The North American Carbon Program Plan (NACP)
A Report of the Committee of the
U.S. Carbon Cycle Science Steering Group

Appendix 2

 Phased Implementation of Biophysical/Biogeochemical Measurements and Models

There are three broad, consecutive phases in implementing the biophysical measurements and modeling part of this program, corresponding to the phased approach described in the section on atmospheric measurements: (1) preliminary work, (2) intensive field studies, and (3) long-term implementation. Preliminary work is to be completed prior to initiation of this program using existing funding mechanisms.

Phase 1: Preliminary Work

Enhancements to Intensive Networks, Extensive Inventories, and Land Cover Data

The existing extensive AmeriFlux network and extensive inventories have gaps in geographic coverage and methodologies that can potentially be addressed to provide complete coverage of the land surface. Identified gaps include developed lands (urban and suburban), rangelands, pinyon-juniper forests, and interior Alaska. Preliminary work should include systematically defining how networks and inventories should be upgraded, and developing a strategic plan to accomplish this goal.

A prototype database of historical information should be developed in the preliminary phase, including the current state of land surface (cover, age since disturbance, type of disturbance, management, biomass, soil carbon stocks). LandSat data collected over the continent during the 1980s, 1990s, and 2000 and 2002 (in preparation for campaigns beginning in 2004) need to be assembled and processed to provide high spatial resolution land cover change information for the last two decades.

Measurement Issues for Intensive Networks and Field Campaigns

With regard to field tests and deployment of new instruments: New methodology for in situ soil C measurements is becoming available. They must be tested, and if suitable, used for more background and benchmark validation measurements. Only a few AmeriFlux sites carry out required biophysical measurements and have the instruments, on-site data processing, and communications required to supply the data at appropriate time scales to integrate with the atmospheric studies. We need to augment capabilities to allow the measurement of all C gas fluxes and to partition the component fluxes at resolutions that will allow the quantification of daily, seasonal, and interannual variability at appropriate spatial scales. New low-power, high-precision, high-frequency detectors for CO2 (NDIR), and CH4 and CO (GC or NDIR-gfc) need to be developed and deployed as part of a low-cost chemistry/meteorology package to expand measurement capability. Related to all proposed measurements, standards need to be developed to prepare for future implementation. Preliminary work should involve instrument development, upgrading of a limited number of sites, and developing and implementing pilot studies of data communication and data fusion.

Model Development and Applications

Analysis needs should be identified early in the program so that model development may provide appropriate information. Input and output variables needed by a variety of models need to be specified. Model comparison studies may be useful. Testing of methods to integrate new measurement protocols with existing intensive and extensive sampling networks is an ongoing activity. Activities for the preliminary phase include developing an understanding of model functionality, including operational input and output specification. Pilot development of actual working models should be undertaken, linked to the pilot work on enhanced intensive sites and inventories.

Evaluation of Information Capabilities of New Remote Sensors

Some remote sensors have been in use long enough that their capabilities are well known (e.g. LandSat-TM). Others, such as EOS-MODIS, are relatively new and evaluation studies are underway. In addition, above-ground biomass measurements using airborne lidar, radar, and hyperspectral techniques should be evaluated further through field testing. Once a sampling strategy has been identified, these approaches can be used in conjunction with in situ measurements and modeling to develop continent-wide data on current carbon stocks, fluxes, and changes in stocks and fluxes.

Phase 2: Intensive Field Studies

Network Design Issues

Proposed designs from the preliminary phase will be rigorously tested and evaluated under field conditions. Particular attention must be given to integrating the designs with atmospheric measurements.

Enhancements to Extensive Inventories

Compilation of historical data and support for intensive studies is required at this phase. It will be necessary to specifically test and evaluate field procedures to attain accurate and seamless extensive data collection. All relevant historical data should be compiled and available at the end of this phase. A major effort is required to address data gaps in extensive inventories by applying substitute methods based on remote sensing, alternative plot networks, and ecosystem models. This supplemental data should be fully compatible with existing inventory data except that the sources of information will be different.

Support for Initial Intensives

Support is needed for the initial intensives of the atmospheric measurements’ “proof of concept” exercise (agricultural and urban test areas), and subsequent phasing of atmospheric measurements over a variety of cover classes. In addition, intensive field studies will be needed to develop and test the multi-tier sample design for land observations on models in representative cover classes. One or more intensive field studies will be needed in agricultural, urban/suburban, forest, wetland, and rangeland cover classes. If possible, such studies should be added to areas where significant intensive process monitoring is already underway, such as areas with AmeriFlux towers and/or LTER monitoring. This will make it possible to provide data on ecosystem response to climate change and to supply the required ground truth for a representative selection of sites.

During intensive field activities and in support of atmospheric sampling, in situ measurements of soil, leaf and canopy carbon and energy fluxes and carbon pools (including isotopic compositions) should be acquired. Additional activities should be conducted during intensive field campaigns:

  • Monitoring disturbance (e.g., fire, forestry, agriculture) during a year of campaigns using satellite observations in combination with in situ measurements.

  • Monitoring phenology over the continent precisely (<= weekly, <= 1 km).

  • Airborne remote sensing of state of vegetation-biomass, stress, and foliar chemistry-using lidar, radar, hyperspectral, multi-angle techniques.

  • Developing a database of biophysical state (LAI/FPAR, soil moisture, meteorological conditions, inundation, disturbance such as fire, logging, other).

  • Compiling appropriate descriptive historical data.

Phase 3: Long-Term Implementation

Based on preliminary studies and intensive campaigns, modifications to long-term networks will be proposed to broadly enhance the ability to monitor fluxes of major C species, and to control plant-soil characteristics and processes, for North America. Key limitations described earlier will be resolved: gaps in spatial coverage will be filled; complete ecosystem C stock changes will be estimated; and temporal resolution will be high (annual to monthly). Comprehensive data and analysis tools will facilitate development of predictive models to evaluate policy scenarios for managing greenhouse gases. Near-real-time, quality controlled data will be delivered to the sites for the data assimilation activities.

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