial distribution of land-use over time, can have complex, immediate, and enduring effects on forest ecosystems and the services they provide. In New England, forest conversion to development, timber harvesting, and protection are the primary land uses that shape contemporary and future forests. The modern land-use regime is playing-out simultaneously with climate change, which is extending the growing season and increasing mid-season respiration and having variable impacts on forest communities throughout the region. The extent, composition, and structure of future forests will all be shaped by the combined influence of the land-use regime and climate change. After completing a detailed quantification of the modern land-use regime, we coupled a mechanistic forest landscape succession model with a cellular automata land-cover change model and performed a simulation experiment designed to better understand the aggregate and relative impacts of climate change and land-use on future forest carbon, composition, and structure within the six New England states over the next 50 years.
We found that in the absence of land-use, simulated climate change (RCP 8.5) resulted in a 5% increase in carbon at year 2060 compared to a “current” climate scenario. The combined effect of climate change, timber harvesting and development resulted in a 12% decrease in carbon compared to a current climate scenario with the absence of land-use at 2060. The decrease in carbon was largely due to timber harvesting in the northern part of the region within corporate-owned lands. Development alone resulted in a 2% reduction in carbon at year 2060 and was associated with the expansion existing urban areas radiating from the city of Boston. However, unlike timber harvesting, development resulted in a permanent loss of forest but occurred on a relatively small component of the landscape. Our results suggest that land use will have larger effects on the future of New England aboveground forest carbon than will climate change and that a continuation of the recent trends in timber harvesting, could have substantial effects on future forest carbon.