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Houghton, R A

Publications and source records attributed to Houghton, R A.

Observations and assessment of forest carbon recovery following disturbance in North America

Disturbance processes of various types substantially modify ecosystem carbon dynamics both temporally and spatially. The recovery of forests from disturbance typically results in carbon sequestration, but the point at which ecosystems move from being net sources to sinks of carbon is quite variable depending on a number of factors. Here we review some of the essential measurements needed to track the dynamics of carbon associated with forest disturbance, the longer-term recovery of carbon pools following disturbance, and consider the measurements used to document recovery, as well as how they vary with the type of disturbance. First we provide a brief overview of the relevance of disturbance to carbon dynamics. Specifically, we address 3 topics: (1) the different measurements needed to characterize recovery from different types of disturbance (e.g. fire, insects, harvest); (2) the essential measurements required to quantify the dynamics of carbon components associated with forest recovery; (3) the utility of multiple types of observations (lines of evidence) in documenting recovery from disturbance. Related to these topics we then explore a series of specific types of disturbance (fire, insects, harvest), and the relative importance of various factors (and associated measurements) that influence carbon pools and fluxes in different systems (boreal and temperate). These topics and associated research questions are focused on North America, but aspects are undoubtedly relevant to other forested ecosystems.

58 GEOSCIENCES↗

Harmonization of Land-Use Scenarios for the Period 1500-2100: 600 Years of Global Gridded Annual Land-Use Transitions, Wood Harvest, and Resulting Secondary Lands

In preparation for the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), the international community is developing new advanced Earth System Models (ESM) to assess the combined effects of human activities (e.g. land use and fossil fuel emissions) on the carbon-climate system. In addition, four Representative Concentration Pathway (RCP) scenarios of the future (2005-2100) are being provided by four Integrated Assessment Model (IAM) teams to be used as input to the ESMs for future carbon-climate projections (Moss et al., 2010). The diversity of approaches and requirements among IAMs and ESMs for tracking land-use change, along with the dependence of model projections on land-use history, presents a challenge for effectively passing data between these communities and for smoothly transitioning from the historical estimates to future projections. Here, a harmonized set of land-use scenarios are presented that smoothly connects historical reconstructions of land use with future projections, in the format required by ESMs.

09 BIOMASS FUELS↗

Update on CO2 emissions

Emissions of CO2 are the main contributor to anthropogenic climate change. Here we present updated information on their present and near-future estimates. We calculate that global CO2 emissions from fossil fuel burning decreased by 1.3% in 2009 owing to the global financial and economic crisis that started in 2008; this is half the decrease anticipated a year ago1. If economic growth proceeds as expected2, emissions are projected to increase by more than 3% in 2010, approaching the high emissions growth rates that were observed from 2000 to 20081, 3, 4. We estimate that recent CO2 emissions from deforestation and other land-use changes (LUCs) have declined compared with the 1990s, primarily because of reduced rates of deforestation in the tropics5 and a smaller contribution owing to forest regrowth elsewhere.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗