Recommended forest indicators for the U.S. National Climate Assessment Indicators system
Part of the Third National Climate Assessment (NCA) of the United States focuses on developing a system of indicators to communicate key aspects of physical climate, climate impacts, vulnerabilities, and preparedness for the purpose of informing decision makers and the public with scientifically valid information. The indicators cover major sectors. A team of experts was formed for each area and tasked with identifying and recommending a core set of indicators based on a set of decision criteria; we studied forests. In addition, the forest team adopted a strategy so that we considered indicators: 1) to span the range of our proposed conceptual model, 2) to result in some indicators that could be reported now, 3) used for other purposes such as sustainability, but that also are related to climate, 4) needed for information to interpret climate effects related to forests, 5) in various stages of development even if data do not exist for reporting, and 6) of notable potential that might need more development or data collection. Our resulting indicator set is designed to efficiently provide a first version that leads research scientists to work on improved indicators, and helps decisionmakers to see the potential in using indicators.
Our conceptual model recognized that climate is only one driver of changes in forests of the US; other drivers include socio-economic factors and other environmental factors such as nutrients, light, and disturbance. All these factors can be impacted by climate. We recommend twelve indicators, grouped by the indicator types of extent, structure and function, ecosystem services, disturbance, biophysical, socioeconomic, climate impacts on the human domain via forest ecosystems, and human domain influences on climate factors via forests. During the analysis stage, we recognized that different technological methods may provide conflicting data for the same indicator. Because of this, we modified our approach and defined indicators to be a description of the factor of interest, adopted the use of metrics to describe specific items that are the actual measures, and presented these metrics for each indicator. We identified multiple linkages that are important between forests and other sectors and land use categories represented by other teams. We recommend that future work be improved by increasing coordination across the land use/land cover sectors.