From: "Harmon, Mark" To: "'nacp@python.as.harvard.edu'" , "'nacp@io.harvard.edu'" Subject: three comments from mark harmon Date: Tue, 11 Sep 2001 16:31:35 -0700 Comments from Mark Harmon, OSU Topic: Extensive Inventories: Sparsely measured C pools. A review of ongoing pilot projects to enhance measurements conducted as part of the national inventories needs to undertaken. Key pools are still not being sampled (stumps and dead roots); methods used to convert from field measurements (volume) to carbon are not complete (in many cases not planned); and methods to indirectly estimate one pool from another are not clear. Note: basically I see the FIA measuring downed wood and standing dead wood (logs and snags) volume. They are not measuring stumps, a key slash pool and one that can be used to estimate dead roots. And although they are going to have excellent volume data, they have not paid attention in general how that volume will be converted to carbon. The fire-fuel method they are planning to use has the density of decaying wood off by as much as 50-100%. That is going to skew the results upward to an unacceptable degree. All this is easy to fix and won't increase costs by much, but it will require some way to give these folks input. Topic: Intensive Research and Monitoring Sites In addition to gaseous exchanges, a subset of intensive sites should be used to improve estimates of dissolved organic carbon (DOC) and particulate organic carbon (POC) exports. While these exports are likely be low in certain ecosystems, there are significant areas of boreal (for DOC) and agricultural (for POC) ecosystems where this is not the case. The addition of these measurements would allow the terrestrial system to be coupled more directly to the oceanic and land margin systems. Measurements and experiments to determine the fate of these potential terrestrial exports also need to be increased. Are these materials oxidized in transit? How long are these materials stored in the transport system? Note: We have ignored these fluxes for long enough. To compare the ground-based to the flux-based measurements we need to find out how large these fluxes are. This need not be an expensive effort and could start with a compilation of numbers and spatial database indicating the range of expected values for ecoregions or biomes, etc. This could then be upgraded by adding more field measurements where needed. Topic: Phase 2:Intensive Field Studies I am not sure where this goes, but monitoring disturbances is noted in this section. In addition to monitoring disturbance during intensive field studies, an effort to describe the nature of these disturbances needs to be undertaken. We need to move beyond where and when disturbances occur to understanding the types of transformations are occurring and at what rates. How much of the system is transferred from live to dead; to charcoal; to the atmosphere? This effort should start with a compilation of studies with a mean and range of transformation constants for a wide range of disturbance types and locations. This can then be supplemented by field measurements for situations with high uncertainty. For disturbances related to natural resource extraction, a compilation of past changes in these transformations would help greatly in any historical reconstruction of the carbon budget. Finally, an investment in linking the ground-based understanding of disturbance transformations to remote sensing would be helpful as it could help stratify disturbances by severity over a wider area.