Abstract:
The LTER network is committed to integrated socio-ecological research designed to foster a sustainable future. Overarching questions include: How will global change alter the futures of regional social-ecological systems? And, how and why do regional social-ecological systems differ in vulnerability, resilience and adaptability to global change? Addressing these questions poses many new challenges. Indeed, research to anticipate ecological change within coupled human and natural systems is met by massive uncertainties, reciprocal feedbacks, and surprises. Scenario thinking to inform quantitative modeling of landscape change and attending ecological responses is among the most promising approaches to emerge. Scenarios typically begin as suites of qualitative narratives—developed by regional stakeholders including social and ecological scientists—that describe an envelope of plausible futures based on contrasting assumptions. The narratives inform and are, in turn, informed by integrated spatial models of socio-ecological change.
In 2008, the Harvard Forest initiated a scenario and landscape simulation project to help anticipate and understand the individual and aggregate impacts of future land use and climate change on forest growth and composition in the state of Massachusetts. In the first phase of this study, we examined twenty years of land-use records and incorporated this information into a spatially interactive forest landscape simulator to assess growth and community interactions among tree species as they were affected by the “current trends” of land-use and climate change. We conducted simulations in a full-factorial design and found that continued forest succession had the largest effect on total AGB, increasing stores from 181.83Tg to 309.56Tg over fifty years. The increase varied from 49 to 112-percent depending on the eco-region within the state. Compared to the “growth-only” simulation, forest conversion reduced total AGB by 23.18Tg (or 18%) over fifty years. Timber harvests reduced total AGB by 5.23Tg (4%). Climate change had a positive effect on growth, increasing total AGB by 17.3Tg (13.5%). Community structure underwent only minor changes owing to the length of the simulation relative to the longenity of the trees. Based on these findings and the naïve assumption that future land use patterns will resemble the recent past, we conclude that continued forest growth and recovery will be the dominant mechanism driving forest dynamics over the next fifty years, and that while climate change may enhance the rate of growth this will be more than offset by land-use, primarily forest conversion to developed uses.
Looking forward, the Harvard Forest is partnering with researchers from forested regions across to U.S. in a new multi-LTER-site effort called: Future Scenarios of Forest Change. This project seeks to address the question: How will global and national drivers of environmental and land use change (climate, national policies, and economic trends) affect the major forested regions of the US over the next half century in terms of key ecological indicators (structure, function, and pattern) and critical ecosystem services (carbon, water, habitat, natural resource production)? The Forest and its partners have successfully competed for seed money, which has funded a national stakeholder outreach program in Washington DC and to a pilot effort to test comparative landscape simulation of future trends in of climate and land use in Massachusetts and Wisconsin. The scenarios group is actively seeking new funds and new collaborators to propel this effort.
