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Welcome to the California Energy Commission
Public Interest Energy Research Program: Final Project Report
Carbon Supply From Changes In Management of Forest, Range, and Agricultural Lands of California

Publication Number: CEC-500-2004-068F
Publication Date: March 2004

The executive summary, abstract and table of contents for this report are available below. This publication is available as an Adobe Acrobat Portable Document Format Files. In order to download, read and print PDF files, you will need a copy of the free Acrobat Reader software installed in and configured for your computer. The software can be downloaded from Adobe Systems Incorporated's website.

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Appendices

Download Appendix I: Value of Aging Timber with Alternative Carbon Calculation (Adobe Acrobat PDF, 4 pages, 192 kilobytes)

Download Appendix II: Quantitative Driver Maps (Adobe Acrobat PDF, 3 pages, 1.3 megabytes - Note file size!)

Download Appendix III: Factor Map Details (Adobe Acrobat PDF, 1 page, 92 kilobytes)

Download Appendix IV: Qualitative Driver Maps (Adobe Acrobat PDF, 3 pages, 328 kilobytes)


ADDENDUM to PIER report # P500-04-068,
Publication Number: CEC-500-2006-093-AD
Publication Date: October 2006
(39 pages, 1.3 megabytes - Note file size!, on line 10/2/2006)



Executive Summary

Objectives

The "Baseline, Classification, Quantification and Measurement for Carbon Market Opportunities in California" project began in 2002. One of the tasks is the estimation of the quantity and cost of carbon storage opportunities in California. The primary outputs from this task are carbon supply curves and corresponding maps for the most important classes of carbon sequestration activities in the land-use change and forestry sector.

Currently, the estimates of carbon sequestration potential most frequently cited are of the theoretical potential, without consideration of current land values and alternate uses. To fill this gap in knowledge, this report sets out to answer the basic question: "How many carbon credits would landowners offer for sale for a particular class of activity at various price points and where are these located?" The information contained in this report can help stakeholders prepare for an uncertain regulatory future by providing more accurate estimates of the quantity of carbon credits that might be available at different price points for different classes of projects. The estimates can help in preparation of a portfolio of potential stakeholder responses for a range of future climate scenarios.

Information about current land use (based on the California Department of Forestry (FRAP 2002), potential changes in land use and the incremental carbon resulting from the change, opportunity costs, conversion costs, annual maintenance costs, and measurement and monitoring costs were obtained and used in the analyses. The analyses are performed in a geographic information system (GIS) to include the diversity of land uses, rates of carbon sequestration, and costs. As a result, not only are more realistic estimates of the potential supply of carbon produced, but the use of GIS shows where the least to most expensive carbon credits will most likely be found. The general approach was to identify and locate classes of land where there is potential to change the use to a higher carbon content, estimate rates of carbon accumulation for each major potential land-use change activity for each land class, assign values to each contributing cost factor, and identify datasets and methods to estimate project risks.

Californian lands are classified into three main groups for the analyses presented here: forests, rangelands, and agricultural lands. Forests (about 23.7 million acres) include conifers, hardwoods, and mixed classes; rangelands (about 56.5 million acres) include a variety of non-woody (e.g., pasture, grasslands) and woody ecosystems (e.g., oak woodlands, chaparral); and agricultural lands (about 9.9 million acres) include a wide range of non-woody crops such as small grains, vegetables, and berries and woody crops such as vineyards and orchards.

The steps needed for estimating the carbon supply for a potential change in land use are:

  1. Identify the classes of land uses and the associated changes in management that could lead to significant increase in carbon stocks

  2. Estimate the area for each potential change in land use

  3. Estimate the quantities of carbon per unit area that could be sequestered for the change in land use over a given time period

  4. Estimate the total costs (opportunity, conversion, maintenance, and measuring and monitoring)

  5. Combine the estimated quantities of carbon per unit area with the corresponding area and cost to produce estimates of the total quantity of carbon that can be sequestered for a given range of costs, in $/metric ton C or $/metric ton CO2.

For forestlands, estimates of the potential carbon benefits were analyzed for four alternatives for 20 year and/or permanent contract periods: (1) allowing timber to age past economic maturity (lengthening rotation time); (2) increasing the riparian buffer zone by an additional 200 feet; (3) changing traditional clear cuts to group selection cuts, and (4) forest fuel reduction to reduce hazard of catastrophic fires, and subsequent use of biomass in power plants. For estimating the costs of allowing timber to age and the costs of enhanced riparian zone management, estimates are based on specific counties for public and private landowners, and then extrapolated to all counties throughout the state. For the group selection cuts, there appears to be little increased carbon sequestration in Sierran mixed conifers or coastal redwoods, but, these costs are provided to serve as an estimate of costs for other areas where a net increase in carbon stocks may occur.

For the fuel reduction alternative, the objective was to estimate the areas and carbon stocks of forests suitable for fuel reduction to reduce their fire risk and that were located within economic range of existing power plants for the high and very high fire risk forests. The analysis used a "Suitability for Potential Fuel Reduction (SPFR)" score on forest landscapes where significant carbon loss from wildland fires exist. Additionally, SPFR scores also ranked areas feasible for removing and transporting fuels to biomass power generating plants. The SPFR scores were created in a GIS using slope, distance to biomass plants, and distance from roads as equal weighted factors in the decision making process. Suitability scores for potential fuel reduction with highest suitability were assigned to areas with gentle grades of slope that are close to roads and biomass power plants. The analysis did not include the economic component due to the lack of a variety of data and resources needed to be confident about projections of carbon supply curves; but the analysis does present a first approximation of the potential reduction in carbon emissions if forest fuels were reduced.

For rangelands, estimates of the potential carbon benefits were analyzed for one alternative—afforestation. Historical evidence suggests that in many areas, large tracts of forest may have once stood where grazing lands now do. Moreover, a significant proportion of today's oak woodlands and annual grassland vegetation types on California's rangelands were also once either dense forests or similar woodlands but with significantly higher biomass than they currently contain. Presently, in much of the state, ranching is the primary activity on what remains of these lands that were once forests or woodlands. The general approach was to identify and locate existing rangelands where biophysical conditions could favor forests, estimate rates of carbon accumulation for the forest types projected to grow, and assign values to each contributing cost factor. The carbon supply is estimated for three time durations: 20 years, 40 years and 80 years of forest growth to reflect the impact of activity duration on the likely supply and to provide an assessment for the near-term and longer-term planning horizons.

For existing agricultural lands, only one major activity was analyzed -conservation tillage (CT) practices, which increases soil carbon up to a period of about 20 years maximum. Due to the high productivity and land values associated with California agriculture, the opportunity costs of displacing agricultural production with afforestation is not likely to be a valid source of carbon sequestration. Although CT has been proven to be a profitable management strategy for certain crops in many regions of the country, there are only very limited data regarding its application in California. Given the lack of research data and the great diversity of crops produced, it is essentially impossible to estimate the costs of CT adoption across the state in a meaningful way.


Outcomes

Although the whole range of costs and potential carbon available are presented in this report, Table S-1 summarizes the amount of carbon and the area available for several classes of opportunities at three price points: —≤ $13.6/ MT CO2 ($50/MT C), ≤ $5.5/MT CO2 ($20/MT C), and ≤$2.7/MT CO2 ($10/MT C). Although California has substantial areas of forests, the cost of carbon sequestration from changing forest management practices is relatively high. No forest management project, regardless of length of project, can provide carbon sequestration at less than $2.70/MTCO2 (Table S-1).

At a price of $13.6/ MT CO2, the total amount of carbon that could be sequestered by afforesting grazing lands and changing forest management over a 20 year period is about 894 MMT CO2 (Table S-1). Approximating this total amount to an annual rate, results in about 45 MMT CO2/ yr. In comparison, the transportation sector emitted 160 MMT CO2/ yr in 1999 and the electricity generation sector emitted about 57 MMT CO2/ yr in 1999. Thus total sequestration at $13.6 per MT could offset about 79% of the electricity generating fossil fuel emissions and 28% of the transportation emissions.

table t-1


The largest potential source of carbon from forest management is for lengthening rotation by five years that can potentially provide 2.16 to 3.91 MMTCO2 at a cost of less than $13.60/MT CO2 depending on whether the carbon is undiscounted or discounted. Increasing the riparian buffer zone by 200 feet could sequester 3.91 MMTCO2 permanently (assuming no catastrophic fire risk) at a cost between $2.7 and $13.6 per MTCO2. This amount could occur on about 43,730 acres of forestland.

Lengthening forest rotation by five years shows that the counties with the least expensive carbon do not produce the highest quantities of carbon (Figure S-1 and S-2). The highest quantities of carbon that could be sequestered by this activity are located in the north coast counties, but these same counties have some of the most expensive carbon. The difference between the two discounted methods relates to different assumptions that could be used about the existing carbon in forest stands. Under method 1, shown in A and B in Figure S-1, carbon emissions in the initial harvest are ignored. Under the alternative accounting method, shown in C in Figure S-1, these initial emissions are considered. The costs tend to be lower for the alternative method of accounting because the emissions from the initial harvest are held off to future periods when rotations are extended, which creates an additional carbon benefit in early periods.

figure s-1

Figure S-1. Distribution, at the county scale, of the cost to sequester carbon (in $/metric t C) via lengthening the forest rotation time by 5 years for two methods of discounting carbon (A. and C.) and for undiscounted carbon (B.).


figure s-2

Figure S-2. Distribution, at the county scale of resolution, of the potential amount of carbon (metric t C) that could be sequestered on all forest lands by lengthening the forest rotation time by 5 years for two methods of discounting carbon (A. and C.) and for undiscounted carbon (B.).


Results are presented on public and on private lands of an analysis of the potential carbon sequestration and costs through expansion of the prohibitive riparian buffers for forestry operations. On public lands, the least expensive carbon, less than $70/t C (or less than $19/MTCO2) generally coincides with those counties that potentially provide the highest quantities (Northeast Cascades and the northern part of North Sierra). On private lands, the trend is roughly the same, except that the most carbon at the least expensive cost is mainly centered in Northeast Cascade counties (Figure S-3). This project type could lead to leakage, because landowners could simply increase the overall size of the areas they propose to cut in order to compensate for the set-asides. The extent of this potential leakage has not been estimated here, but should be considered as part of carbon sequestration plans.

figure s-3

Figure S-3. Distribution, at the county scale of resolution, of the quantity (metric tons) and cost ($/metric t C) of sequestering carbon by extending riparian buffers 200 feet along perennial streams on public and private lands.


From the forest fuel reduction analysis, the area of forests in the upper 25% of the Suitability Potential for Fuel Reduction scores accounted for 774,827 hectares, areas that could be considered as suitable candidates for fuel reduction projects (Figure S-4). The forest area contained an estimated cumulative carbon stock of 74.2 MMT, and based on parallel work on California's baseline in the forestry sector, the estimated emissions from these forests if they burned could be as much as 23 million t C.

figure s-4

Figure S-4. Map of suitability potential for fuel reduction (SPFR) for California forests.


For afforestation of rangelands, longer durations clearly produce lower cost carbon but landowners may be more hesitant to commit land to projects of such duration (Figure S-5). Afforestation of rangelands (up to 13.34 million acres potentially available) provides the most carbon at the least cost (≤$2.7/MT CO2 )—about 33 MMTCO2 at 20 years to 4.57 billion MTCO2 at 80 years (Table S-1). The counties with the least expensive carbon from afforesting rangelands are also the same counties that potentially can sequester the most.

figure s-5

Figure S-5. Total carbon sequestered by afforestation of rangelands (metric tons; left) and area-weighted average cost per metric ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and after 20, 40, and 80 years.


The potential occurrence of fire is probably the largest risk to carbon sequestration by afforestation activities in California. Thus, in addition to the costs of physical management of the afforested areas, attention must be paid to the threat of fire to these investments. Because it is impossible to estimate what fuel loads will be present at a site after an afforestation activity, only the Fire Rotation Interval map (from CDF-FRAP) was used for the analysis. The majority of the potential areas for afforestation (49%) fall within the lowest risk category of fire rotation interval, and an additional 29% of the lands fall within the 100-300 year fire rotational interval. However, from a cost perspective, the ‘High' to ‘Very High' rotation intervals contain potentially some of the least costly carbon credits.

Of the possibilities for sequestering C on agricultural land in California, conservation tillage (CT) seems to offer the greatest potential. Based on a range of C sequestration rates of 0.35-0.61 MT/ha/year, it is estimated that California agricultural land could produce up to 3.9 MMTCO2 /year through CT. The cost to sequester this amount of carbon is unknown for California, but in other regions of the United States this can incur little extra cost. However, it is unlikely that CT will be adopted on much of California's high-value and specialty crop land. The most likely crops for which CT will be adopted are tomatoes, cotton, beans, and corn, which do represent a large area of California agricultural land.

The vast majority of the potential soil carbon sequestration is located in the Sacramento and San Joaquin valleys in the central part of the state (Figure S-6). Additional smaller pockets can be seen in far northern and far southern counties, as well as along the central coast.

figure s-6

Figure S-6. Aggregated soil carbon sequestration estimates under conservation tillage regimes on row crops and small grains.



Abstract

The project described in Carbon Supply for Forest, Range, and Agricultural Lands of California was a portion of the Baseline, Classification, Quantification, and Measurement for Carbon Market Opportunities in California project. This project estimated the quantity and cost of carbon storage opportunities in California and developed carbon supply curves for the most important classes of carbon sequestration activities in land-use change and forestry projects.

The research found that the cost of carbon sequestration from changing forest management practices is relatively high. No forest management project, regardless of length of project, can provide carbon sequestration at less than $2.70/MTCO2. The largest potential source of carbon from forest management is for lengthening rotation by five years, which can potentially provide 2.16 to 3.91 MMTCO2 at a cost of less than $13.60 per ton.

For afforestation of rangelands, longer durations produce lower cost carbon. Afforestation of rangelands provides the most carbon at the least cost (≤ $2.7/MT CO2) - about 33 MMTCO2 at 20 years to 4.57 billion MTCO2 at 80 years.

Conservation tillage (CT) seems to offer the greatest potential for producing carbon on agricultural land in California. It is estimated that California agricultural land could produce up to 3.9 MMTCO2 /year through CT.

This report can help stakeholders more accurately estimate the quantity of carbon credits that might be available at different price points for different classes of projects. The estimates can help in preparation of a portfolio of potential stakeholder responses for a range of future climate scenarios.



Table of Contents

Preface ii

Abstract xi

Executive Summary 1

1.0 FORESTS 10

1.1. Introduction 10

1.1.1. Discount Rates 10

1.2. Increasing Forest Rotation Age 13

1.2.1. Empirical estimates of marginal costs 22

1.2.2. Potential Carbon Sequestration in Region 29

1.3. Riparian Zone Management 35

1.4. Group Selection Harvests 42

1.5. Forest Fuel Reduction 46

1.5.1. Approach 48

1.6. References 56

2.0 RANGELANDS 58

2.1. Rangelands of California 58

2.2. Objectives of Study 59

2.3. Methods 59

2.3.1. General Approach 59

2.3.2. Scale of Analyses 63

2.3.3. Definition and Area of Rangelands 63

2.3.4. Identification of Rangeland Suitable for Afforestation 67

2.3.5. Analysis of Carbon Sequestration Costs 85

2.4. Results 91

2.5. Discussion 105

2.5.1. Suitability of Sites for Tree Growth 105

2.5.2. Soil Types 109

2.5.3. Ecoregions and historical vegetation maps 110

2.6. Future Steps 110

2.6.1. Analysis of Ecological Effects of Afforestation of Rangelands 110

2.6.2. Effects of Urbanization on Opportunity Costs of Rangelands 111

2.6.3. Reductions in Cattle Populations and Consequent Effects on GHG Emissions 111

2.6.4. Changes in Rangelands Management 112

2.6.5. Estimating the Risk of Fire 114

2.6.6. Impacts of Climate Change 115

2.7. References 115

3.0 AGRICULTURAL LAND 120

3.1. Introduction 120

3.2. Management practices to increase soil organic carbon 122

3.2.1. Conservation tillage 122

3.3. References 126


Appendices

Appendix A: Value of Aging Timber with Alternative Carbon Calculation

Appendix B: Quantitative Driver Maps

Appendix C: Factor Map Details

Appendix D: Qualitative Driver Maps


List of Figures

Figure S-1. Distribution, at the county scale, of the cost to sequester carbon (in $/metric t C) via lengthening the forest rotation time by 5 years for two methods of discounting carbon (A. and C.) and for undiscounted carbon (B.). 4

Figure S-2. Distribution, at the county scale of resolution, of the potential amount of carbon (metric t C) that could be sequestered on all forest lands by lengthening the forest rotation time by 5 years for two methods of discounting carbon (A. and C.) and for undiscounted carbon (B.). 5

Figure S-3. Distribution, at the county scale of resolution, of the quantity (metric tons) and cost ($/metric t C) of sequestering carbon by extending riparian buffers 200 feet along perennial streams on public and private lands. 6

Figure S-4. Map of suitability potential for fuel reduction (SPFR) for California forests. 7

Figure S-5. Total carbon sequestered by afforestation of rangelands (metric tons; left) and area-weighted average cost per metric ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and after 20, 40, and 80 years. 8

Figure S-6. Aggregated soil carbon sequestration estimates under conservation tillage regimes on row crops and small grains. 9

Figure 1-1. Growing stock volume yield function for high site Douglas Fir in California. 18

Figure 1-2. Tons carbon per hectare stored in aboveground biomass and products, assuming stands are initially 63 years old. 19

Figure 1-3. Difference in net annual flux for the longer rotation scenario versus the baseline scenario (long rotation net annual flux of carbon - baseline rotation net annual flux of carbon). 20

Figure 1-4. Marginal cost of aging timber with permanent contract on private land only (discounted carbon) 31

Figure 1-5. Marginal cost of aging timber with 20-year contracted on private land only (discounted carbon) 32

Figure 1-6. Marginal cost of aging timber with 20-year contract on private land only (undiscounted carbon) 32

Figure 1-7. Distribution, at the county scale of resolution, of the potential amount of carbon with 20-year contracts that could be sequestered on all lands by lengthening the forest rotation time by 5 years for A. discounted carbon, B. undiscounted carbon, and C. discounted carbon (for A. and B. see Tables 1-15 and 1-16, and for C. see Appendix A, Table A3 for details). 33

Figure 1-8. Distribution, at the county scale, of the cost to sequester carbon (in $/t C)with 20-year contracts via lengthening the forest rotation time by 5 years for A. discounted carbon, B. undiscounted carbon, and C. discounted carbon (for A. and B. see Tables 1-15 and 1-16, and for C. see Appendix A, Table A3 for details). To convert to $/short t CO2, divide $/t C by 4.0. 34

Figure 1-9. Tons carbon per hectare stored in above-ground biomass and products, assuming stands are initially 48 years old. 36

Figure 1-10. Distribution at the county scale of the quantity and cost of sequestering carbon by extending riparian buffers 200 feet along perennial streams on public and private lands. 41

Figure 1-11. National Interagency Fire Statistics showing the area burned by wildfires in the U.S. from 1960 to 2002. 46

Figure 1-12. National Interagency Fire Statistics showing federal expenditures in millions of dollars from 1994 to 2002. 47

Figure 1-13. Distribution of California's forests at high and very high risk for catastrophic fire. 49

Figure 1-14. Factor image for distance from roads used in the MCE on a scale of 0 to 255 where 0 is the least suitable (furthest from roads) and 255 is the most suitable (closest to roads). The zoomed image shows greater detail in the database. 50

Figure 1-15. Slope suitability factor map and zoomed image detailing suitable slopes with zero value having the least SPFR scores and 255 the most SPFR scores. 51

Figure 1-16. Suitability map showing distances from biomass plants where the highest SPRF scores are assigned to values close to the power generating plants. 51

Figure 1-17. Suitability scores for potential fuel reduction with highest suitability assigned to areas with gentle grades of slope that are close to roads and biomass power plants. 52

Figure 1-18. Area of forests at very high and high risk in each SPFR class. The score of 190 and above considered arbitrarily to be "high suitability" for fuel reduction because the forests are on gentle slopes, near a road, and near a power plant. 53

Figure 1-19. Forest composition of the SPFR classes for areas at high and very high risk for fire. 54

Figure 1-20. Map of carbon stocks for California forests 54

Figure 1-21. Carbon stocks by SPFR classes for forests at high and very high risk for fire. 55

Figure 1-22. Cumulative carbon stocks in forests at high and very high risk for fire with a SPFR classes greater than 190. 55

Figure 2-1. Photographs of California rangelands. 58

Figure 2-2. Flowchart of carbon supply curve analysis with key assumptions listed below each step. 62

Figure 2-3. CDF-FRAP multi-source land-cover map classified into major land cover types (more than 77 WHR classes are actually present in the map). 66

Figure 2-4. Reclassification of multi-source land-cover map. 66

Figure 2-5. Steps used to develop a suitability map for converting existing rangelands to forests. (AWC = Available Water Capacity of soil) 67

Figure 2-6. Proportion of actual forest in each of the Elevation map classes. Units are feet above sea level. 68

Figure 2-7. Proportion of actual forest in each of Mean Annual Temperature map classes. 69

Figure 2-8. Proportion of actual forest in each of Soil Available Water Capacity map classes. 69

Figure 2-9. Proportion of actual forest in each of Precipitation map classes. 70

Figure 2-10. Proportion of actual forest in each of Slope map classes. 70

Figure 2-11. All areas "suitability" for forest growth (left) and rangeland areas "suitability" for forest growth (right) according to the model. Low score means unsuitable for forests, and the higher the score the more suitable for forest growth. 71

Figure 2-13. Distribution of 3 WHR generalized classes within the forest suitability classes. (This is the intersection of Figures 2-4 and 2-11). 73

Figure 2-14. Distribution of 12 WHR generalized classes within the forest suitability classes. 74

Figure 2-15. Distribution of rangeland WHR classes within the forest suitability classes. 75

Figure 2-16. Map of populated places (dots), Montane Chaparral areas, and selected place names with reference to forests or forestry (squares). 76

Figure 2-17. California Biodiversity Council (CBC) Bioregions map (DCF-FRAP, 2003). Inset box shown in Figure 2-18. 77

Figure 2-18. An example of the stratification of the suitability map by county and bioregion in an area of southern California. For each suitability class in each county's bioregion, a woody WHR-type was assigned based on its dominance in area in the class. 78

Figure 2-19. Map of candidate areas, i.e., those areas of rangelands with a canopy coverage of less than 40% and that scored higher than 20 on the suitability map. 80

Figure 2-20. The breakdown of the candidate cells in California. Candidates for carbon sequestration activity through forestry ("suitable rangelands with CC<40%--about 23% of California or 9.4 million hectares). "Suitable" areas are those that scored higher than 20 on the suitability map. (CC=canopy cover). 81

Figure 2-21. Forest biomass carbon accumulation potential for selected California conifers. Redwood curve is shown for the more common low-productivity stands. 83

Figure 2-22. Forest biomass carbon accumulation potential for selected California hardwoods. 83

Figure 2-23. Net potential carbon accumulation curves applied to potential woody-species distributions over three potential periods. 84

Figure 2-24. Results of multivariate regression for forage productivity across all land-cover classes, in pounds per acre per year. Black areas represent water bodies. [NOTE: To convert from lbs/acre per year to t/ha per year divide by 906.9.] 88

Figure 2-25. Results of multivariate regression for forage productivity across rangeland classes only, in pounds per acre per year. [NOTE: To convert from lbs/acre per year to t/ha per year divide by 906.9.] 88

Figure 2-26. Two forage production-modeling approaches: category-weighted approach (CWA) and multi-variant regression approach (MVR). [NOTE: Trend lines were forced through zero.] 89

Figure 2-27. Frequency of WHR classes by forage production potential. 90

Figure 2-28. Cost of carbon sequestration through afforestation of California rangelands (100 meter grid cells). To convert to $/metric t CO2, divide by 3.6. 93

Figure 2-29. Carbon supply curves for afforestation activities on candidate rangelands at 20, 40 and 80 years. To convert to $/metric t CO2, divide by 3.6. 94

Figure 2-30. Land supply curves for afforestation activities on candidate rangelands of varying $/t C values. To convert to $/metric t CO2, divide by 3.6. 95

Figure 2-31. Average annual carbon accumulation across potential 20, 40 and 80-year time periods for $20/t C or less ($5.5/metric t CO2). 96

Figure 2-32. Summaries by county of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 20 years. Red counties are those with the highest proportion of land, the most carbon and at the lowest cost. 98

Figure 2-33. Summaries by ownership class of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 20 years. Ownership classes are, a. ‘private', b. ‘public -non-federal' and c. ‘public -federal'. 99

Figure 2-34. Summaries by county of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 40 years. Red counties are those with the highest proportion of land, the lowest cost carbon, and the most carbon. 100

Figure 2-35. Summaries by ownership class of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 40 years. Ownership classes are, a. ‘private', b. ‘public -non-federal' and c. ‘public -federal'. 101

Figure 2-36. Summaries by county of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 80 years. Red counties are those with the highest proportion of land, the most carbon, and at the lowest cost. 102

Figure 2-37. Summaries by ownership class of (from left to right) proportion of afforestable rangeland, area-weighted average cost per ton of carbon (to convert to $/ metric t CO2, divide by 3.6) and total carbon sequestered after 80 years. Ownership classes are, a. ‘private', b. ‘public -non-federal' and c. ‘public -federal'. 103

Figure 2-38. California redwood harvest. Photo: Union Lumber Company Collection. Note man in lower right (from Andrews 1956). 106

Figure 2-39. Photo: H.E. Roberts (from Andrews 1956) 107

Figure 2-40. Photo: Union Lumber Company Collection (from Andrews 1956). 107

Figure 2-41. Photo: Union Lumber Company Collection (from Andrews 1956). 108

Figure 2-42. Photo: Hammond Lumber Company Collection (from Andrews 1956). 108

Figure 2-43. Serpentine soils in California as mapped by STATSGO dominant soil components. 109

Figure 2-44. Fire rotation interval map provided by the California Department of Forestry - Fire and Range Assessment Program (CDF-FRAP) 114

Figure 3-1. Agricultural and herbaceous National Land Cover Dataset classes and land areas in California. 121

Figure 3-2. Aggregated soil carbon sequestration estimates under conservation tillage regimes on row crops and small grains. 125


List of Tables

Table S-1. Summary of the quantity of carbon (million metric tons CO2 [MMT CO2]) and area (million acres) available at selected price points—≤ $13.6/MTCO2 ($50/MT C), ≤ $5.5/MT CO2 ($20/MT C), and ≤$2.7/MT CO2 ($10/MT C) —for several classes of activities on existing rangelands and forestlands over 20-year, 40-year, 80-year, and permanent (forest management—riparian buffer) durations. 3

Table 1-1. Timberland area, proportion of timberland type that is private, and proportions in different age classes for private and public lands. 14

Table 1-2. Estimated yield function parameters. Maximum yield using equation (3) is calculated for 120 year old stands. Maximum yield from FIA data is calculated as the maximum yield observed in the data. 15

Table 1-3. Carbon biomass parameters 15

Table 1-4. Carbon values for high site Douglas Fir 22

Table 1-5. Timber prices for the period January 1, 2003-June 30, 2003, obtained from the California State Board of Equalization Harvest Schedule. 23

Table 1-6. Prices, optimal rotation ages, timber yield and site values. 25

Table 1-7. Prices, timber yield and site value under regulated rotations. 25

Table 1-8 (Permanent Contract - Discounted Carbon). Net carbon sequestered and $ per ton for increasing rotation ages X years above economically optimal rotation ages (the rotation ages for this analysis are shown in Table 1-6) in California timber region 7. 26

Table 1-9 (Permanent Contract - Discounted Carbon): Net carbon sequestered and $ per ton for increasing rotation ages X years above the legally mandated rotation age in California timber region 7. 26

Table 1-10 (20-yr Contract- Discounted Carbon). Net carbon sequestered and $ per ton for increasing rotation ages X years above economically optimal rotation ages (the rotation ages for this analysis are shown in Table 1-6) in California timber region 7. 27

Table 1-11 (20-yr Contract- Discounted Carbon). Net carbon sequestered and $ per ton for increasing rotation ages X years above the legally mandated rotation age in California timber region 7. 27

Table 1-12 (20-yr Contract- UnDiscounted Carbon). Net carbon sequestered and $ per ton for increasing rotation ages X years above economically optimal rotation ages (the rotation ages for this analysis are shown in Table 1-6) in California timber region 7. 28

Table 1-13 (20-yr Contract- UnDiscounted Carbon). Net carbon sequestered and $ per ton for increasing rotation ages X years above the legally mandated rotation age in California timber region 7. 28

Table 1-14 (Permanent Contract - Discounted Carbon). Aggregate estimated carbon potential with holding timber past economically optimal rotation periods. 29

Table 1-15 (20-yr Contract- Discounted Carbon). Aggregate estimated carbon potential with holding timber past economically optimal rotation periods. 30

Table 1-16 (20-yr Contract- UnDiscounted Carbon). Aggregate estimated carbon potential with holding timber past economically optimal rotation periods. 30

Table 1-17. Carbon values for high site Douglas Fir comparing baseline rotations to riparian zones 36

Table 1-18 (Permanent Contract - Discounted Carbon). Net carbon sequestered and $ per ton, using three different methods (see text), for setting aside economically mature forests permanently in California timber region 7. 38

Table 1-19 (Permanent Contract - Discounted Carbon). Net carbon sequestered and $ per ton, using three different methods (see text), for setting aside mature forests at legal harvest ages permanently in California timber region 7. 39

Table 1-20. Estimated stream reach, additional riparian area, mature additional riparian area, quantity of carbon in mature areas, and total costs of riparian area protection for a 200' extension of riparian zones. 40

Table 1-21. Average tree size and trees per unit area for private lands in California 43

Table 1-22. Total costs for manual logging operations on 10% and 40% slopes in California (50 ft3 average tree size, 150 trees per acre; 20 acre site). 44

Table 1-23. Cost differences between group-selection cuts and clear cuts. 45

Table 2-1. Scales and resolutions of the datasets used by the models. 63

Table 2-2. The WHR rangelands reclassification system developed in consultation with University of California-Davis, California Rangelands Research and Information Center (CRRIC). 64

Table 2-3. Factor maps used. See Appendix C for the dataset descriptions. 68

Table 2-4. WHR density classes and associated tree or shrub canopy closure definitions. 79

Table 2-5. Revenue and costs associated with cattle ranching in California. 86

Table 2-6. Quantity of carbon and area of rangeland associated with cost of up to $20 per ton C or $5.5/metric t CO2. 97

Table 2-7. Datasets used in alternate modeling approach. 110

Table 2-8. Percentage of candidate cells identified by the model that falls within CDF-FRAP fire rotation interval classes. 115

Table 3-1. California's top 10 commodities by value (year 2000). 120

Table 3-2. Estimated C sequestration rates by soil texture class 123

Table 3-3. Land area (ha) and carbon (t C) potential by texture class. 124

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