Carbon Sequestration Potential in Canada, Russia and the United States
Under Article 3.4 of the Kyoto Protocol
Kevin Gurney and Jason Neff
Department of Atmospheric Science
Colorado State University,
Natural Resources Ecology Laboratory
Colorado State University
July 2000
Table of Contents
1.
Introduction…………………………………………………………………………………….. 1
2.
Caveats …………………………………………………………………………………………. 1
3.
Proposed sequestration activities……………………………………………………………… 2
3.1 Cropland Management………………………………………………………………………. 2
3.2 Rangeland Management……………………………………………………….…………….. 5
3.3 Forest Management……………………………………………………..……..………….…. 6
3.3.1
Nutrient fertilization………………………………………………………………… 6
3.3.2
Fire Management………………………………………………………….……….. 8
3.3.3
Pest Management………………………………………………………….………... 9
3.3.4
Additional forestry activities……………………………………………………….. 10
3.4 Total sequestration potential………………………………………………….……………... 11
4.
Discussion…………………………………………………………………………….…………. 12
4.1 Cross-cutting scientific/technical issues……………………………………………………... 12
4.2 Cross-cutting methodological issues……………………………………….………………... 14
4.3 Benefits………………………………………………………………….…….……………... 15
5.
Conclusions……………………………………………………………………………………… 15
6.
References…………………………………………………………………………………….…. 17
7.
Units and Abbreviations……………………………………………………….………….….… 22
List of Figures
Figure 1. Simulated total soil carbon for the central U.S. corn belt (Lal et al., 1998)…………………... 23
Figure 2. Sensitivity of fire suppression emission reductions to reduction level
and area burned…………………………………………………………………….………… 24
Figure 3. Zonally averaged simulated versus observed CO 2 concentration
(Keeling et al., 1989)………………………………………………………………………… 25
List of Tables
Table 1. Cropland management sequestration……………………………………………….………….
Table 2. Rangeland management sequestration…………………………………………………………
Table 3. Nitrogen fertilization response ………………………………………………….……………..
Table 4. Forest management sequestration……………………………………………………………..
Table 5. Mean global carbon budget for the 1980s (after Schimel et al., 1996)…………………………
26
26
27
27
28
1. Introduction
As the negotiations regarding the international treaty on climate change, known as the Kyoto Protocol,
move forward, the possibility of transferring carbon between the atmosphere and the biosphere as an
offset to industrial greenhouse gas emission reduction commitments has taken on increased emphasis.
While inclusion of atmospheric/biospheric exchange may penalize some countries that are increasing their
net biotic emissions, much of the motivation comes from the interest in substituting fossil fuel emission
reductions with carbon sequestration in vegetation and soils.
The inclusion of atmospheric/biospheric exchange stems from two paragraphs within the section of the
Protocol in which the agreed-to levels of emission reductions are specified (United Nations, 1997). The
first of these paragraphs, Article 3.3, allows participating countries to modify their greenhouse gas (GHG)
emission reduction commitments by activities limited to afforestation, reforestation, and deforestation. 1,2
These activities must have occurred “since 1990” and must be “human-induced”. While the precise
meaning of this paragraph has yet to be enumerated, the expectation is that growing trees where none had
been before would be interpreted as an emission reduction but clearing of land without some form of
reasonable biotic regeneration would be considered as additional emissions (United Nations, 1998).
The second paragraph relating to this issue, Article 3.4, leaves open the option of adding biotic exchange
activities, other than those specified in Article 3.3, to further modify the emission reduction commitments
agreed-to by participating countries.
Much attention to date has been devoted to the details of Article 3.3 such as defining “afforestation”,
“deforestation”, and “reforestation”. However, discussion has recently begun on Article 3.4. Much of
this relates to what additional biotic exchange activities should be allowed as further offsets to fossil fuel
emission reductions (United Nations, 1999a; Nabuurs, 1999). The most commonly cited categories
include carbon sequestration within agricultural, rangeland and forest systems.
Though the details of how such activities might be included in the calculus of the Protocol have yet to be
specified, it is instructive to examine the magnitude of these proposed activities to offset greenhouse gas
emission reductions and place them within the political context of the Protocol. This has been done for
three key countries with large and active biospheric carbon stocks: Canada, Russia, and the United States.
2. Caveats
A few caveats must be made in relation to the carbon sequestration estimates presented here. First, the
estimates represent technically feasible sequestration potential given the current status of land-use within
Canada, Russia, and the United States. A number of barriers may exist for realizing these technical
potentials, not the least of which are constraints such as financial burden or social barriers.
Where possible, these estimates also attempt to limit the sequestration potential to activities considered
additional to what might be considered “business as usual”. This is a key political issue within the
confines of the Kyoto Protocol often referred to as “additionality”. Article 3.4 of the Protocol includes no
explicit provision for additionality. It does, however, indicate that the negotiators must determine "how"
activities are to be added to Article 3.4 leaving open the possibility that additionality may be a
consideration. Furthermore, Article 12, referring to the enactment of emission offsetting projects in other
countries, does certify emission reduction projects that are “additional to any that would occur in the
1
The commitments are stated as a percent change from the baseyear amount, 1990 gross emissions. Countries for whom net
biotic exchange in land-use change and forestry were positive are allowed to include this in their baseyear amount. For all
others, these emissions are not included in the baseyear amount.
2
“Participating” countries refers to the 39 parties listed in Annex B of the Protocol , who have agreed to adopt numerical targets.
This collection of parties comprises most the “industrial” world.
1
absence of the certified project activity” (United Nations, 1997). As explained later, additionality may
prove to be a necessary provision in the further elaboration of Article 3.4.
It is not yet apparent whether or not carbon sequestration credit gained under Article 3.4 will be applied to
the first commitment period specified within the Protocol.3 Though it is possible that these activities will
only be applied to future commitment periods, they are cast here in relation to the first commitment period
targets.
Finally, it must be understood that all the estimates presented here are prone to considerable amounts of
uncertainty. They are gathered from land use datasets and studies that employ different methodologies
and assumptions about driving variables. To the extent possible, adjustments have been made to bring
them all within the same metric. Some of the sequestration activities discussed in this report have
received country-scale analysis by others and, as such, have been incorporated directly. However, some
of the activities presented here have had only global or very little country-scale analysis. In these
instances, original estimates have been constructed.
The sequestration potentials presented here are cast relative to two different benchmarks. The first
benchmark is the magnitude of emissions reduction below 1990 levels agreed to in the construction of the
Kyoto Protocol in 1997. Canada agreed to a 6% reduction which amounts to roughly 10 Mt C/year
(United Nations, 1999b).4 Russia agreed to stabilize their emissions at 1990 levels (United Nations,
1999b). Finally, the United States agreed to a 7% reduction which amounts to roughly 115 Mt C/year (US
EPA, 1999). Casting the sequestration potential of activities within Article 3.4 relative to this amount
highlights the political implications of additional activities.
The other benchmark relates to the reduction that would be necessary in the future if emissions follow
current projections. At some point prior to the first commitment period, participating countries would
need to engage in some form of reduction program to meet their Kyoto commitment. Were emission
reductions begun in 1997 (the last year of reliable emissions data), Canada would need a reduction of
approximately 33 Mt C/year in order to meet their target in the first commitment period (United Nations,
1999b). Were emission reductions begun in 2005, the required reduction would be approximately 49 Mt
C/year. The same two benchmarks applied to the United States come to 300 and 515 Mt C/year,
respectively (US EPA, 1999). It is physically meaningful to place the carbon sequestration potential
within this context. This will give an indication of how much of the necessary reduction additional
activities within article 3.4 might achieve were they pursued to the maximum technically feasible level.
Russian emissions dropped considerably after 1990 and are not expected to recover to 1990 levels by the
first commitment period. Current projections suggest that the Russian Federation will emit at levels
roughly 250 Mt C/year below their levels in 1990 (United Nations, 1999b). Therefore, any additional
carbon sequestration will likely add to this projected surplus.
With these two values as benchmarks the relative magnitude of the carbon sequestration activities under
Article 3.4 can be placed into a meaningful context.
3. Proposed sequestration activities
3.1 Cropland management
Compared to native ecosystems, land that has undergone cultivation generally contains smaller amounts
of carbon (Paustian et al., 1997a). Figure 1 shows a simulation of this effect for a substantial portion of
the Central United States. This and similar studies indicate that soils typically lose up to 50% of their
original carbon content in the first few decades following cultivation (Schlesinger, 1986).
3
The first commitment period spans the years 2008 to 2012. As yet, no future commitment periods have been specified.
4
Because the commitment period is a five year interval, this is the average reduction within this period.
2
Under non-managed conditions, soils lose carbon primarily through microbial respiration. This loss is
typically balanced by input from aboveground litter deposition and root turnover in the soil column.
Cultivation of land for agricultural purposes, however, typically increases the rate of soil carbon loss and
slows the rate of soil carbon input (Paustian et al. 1997b). The former occurs because plowing increases
the availability of soil organic material, affording microbes greater access to the carbon within soil
aggregates. Erosion further increases the loss of carbon through wholesale removal of soil. Cultivation
slows the input of carbon to the soil by the removal of aboveground biomass at harvest.
Reversing the decline in soil carbon is desirable from a purely agricultural perspective, as greater levels of
soil carbon indicate higher soil quality. Many of the practices recommended in the past as aids to
increasing soil carbon are now cited by those suggesting agricultural soils as a means to assist in
atmospheric CO2 removal.
The sequestration activities commonly considered under cropland management can be classified as land
conversion, land restoration, or improved management of cultivated land. Land conversion generally
refers to temporary “set-asides” or retirement of cultivated land. An example from the United States is
the Conservation Reserve Program (CRP) in which agricultural land is removed from production for tenyear periods, primarily to reverse degradation and control over-production. Removal is often
accompanied by reseeding with perennial vegetation which can increase the soil carbon content. Land
conversion also includes projects such as the creation of cultivated field borders, wetland restoration, and
grassed waterways. It is worth noting that if set-aside lands are returned to cultivation, the carbon gained
during the retirement period may be lost to the atmosphere, leading to no net atmospheric carbon removal
in the long-term.
Recent estimates suggest that there are currently 0.5 Mha of land in Canadian set-aside programs but that
an estimated 0.5 Mha of additional land could be added with directed policy (Bruce et al, 1999). Uptake
rates are estimated at 60 g C/m2/year for existing land and 80 g C/m2/year for new lands. Assuming the
existing set-aside land constitutes an approximation to a baseline, Canada could achieve approximately
0.4 Mt C/year of sequestration in the 2008 to 2012 period. The same authors estimate that there are 8.7
Mha of potential set-aside land in the United States (12.8 Mha are currently in the Conservation Reserve
Program) which, when considered with an uptake rate of 80 g/m2/year, comes to a sequestration rate of 7
Mt C/year.
Estimates for Russia are not available.
It is important to note that uptake rates of 80 g/m2/year will likely only occur in the first decade or two
after initial retirement of cultivated land. Other authors have found much lower uptake rates on land that
had been retired many decades prior to measurement (Burke et al, 1995). This is a critical factor if this
sequestration activity is to be considered in Kyoto Protocol commitment periods beyond the first.
Land restoration refers to the active restoration of eroded and severely degraded land. Eroded lands are
those that experience erosion at rates exceeding 11.2 Mg/ha/year (Lal et al., 1998). In Canada and the
United States, estimates suggest that approximately 1.5 Mha and 28.6 Mha, respectively are available for
restorative measures such as reversion to natural vegetation and fertilization (Bruce et al., 1999).
Degraded lands refer to minelands and salt-affected soils of which about 0.1 Mha and 0.6 Mha are
suggested as available. Approximately 2.2 Mha and 20 Mha of salt-affected soils are considered available
for restoration in Canada and the United States, respectively. Combining these available areas with
uptake rates ranging from 10 to 100 g/m2/year (varying with the practice and land-type included) results
in an annual potential sequestration rate of 1 Mt C/year for Canada and 17 Mt C/year for the United States
(Lal et al, 1998; Bruce et al, 1999).
Estimates for Russia are not available.
Improved management of cultivated land refers to improved tillage, water management, and cropping
practices that can increase the levels of soil carbon. Improved tillage practices encompass a variety of
tillage systems that reduce the loss of soil and water from cultivated land. Such “conservation tillage”
3
(CT) systems leave more crop residue on the soil surface and lessen the amount of soil aggregate
disturbance relative to conventional tillage practices, thereby increasing soil carbon levels. Other
improved management techniques such as the expansion of irrigation in dry areas, can increase soil
carbon by increasing aboveground and belowground biomass production. However, irrigation is often
associated with significant energy use and when practiced in arid regions, may result in net carbon loss
due to the precipitation of calcium carbonate from irrigation water with dissolved calcium (Schlesinger,
1999). This could significantly limit the sequestration potential of irrigation.
Finally, improved cropping practices such as increased fertilization, increased rotation and cover crop use,
and elimination of summer fallow can lead to greater amounts of soil carbon. Once again, however,
increased energy use must be considered in order to arrive at a true net sequestration potential. For
example, a recent discussion suggested that the net effect of inorganic fertilizer is fundamentally sensitive
to the trade-offs between fertilization levels and marginal productivity (Schlesinger, 1999; Izaurralde et al,
2000). With an economically optimal level of fertilization, net carbon storage can be achieved, though
modified by the energy costs associated with manufacture, transport, and application. Exceeding optimal
application levels, however, can eliminate carbon sequestration gains.
Much research has been performed on the impact of different agricultural practices on soil carbon. Most
of this has focused on soil quality and nutrient dynamics. For example, one recent study used the
CENTURY biogeochemistry model to simulate soil carbon sequestration in Canada under summer fallow
reduction (Dumanski et al., 1998). Depending upon the choice of crop in the summer fallow reduction
(hay versus cereal), approximate annual sequestration rates came to 0.4 Mt C/year and 1.8 Mt C/year for
hay and cereal, respectively.
Other studies have considered the impact of tillage reduction on carbon sequestration. A recent study
suggests that adopting reduced-till on 50% of Canada's arable land results in an average sequestration of
approximately 4 Mt C/year (Nabuurs et al., 1999). Another recent study arrived at a similar estimate of
4.3 Mt C/year (STOP, 1999). This same work estimated Canadian summer fallow reduction at roughly
0.7 Mt C/year.
A study by Bruce et al (1999) combined practices such as reduced tillage, reduced summer fallow,
improved nutrition, and improved amendments and irrigation to arrive at a total sequestration of 7.4 Mt
C/year for Canada. Many of these practices will be employed in the future irrespective of climate change
policy. Though difficult to estimate, the studies cited thus far imply 1 to 2 Mt C/year as a reasonable
baseline for Canada.
Estimates of sequestration due to improved land management in the United States vary somewhat due
mostly to assumptions regarding the amount of land that might be incorporated into best management
practices in the future. A recent study by Donigian et al (1997) indicate that approximately 6 Mt C/year
might be sequestered due to the use of cover crops on all US cropland beyond a projected baseline.
Another estimate placed the total at 10.2 Mt C/year, though no explicit baseline was included (Lal et al,
1998).
Increased employment of reduced or no-tillage practices have been estimated at anywhere from 5 to 40
Mt C/year depending upon assumptions about uptake rate (18 to 40 g/m2/year) and land area considered
(20 to 123 Mha) (Lal et al, 1998; Nabuurs et al 1999; Kern and Johnson, 1993; Donigian et al, 1997).
The Bruce et al (1999) study which combined a variety of management practices including no-till and
increased use of cover crops among others, concluded that improved management in the US could
average roughly 20 Mt C/year (a baseline has been removed).
Though the estimates for improved cropland management in the US vary quite a bit, we present a range of
10 to 50 Mt C/year as a reasonable estimate of potential US sequestration in this category.
4
Estimates of cropland sequestration in Russia considered a variety of practices. Assuming conservation
tillage is applied to 33 Mha of cropland (133 Mha total) with an uptake rate of 20 g/m 2/year, this practice
could total 6.7 Mt C/year (GCSI, 1999). An estimate of a baseline for this activity in Russia is 4.2 Mt
C/year. The same study estimated the sequestration resulting from an improvement in irrigation of
currently irrigated land (which totals 5.4 Mha). With an uptake rate of 10 g C/m2/year, sequestration for
this activity totals 0.5 Mt C/year. Finally, improved productivity is considered with an average uptake
rate of 20 g/m2/year. It is difficult to estimate to what extent improved productivity might be applied to
Russian cropland. Assuming an adoption range of 10 to 20% of current cropland in Russia, the total
sequestration rate in this category could come to 2.7 to 5.4 Mt C/year.
The above estimates for cropland management in Canada, Russia, and the United States are presented in
Table 1.
3.2 Rangeland Management
Management of rangelands has also been suggested as a means by which carbon can be removed from the
atmosphere. Like agricultural sequestration discussed above, this also removes atmospheric carbon by
transferring it to vegetation and ultimately into the soil.
Within temperate countries rangeland can be classified into two broad categories. The first, extensive
rangeland, refers to grazing areas for which no amendments, such as fertilizer or water, are applied. The
other broad classification is referred to as intensive rangeland or pasture; grazing areas which are
managed with the addition of amendments to maintain high forage quality.
Research aimed at understanding the relationship between grazing pressure and soil organic matter
indicate that the relationship is a complicated one (Milchunas and Lauenroth, 1993; Frank et al., 1995;
Burke et al., 1997; Manley et al., 1995). In some cases, increasing pressure leads to increases in soil
carbon while in other instances a reduction in grazing pressure leads to a reduction in soil carbon
(Milchunas and Lauenroth, 1993). These counterintuitive results point to the fact that the dynamics
determining soil organic matter in grazed systems is not a straightforward one and includes factors such as
grazing history, soil type, and plant species composition.
In contrast, a number of activities can be performed on intensive rangelands to sequester carbon such as
rotational grazing, fertilization, irrigation, and sowing of favorable forage grasses and legumes. Were the
best management practices to be engaged on all of Canadian and US intensive rangeland, estimates have
placed this potential at an average sequestration rate of approximately 0.6 Mt C/year and 9 Mt C/year,
respectively (Bruce et al., 1999). This estimate assumes that an uptake rate of 20 g C/m2/year is achieved
over approximately 4.3 Mha and 51 Mha of Canadian and US pastureland, respectively. 5,6 As with some
of the agricultural practices, fertilization and irrigation may incur an energy penalty that negates some or
all of the sequestration achieved.
The study by STOP (1999) included a more gradual introduction of improved practices in Canada arriving
at a sequestration rate of 0.2 Mt C/year by the first commitment period.
In Russia, a recent study assumed an average uptake rate of 5.5 g/m2/year applied across 78 Mha of
intensive rangeland, arriving at a total sequestration rate of 4.3 Mt C/year (GCSI, 1999). This is likely to
be an unrealistic adoption rate in the near term. Assuming between 10 and 20% of available Russian
pasture were engaged in improved pasture management, the sequestration rate would be 0.4 to 0.8 Mt
C/year.
The above estimates for rangeland management in Canada, Russia, and the United States are presented in
Table 2.
5
A slight reduction is made to account for a presumed baseline of “business as usual” activity.
6
A recent meta-study found an average uptake rate of 49 g C/m2/year for the US and Canada. This would more than double the
estimate given here (Rich Conant, personal communication).
5
3.3 Forest Management
Forests can be managed to increase carbon stored in both above and belowground biomass. Like the other
strategies outlined in this paper, carbon sequestration techniques in forests have been practiced in the past
for reasons such as maximizing yield and biodiversity.
Forest management practices considered for carbon sequestration include the addition of amendments
such as nitrogen fertilizer, longer rotations, less invasive selective cutting, soil conservation, safeguarding
regeneration (from pests, fire, etc), recycling forest products, genetic engineering, and lengthening the
residence time of durable products or forest products in landfills.
Most of the analysis performed on national carbon sequestration in the forest sector has focused on
activities covered under Article 3.3; afforestation, deforestation, and reforestation. A far smaller amount
of analysis has been performed on the implications of Article 3.4.
3.3.1 Nutrient fertilization
Nitrogen availability limits productivity in many temperate forest ecosystems and the addition of nitrogen
fertilizer generally increases forest growth (Peterson and Peterson, 1995; Van Cleve, 1973). The response
of forest ecosystems to nitrogen additions are, however, variable and depend upon a wide range of factors
including soil type, pre-existing nitrogen levels, plant nitrogen demand and stand characteristics such as
age and health. While forest growth is frequently limited by nitrogen availability alone, the addition of
nitrogen in combination with phosphorus and potassium can lead to even larger increases in productivity
(Peterson and Peterson, 1995; Morrison et al, 1997).
The growth of boreal forests, the dominant type in Canada and Russia, are also constrained by a number
of additional factors, not the least of which is a harsh climate. In the United States, approximately 1/6 th of
the forest area is limited by water and/or temperature and is therefore unlikely to respond significantly to
fertilization (Hagenstein, 1992). These additional constraints can limit forest response and may make
fertilization more effective in climatically favorable areas (Van Cleve and Zasada, 1976). In addition,
fertilization tends to be most effective on lands that are neither exceedingly fertile nor exceedingly poor.
The intermediate range of ecosystem fertility is generally the target for commercial fertilization operations
(FFH, BC gov, 1995).
In managed forest ecosystems in Canada, fertilization is used to accelerate stand development and is
generally applied to young and intermediate age forest stands under active management (FFH, BC Gov,
1995). Publications by the government of British Columbia’s forestry department recommend
fertilization of Douglas fir and perhaps western hemlock and Sitka Spruce (FFH, BC Gov, 1995).
Although it is possible to increase the growth of mature stands in forest reserves not managed for timber
harvest, these increases are likely to be smaller than in younger forests (e.g.Van Cleve and Zasada, 1976;
Morrison et al, 1976), though this is not always the case (Miller and Webster, 1979). Forests
characterized as over mature (a considerable fraction of Canadian and Russian forests) are unlikely to
respond strongly to nitrogen additions because other factors limit their growth rates. There is substantial
variation in the response of different tree species to fertilization and important interaction between site
characteristics and fertilization responses (Morrison et al, 1976; Morrison et al, 1977; Nams et al (1993) et
al, 1993; Peterson and Peterson, 1995).
There is little information on the response of interior Canadian (or Russian) forests to large-scale
fertilization. However, black spruce, white spruce and aspen make up a large portion of the interior and
boreal forests of Russia and Canada and all of these species have been shown to respond positively to
fertilization (Morrison et al, 1976; Morrison et al, 1977; Nams et al, 1993; Peterson and Peterson, 1995).
It is important to note that there are a variety of uncertainties and limitations in estimating carbon
sequestration as a result of nitrogen fertilization in forest systems. A review of existing studies on this
6
topic highlights the fact that different tree species may respond quite differently to nitrogen fertilization.
For example, in studies on the same site in Southwestern Yukon, Canada, nitrogen additions increased
twig growth in white spruce by 60-160% while having no significant effects on balsam poplar (Nams et
al, 1993).
Fertilization may also alter soil carbon storage but these aspects of ecosystem responses to fertilization are
poorly understood. There is evidence that nitrogen fertilization increases the decomposition of cellulose
and litter in a range of systems including prairie (Hunt et al, 1988) and pine forests, alpine meadows
(Arnone et al, 1997), and dwarf shrub pine systems (Paavilainen, 1984). However, there is also evidence
to suggest that nitrogen fertilization has no effect on decomposition of litter in jack pine and red cedar
forests (Prescott, 1995), peat lands (Aerts et al, 1995), or root decomposition in loblolly pine plantations
(King et al, 1997). In some cases, it appears that even the form of nitrogen added to soils can influence
the direction of the decomposition response: in an experiment with western hemlock litter, decomposition
increased following urea additions, but decreased after nitrate additions (Gill and Lavender, 1983).
These variable responses in soil carbon are significant because of the large stock of soil carbon in boreal
ecosystems. In fertilization trials in Sweden, Mäkipää et al, (1998) observed a 14% increase in soil
carbon stocks over a 26-30 year period of fertilization, corresponding to an annual increase of 73-85 kg
C/ha. Extrapolated to the 120 Mha of managed Canadian forest, these rates of carbon uptake would
translate into 8.7 to 10.2 Mt C/year due to soil carbon storage alone. However, even at these large storage
rates, these increases would not be detectible on short time scales (less than 2-5 years) using conventional
soil carbon measurements that have analytical errors of 1-2%.
For the purposes of this assessment, we have not attempted to evaluate species-specific responses to
fertilization nor have we estimated interactions between site quality and fertilization response. To carry
out these assessments would push the limits of currently available scientific data. Instead, we constrain
this analysis to forested areas that are relatively easy to access, (defined as those already under
management) and forests in the immature, young and middle-aged age classes as candidate lands for
fertilization induced carbon sequestration in Canada and Russia.
The proportional increases in biomass in selected boreal forest fertilization studies are shown in Table 3.
In general, nitrogen fertilization increases carbon sequestration into aboveground biomass by 10 to 100%,
for either overall site NPP or volume increment measurements. A recent review suggested that the
potential for carbon uptake associated with fertilization in Canada ranges from 0.03 to 0.19 t C/ha/year
and 0.08 to 0.48 for the United States (Nabuurs et al, 1999). Higher values may also be possible. For
example, Lunnan et al, (1991) report uptake rates of 0.7 to 0.8 t C/ha/year for two boreal pine forests in
Norway. For boreal Scotts Pine, Mäkipää et al (1998) use a combination of experimental data and models
to estimate an annual fertilization uptake of 0.4 t C /ha/year for a dry forest.
Published estimates of the potential for nitrogen fertilization induced carbon uptake across the exploitable
forests in the United States (196 Mha) come to 15.7 to 94.1 Mt C/year (Nabuurs et al, 1999). In contrast
to the United States where the timber productive land is dominated by young age classes due to intensive
harvesting for the past century, Canada and Russia contain relatively large portions of old growth forest
(particularly in the boreal regions) that have not been actively harvested, due to inaccessibility,
unfavorable climatic conditions and lower population densities.
The extent of timber productive forest in Canada is roughly 245 million hectares (Lowe et al, 1994). Each
year approximately 700,000-900,000 hectares of Canadian forests enter management (less than 1% of the
total managed forest area in Canada). While it may be expensive and environmentally disruptive to
fertilize vast tracks of forest (see discussion below), there is no question that there are large areas of
Canadian forest land that could, in theory, be fertilized to increase carbon sequestration rates. To estimate
the potential carbon uptake of widespread fertilization activities in Canada we have excluded mature and
overmature forests in the Canadian timber productive forest and all forests that are not managed for
timber harvests. The remaining 142 million hectares are made up of young aged stands some small
fraction of which have previously received fertilizer applications. Applying the Nabuurs et al (1999)
estimated Canadian uptake rates to this area yields an annual sequestration of 4.2 to 27 Mt C/year. Using
7
higher values of uptake such as those reported by Lunnan et al, (1991), yields a sequestration estimate of
107 Mt C/year for Canada.
In Russia, the area of managed forest is 761 million hectares, 19% of which is located in forest tundra,
sparse taiga, steppe, semi-dessert and dessert (Shvidenko et al, 1997). These areas will be excluded from
the analysis presented here. The remaining 616 million hectares include a mixture of age classes ranging
from young to overmature. Excluding the mature and overmature stands, there are approximately 230
million hectares of young to intermediate aged Russian forests under management which could be
fertilized to increase carbon sequestration. Application of the Nabuurs et al, (1999) fertilization/carbon
uptake rates over this entire zone yields uptake estimates of 7 to 44 Mt C/year and at a higher uptake rate
of 0.8 t C/ha/year, Russian forests could sequester up to 184 Mt C/year.
Nitrogen additions to ecosystems have a range of effects besides increasing carbon storage. For example,
nitrogen additions generally increase the loss of nitrous oxide (N 2O), a potent greenhouse gas, from soils.
While absolute emissions rates are considerably lower than carbon fluxes from terrestrial ecosystems,
N2O is roughly 200 times more powerful as a greenhouse gas and fertilization increase N 2O emissions
into the atmosphere many fold (Schimel et al, 1996). Nitrogen additions also frequently reduce rates of
methane (CH4) oxidation in soils, thereby either reducing soil sinks for CH 4 or increasing CH4 fluxes from
soils (Delgado et al, 1996; Neff et al, 1994). Widespread application of nitrogen fertilizer for the purpose
of carbon sequestration in northern latitude ecosystems will almost certainly increase the production and
loss of N2O and methane from these systems partially offsetting the atmospheric carbon removal. More
research is required to understand these tradeoffs.
We have not attempted to subtract a baseline for fertilization activities because it is not currently a
widespread activity in forest management, particularly in Canada and Russia. If fertilization is considered
as a tool for carbon sequestration in Russian, Canadian, and US forests, a detailed analysis of the costs,
and relative benefits of fertilization in multiple forest and soil types will be required. Until such an
analysis is completed, it will be difficult to reduce the range of uncertainty in estimates of the potential
carbon accumulation possible with increased used of fertilization in forest management.
3.3.2 Fire Management
The global emissions of carbon from fires in boreal forests may approach 1 Pg of carbon per year (Harden
et al, in press; Kasischke et al, 1995). Boreal forest fire emissions have been substantially altered by fire
suppression over the past century, and may soon increase in response to regional climate warming (Linder
et al. 1997; Kronberg, 1998; Harden et al., in press; Solomon et al, 1993; Wotton and Flannigan, 1993).
Even small increases in fire suppression activities can have large impacts on carbon emissions because of
the large fluxes involved.
Annual burns in Canada and Russia cover millions of hectares of forest. In Canada, 3 million hectares of
forests burned in 1996 (increased from 1 million in 1980) however the area burned varies substantially
from year to year (Simard, 1997). In Russian forests an average of 1.5 million hectares burned annually
from 1986 to 1995 with a range from 0.17 million hectares in 1990 to 4.4 million hectares in 1987
(Shvidenko et al, 1998).
The severity of a fire and the landscape in which it occurs strongly influence the amount of carbon that is
lost during combustion and subsequent decomposition of soils and residues. On average, 30 to 100% of
above ground biomass is consumed in fires (Dyrness and Norum, 1983; Stocks, 1987). With boreal forest
carbon content of 4 to 12 kg C/m2 in living biomass and ground layer vegetation, a year in which 3
million acres burned would lead to a net emissions range of 60 to 180 Mt of C/year in Canadian forests.
This assumes a 50% loss of the biomass pools. Using similar carbon contents and biomass loss in
Russian forests, annual carbon emissions from a 1.5 Mha fire are likely to be in the range of 30 to 90 Mt
per year. These fluxes are due to combustion alone and do not take into account emissions from
accelerated soil respiration following fire. The flux of CO 2 from soils to the atmosphere resulting from
post-fire enhancement of soil respiration can be up to 6 times larger (Levine 1991; Melillo et al. 1988)
than losses of carbon due to combustion.
8
In boreal forests (largely in Canada and Russia), Kurz and Apps (1995) have estimated that a 50%
reduction in forest fires each year would result in the storage of 2.3 Gt of carbon by 2050 (46 Mt C/year
reduction). Because fire frequency, extent and severity are highly variable, a range of emissions reduction
scenarios are shown in Figure 2. The scenarios range from 5% to 20% reductions in fire extent for
Canada and Russia. By way of comparison, 51% of the land area of Alaska is designated in a nonsuppression category with the remaining 49% subject to varying degrees of fire suppression activities
(Alaska Department of Forestry). Additional credit for carbon sequestration associated with fire
suppression would presumably require increased levels of suppression activities. All three countries have
similar low and high values for the area consumed in annual fires so Figure 2 can be taken to represent the
high and low values for incremental increases in fire suppression activities in any of the three countries.
There are a number of problems associated with using fire management as a tool for carbon sequestration.
One of the most difficult issues is establishing a baseline value for fire emissions in a given year. Credit
for fire suppression might include all activities aimed at combating fires or alternatively could include
credit for fires outside previously established zones of active suppression (STOP, 1999). However, even
if agreement on which fire suppression activities are allowable could be reached, there are substantial
technical hurdles in evaluating the difference between how much carbon would have been lost without
suppression vs. how much actually was lost during suppression activities. Imposition of required
determination of management impacts on fire losses would add significantly to the difficulty of assessing
carbon losses (and avoided losses).
A second issue involving fire suppression revolves around the time scale of emissions reduction. In the
short term avoided fire emissions can have a large impact on atmospheric carbon. In the long term
(decades to centuries), fire suppression activities are likely to lead to larger and more severe fires and
therefore to increased carbon emissions in the future. Decades of fire suppression in Canada are, at least,
partially attributed to the increases in fire severity and extent in recent years (Linder et al. 1997;
Kronberg, 1998; Harden et al. in press; Solomon and Leemans, 1997; Wotton and Flannigan, 1993). For
these reasons, activities taken during the current commitment period will have large impacts on latter
commitment periods and the mechanisms for handling these types of delayed effects are not yet
established and will be difficult to define.
Given these difficulties, we present a range of fire suppression carbon sequestration potentials in Figure 2.
It should be understood that there is not, and will never be, a single number that reflects the potential for
fire suppression induced carbon sequestration. The large year to year variability in fire extent and carbon
losses, particularly from boreal forests, precludes simple estimations of potential carbon sequestration. To
frame the question, we take an average value of 1.5 million hectare burned and a 5 - 20% fire reduction
range over land areas with a 3 fold span of carbon content. To narrow this estimate would require
unjustified assumptions given the variability in both location and magnitude of fires in Canada, Russia,
and the United States.
3.3.3 Pest Management
The area of forest impacted by pest outbreaks in Canada, Russia, and the United States covers millions of
hectares per year. In Canada, the loss of wood to pests is 70% of the loss to fire according to STOP
(1999). In Russia, large areas of forest are also impacted by pest outbreaks but the estimates are lower
than for Canadian forests with an average of approximately 30,000 hectares having been affected annually
between 1991-1993 (IIASA report). Estimates of potential reductions in pest outbreaks with the use of
large scale spraying of pesticides are similar to forest fire reduction estimates, at least for Canada and the
United States. Nabuurs et al (1999) use an estimate of 50% reductions in pest outbreaks to suggest that 2.3
Gt of C per year could be preserved in these countries. More realistic reductions are likely in the range of
5-10% and would yield carbon savings of 5 to 60 Mt per year for Canada and the United States. With
little data available, the same is assumed for Russia.
9
3.3.4 Additional forestry activities
There are a number of additional forestry activities that may affect carbon sequestration rates. These
activities include improvements in the genetic stock of newly planted trees, changes in the spacing of
young stands (juvenile spacing), thinning of older stands and changes in rotation length. Each of these
activities will have differing effects depending on the type of trees and site fertility. Estimates of the
potential increases in carbon storage with different management activities have been made for Canadian,
Russian, and US forests.
Thinning of forests may or may not increase forest growth. There is evidence showing no growth
response to thinning (Shvidenko et al, 1997; Schroeder, 1991) and increased growth response to thinning
(CPPA, 1998). For densely packed stands, thinning Douglas fir plantations can increase carbon storage
by 11% over 50 years but analysis of other forest types such as loblolly pine indicate that thinning may
actually reduce net carbon storage (Schroeder, 1991). These issues make it difficult to estimate the
sequestration potential of forest thinning. There are however, several published sequestration estimates
associated with thinning which can be used to place bounds on this forest management activity.
For Canada, the Canadian Pulp and Paper Association estimates that thinning could increase carbon
storage by 7 Mt C/year (CPPA, 1998). For Russian forests, simulations of large scale forestry activities
place the potential carbon sink associated with thinning and selective felling at 0 to 2 Gt over 40 years for
a rate of 0 to 50 Mt C/year depending on assumptions about the effect of thinning on carbon growth
(Shvidenko et al, 1997).
In the US, it has been estimated that approximately 80 Mt C/year could be sequestered into U.S.
timberlands averaged over the next 100 years (Vasievich and Alig, 1996; Row, 1996). 7 This study relies
primarily on improved regeneration (rapid and improved planting and seeding) and stand thinning.
Included in this value is the sequestration due to increasing carbon mass in durables (furniture, lumber,
etc.) and in landfills.
At this stage of research, it is difficult to narrow these estimates because of conflicting information stand
thinning impacts and because of the need to carefully account for the fate of carbon removed from forests
as well as the time scale considered.
The effect of changes in forest rotation length on carbon storage depend entirely on the period of time
considered in the analysis and the fate of products removed from the forest. A change in rotation length
also reflects a transient increase in carbon storage as the average carbon content increases from a lower to
a higher value. Older forests contain more carbon than younger forests but the rate of carbon gain
decreases as forests age (Birdsey, 1992). Increasing the average rotation length of a forest will increase
carbon storage only until a new average carbon storage is reached. The only way to sustain carbon
sequestration with increasing rotation length is to continually increase rotation ages and this can only be
done if the older forest will store more carbon than a younger one. It should also be understood that the
marginal gain of increasing forest rotation times decreases as the average forest age approaches maturity.
Secondly, increasing rotation lengths will only count as carbon sequestration as long as the products of
forest removals remain constant. A younger forest that is harvested to create durable products (e.g. timber
for houses) could have greater carbon sequestration potential than an older forest that is harvested for
short-lifetime products (e.g. paper).
Given these caveats, there are estimates of the potential for increased carbon sequestration associated with
increased rotation length of 0.059 t C/ha/year for Canadian Red Spruce forests over the next 50 years
(Woodrising Consulting, 1999). Applied to the younger age classes described in the fertilization section
above, this amounts to carbon sequestration of 8 Mt C/year for Canada and 14 Mt C/year for Russia.
Another estimate for Canada and the US by Nabuurs et al (1999) assumed a 15% increase in rotation
length in exploitable Canadian (112 Mha) and US forests (196 Mha) would increase the average content
7
This estimate attempts to remove the energy offset sequestration as presented by Row 1996.
10
of carbon in these forests by 5% based on some simulation performed on Dutch tree species. This
simulation arrived at a sequestration rate of 2.5 and 7 Mt C/year for Canada and the United States,
respectively. These estimates should be viewed with considerable caution for the reasons outlined above
and considered temporary measures that cannot be sustained for long periods of time.
Improved rates of paper recycling can also enhance carbon sequestration. A 1995 United States EPA
study concluded that were 45% of US paper products to be derived from recycled fiber (a 50% increase
over current rates) starting in the year 2000, an average carbon sequestration rate of 15.6 Mt C/year could
be achieved by 2010 (US EPA, 1995). Consistent with this estimate, a 1995 study assumed that recycling
rates increased 20% over current values resulting in about 8 Mt C/year sequestration in the US (Turner,
1995). Similar studies are not available for Canada or Russia.
An important caveat to the recycling estimates is the likelihood of “demand leakage”. The reduced
pressure on forest resources may cause price declines thereby stimulating increased demand from other
forest product users. This may result in little net gain from a carbon sequestration standpoint. This raises
an important general consideration when estimating carbon sequestration within the forest sector. Unlike
agricultural soils and rangeland management, much of the sequestered carbon is contained within a
market commodity. Changes in the supply of that commodity due to carbon sequestration activities, for
example, could have complicated economic feedbacks within the various markets using forest products.
True estimates of carbon sequestration within the forest sector require the use of fully coupled
economic/forest resource models. None of the estimates presented here, perform such an exercise.
The above estimates for all forest management activities in Canada, Russia, and the United States are
presented in Table 4.
3.4 Total sequestration potential
There are numerous management practices described in this paper that may likely be applied
simultaneously to the same piece of forest or agricultural land. This issue complicates interpretation of
the potential for carbon sequestration over large areas of land and highlight why analyses of potential C
gain in vegetation and soils must be approached with caution. For certain activities in forests such as
thinning and fertilization, there are strong interactive effects. For example fertilization in unthinned
stands may increase tree mortality due to increased competition for space and light (Schroeder, 1991). In
this particular case, it may be that fertilization and thinning, when used alone, have little benefit for
increased carbon sequestration but when used jointly can lead to large growth increases (Schroeder,
1991). imilar trade-offs are likely for simultaneous use of fertilization with changes in rotation length or
fertilization in combination with no-till agriculture. The total sequestration estimates presented in this
report do not attempt to unravel these interactions but report a strict sum of the activities outlined as if
they were practices in isolation.
Summing the potential from each of these categories comes to roughly 31 to 211 Mt C/year for Canada,
34 to 337 Mt C/year for Russia and 161 to 277 Mt C/year for the United States. Considering just the
lower end of these ranges, this translates into over 250% of the 6% Canadian reduction target negotiated
in Kyoto and meets over 50% of the needed reductions were Canada to begin concerted action in 2005. In
the case of the United States, the lower end of the range presented here will meet roughly 140% of the 7%
reduction target (~115 Mt C/year) and 30% of the reduction from 2005 (~520 Mt C/year).
Since Russia agreed to stabilize their emissions at 1990 levels in the first commitment period and they are
expected to arrive at emissions that are 250 Mt C/year below 1990 levels in the first commitment period,
the sequestration potential outlined here adds to that expected surplus.
In 1990, carbon emissions from the Annex 1 countries (excluding Russia and Ukraine) 8 totaled 3798 Mt
C/year. By 1997, this values had risen to 3889 Mt C/year. With a reduction target of 5.2% below 1990
8
Because of the collapse of these economies after 1990, including these countries in the Annex 1 total places the Annex1 total
in 1997 very close to the Kyoto target reduction of 5.2%.
11
levels, the Annex 1 countries together would have to reduce their emissions 289 Mt C/year from their
1997 levels in order to comply with the Kyoto Protocol (United Nations 1999b). The lower end of the
sequestration potential range for Canada, Russia, and the United States alone would meet 76% of this
reduction. The upper end of the potential sequestration ranges presented here could meet all of this
needed reduction.
4. Discussion
It is clear from the numbers presented that the potential to sequester carbon in Canada, Russia, and the
United States under Article 3.4 of the Kyoto Protocol is certainly not trivial in either a political or
physical context. The reduction targets agreed to in 1997 implicitly included estimates of what might be
achieved under some reasonable definition of Article 3.3. However, the targets were not predicated upon
how much offsetting might result from additional activities now being contemplated within Article 3.4. If
these sequestration potentials are used as offsets to emissions reduction in the first commitment period,
this could be interpreted as renegotiation of the Kyoto Protocol targets and might allow fossil-fuel
emissions to rise beyond that expected at the time negotiations were made. For this and other reasons
discussed in the following section, sequestration under article 3.4 may best be utilized in the second or
later commitment periods.
Aside from the challenge inherent in estimating the magnitude of these activities, a series of potentially
difficult issues may arise were these sequestration activities to be considered within the management
regime outlined in the Protocol. Some of these issues can be considered scientific or technical problems
in that they push the boundary of what is currently known or technically possible regarding carbon
biogeochemistry. Others raise complex methodological issues that will require considerable attention
before a meaningful accounting of these proposed sequestration activities can be formed into negotiated
text.
4.1 Cross-cutting scientific/technical issues
The missing sink: A simple budget of the global carbon cycle is presented in Table 2. The magnitudes of
measured atmospheric storage and emissions due to human activities indicate that roughly one-half of the
amount of CO2 emitted into the atmosphere each year must be removed. In order to balance the global
budget given these relatively well-known flows of carbon, additional uptake must be occurring. 9 Some of
this uptake has been attributed to forest regrowth in the mid-latitudes following the reversion of former
agricultural land back to forest. The remaining uptake, approximately 1.3  1.5 Mt of carbon each year,
has come to be called "the missing sink".
Work in the late 1980s concluded that this missing sink must be acting in the Northern Hemisphere
(Enting and Mansbridge, 1989; Keeling and Heimann, 1986; Tans et al., 1990; Keeling et al., 1989). The
most compelling evidence of this is presented in Figure 3. Model simulations of the latitudinal gradient of
CO2 concentration due to fossil-fuel emissions are placed alongside the latitudinal gradient of CO 2
measurements for the 1980s. Both the oceanic uptake and any mechanism (source or sink) at work in the
tropics will not cause a change in the latitudinal gradient because these exchanges affect both hemispheres
equally. Therefore, the only way in which the latitudinal gradient can be made to conform to the
observational data is by removal of CO2 in the northern hemisphere.10
Further work in the 1990s with carbon isotopes, 3D inverse modeling, and atmospheric oxygen all point
to the terrestrial biosphere as the location of the missing uptake of carbon (Francey et al., 1995; Ciais et
al., 1995; Enting et al., 1995; Keeling et al., 1996; Fan et al., 1998). The longitudinal distribution
remains somewhat controversial and the mechanism has yet to be firmly established though many
9
Of the inputs and outputs, tropical deforestation is considered the least well known and the subject of ongoing revision.
10
A source in the Southern Hemisphere could also cause a shift in the latitudinal gradient. However, this scenario appears
unlikely due to the limited landmass.
12
researchers believe that photosynthesis within mid- and high-latitude forests may be exceeding current
rates of respiration, causing a net addition of carbon to the biosphere (Houghton et al., 1998).11
Unless the language is constructed carefully, Article 3.4 could inadvertently include credit for uptake by
the missing sink. In drafting Article 3.3, negotiators attempted to ensure that only carbon sequestering
activities that were “human-induced” and had begun “since 1990” could be considered as emission
reduction offsets. If the intent is to grant credit for such intentional climate-related activities, this same
language must find its way into the construction of Article 3.4. If not, Article 3.4 could provide an
avenue through which carbon uptake due to missing sink mechanisms might be used as offsetting credits.
For example, current projections for forest biomass accumulation estimate that U.S. forests will be
sequestering carbon at a rate of about 200 Mt C/year in the year 2010 (Birdsey and Heath, 1995). This
rate of carbon uptake is based on current “business as usual” activities. This sequestration is most likely
not directly human-induced and may be due to an, as yet unknown, mechanism underlying the missing
sink. Were the U.S. to gain credit for this uptake, the 7% below 1990 reduction agreed to in Kyoto would
become, in effect, a license to raise emissions 5% over 1990 levels (Lashof and Hare 1999).
Even if Article 3.4 were drafted such that activities were limited to direct human-induced action since
1990, the missing sink may still confound attempts to give appropriate credit. For example, were forest
managers to increase fertilization on forest areas in the U.S., it would be unclear whether the gain in
biomass was due to direct action by managers or due to mechanisms driving the missing sink. Careful
construction of control plots would be required to ensure appropriate credit.
Exogenous permanence: Once it is agreed that biotic sequestration activities can be used to offset
emission reductions, the sequestered carbon must be measured and tracked into the indefinite future. A
current hypothesis regarding future carbon biogeochemistry suggests that as the planet warms, significant
amounts of biotic carbon may enter the atmosphere due to increased heterotrophic respiration (Melillo et
al., 1996; Woodwell et al., 1995). Furthermore, changing climate may lead to a degradation of biotic
systems in different locations due to increased fire, pests, or ecosystem shifts. This suggests that carbon
sequestered in biotic systems may be relatively unstable and sensitive to forces outside of human control.
This raises some complex questions regarding accounting equity as well. Were a given amount of carbon
sequestered by a country to re-enter the atmosphere due to warming, should the loss of soil carbon be
counted as an emission?12 From the vantage point of the atmosphere, net sequestration has not occurred.
Measurement challenges: Many of the activities presented here as potential candidates for carbon
sequestration in Article 3.4 are based on moving carbon from the atmosphere to the soil. While individual
measurements of soil carbon can be quite accurate, evidence of a statistically significant changes require
many years (WBGU, 1998). Furthermore, the soil/vegetation properties of many countries exhibit large
amounts of spatial heterogeneity within forests or agricultural areas. Accurately portraying sequestration
across such spatial heterogeneity is a particular challenge. Careful selective measurements combined with
biogeochemical models will likely be necessary.
An inherent tension exists between the desire to comprehensively account for biotic carbon exchange and
the ability to measure and monitor managed biota. Comprehensiveness is appealing in that it represents
the true net source or sink from a countries managed biota. Yet, for most industrialized countries this
encompasses nearly all of the national terrestrial biosphere. This poses significant measurement
challenges both in terms of accuracy and spatial coverage. Furthermore, while the US may be able to
mount sophisticated biospheric carbon exchange measurements, this may be less true of other countries.
In contrast, confining carbon credit to only certain activities may grossly misrepresent the net managed
biotic exchange.
11
Were CO2 fertilization responsible for this lag between photosynthesis and respiration, net carbon uptake would eventually
end.
12
This raises particularly difficult questions were the country in question a small contributor to CO2 levels in the atmosphere.
13
Monitoring and verification: Unlike aboveground biomass, carbon sequestered in the soils cannot, at the
present, be monitored remotely. Therefore, monitoring and verification of sequestered carbon may
require in situ measurement. Article 3.3 requires the activities defined therein to be “transparent” and
“verifiable”. How far countries are willing to take the burden of transparency and verification may be a
crucial factor in approving many of the activities proposed for Article 3.4.
Transience: The sequestration activities discussed in this report should be viewed as temporary
phenomena. In most cases, the goal is to change a biotic system from one equilibrium state to another.
The carbon sequestration benefit typically accrues during the transition phase. For example, initiating notill agriculture on a particular piece of farmland will sequester carbon until the overall rate of respiration
from the growing soil carbon approximates the rate of photosynthesis aboveground. Similarly, increasing
the rotation length of a forest stand will accrue carbon only between the change from a shorter to a longer
rotation length. After that point, carbon sequestration ceases. Only by continually lengthening a
particular forest rotation would sequestration continue, but only then with diminishing results as a forest
stand reaches old-growth status.
4.2 Cross-cutting methodological issues
Baseline/additionality: Because the activities proposed for Article 3.4 refer mostly to improved
management in currently managed systems, some form of strict additionality may be necessary to avoid
unintended carbon credit. As was noted before, much of the terrestrial biota in industrialized countries is
considered “managed”. Requiring that activities have begun “since 1990”, as used in Article 3.3, may be
an insufficient constraint as it may be operationally difficult to distinguish “new” management activities
from those currently practiced.
However, determination of additionality is operationally difficult and a topic of growing concern for
negotiators. Many countries will likely have engaged in activities that sequester carbon were climate
change not an issue of concern. For example, improved forest management and improved soil quality
have been programmatically pursued in the U.S. for years. Determining which of these are truly
additional and which are not may require the construction of national sequestration baselines against
which additional activities are discerned.
Endogenous permanence: As was mentioned previously, inclusion of biotic sequestration into the
calculus of the Kyoto Protocol requires both measuring and tracking biotic carbon into the indefinite
future. Like climate change itself, the timescales of such a task are measured in decades to centuries.
Building institutions that can function consistently and reliably across such timescales may be unrealistic
given the historical permanence of human institutions. Decisions regarding the fate of nuclear waste have
been faced with similar concerns (Makhijani and Saleska, 1992).
Perverse incentives: As with Article 3.3, Article 3.4 has the potential to create perverse incentives. The
most commonly cited is the incentive to decarbonize biotic systems prior to the first commitment period
in order to maximize the carbon uptake when credit is computed. Biotic sequestration also presents a
strong argument for contiguous periods in the future for the same reasons.
Keep it simple: The Kyoto Protocol is the product of many years of arduous and complicated negotiating.
In the long-term, averting serious climate change will be best served by maintaining a reasonable level of
simplicity regarding the management of greenhouse gas emissions. While technically feasible for a few
countries, a global carbon management system that includes biospheric exchange may digress into
incomplete reporting, conflicting verification, and biased results. The result could be a rising cynicism on
the part of the public and negotiators and a general reduction in the political will to ensure sufficient
greenhouse gas reductions in the future. Far greater than potential loopholes or commitment delays, a loss
of political leadership and focus could send the international negotiations back a decade or more.
14
4.3 Benefits
Though a number of potential problems have been raised in the preceding paragraphs, there are also some
accepted benefits that could accrue from the addition of sequestration activities discussed in this paper.
First, Article 3.4 may penalize countries for forest degradation. Current discussions on the interpretation
of Article 3.3 suggest that countries that do not engage in deforestation but degrade forests will not have
the lost carbon counted as an emission. However, such a carbon loss may be accounted for in Article 3.4,
were forest sources as well as forest sinks explicitly included.
Were conservation of old-growth forests considered a carbon sequestering activity, additional impetus
may be created for preserving primary forest in the U.S. Similarly, Article 3.4 may stimulate a reversion
of some managed systems back to native conditions, because these tend to contain more carbon than when
under management. A good example is the restoration of wetlands and peat lands which in their native
state contain vast stores of carbon. However, this last measure may not yield the benefits expected as
wetlands do emit significant amounts of methane, a powerful greenhouse gas. The balance between
carbon sequestration and methane emissions needs further research before the net effect can be
conclusively determined.
As mentioned previously, carbon sequestration in agricultural soils enhances soil quality, leading to
greater productivity and fewer inputs of fertilizer and other amendments. Many of the individual
practices being discussed within agricultural soil carbon sequestration have additional co-benefits such as
lower farming costs and reduced pollution.
Finally, carbon sequestration may stimulate more sustainable forest and agricultural practices by
rewarding higher levels of carbon in biotic systems. For example, less invasive selective cutting in forests
lessens the carbon loss from soils and collateral damage and is also considered more sustainable from a
biodiversity perspective (Putz and Pinard, 1993).
5. Conclusions
Article 3.4 of the Kyoto Protocol was constructed to allow biotic carbon sequestration activities to be used
to offset national emission reductions. Though specific activities and the details of how they might be
included have not been negotiated broad carbon sequestration categories and activities have been
proposed. The most commonly cited are: cropland management, rangeland management, and forest
management.
A review of the work that has been performed on quantifying the sequestration potential of these
categories indicates that they could potentially meet a significant portion of the Canadian commitment
under the Kyoto Protocol and could add to the projected Russian carbon surplus. Should the lower end of
the sequestration range presented in this report be employed, it is possible for the Canada to meet over
250% of the 6% reduction target negotiated in Kyoto and account for over 50% of the needed reductions
in 2005 were their national emission to grow as they are currently projected. Were this level of
sequestration applied to the first commitment period, this would change the Canadian target from a 6%
emissions reduction to a 17% emissions increase.
Should the lower end of the sequestration range be employed within the United States, it is possible for
that country to meet approximately 140% of the 7% reduction target negotiated in Kyoto and meet
roughly 30% of the needed reductions in 2005. These levels of sequestration would effectively change
the 7% reduction to a 11% emissions increase.
The sum of the lower end of the Canadian, Russian, and US sequestration could meet 76% of the entire
Annex 1 country reduction (289 Mt C/year). The upper end of the potential sequestration ranges
presented here could meet all of this needed reduction.
15
With this sizeable sequestration potential comes a number of potential difficulties. Unless care is taken to
construct the language of Article 3.4, countries may accrue credit for current carbon uptake attributable to
the “missing sink”, seriously undermining the emissions reductions that have been agreed to thus far.
Proper experimental controls may be necessary to separate carbon uptake due to intentional humaninduced activity and carbon uptake due to processes underlying the missing sink.
Furthermore, current hypotheses concerned with the fate of biotic carbon suggest that as the world warms
carbon sequestered now may re-enter the atmosphere at a later time. Compared to avoiding the use of
carbon sequestered in fossil fuel form, biotic sequestration may be inherently unstable and require longterm accounting and tracking of biotic resources. The institutional requirements will be significant and
could result in a diffusion of the focus needed to avert serious climate change in the future.
These problems must be weighed against a series of co-benefits that may accrue from carbon sequestering
activities such as the slowing of forest degradation, protection of old-growth forests, stimulation of
sustainable forestry and agriculture, and reversion from managed to native ecosystems.
16
6. References
Aerts, R., R. Van Logtestijn, M. Van Staalduinen, S. Toet (1995). Nitrogen supply effects on productivity
and potential leaf litter decay of Carex species from peatlands differing in nutrient limitation. Oecologia
104 (4), 447-453.
Arnone, J. A., G. Hirschel (1997). Does fertilizer application alter the effects of elevated CO-2 on Carex
leaf litter quality and in situ decomposition in an alpine grassland. Acta Oecologia 18 (3), 201-206.
Birdsey, R.A. (1992). Carbon storage in trees and forests, in Forests and Global Change, Vol 1:
opportunities for increasing forest cover, R.N. Sampson and D. Hair (eds). American Forests Publication,
Washington, D.C. pp 23-41.
Birdsey, R.A., and Heath, L.S. (1995) Carbon changes in US forests. In Joyce, L.A. (ed.) Productivity of
America's Forests, United States Department of Agriculture, General Technical Report RM-GTR-271.
Bruce, J.P., M. Frome, E. Haites, H. Janzen, R. Lal and K. Paustian, K. (1999) Carbon sequestration in
soils. Journal of Soil and Water Conservation, First quarter, 382-389.
Burke, I.C, Lauenroth, W.K., and Coffin, D.P. (1995) Soil organic matter recovery in semiarid grasslands:
implication for the conservation reserve program, Ecological applications, 5 (3), 793-801.
Burke, I., Lauenroth, B., and Milchunas, D. (1997) Biogeochemistry of managed grasslands in Central
North America. In: Paul, E.A., Paustian, K., Elliot, E.T., and Cole, C.V. (eds.), Soil Organic Matter in
Temperate Agroecosystems, CRC Press, Boca Raton.
Ciais, P., Tans, P.P. , Trolier, M., White, J.W.C., and Francey, R.J. (1995) A large northern hemisphere
terrestrial CO2 sink indicated by the 13C/12C ratio of atmospheric CO2. Science 269, 1098-1102.
Canadian Pulp and Paper Association. 1998. Potential impacts of forestry initiatives on Canada’s carbon
balances: A position paper of the CPPA. Unpublished document, Version 3-4, 4/12/98. Montreal, Canada.
40 pp.
Delgado JA, Mosier AR. (1996). Mitigation alternatives to decrease nitrous oxides emissions and ureanitrogen loss and their effect on methane flux. Journal of Environmental Quality 25 (5), 1105-1111
Donigian et al, (1997) Modeling Soil Carbon and Agricultural Practices in the Central U.S.: An Update of
Preliminary Study Results, in Soils and the Carbon Cycle, Lal et al. (eds), pp. 499-518.
Dumanski, J., R.L. Desjardins, C. Tarnocai, C. Monreal, E.G. Gregorich, V. Krirkwood, C. Campbell.
(1998). Possibilities for future carbon sequestration in Canadian agriculture in relation to land use
changes,” Climatic Change, 40, 81-103.
Dyrness, C.T., R.A. Norum. (1983). The effects of experimental fires on black spruce forest floors in
interior Alaska. Canadian Journal of Forest Research. 13, 879-893.
Enting, I.G., and Mansbridge, J.V. (1986) Seasonal Sources and Sinks of Atmospheric CO 2: Direct
Inversion of Filtered Data. Tellus 41B, 111-126.
Enting, I.G., Trudinger, C.M., and Francey, R.J. (1995) A synthesis inversion of the concentration and
13C of atmospheric CO2. Tellus 47B (1/2), 35-52.
Forest Fertilization Guidebook (1995). Government of British Columbia, Ministry of Forests. Queen’s
printer for British Columbia, Victoria, British Columbia
Fan, S.M., Gloor, M., Mahlman, J., Pacala, S., Sarmiento, J., Takahashi, T., and Tans, P. (1998) A large
terrestrial carbon sink in North America implied by atmospheric and oceanic carbon dioxide data and
models. Science 282, 442-446.
Francey R.J., Tans, P.P., Allison, C.E., Enting, I.G., White, J.W.C., and Trolier, M. (1995) Changes in
oceanic and terrestrial uptake since 1982. Nature 373, 326-330.
Frank, A.B., Tanaka, D.L., Hofmann, L., and Follett, R.F. (1995) Soil carbon and nitrogen of Northern
Great Plains grasslands as influenced by long-term grazing. Journal of Range Management 48, 470-474.
17
Gill, R. S., D.P. Lavender (1983). Litter decomposition in coastal hemlock (Tsuga heterophylla) stands:
Impact of nitrogen fertilizers on decay rates. Canadian journal of forest research 13 (1), 116-121.
Global Change Strategies International Inc. (1999). Final Report for National Climate Change Sinks Issue
Table on Soil Carbon Sinks Potential in Key Countries. Ottawa Canada, May 14.
Hagenstein, P.R. (1992). Forestry mitigation decisions made thus far. In Forests and Global Change Vol.
1: Opportunities for increasing forest cover (R.N. Sampson and D. Hair, eds). pp 225-231.
Harden J. W., S.E. Trumbore, B.J. Stocks, A. Hirsch, S.T. Gower, K.P. O'Neill, E.S. Kasischke. (in press)
The role of fire in the boreal carbon budget. Global Change Biology.
Houghton, R.A., Davidson, E.A., and Woodwell, G.M. (1998) Missing sinks, feedbacks, and
understanding the role of terrestrial ecosystems in the global carbon balance. Global Biogeochemical
Cycles 12 (1), 25-34.
Hunt, H. W., E.R. Ingham, D.C. Coleman, E.T. Elliott, C.P.P. Reid (1988). Nitrogen limitation of
production and decomposition in prairie, mountain meadow and pine forest. Ecology 69 (4), 1009-1016.
Izaurralde, R.C., McGill, W.B., and Rosenberg, N.J. Carbon cost of applying nitrogen fertilizer. Science,
288, 809.
Kasischke E. S., N. L. Christensen Jr., and B.J. Stocks. (1995a) Fire, global warming, and the carbon
balance of boreal forests. Ecological Applications 5, 437-451.
King, J. S., L.H. Allen, P.Dougherty, B.R. Strain (1997). “Decomposition of roots in loblolly pine:
Effects of nutrient and water availability and root size class on mass loss and nutrient dynamics.” Plant
and Soil 195 (1), 171-184.
Keeling, C.D. and Heimann, M. (1986) Meridional eddy diffusion model of the transport of atmospheric
carbon dioxide, 2. Mean annual carbon cycle. Journal of Geophysical Research 91, 7782-7796.
Keeling, C.D., Bacastow, R. B., Carter, A.F., Piper, S.C., Whorf, T.P., Heimann, M., Mook, W.G., and
Roeloffzen, H. (1989) In: Peterson, D.H. (ed.) Aspects of Climate Variability in the Pacific and Western
Americas, Geophysical Monograph 55, American Geophysical Union, Washington DC, pp. 305-363.
Keeling, R.F., Piper, S.C., and Heimann, M. (1996) Global and hemispheric CO 2 sinks deduced from
changes in atmospheric O2 concentration. Nature 381, 218-221.
Kern and Johnson (1993). Conservation tillage impacts on national soil and atmospheric carbon levels.
Soil Science Society of America Journal. 57: 200-210.
Kronberg, B., M.J. Watt, S.C. Polishuk, 1998. Forest-climate interactions in the Quetico-Superior Ecotone
(Northwest Ontario and Northern Minnesota). Environmental Modeling and Assessment, 50 (2), 173-187.
Kurz, W.A., M.Apps. (1995). An analysis of future carbon budgets of Canadian boreal forests. Water,
Air and Soil Pollution 82: 321-331.
Lal, R., J.M Kimble, R.F. Follett, C.V. Cole. (1998). The potential of U.S. cropland to sequester carbon
and mitigate the greenhouse effect. Sleeping Bear Press Inc.
Lashof, D. and Hare, B. (1999) The role of biotic carbon stocks in stabilizing greenhouse gas
concentrations at safe levels. Environmental Science and Policy, forthcoming.
Levine, J.S., 1991. Global biomass burning: atmospheric, climate and biospheric implications. MIT Press,
Cambridge MA, 344 pp.
Linder, P., E. Elfving, O. Zackrisson, 1997. Stand structure and succession trends in virgin boreal forest
reserves in Sweden. Forest Ecology and Management, 98 (1), 17-33.
Lowe, J.J., K. Power, S.L. Gray. 1994. Canada’s Forest Inventory 1991. Natural Resources Canada,
Canadian Forest Service. Petawawa National Forestry Institute. Chalk River, Ontario. Info. Rep. PI-X115. 67 pp. and maps.
18
Lunnan, A., S.R, Navrud, P.K., Rstad, K. Simonsen, B. Solberg (1991) Forestry and forest production in
Norway as a measure against CO2-accumulation in the atmosphere. Aktuelt fra Skogforsk nr 6-1991.
Institutt for skogfag, NLH.
Makhijani, A., and Saleska, S. (1992) High level dollars low-level sense. A report for the Institute for
Energy and Environmental Research, Apex Press, New York.
Mäkipää, R., T. Karjalainen, A. Pussinen, M. Kukkola. (1998). Effects of nitrogen fertilization on carbon
accumulation in boreal forests: Model computations compared with the results of long term fertilization
experiments. Chemosphere, 36 (4-5), 1155-1160
Manley, J.T., Schuman, G.E., Reeder, J.D., and Hart, R.H. (1995) Rangeland soil carbon and nitrogen
responses to grazing. Journal of Soil and Water Conservation 50 (3), 294-298.
Mellilo, J.M., J.R. Fruci, R.A. Housghton, B. Moore, D.L. Scole, 1988. Land use change in the Soviet
Union between 1850 and 1980: causes of a net CO2 release to the atmosphere. Tellus, 40, 116-128.
Melillo, J.M., Prentice, I.C., Farquhar, G.D., Schulze, E.-D., Sala, O.E. (1996) Terrestrial biotic responses
to environmental change and feedbacks to climate. In: Houghton, J.T., Meiro Filho, L.G., Callander, B.A.,
Harris, N., Kattenberg, A., and Maskell, K. (eds.), Climate Change 1995: The Science of Climate Change,
Cambridge University Press, Cambridge, UK.
Milchunas, D. and Lauenroth, B. (1993) Quantitative effects of grazing on vegetation and soils over a
global range of environment. Ecological Monographs 63 (4), 327-366.
Miller, R.E., S.R. Webster. (1979). Fertilizer response in mature stands of Douglas-fir. Pages 126-132 in
S.P. Gessel, R.M. Kenady, and W.A. Atkinson (eds), Proceedings: Forest Fertilization Conference.
College of Forest Resources. University of Washington, Seattle, Washington.
Morrison, I.K., H.S.D. Swan, N.W. Foster, D.A. Winston. (1977). Ten-year growth in two fertilization
experiments in a semimature jack pine stand in Northwestern Ontario. The Forestry Chronicle, pp. 142146.
Morrison, I.K., H.S.D. Swan, N.W. Foster, D.A. Winston. (1976). Ten-year growth response to fertilizer
of a 90-year old black spruce stand in Northwestern Ontario. The Forestry Chronicle, 233-236.
Nams, V.O., N. F.G. Folkard, J.N.M. Smith (1993). Effects of nitrogen fertilization on several woody and
nonwoody boreal forest species. Canadian Journal of Botany. 71, 93-97.
Nabuurs, G.J., Dolman, A.J., Verkaik, E., Whitmore, A.P., Daamen, W.P., Oenema, O., Kabat, P.,
Mohren, G.M.J. (1999) Resolving issues on terrestrial biospheric sinks in the Kyoto Protocol. Dutch
National Research Programme on Global Air Pollution and Climate Change. Report No. 410 200 030.
Neff, Bowman, Holland, Fisk and Schmidt (1994). Fluxes of nitrous oxide and methane from nitrogen
amended soils in a Colorado alpine ecosystem. Biogeochemistry, 27, 23- 33.
Paustian, K., Andren, O., Janzen, H.H., Lal, R., Smith, P., Tian, G., Tiessen, H., Van Noordwijk, M., and
Woomer, P.L. (1997a) Agricultural soils as a sink to mitigate CO 2 emissions. Soil Use and Management
13, 230-244.
Paustian, K., Collins, H.P., and Paul, E.A. (1997b) Management Control on Soil Carbon. In: Paul, E.A.,
Paustian, K., Elliot, E.T., and Cole, C.V. (eds.), Soil Organic Matter in Temperate Agroecosystems, CRC
Press, Boca Raton.
Paavilainen, E. (1984). “Fertilization and nutrient cycles in peatland forests.” Suo 35 (4-5), 91-93.
Peterson, E.B., N.M. Peterson, (1995). Aspen managers handbook for British Columbia. Canadian Forest
Service and B.C. Ministry of Forests, Victoria. FRDA Rep. No. 230.
Prescott, C. E. (1995). “Does nitrogen availability control rates of litter decomposition in forests?” Plant
and Soil 168-169 (0), 83-88.
Putz, F.E. and Pinard, M.A. (1993) Reduced-impact logging as a carbon-ofset method. Conservation
Biology 7 (4), 755-757.
19
Schimel, D., Alves, D., Enting, I., Heimann, M., Joos, F., Raynaud, D., Wigley, T., Prather, M., Derwent,
R., Ehhalt, D., Fraser, P., Sanhueza, E., Zhou, S., Jonas, P., Charlson, R., Rohde, H., Sadasivan, S., Shine,
K.P., Fouquart, Y., Ramaswamy, V., Solomon, S., Srinivasan, J., Albritton, D., Isaksen, I., Lal, M., and
Wuebbles, D. (1996) Radiative Forcing of Climate. In: Houghton, J.T., Meiro Filho, L.G., Callander,
B.A., Harris, N., Kattenberg, A., and Maskell, K. (eds.), Climate Change 1995: The Science of Climate
Change, Cambridge University Press, Cambridge, UK.
Schlesinger, W.H. (1986) Changes in soil carbon storage and associated properties with disturbance and
recovery. In: Trabalka, J.R. and Reichle, D.E. (eds.) The Changing Carbon Cycle: a Global Analysis,
Springer-Verlag, New York.
Schlesinger, W.H. (1999) Carbon and agriculture: carbon sequestration in soils. Science, 284, 2095.
Schroeder, P. (1991) Can intensive management increase carbon storage in forests?. Environmental
Management 15 (4), 475-481.
Shvidenko, A., S. Nilsson, V. Roshkov. (1997). Possibilities for increased carbon sequestration through
the implementation of rational forest management in Russia. Water Air and Soil Pollution. 94, 137-162.
Shvidenko, A., S. Nilsson, V. Stolbovoi, D. Wendt. (1998). Background information for carbon analysis
of the Russian forest sector. International Institute for Applied Systems Analysis Publication, Laxenburg,
Austria. 125 pp.
Sinks Table Options Paper: land-use, land-use change and forestry in Canada and the Kyoto Protocol,
(1999). National Climate Change Process, September 23, 1999. 174 pp.
Sohngen, B.L., R.W. Haynes. (1997). The potential for increasing carbon storage in United States
unreserved timberlands by reducing forest fire frequency: An economic and ecological analysis. Climate
Change 35, 179-197.
Solomon, A.M., I.C. Prentice, R. Leemans, W.P. Cramer. (1993). The interaction of climate and land use
in future terrestrial carbon storage and release. Water Air and Soil Pollution. 70, 595-614.
Stocks, B.J., (1987). Fire behavior in immature jack pine. Canadian Journal of Forest Research. 17, 8086.
Tans, P., Fung, I., and Takahashi, T. (1990) Observational Constraints on the Global Atmospheric CO 2
Budget. Science 247, 1431-1438, March 23.
Turkington R., E. John, C.J. Krebs, M.R.T. Dale, V.O. Nams, R. Boonstra, S. Boutin, K. Martin, A.R.E.
Sinclair, J.N.M. Smith. (1998). The effects of NPK fertilization for nine years on boreal forest vegetation
in northwestern Canada. Journal of Vegetation Science 9, 333-346.
Turner, D.P., Koerper, G.J., Harmon, M.E., and Lee, J.J. (1995) Carbon sequestration by forests of the
United States: Current status and projections to the year 2040. Tellus 47B, 232-239.
United Nations (1997) Kyoto Protocol to the United Nations Framework Convention on Climate Change.
FCCC/CP/1997/L.7/Add.1, 10 December.
United Nations (1998) Methodological Issues: Issues related to land-use change and forestry, Note by the
Secretariat. FCCC/SBSTA/1998/INF.1, 18 May.
United Nations (1999a) Methodological Issues: Land-use, land-use change and forestry (Decision 1/CP.3,
paragraph 5 (a)). FCCC/SBSTA/1999/MISC.2, 8 April.
United Nations (1999b) National Communications from Parties Included in Annex 1 to the Convention:
Greenhouse Gas Inventory Data, 1990-1997. FCCC/SBI/1999/12, 29 September.
U.S. Environmental Protection Agency (1999) Inventory of U.S. greenhouse gas emissions and sinks:
1990-1997. Office of Policy, United States environmental Protection Agency.
U.S. Environmental Protection Agency (1995) Climate Change Mitigation Strategies in the Forest and
Agricultural Sectors. Office of Policy, Planning, and Evaluation, United States Environmental Protection
Agency 230-R-95-002.
20
Van Cleve, K. (1973). Short-term growth response to fertilization in young quaking aspen, Journal of
Forestry. 71, 758-759.
Van Cleve, K., J.C. Zasada. (1976). Response of 70 year old white spruce to thinning and fertilization in
interior Alaska. Canadian Journal of Forest Research. 6, 145-152.
WBGU (1998) The accounting of biological sinks and sources under the Kyoto Protocol: a step forwards
or backwards for global environmental protection?. German Advisory Council of Global Change. Special
Report.
Woodwell, G.M., Mackenzie, F.T., Houghton, R.A., Apps, M.J., Gorham, E., and Davidson, E.A. (1995)
Will the warming speed the warming?. In: Wodwell, G.M. and Mackenzie, F.T. (eds.) Biotic feedbacks in
the global climate system. Oxford University Press, New York.
Wotton, B.M., M.D. Flannigan, 1993. Length of the fire season in a changing climate. The Forestry
Chronicle, 69. 187-192.
21
7. Units and Abbreviations
Mt C/year:
million metric tonnes of carbon per year
ha:
hectares
Mha:
million hectares
t C/ha/year:
2
metric tonnes of carbon per hectare per year
g C/m /year
grams of carbon per meter squared per year
Gt
billion tonnes
22
Figure 1. Simulated total soil carbon for the central U.S. corn belt (Lal et al., 1998).
23
Figure 2. Sensitivity of fire suppression emission reductions to reduction level and area burned.
24
Figure 3. Zonally averaged simulated versus observed CO2 concentration (Keeling et al., 1989).
25
Table 1. Cropland management sequestration
Available area
Carbon uptake rate
Annual sequestration
(Mha)
(g/m2/year)
(Mt C/year)
Land conversion
0.5
80
0.4
Land restoration
3.8
10 - 100
1.0
20 – 40
15 - 80
3.0 - 6.5
Country/Activity
Canada
Improved management of
cultivated land
Total
4.4 - 7.9
Russia
Land conversion
NA
NA
NA
Land restoration
NA
NA
NA
10 - 20
5.7 – 8.4
Improved management of
cultivated land
15 – 30
5.7 – 8.4
Total
United States
Land conversion
8.7
80
7
Land restoration
49.2
10 - 100
17
20 - 123
20 - 40
10 - 50
Improved management of
cultivated land
Total

34 - 74
All values have been rounded.
Table 2. Rangeland management sequestration
Country/Activity
Available area
Carbon uptake rate
Annual sequestration
(Mha)
(g/m2/year)
(Mt C/year)
Canada
Pasture improvement
4.3
20
0.2 - 0.6
7.8 - 16
5.5
0.4 – 0.8
51
20
9
Russia
Pasture improvement
United States
Pasture improvement

All values have been rounded.
26
Table 3. Nitrogen fertilization response
Species & Fertilization Rate
Location
% Growth Increase
(Kg N/ha/year)
Reference
Sweden
Scots Pine – 20-28
Mesic Site - 37% (stemwood)
Dry site – 36% (stemwood)
S. Yukon, Canada
White Spruce – 180
10-50% (growth rate increase)
Nams et al, 1993
Turkington et al, 1998
N. Saskatchewan, Canada
Aspen stand – 100-200
50% (NPP for N additional alone)
111% (NPP for N, P, K additions)
Peterson and Peterson, 1995
Mäkipää al, 1998
Table 4. Forest management sequestration
Country/Activity
Available area
Carbon uptake rate
Annual sequestration
(Mha)
(g/m2/year)
(Mt C/year)
Canada
Nitrogen fertilization
142
Fire suppression
3.0 - 75
4.2 - 107
1.5
-
2 - 20
Pest control
-
-
5 - 60
Stand thinning
-
-
7
112 - 142
-
2.5 - 8
Increase rotation length
Total
20.7- 202
Russia
Nitrogen fertilization
230
Fire suppression
1.5
-
2 - 20
Pest control
-
-
5 - 60
Stand thinning
-
-
0 - 50
230
-
14
Increase rotation length
3.0 - 75
Total
7 - 184
28 - 328
United States
Nitrogen fertilization
196
-
16 - 94
Fire suppression
1.5
-
2 - 20
Pest control
-
-
5 - 60
Stand thinning (includes
improved regeneration)
-
-
80
Increase rotation length
196
-
7
-
-
8 - 15.6
Increased recycling
Total

118 - 277
All values have been rounded.
27
Table 5. Mean global carbon budget for the 1980s (after Schimel et al., 1996).
Gt C/year
CO2 sources
Emissions from fossil fuel combustion and cement production
5.5  0.5
Net emissions from changes in tropical land-use
1.6  1.0
Total Anthropogenic Emissions
7.1  1.1
Partitioning amongst reservoirs
Storage in the atmosphere
Ocean uptake
2.0  0.8
Uptake by Northern Hemisphere forest regrowth
0.5  0.5
Other sinks
1.3  1.5
28