Assessment of the Influence of Disturbance, Management Activities, and Environmental Factors on Carbon Stocks of U.S

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Assessment of the Influence of Disturbance, Management Activities, and Environmental Factors on Carbon Stocks of U.S. National Forests

General Technical Report RMRS-GTR-402

Appendix 3: Eastern Region, Individual Forests

Office of Sustainability and Climate National Forest System

November, 2019

United States Department of Agriculture

Forest Service

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Citation: Birdsey, Richard A.; Dugan, Alexa J.; Healey, Sean P.; Dante-Wood, Karen; Zhang, Fangmin; Mo, Gang; Chen, Jing M.; Hernandez, Alexander J.; Raymond, Crystal L.; McCarter, James. 2019. Assessment of the influence of disturbance, management activities, and environmental factors on carbon stocks of U.S. national forests. Gen. Tech. Rep. RMRS-GTR-402. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Abstract: This report assesses how carbon stocks at regional scales and in individual national forests are affected by factors such as timber harvesting, natural disturbances, climate variability, increasing atmospheric carbon dioxide concentrations, and nitrogen deposition. Previous baseline assessments of carbon stocks (https://www.fs.fed.us/managing-land/sc/carbon) evaluated observed trends based on forest inventory data but were limited in ability to reveal detailed causes of these trends. The expanded assessments reported here are based on an extensive disturbance and climate history for each national forest, and two forest carbon models, to estimate the relative impacts of disturbance (e.g., fires, harvests, insect outbreaks, disease) and nondisturbance factors (climate, carbon dioxide concentrations, nitrogen deposition). Results are summarized for each region of the National Forest System in the main document. A set of appendixes (available online) provides more detailed information about individual national forests within each region. Results are highly variable across the United States. Generally, carbon stocks are increasing in forests of the eastern United States as these forests continue to recover and grow older after higher historical harvesting rates and periods of nonforest land use. In contrast, carbon stocks in forests of the western United States may be either increasing or decreasing, depending on recent effects of natural disturbances and climate change. The information supports national forest units in assessing carbon stocks, quantifying carbon outcomes of broad forest management strategies and planning, and meeting carbon assessment requirements of the 2012 Planning Rule and directives. Results of these expanded assessments will provide context for project-level decisions, separated from the effects of factors that are beyond land managers’ control.

Keywords: forest carbon stock, national forest, land management, natural disturbance, climate change

Acknowledgements: Individuals from the USDA Forest Service Washington Office provided valuable guidance and support for this research, particularly Duncan McKinley and Cindi West. The research could not have been done without substantial participation by technicians at Utah State University. The authors wish to acknowledge contributions from the staff of the Forest Service’s Northern Research Station and Rocky Mountain Research Station for providing technical support and data used in this report, particularly Chris Woodall, Grant Domke, and Jim Smith. Throughout development of this report, the authors received significant input and feedback from individual national forests which helped us compile the material in a useful and understandable way. We also thank technical reviewers Grant Domke, Bill Connelly, Nadia Tase, Jim Alegria, Dave L. Peterson, Barry Bollenbacher, Elizabeth Wood, Marilyn Buford, and Leslie Brandt.

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Contents

1. Disturbance trends

2. Effects of disturbance and management activities (ForCaMF)

3. Management implications of ForCaMF results

4. Effects of disturbance, management, and environmental factors (InTEC)

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1. Disturbance trends

Disturbance records were summarized by type (fire, harvest, abiotic, and insects) and by magnitude in Figure 1.1 a-n. Harvest was mapped in each unit, although cutting never affected more than 1% of any one national forest in any year from 1990 to 2011. Several units experienced periodic, relatively small fires. There were locally important instances of “abiotic” disturbance, including a wind storm in 1999 in the Superior National Forest (Nelson et al, 2009) and an ice storm in 2009 in the Mark Twain National Forest.

Disturbance Type Disturbance Magnitude

1 1 a) Allegheny 4 Harvests 3 2 1

0 0 Percentage Percentage of forest disturbed

1 1 b) Chequamegon-Nicolet Abiotic 4 Insects 3 Harvest Fire 2 1

Percentage Percentage of forest disturbed 0 0

Year Year

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1 1 c) Chippewa 4 Abiotic Insects 3 Harvest 2

Fire 1 Percentage Percentage of forest disturbed 0 0

1 1 d) Green Mountain & Finger Lakes

Abiotic 4 Insects 3 Harvest 2 Fire 1

Percentage Percentage of forest disturbed 0 0

1 1 e) Hiawatha Abiotic 4 Harvest 3 Fire 2 1

Percentage of Percentage disturbed forest 0 0

Year Year

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1 1 f) Hoosier

4 Insects 3 Harvest 2 Fire 1

Percentage Percentage of forest disturbed 0 0

1 1 g) Huron-Manistee Abiotic 4 Insects 3 Harvest 2 Fire 1

Percentage Percentage of forest disturbed 0 0

3 3 h) Mark Twain

Abiotic 4 2 2 Insects 3 Harvest 2 Fire 1 1 1

Percentage Percentage of forest disturbed 0 0

Year Year

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1 1 i) Monongahela Insects 4 Harvest 3 Fire 2 1

0 0 Percentage of Percentage disturbed forest

1 1 j) Ottawa Abiotic Insects 4 Harvest 3 Fire 2 1

Percentage Percentage of forest disturbed 0 0

0.3 0.3 k) Shawnee 3 0.2 0.2 2 Harvest 1 0.1 0.1

0 Percentage Percentage of forest disturbed 0

Year Year

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4 4 l) Superior Abiotic 4 Insects 3 3 3 Harvest 2 Fire 2 2 1

1 1

Percentage Percentage of forest disturbed 0 0

1 1 m) Wayne

Harvest 4 3 2 1

Percentage Percentage of forest disturbed 0 0

1 1 n) White Mountain 4 3 Insects 2 Harvest 1 Fire

Percentage of Percentage disturbed forest 0 0

Year Year

Figure 1.1. Annual rates of disturbance in the Eastern Region, mapped using visual interpretation of several independent datasets and summarized as the percentage of the forested area disturbed from 1991 through 2011 by (a) disturbance types including fire, harvests, insects, and abiotic; and b) magnitude classes, characterized by percentage change in canopy cover (CC) and categorized as follows: (1) 0 to 25 percent CC, (2) 25 to 50 percent CC, (3) 50 to 75 percent CC, and (4) 75 to 100 percent CC.

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2. Effects of disturbance and management activities (ForCaMF)

ForCaMF uses carbon (C) dynamics derived from the combination of FIA plot data and FVS to interpret the consequences of recorded harvests and natural disturbances from 1990 to 2011. Figure 2.1 shows the evolution of C impacts resulting from the disturbance patterns shown in Figure 1.1. Units in Figure 2.1 represent reduced C storage per square meter. Error bars around the impact of each type of disturbance represent 95% confidence intervals derived from 500 simulations of all recognized constituent uncertainties, as described in the main document. Figure 2.2 summarizes the ForCaMF output shown in Figure 2.1: the pie charts represent the proportional importance of each type of disturbance as measured in 2011 (the last date in Figure 2.1).

For several National Forests (White Mountain, Wayne, Shawnee, Ottawa, Allegheny), the only measured 1990-2011 disturbance impacts on C storage were from harvests. For several others, non-harvest impacts were measured, but were minimal (Monongahela, Hiawatha, Green Mountain and Finger Lakes, and Chippewa). In the Hoosier and Shawnee, even rates of harvest were negligible, and disturbance during the study period had very little effect on the C cycle. The impacts of the ice storm in the Mark Twain and the wind storm in the Superior (both labeled “abiotic” in Figure 1.1) were striking; together with scattered smaller events, they represented 10% of the disturbance impact on C storage at the Regional level. Fire within the Region was largely confined to the Superior National Forest, including the large Ham Lake fire of 2007 (see Figure 1.1), and there was fire activity in several other years.

Some of the harvest across forests in this region may have been designed to salvage timber following fire or storm activity. Given the mapping methods used here, it is likely that both the original disturbance and the subsequent harvest were detected and mapped. For purposes of this assessment, losses of C storage potential (Figure 2.2) occurring between the two events (e.g., losses in a fire due to combustion and immediate emission) were attributed to the first process. Salvage operations and subsequent C dynamics were associated with harvests. For managers wishing to assign salvage impacts solely to the original disturbance, this decision within ForCaMF over-stated the impact of harvest.

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2.1a. Allegheny National Forest 2.1b. Chequamegon - Nicolet National Forest

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011 C) C)

2 2

- - -75 -75

-175 -175

-275 -275 Lost Potential Storage (g m (g Storage Potential Lost

m (g Storage Potential Lost

-375 -375

2.1d. Green Mountain & Finger Lakes 2.1c. Chippewa National Forest National Forests

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011

C) C)

2 2

2 2 - - -75 -75

-175 -175

-275 -275 Lost Potential Storage (g m (g Storage Potential Lost (gm Storage Potential Lost -375 -375

2.1e. Hiawatha National Forest 2.1f. Hoosier National Forest

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011

C) C)

2 2

- - -75 -75

-175 -175

-275 -275

Lost Potential Storage (g m (g Storage Potential Lost Lost Potential Storage (g m (g Storage Potential Lost

-375 -375

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2.1g. Huron-Manistee National Forest 2.1h. Mark Twain National Forest

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011

2 2

- - -75 -75

-175 -175

-275 -275

Lost Potential Storage (gm Storage Potential Lost Lost Potential Storage (gm Storage Potential Lost

-375 -375

2.1i. Monongahela National Forest 2.1j. Ottawa National Forest

1990 1993 1996 1999 2002 2005 2008 2011

2 2 -

2 2

- -75 -75

-175 -175

-275

-275 Lost Potential Storage (gm Storage Potential Lost Lost Potential Storage (gm Storage Potential Lost -375 -375

2.1k. Shawnee National Forest 2.1l. Superior National Forest

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011

2 2 - -75

C) C) -75

2 2 -

-175 -175

-275

Lost Potential Storage (g m (g Storage Potential Lost Lost Potential Storage (gm Storage Potential Lost

-375 -375

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2.1m. Wayne National Forest 2.1n. White Mountain National Forest

1990 1993 1996 1999 2002 2005 2008 2011 1990 1993 1996 1999 2002 2005 2008 2011

2 2

2 2 - -75 -75

-175 -175

-275 -275

Lost Potential Storage (gm Storage Potential Lost Lost Potential Storage (gm Storage Potential Lost

-375 -375

Figure 2.1. The impact of different kinds of disturbance, occurring from 1990 through 2011, on carbon (C) stores in the Eastern Region. The difference in storage for each year is shown between an “undisturbed” scenario and a scenario that includes only observed amounts of the specified type of disturbance. Error bars represent a 95-percent confidence interval; 100 g/m2 equals 1 metric tonne (or Mg)/ha..

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Figure 2.2. Proportional effect of different kinds of disturbance on carbon storage in each national forests in the Eastern Region for the period 1990 through 2011. “Wind” is a combination of ice and wind storms and was labelled “abiotic” in Figure 1.

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3. Management implications of ForCaMF results

Earlier baseline assessments (http://www.fs.fed.us/climatechange/advisor/products.html) presented inventory-derived estimates of how much carbon is stored in the forests and in the harvested wood product pools of each national forest. The ForCaMF analyses here focused on how different types and intensities of disturbance have influenced those stocks in recent decades. Specifically, results given in Section 6.1 of the main report and previous sections of this appendix provide details about: 1) patterns of disturbance; 2) how disturbance impacts on C storage evolved in each forest from 1990 to 2011, and; 3) the level of uncertainty associated with assessments of each forest. In this section, we bring this information together to answer the simple questions of: “How much do disturbances really disrupt C storage?” and “which disturbance processes in each forest are the most important?”

In highlighting what information managers and planners can gain from these analyses, it is useful to remember that C storage is simply one ecological service, among many, that forests provide. That service mitigates the climate impacts of greenhouse gases emitted through the use of fossil fuels by removing carbon dioxide (CO2) from the atmosphere. Figure 3.1 shows how much less C (by percentage) was stored in each forest in 2011 because of different types of disturbance since 1990. Disturbance patterns continue to change, but this assessment of the recent past represents the best available insight into how sensitive National Forest C storage is to fire, harvest, insects, disease, and weather events. Residual disturbance effects (e.g., decaying dead C) of monitored events will depress C storage for many years after 2011, just as many pre-1990 disturbances continue to affect current stocks. In most cases, forests re-grow after disturbance and become C sinks for many decades or centuries after a relatively short period of reduced C stocks. In some regions where C stocks have reached elevated levels because of disturbance suppression, a lower level of C stock may be more sustainable compared with the recent past.

The period of this snapshot was somewhat arbitrary; however, every analysis needs sideboards, and the period used here coincides with our best monitoring data (satellite imagery, Agency activity records, FIA data). The percentages recorded in Figure 3.1 may seem relatively small, but they often represent very large amounts of climate mitigation benefit. For instance, if a National Forest has half a million hectares of forestland that FIA tells us is storing 50 Mg of C per hectare, and ForCaMF tells us that there would be 2% more C without insect activity from 1990-2011, that is a difference of half a million metric tonnes (Mg) of C, or 1.835 million tonnes of CO2 (using a 3.67 conversion ratio for C to CO2). For perspective, this is approximately the amount of CO2 released by burning around 200 million gallons of gasoline (US Energy Information Administration), and its offset value (amount it would be worth if its continued storage were sold on an open market at a conservative price of $10/tonne) would be almost $20 million.

There are certain ways that Figure 3.1 does not tell the complete story. The FVS model, which supplies stand dynamics within ForCaMF, does not cover soil organic C, and Figure 3.1’s calculations exclude soils. Fortunately, the InTEC model presented in this assessment do provide insight into soil C dynamics. More importantly, there are some types of disturbance known to be important that were excluded. For instance, root diseases are known to be prevalent in many parts of the country, but they can be difficult to detect with satellite or aerial imagery because their effects in most years can be limited to reduced growth and suppression of regeneration. ForCaMF was used to assess the impacts of root disease in only 6 national forests, all in the Northern Region. That analysis, which was only possible because of a specialized “regional add-on” variable to core FIA measurements, showed significant root disease

Page 18 of 63 impacts that equaled the impacts of fire despite several large fire events in the Region (Healey et al., 2016). We know that we are missing similar processes across the country that are not well addressed by available monitoring data.

Disturbances due to climate variability were assessed with the InTEC model which includes precipitation and temperature as major factors affecting forest processes. The effects of climate variability may be positive or negative, and are often highly variable from year to year, depending on the region and how the climate variables interact to affect photosynthesis and respiration. The effects of climate also interact with other atmospheric changes particularly increasing atmospheric CO2 concentration and nitrogen deposition, both of which typically enhance growth rates of forests.

Lastly, this assessment does not consider storage of harvested C in product pools. Conversion of forest material to durable wood products defers emissions of the associated C until decay or combustion occurs following disposal. Earlier baseline assessments and assessments by Stockmann et al. (2012) quantified C stocks in wood products that remain in use or landfills, and work is ongoing to combine ForCaMF and product C dynamics models. In the present assessment, however, harvest effects (like the effects of all disturbances) are restricted to ecosystem stocks, a limitation that overstates the emissions of CO2 from harvest from an atmospheric point of view. The effect of substituting wood products for other materials such as concrete and aluminum are not considered in any of the assessments but are potentially significant and will be assessed in future work.

It is outside the scope of this assessment to suggest the importance of ecosystem services associated with C relative to other values such as water yield or habitat conservation. What we do provide is tangible information about how management and disturbance prevention/suppression can impact (and has impacted) the climate change mitigation a national forest generates. To the degree planners value C storage as a service, the disturbance rates published here, along with resultant C storage differences, can frame management goals moving forward.

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White Mountain

Monongahela Wind Insects Harvest Fire All disturbances

Green Mountain

Allegheny

Wayne

Chequamegon-Nicolet

Hoosier

Hiawatha

Superior

Shawnee

Ottawa

Mark Twain

Huron-Manistee

Chippewa

REGION 9

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5%

2011 Non-Soil Carbon Storage Reduction due to 1990-2011 Disturbances

Figure 3.1. Carbon stock reduction in 2011 due to disturbances occurring from 1990 through 2011, by each national forest and for all national forests combined in the Eastern Region. Percent reduction represents how much nonsoil carbon was lost from the baseline forest inventory carbon stock estimates. “Wind” is a combination of ice and wind storms and was labelled “abiotic” in Figure 1.

4. Effects of disturbance, management, and environmental factors (InTEC) for individual National Forests in the Eastern Region

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The set of figures for each of 10 National Forests units in the Eastern Region were generated from both input datasets and outputs from the InTEC model. Note that the numbering sequence of figures in this section is repeated for each National Forest. The input dataset figures presented here include stand age- forest type distributions (Figure 4.1), net primary productivity and stand age relationships (Figure 4.2), total annual precipitation (Figure 4.3a), mean annual temperature (Figure 4.3b), and total annual nitrogen (N) deposition (Figure 4.3c) from 1950-2010. A single atmospheric CO2 dataset indicating an increasing trend from 280 ppm in 1901 to 390 ppm 2010 (Keeling et al. 2009) was used for all National Forest units across the U.S. The disturbance type and magnitude figures (Figure 1.1) are also referenced as they are useful for understanding model results. Summary figures of the input datasets have been included in these reports because they provide useful context for interpreting the model outputs.

Model outputs presented here include C stock changes and C accumulation due to disturbance and non- disturbance factors, and C emissions due to disturbances alone from 1950-2011. C stock change outputs show the change in C stocks over the course of a year, thus the value in a given year is the difference between total C stocks in that year and total C stocks in the previous year. C stock change is equivalent to Net Biome Production, which is the total photosynthetic uptake of C by the forest minus the loss of C due to autotrophic and heterotrophic respiration and disturbances. The change in C stocks have been attributed to the following effects: (1) individual non-disturbance factors (climate, N deposition, CO2 concentrations) (Figure 4.4a), (2) combined disturbances factors (fire, harvests, insects, aging and regrowth) (Figure 4.4b), (3) combined non-disturbance factors (Figure 4.4b), and (4) all factors which is the sum of all non-disturbance and disturbance effects (Figure 4.4c). A positive C stock change value in a given year signifies that the factor(s) caused the forest to absorb more C from the atmosphere than it emitted, thus acting as a C sink. A negative C stock change value indicates that the factor(s) caused the forest to release more C to the atmosphere than it absorbed, thus acting as a C source.

Consecutively summing the annual C stock changes (Figure 4.4a-4.4c) yields the total accumulated ecosystem C since 1950 (Figure 4.4d). Positive values indicate accumulated effects that enhanced the total C stock, and negative values represent accumulated effects that reduced the total C stock. The total C emissions due to disturbances alone are also included (Figure 4.4e) and when added to the C stock change (NBP), yields the Net Ecosystem Productivity. The results of the InTEC model runs are numerous and include mapped outputs, C densities, and the effects of both non-disturbance and disturbance factors on individual component pools (e.g. aboveground live C, soil C), thus only summary results are presented here.

For further examples of how to interpret the figures in this section, see Section 6.1 of the main report which provides explanation of the regional InTEC results.

Allegheny National Forest

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25 (1) Aspen/birch Maple/Beech/Birch 20 Elm/ash/cottonwood Oak/gum/cypress 15 Oak/hickory Oak/pine Spruce/fir

10 White/Red/Jack pine Percentage Percentage of forest 5

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Allegheny National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

10 (2) 9

8 1)

- 7 1 yr 1

- 6 5 4 NPP (t ha C 3 White/Red/Jack pine Spruce/fir 2 Oak/pine Oak/hickory 1 Oak/gum/cypress Elm/ash/cottonwood Maple/Beech/Birch Aspen/birch 0 0 20 40 60 80 100 120 140 160 180 200 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Allegheny National Forest.

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160 10 (3a) (3b) 140 9

120 C) 100 ° 8 80 7 60 6

40 Total precip Temperature Temperature ( Precipitation(cm) 20 5 Mean temp 0 4 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 100 (3c) 80

20 Total Ndep Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Allegheny National Forest. Linear trend lines shown in black.

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1 1

(4a) Climate effects (4b)

1) -

CO2 effects 1) - N deposition effects

0 0

Disturbance\aging effects C stock stock C change (Tg yr C

C stock stock C change (Tg yr C Non-disturbance effects -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1 15 (4c) 1) (4d) - 10

0 0 All effects -5 Disturbance\aging Climate Accumulated Accumulated (Tg) C -10

C stock stock C change (Tg yr C All effects CO2 N deposition -1 -15 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.2

(4e)

1) - C emission due to disturbance

0.1 C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Allegheny National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

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Chequamegon-Nicolet National Forest

25 (1)

20 Aspen/birch Maple/beech/birch Elm/ash/cottonwood 15 Oak/gum/cypress Oak/hickory 10 Oak/pine

Percentage Percentage of forest Spruce/fir 5 White/red/jack pine

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Chequamegon-Nicolet National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir Oak/pine Oak/hickory 9 (2) Oak/gum/cypress Elm/ash/cottonwood

8 Maple/beech/birch Aspen/birch 1)

- 7 1 yr 1 - 6 5

4 NPP (t ha C 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Stand age (year) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Chequamegon-Nicolet National Forest.

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160 8 (3a) 140 7 (3b)

120 6 C) 100 ° 5 80 4 60 3

40 Total precip 2

Temperature Temperature ( Precipitation(cm) 20 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

60 Total Ndep

20 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Chequamegon-Nicolet National Forest. Linear trend lines shown in black.

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3 3

(4a) (4b)

1) -

2 1) 2 -

1 1

0 0

-1 -1 Climate effects

-2 CO2 effects -2 Disturbance/aging effects C stock stock C change (Tg yr C N deposition effects stock C change (Tg yr C Non-disturbance effects -3 -3 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 3 50 (4c)

1) 40 (4d) - 2 30 1 20 10 0 0 -10 All effects -1 -20 Disturbance/aging All effects Climate -2 Accumulated (Tg) C -30 CO2 C stock stock C change (Tg yr C -40 N deposition -3 -50 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.4

(4e) 1) - 0.3 C emissions due to disturbance 0.2

0.1 C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Chequamegon-Nicolet National Forest due to: (a) individual non-disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

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Chippewa National Forest 14 (1) 12 Aspen/Birch 10 Maple/beech/birch Elm/ash/cottonwood 8 Oak/hickory Oak/pine 6 Spruce/fir White/red/jack pine

4 Percentage Percentage of forest 2

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Chippawa National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir 9 Oak/pine Oak/hickory (2) Elm/ash/cottonwood Maple/beech/birch 8 Aspen/Birch

1) 7 -

1 yr 1 6 - 5 4

NPP (t ha C 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Chippawa National Forest.

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120 8 (3a) (3b) 100 7

6 C)

80 ° 5 60 4

40 3

Total precip 2 Temperature Temperature ( Precipitation(cm) 20 Mean temp 1 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

60 Total Ndep

20 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Chippawa National Forest. Linear trend lines shown in black.

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1 1

(4a) (4b)

1) -

0 0

Climate effects

CO2 effects Disturbance\aging effects C stock stock C change (Tg yr C

N deposition effects stock C change (Tg yr C Non-disturbance effects -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1 10

(4c) (4d)

1) - 5

0 0 All effects Disturbance\aging -5

All effects Accumulated (Tg) C Climate

C stock stock C change (Tg yr C CO2 N deposition -1 -10 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.4

(4e)

1) - 0.3 C emission due to disturbance 0.2

0.1 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Chippawa National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

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Green Mountain and Finger Lakes National Forests 18 (1) 16 Aspen/birch Maple/beech/birch 14 Elm/ash/cottonwood 12 Oak/gum/cypress Oak/hickory 10 Oak/pine 8 Spruce/fir White/Red/Jack pine

6 Percentage Percentage of forest 4 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Green Mountain and Finger Lakes National Forests displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/Red/Jack pine Spruce/fir Oak/pine Oak/hickory 10 (2) Oak/gum/cypress Elm/ash/cottonwood 9 Maple/beech/birch Aspen/birch

1) 8 -

1 yr 1 7 - 6 5

NPP (t ha C 4 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 240 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Green Mountain and Finger Lakes National Forests.

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200 8 (3a) (3b) 175 7

150 6 C) 125 ° 5 100 4 75 3

50 Total precip 2

Temperature Temperature ( Precipitation(cm) 25 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 8 (3b) 7

6 C) ° 5 4 3

2 Mean temp Temperature Temperature ( 1 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Green Mountain and Finger Lakes National Forests. Linear trend lines shown in black.

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1 1

(4a) (4b)

1) -

0 0

Climate effects CO2 effects Disturbance\aging effects

N deposition effects C stock stock C change (Tg yr C

C stock stock C change (Tg yr C Non-disturbance effects -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1 10

(4c) (4d)

1) - 5

0 0 All effects Disturbance\aging -5

Accumulated Accumulated (Tg) C Climate All effects CO2 C stock stock C change (Tg yr C N deposition -1 -10 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.1

(4e)

1) - C emission due to

disturbance C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Green Mountain and Finger Lakes National Forests due to: (a) individual non-disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre-1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 33 of 63

Hiawatha National Forest 20 (1) 18 16 Aspen/birch 14 Maple/Beech/Birch Elm/ash/cottonwood 12 Oak/gum/cypress 10 Oak/hickory 8 Oak/pine

6 Spruce/fir Percentage Percentage of forest 4 White/red/jack pine 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Hiawatha National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir Oak/pine Oak/hickory 9 (2) Oak/gum/cypress Elm/ash/cottonwood

8 Maple/Beech/Birch Aspen/birch 1)

- 7 1 yr 1 - 6 5

4 NPP (t ha C 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Hiawatha National Forest.

Page 34 of 63

160 8 (3a) (3b) 140 7

120 6 C) 100 ° 5 80 4 60 3

40 Total precip 2

Temperature Temperature ( Precipitation(cm) 20 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 70 (3c) 60

50 Total Ndep 40 30 20

10 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Hiawatha National Forest. Linear trend lines shown in black.

Page 35 of 63

2 2

(4a) (4b)

1) - 1 1

0 0

-1 Climate effects -1

CO2 effects Disturbance\aging effects C stock stock C change (Tg yr C

N deposition effects stock C change (Tg yr C Non-disturbance effects -2 -2 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 2 50 (4c) (4d)

1) 40 - 30 1 20 10 0 0 -10 All effects Disturbance\aging -20 -1 Climate All effects Accumulated (Tg) C -30 CO2 C stock stock C change (Tg yr C -40 N deposition -2 -50 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.3 (4e)

1) C emission due - 0.2 to disturbance

0.1

C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Hiawatha National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 36 of 63

Hoosier National Forest

16 (1) 14 Maple/beech/birch 12 Elm/ash/cottonwood 10 Oak/hickory Oak/pine 8 Loblolly/Shortleaf pine 6 White/Red/Jack pine

Percentage Percentage of forested 4

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Hoosier National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

12 (2)

1) -

1 yr 1 -

NPP (t ha C 4

White/Red/Jack pine Loblolly/Shortleaf pine 2 Oak/pine Oak/hickory Elm/ash/cottonwood Maple/beech/birch 0 0 20 40 60 80 100 120 140 160 180 200 220 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Hoosier National Forest.

Page 37 of 63

180 15 (3a) (3b) 160 14 140

13 C)

120 ° 100 12 80 11 60 10

40 Total precip

Temperature Temperature ( Precipitation(cm) 20 9 Mean temp 0 8 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 100 (3c) 80 Total Ndep 60

20 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Hoosier National Forest. Linear trend lines shown in black.

Page 38 of 63

1 1

(4a) Climate effects (4b)

1) -

CO2 effects 1) - N deposition effects

0 0

Disturbance\aging effects C stock stock C change (Tg yr C

C stock stock C change (Tg yr C Non-disturbance effects -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year

1 10 1)

- (4c) (4d)

0 0 All effects Disturbance\aging

-5 Climate Accumulated Accumulated (Tg) C

C stock stock C change (Tg yr C All effects CO2 N deposition -1 -10 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.1

(4e) 1) - C emission due to

disturbance C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Hoosier National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 39 of 63

Huron-Manistee National Forest 18 (1) 16 Aspen/birch Maple/Beech/Birch 14 Elm/ash/cottonwood 12 Oak/gum/cypress Oak/hickory 10 Oak/pine 8 Spruce/fir White/red/jack pine

6 Percentage Percentage of forest 4 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Huron-Manistee National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir Oak/pine Oak/hickory 9 (2) Oak/gum/cypress Elm/ash/cottonwood

8 Maple/Beech/Birch Aspen/birch 1)

- 7 1 yr 1

- 6 5

4 NPP (t ha C 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Huron-Manistee National Forest.

Page 40 of 63

140 10 (3a) (3b) 120 9

100 8

C) ° 80 7 60 6 40 5

Total precip Temperature Temperature ( Precipitation(cm) 20 4 Mean temp 0 3 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 70 (3c) 60 50 40 30 20 Total Ndep

10 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Huron-Manistee National Forest. Linear trend lines shown in black.

Page 41 of 63

2 2

(4a) (4b)

1) - 1 1

0 0

-1 Climate effects -1

CO2 effects Disturbance\aging effects C stock stock C change (Tg yr C

N deposition effects stock C change (Tg yr C Non-disturbance effects -2 -2 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 2 30

(4c) (4d) 1) - 20 1 10

0 0 All effects -10 Disturbance\aging -1 Climate All effects Accumulated (Tg) C -20 CO2 C stock stock C change (Tg yr C N deposition -2 -30 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.4

(4e) 1) - C emission due 0.3 to disturbance

0.2

0.1 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Huron-Manistee National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 42 of 63

Mark Twain National Forest

20 (1) 18 16 Maple/beech/birch Elm/ash/cottonwood 14 Oak/hickory 12 Oak/pine 10 Other eastern softwoods Loblolly/Shortleaf pine 8 White/Red/Jack pine

6 Percentage Percentage of forest 4 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Mark Twain National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/Red/Jack pine Loblolly/Shortleaf pine 12 Oak/pine Oak/hickory (2) Elm/ash/cottonwood Maple/beech/birch

1) -

1 yr 1 -

NPP (t ha C 4

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Mark Twain National Forest. The Loblolly/shortleaf curve was applied to the Other Eastern Softwoods forest type.

Page 43 of 63

180 16 (3a) (3b) 160 15 140

14 C)

120 ° 100 13 80 12 60 11

40 Total precip Temperature Temperature (

Precipitation(cm) Mean temp 20 10 0 9 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

60 Total Ndep

20 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Mark Twain National Forest. Linear trend lines shown in black.

Page 44 of 63

4 4 (4a) (4b)

1) 3 3

1) - 2 2 1 1 0 0 -1 -1 -2 Climate effects -2 CO2 effects Disturbance\aging effects C stock stock C change (Tg yr C -3 -3 N deposition effects stock C change (Tg yr C Non-disturbance effects -4 -4 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 4 80 3 (4c) (4d)

1) 60 - 2 40 1 20 0 0 All effects -1 -20 Disturbance\aging

-2 Accumulated (Tg) C -40 Climate All effects -60 CO2

C stock stock C change (Tg yr C -3 N deposition -4 -80 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1.0

(4e)

1) - 0.8 C emission due to disturbance 0.6

0.4

0.2 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Mark Twain National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1951-2011 excluding C accumulated pre- 1951; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 45 of 63

Monongahela National Forest

30 (1) 25 Aspen/birch Maple/beech/birch 20 Elm/ash/cottonwood Oak/hickory 15 Oak/pine Loblolly/Shortleaf pine Spruce/fir

10 White/Red/Jack pine Percentage Percentage of forest 5

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Monongahela National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below. White/Red/Jack pine Spruce/fir 12 Loblolly/Shortleaf pine Oak/pine (2) Oak/hickory Elm/ash/cottonwood Maple/beech/birch Aspen/birch

- 1 yr 1

- 8

6 NPP (t ha C 4

0 0 20 40 60 80 100 120 140 160 180 200 220 240 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Monongahela National Forest.

Page 46 of 63

200 12 (3a) (3b) 11 160

C) ° 120 9

80 8

Total precip 7 Temperature Temperature (

Precipitation(cm) 40 6 Mean temp 0 5 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 100 (3c) 80

20 Total Ndep Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Monongahela National Forest. Linear trend lines shown in black.

Page 47 of 63

2 2

(4a) (4b)

1) - 1 1

0 0

-1 Climate effects -1

CO2 effects Disturbance\aging effects C stock stock C change (Tg yr C

N deposition effects stock C change (Tg yr C Non-disturbance effects -2 -2 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 2 30

(4c) (4d) 1) - 20 1 10

(4e)

1) - C emission due to disturbance

0.1 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Monongahela National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 48 of 63

Ottawa National Forest 25 (1)

20 Aspen/birch Maple/Beech/Birch Elm/ash/cottonwood 15 Oak/hickory Spruce/fir

10 White/red/jack pine Percentage Percentage of forest 5

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Ottawa National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir 9 (2) Oak/hickory Elm/ash/cottonwood 8 Maple/Beech/Birch Aspen/birch

1) -

1 yr 1 - 5 4

Page 49 of 63

120 8 (3a) (3b) 100 7

6 C)

80 ° 5 60 4 40 3

Total precip 2 Temperature Temperature ( Precipitation(cm) 20 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 70 (3c) 60

50 Total Ndep 40 30 20

10 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Ottawa National Forest. Linear trend lines shown in black.

Page 50 of 63

2 2

(4a) (4b)

1) - 1 1

0 0

Climate effects -1 -1 Disturbance/aging effects CO2 effects

C stock stock C change (Tg yr C Non-disturbance effects N deposition effects stock C change (Tg yr C -2 -2 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 2 30 (4c) (4d)

20 1) - 1 10

0 0 All effects -10 Disturbance/aging -1 All effects Accumulated Accumulated (Tg) C Climate -20 CO2

C stock stock C change (Tg yr C N deposition -2 -30 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.2

(4e) 1) - C emissions due to disturbance

0.1 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Ottawa National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 51 of 63

Shawnee National Forest 18 (1) Maple/beech/birch 16 Elm/ash/cottonwood Oak/gum/cypress 14 Oak/Hickory 12 Oak/pine Other eastern softwoods 10 Loblolly/Shortleaf pine 8 White/Red/Jack pine 6

Percentage Percentage of forest 4 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Shawnee National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/Red/Jack pine Loblolly/Shortleaf pine Oak/pine Oak/Hickory 12 Oak/gum/cypress Elm/ash/cottonwood (2) Maple/beech/birch

1) -

1 yr 1 -

NPP (t ha C 4

0 0 20 40 60 80 100 120 140 160 180 200 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Shawnee National Forest. The Loblolly/shortleaf curve was applied to the Other Eastern Softwoods forest type.

Page 52 of 63

200 17 (3a) (3b) 16 160

C) ° 120 14

80 13

Total precip 12 Temperature Temperature (

Precipitation(cm) 40 11 Mean temp 0 10 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

60 Total Ndep

20 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Shawnee National Forest. Linear trend lines shown in black.

Page 53 of 63

1 1

(4a) (4b)

1) -

0 0

Climate effects CO2 effects Disturbance\aging effects

C stock stock C change (Tg yr C N deposition effects C stock stock C change (Tg yr C Non-disturbance effects -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1 15

(4c) (4d) 1) - 10

0 0 All effects -5 Disturbance\aging

All effects Climate Accumulated Accumulated (Tg) C

-10 CO2 C stock stock C change (Tg yr C N deposition -1 -15 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.1

(4e) 1)

- C emission due to

disturbance C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Shawnee National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 54 of 63

Superior National Forest

14 (1) 12 Aspen/Birch Maple/beech/birch 10 Elm/ash/cottonwood 8 Oak/gum/cypress Oak/hickory 6 Oak/pine Spruce/fir White/red/jack pine

Percentage of Percentage forset 4

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Superior National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/red/jack pine Spruce/fir Oak/pine Oak/hickory 8 Oak/gum/cypress Elm/ash/cottonwood (2)

7 Maple/beech/birch Aspen/Birch

1) -

1 yr 1 - 5

4 NPP (t ha C 3

0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Superior National Forest.

Page 55 of 63

120 7 (3a) (3b) 100 6

5 C)

80 ° 4 60 3 40

Total precip 2 Temperature Temperature ( Precipitation(cm) 20 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 50 (3c) 40

20 Total Ndep

10 Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Superior National Forest. Linear trend lines shown in black.

Page 56 of 63

3 3

(4a) Climate effects (4b)

1) - 2 CO2 effects 1) 2 N deposition effects - 1 1

0 0

-1 -1

-2 -2 Disturbance\aging effects C stock stock C change (Tg yr C

C stock stock C change (Tg yr C Non-disturbance effects -3 -3 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 3 30 (4c) (4d)

2 20

1) - 1 10

0 0 All effects -1 -10 Disturbance\aging Climate All effects Accumulated (Tg) C -2 -20 CO2

C stock stock C change (Tg yr C N deposition -3 -30 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1.0

(4e) 1) - 0.8 C emission due to disturbance 0.6

0.4

0.2 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Superior National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 57 of 63

Wayne National Forest

14 (1) Aspen/birch 12 Maple/beech/birch Elm/ash/cottonwood 10 Oak/gum/cypress Oak/hickory 8 Oak/pine Loblolly/Shortleaf pine White/Red/Jack pine 6

Percentage Percentage of forest 4

Stand age (years) Figure 4.1. Age class distribution in 2011 in the Wayne National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/Red/Jack pine Loblolly/Shortleaf pine Oak/pine Oak/hickory 12 Oak/gum/cypress Elm/ash/cottonwood (2) Maple/beech/birch Aspen/birch

- 1 yr 1 - 8

6 NPP (t ha C 4

0 0 20 40 60 80 100 120 140 160 180 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the Wayne National Forest.

Page 58 of 63

160 14 140 (3a) (3b) 13

120 C) 100 ° 12 80 11 60 10

40 Total precip Temperature Temperature ( Precipitation(cm) 20 9 Mean temp 0 8 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

60 Total Ndep

Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year

Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the Wayne National Forest. Linear trend lines shown in black.

Page 59 of 63

1 1

(4a) Climate effects (4b)

1) -

CO2 effects 1) - N deposition effects

0 0

Disturbance\aging effects

C stock stock C change (Tg yr C Non-disturbance effects C stock stock C change (Tg yr C -1 -1 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 1 10

(4c) (4d)

1) - 5

0 0 All effects Disturbance\aging All effects -5 Climate Accumulated Accumulated (Tg) C CO2

C stock stock C change (Tg yr C N deposition -1 -10 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.1 (4e)

1) C emission due to -

disturbance C emissions emissions C (Tg yr C 0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the Wayne National Forest due to: (a) individual non-disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non- disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre-1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

Page 60 of 63

White Mountain National Forest 18 (1) 16 Aspen/birch 14 Maple/Beech/Birch 12 Elm/ash/cottonwood Oak/gum/cypress 10 Oak/hickory 8 Oak/pine Spruce/fir

6 White/Red/Jack pine Percentage Percentage of forest 4 2 0

Stand age (years) Figure 4.1. Age class distribution in 2011 in the White Mountain National Forest displaying the percentage of forested area of each forest type in 10-year age classes. Forest types are symbolized by stacked, colored bars that also correspond to the forest types in Figure 2 below.

White/Red/Jack pine Spruce/fir 10 (2) Oak/pine Oak/hickory 9 Oak/gum/cypress Elm/ash/cottonwood Maple/Beech/Birch Aspen/birch

8 1)

- 7 1 yr 1 - 6 5 4 NPP (t ha C 3 2 1 0 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Stand age (years) Figure 4.2. Relationship between net primary productivity (NPP) and stand age for each forest type in the White Mountain National Forest.

Page 61 of 63

200 7 (3a) (3b) 6 150

C) ° 4 100 3

50 Total precip 2 Temperature Temperature ( Precipitation(cm) 1 Mean temp 0 0 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 80 (3c)

20 Total Ndep Nitrogendeposition (g/m2) 0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.3. (a) Total annual precipitation (cm), (b) average annual temperature (°C), and (c) total annual nitrogen deposition from 1951-2011 in the White Mountain National Forest. Linear trend lines shown in black.

Page 62 of 63

2 2

(4a) Climate effects (4b)

1) -

CO2 effects 1) - 1 N deposition effects 1

0 0

-1 -1

Disturbance\aging effects C stock stock C change (Tg yr C

C stock stock C change (Tg yr C Non-disturbance effects -2 -2 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 2 20

(4c) (4d) 1) - 1 10

0 0 All effects Disturbance\aging -1 -10 Climate All effects Accumulated (Tg) C CO2

C stock stock C change (Tg yr C N deposition -2 -20 1951 1961 1971 1981 1991 2001 2011 1951 1961 1971 1981 1991 2001 2011 Year Year 0.2 (4e)

1) C emission due to - disturbance

0.1 C emissions emissions C (Tg yr C

0.0 1951 1961 1971 1981 1991 2001 2011 Year Figure 4.4. Changes in carbon stocks in the White Mountain National Forest due to: (a) individual non- disturbance factors alone including climate variability, atmospheric CO2 concentration, and nitrogen deposition; (b) all disturbance factors such as fire, harvest, and insects, as well as regrowth and aging and the sum of all non-disturbance factors combined; and (c) all factors combined which is the sum of disturbance\aging and non-disturbance effects; (d) Accumulated C due to individual disturbance\aging and non-disturbance factors and all factors combined from 1950-2011 excluding C accumulated pre- 1950; and (e) C emissions due to disturbance events only. Positive values in Figures 4.4 a-c represent C sinks from the atmosphere or enhancement effects, whereas negative values represent C sources to the atmosphere, or detraction effects.

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