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Quick Estimates of Carbon in Loblolly Pine Plantations Using Carbon-Basal Area Ratios

Filed Under:
Publication Number: P3841
View as PDF: P3841.pdf

Many people have concerns about global warming, climate change, depletion of the ozone layer, and related issues. These concerns make carbon released into the atmosphere a significant issue. Regardless of personal feelings about the politics of these issues, carbon sequestration and storage in forests is a necessity for life. Have you ever wondered how much carbon is sequestered and stored in your loblolly pine (Pinus taeda L.) plantation?

Recently, forest carbon markets have once again become an opportunity for forest landowners to receive some supplemental income. At a basic level, these markets allow industries that are emitting carbon during their production process to offset those emissions by purchasing carbon credits from others that are sequestering carbon beyond their usual practices. Carbon credits can be purchased from forest landowners who are sequestering carbon beyond what they normally would do without the presence of a forest carbon market—or their business-as-usual (BAU) forest management practices. Carbon markets allow these industries to offset their carbon emissions from landowners who are sequestering an additional amount of carbon beyond their BAU, hence the concept of additionality.

Increasingly, nonindustrial private forest (NIPF) landowners who own smaller acreages in Mississippi have access to forest carbon markets that allow them to participate more actively. Some refer to NIPF landowners as family forest owners. NIPF and larger public and private forest landowners alike will be interested in knowing how many metric tons of carbon and carbon dioxide equivalents (abbreviated as MtCO2e) their plantation is sequestering and storing.

This publication describes a quick and low-cost means of obtaining a carbon per acre estimate. It then shows how carbon per acre is mathematically converted into metric tons, as well as how carbon is converted into metric tons of carbon dioxide equivalents (MtCO2e) by using basic assumptions about the chemistry of wood. By using variable-radius sampling, we can take advantage of relationships between tree stem growth and carbon production, to ultimately estimate carbon per acre.

 

described in text

Figure 1. Basal area of a forest at a height of 4.5 feet above the ground (diameter at breast height or simply dbh) is a common measure used to quantify site occupancy of the overstory trees. It gives us an idea of the amount of competition for limited site resources of light, moisture, and nutrients. Subsequently, it is commonly used as a tool to determine when thinnings or other forest management techniques should be conducted. It is also an indirect measure of wildlife habitat.

 

Two images of pine plantations.

Figure 2. There is often a strong relationship between the basal area of a loblolly pine plantation and the amount of carbon being sequestered and stored within the overstory trees. Additionally, basal area is often a very good predictor of understory biomass. If there is a strong relationship (or strong correlation) between basal area and carbon, then by knowing basal area per acre, you essentially know carbon per acre. We can use this to our advantage. Basal area can be quickly obtained using variable-radius sampling protocols, and then a regionwide carbon-basal area ratio (CBAR) can be used to estimate carbon per acre in the trees.

 

Estimating Carbon Using Variable-Radius Sampling and CBAR

Basal area per acre is a useful measure that provides information about the amount of site occupancy by the trees within a forest. Variable-radius sampling is highly advantageous because a very quick estimate of basal area can be obtained by merely counting the number of “in” trees, and then multiplying the number of “in” trees by a user-selected basal area factor (BAF).

Historically, volume-basal area ratios (VBARs) and weight-basal area ratios (WBARs) have been associated with variable-radius sampling. This publication introduces the concept of a carbon-basal area ratio (CBAR). We can assume that for each square foot increase in basal area, there is an associated increase in carbon.

Variable-radius sampling is known by a variety of names, including point sampling, horizontal-point sampling, angle-gauge sampling, horizontal-angle sampling, and prism sampling, among others. Due to the protocol of variable-radius sampling, for a particular BAF, an “in” tree always represents the same amount of basal area per acre. Therefore, if a 20 BAF is used, each “in” tree—or each sampled tree—represents 20 square feet of basal area per acre. The most common BAF in this region is 10, but a 20 BAF is often preferable, and a 5 BAF could be useful, as well. Remember, it is best to sample around 6 to 10 trees per sampling point. For the sake of convention, the term “point” is used rather than “plot” since we are referring to inventories being conducted using variable-radius sampling and not fixed-radius sampling.

When conducting quick assessments, it is often sufficient to estimate carbon based upon the easily and quickly obtainable basal area per acre. After obtaining an estimate of basal area per acre, the amount of carbon per acre can be obtained by simply multiplying that amount by an average CBAR. Thus, individual tree diameters and heights do not need to be measured. To estimate carbon per acre, for example, use the following formula after obtaining an estimate of basal area per acre:

Carbon Per Acre = CBAR x BA [1]

Where:

CBAR = average carbon-basal area ratio, and

BA = an estimate of basal area per acre from variable-radius points.

There are several methods for obtaining an estimate of basal area per acre: (1) simply use your thumb (Figure 3); (2) use the Mississippi State University (MSU) Basal Area Angle Gauge; (3) perform a quick prism sweep of the forest; or (4) use a Jim-Gem® Cruz-All. Calculations can be as simple as establishing three or four points within a forest and then averaging the three or four basal area per acre estimates. Or you can perform a more extensive inventory—one point per acre or the number of points necessary to meet some desired level of precision. The sampling approach described here is for those cases when a relatively low intensity of sampling is sufficient. This inventory protocol will provide only basic information about a landowner’s forested condition. Basal area often can be estimated in 2 minutes and even less time at an individual point using a thumb, prism, or any other angle gauge to project horizontal angles.

 

A woman uses her thumb to measure pine trees.
Figure 3. A thumb can be used to project an “imaginary” horizontal angle, which can be equated to a basal area factor (BAF). If you extend your thumb some distance from your eye, assuming the vertex of the angle (where the angle begins) is located in your eye, then an imaginary horizontal angle is projected out to your thumb and beyond (depicted on the right). This is the same approach used for stick angle-gauges, Cruz-All tools, etc. Depending on the width of your thumb and your arm distance, you can use this approach to generate your own BAF. Whenever the width of the thumb is smaller than the tree image at 4.5 feet above the ground (diameter at breast height) the tree is “in.” To obtain basal area per acre, just multiply the number of “in” trees at each point by your thumb-specific BAF.

 

The Importance of Knowing the Definition of Carbon

If you have been associated with forest carbon or participated in forest carbon markets, you know there is a wide range of interpretations, verbiage, definitions, units, and carbon pools that can be included or excluded from a particular analysis and market. The term “carbon pool” refers to the components of a forest that are sequestering carbon. From a forest carbon market perspective, it refers to the components of a forest that are being evaluated for their sequestration and storage.

When we talk about the amount of carbon being stored in a plantation, there are terms that need definition. For instance, are we talking about the amount of carbon within tree stems, or are branches included? Are roots and foliage also included. Within a loblolly pine plantation, is it just the planted trees, or does it also include loblolly pine wildlings (nonplanted loblolly pine), other pine species, or any hardwoods such as oak, hickory, or sweetgum. For the trees, is it only the living material or dead material as well? Is the understory vegetation carbon pool being considered? Carbon markets have also tried to monitor the amount of carbon sequestered and stored within harvested wood products obtained from forests. What is the long-term carbon storage of lumber, plywood, paper, or other products?

As you can see, it is essential that you know what carbon pools are being included in your estimate. Also, what units of measurement are you using—pounds, tons, or metric tons? Are you measuring basal area in square feet per acre or square meters per hectare?

For this publication, carbon estimates are only for the LIVING trees sampled during the basal area inventory. Additionally, the amount of carbon being sequestered, or stored, includes only the woody components of a tree, so the foliage is not included in the carbon estimate. Both aboveground and belowground components are estimated. Therefore, the carbon estimates presented here are not exhaustive.

Converting Carbon Into Metric Tons

Carbon is often reported, described, and discussed in terms of metric tons, where a metric ton is about 2,205 pounds. To use the approach described in this publication, any carbon estimate must first be in pounds or converted to pounds. After converting the estimate to pounds, divide it by 2,205.

Users may also see carbon reported in metric units such as kilograms. To convert from kilograms to pounds, multiply the kilogram estimate by 2.205.

Occasionally carbon is reported in tons—not metric tons. In these instances, divide the carbon in pounds by 2,000.

Always make sure that you clearly understand the units of a carbon measurement.

Converting Carbon Into Metric Tons of Carbon Dioxide Equivalents

Many people talk about metric tons of carbon dioxide equivalents, which is often abbreviated as MtCO2e. You can calculate a carbon dioxide equivalent based on the atomic weights (mass) of carbon and oxygen. Carbon has an atomic weight around 12, and oxygen has an atomic weight around 16 (12 + [16 x 2] = 44). If we divide 44 from carbon dioxide by 12 from carbon, we get a multiplier for carbon dioxide equivalency of 44/12 = 3.667. To obtain the amount of carbon dioxide being sequestered within a forest, multiply any carbon estimate by 3.667. This constant applies whether carbon is in pounds, kilograms, tons (2,000 pounds), or metric tons (2,205 pounds). For simplicity, we assume this exact multiplier applies to all tree species.

Examples of How to Estimate Carbon

Example One — Estimating Carbon Per Acre of Loblolly Pine

Landowners have heard a lot about forest carbon markets and the benefits of carbon sequestration for our environment, so they are curious about how much carbon is “sequestered” in the pine trees in their 10-year-old plantation.

This example assumes that you use the thumb method to obtain an estimate of basal area per acre. For this example, assume that your thumb has a BAF of 8. You establish three points, and there is a total of 24 “in” trees. Thus, across the three points, there is an average basal area per acre of 64 square feet (8 BAF x 8 “in” trees per point on average = 64). For simplicity, to use Table 1, round the 64 square feet per acre to 65 square feet. Based on Table 1, you obtain a CBAR of 358 pounds. Then multiply 358 by 64 square feet; this yields an estimate of around 22,912 pounds of carbon per acre being stored in your plantation. Now, let’s convert the carbon into metric tons (2,205 pounds per metric ton). Divide 22,912 pounds per acre by 2,205 pounds. Therefore, you estimate your 10-year-old plantation is “sequestering” around 10.39 metric tons per acre in this example.

Many people talk about metric tons of carbon dioxide equivalents (MtCO2e). An equivalent can be calculated based on the atomic weights (mass) of carbon and oxygen. Carbon has an atomic weight around 12, and oxygen has an atomic weight around 16 (12 + [16 x 2] = 44). If we divide 44 from carbon dioxide by 12 from carbon, we get a multiplier for carbon dioxide equivalency of 44/12 = 3.667. Thus, in this example, your forest has a carbon dioxide equivalent of around 38.1 metric tons, or 38.1 MtCO2e.

Example Two — Estimating Carbon Per Acre of Loblolly Pine and Hardwoods

Let’s assume that you are meeting with an Extension specialist or consulting forester and decide to “walk” your property. After visiting a loblolly pine plantation that also contains some hardwoods, you have questions about carbon sequestration and storage in this stand. You are not sure of the age of the plantation because you recently inherited the property. Out of curiosity, the consultant decides to quickly measure three variable-radius sampling points by using a 10 BAF prism. Across the three points, the average loblolly pine basal area per acre is estimated to be 120 square feet per acre. In addition, there is 10 square feet of basal area per acre of hickory, 20 square feet of basal area per acre of sweetgum, and 3.33 square feet of basal area of ash. How do you get 3.33 square feet when using three points? Since you don’t know the plantation age, and you want to estimate carbon for species other than loblolly pine, you must use Table 3. If you knew the plantation age, only for loblolly pine, we could first use Tables 1 or 2 and then use Table 3 to estimate carbon for all other species.

Remember, the average basal area per acre estimate is across the three points. Thus, at two points there were no “in” ash trees; at one point, there was one ash tree sampled. Since the consultant used a 10 BAF prism, across the three points, on average, there is 3.33 square feet per acre (10 / 3). Also, notice in Table 3 that there is no CBAR specifically for ash trees. Thus, ash is lumped into the “Other hardwood” category, and you will use a CBAR of 489 pounds per square foot of basal area. Therefore, your estimate is 1,628.37 pounds of carbon per acre in ash (489 pounds x 3.33 square feet of basal area per acre).

A similar procedure is used for the hickory and sweetgum, resulting in 6,070 and 8,960 pounds per acre of carbon in these trees, respectively. For loblolly pine, since you don’t know the age, you cannot use Tables 1 and 2, so you need to use Table 3. In this example, you have 120 square feet per acre of basal area for loblolly pine. And the number of pounds per square foot of basal area is 591. Therefore, your estimate is around 70,920 pounds per acre of carbon in these trees.

Example Three — Estimating Carbon Per Acre of Loblolly Pine and Other Pine Species

In this example, let’s assume you want to find out how much carbon is “sequestered” in the pine trees of a 25-year-old plantation. However, it includes some pine species other than loblolly pine. In this case, you establish two points using the MSU Basal Area Angle Gauge, which has a BAF of 10. Across the two points, there are 14 sampled loblolly pine trees, or “in” trees. Thus, across the two points, there is 140 square feet of basal area; since there are two points, you must divide that number by two to obtain an average basal area per acre of 70 square feet (10 BAF x 14 “in” trees on two points, average = 70). Table 2 provides an estimate that the 25-year-old plantation is sequestering 20.12 metric tons per acre. When using Table 1, the same value is obtained (634 x 70 square feet per acre, and then dividing by 2,205).

In addition to the loblolly pine trees, there are also three “in” trees of longleaf pine, across the two points. Thus, three sampling points multiplied by 10 square feet of basal area equals 30 square feet; when divided by two points, we obtain an estimate of 15 square feet of basal area per acre. We can use the “Other pine” category in Table 3 for these longleaf pine trees. For the “Other pine” category, the amount of carbon is estimated to be 610 pounds per square foot of basal area. Therefore, after doing the math (610 x 15 square feet of basal area), we estimate there is around 9,150 pounds of carbon per acre. For metric tons, we can divide the 9,150 pounds by 2,205 (pounds per metric ton) and get 4.15 metric tons per acre.

For MtCO2e, the carbon dioxide equivalency multiplier of 44/12 = 3.667 should be used. Remember that, in forestry, we often make simplifying assumptions given the costs of obtaining more detailed measurements, so we assume across all species that the 3.667 constant is applicable. Thus, this landowner’s forest has a carbon dioxide equivalent of around 73.78 MtCO2e for the loblolly pine and around 15.22 MtCO2e for the longleaf pine. These two values total to 89.00 MtCO2e.

 

Table 1. CBARs (in pounds) presented below can be used for loblolly pine based on the basal area per acre estimate (diameter at breast height [dbh], 4.5 feet above the ground) and when stand age is known.1

Basal area per acre (square feet)

10-year-old stand

15-year-old stand

20-year-old stand

25-year-old stand

30-year-old stand

35-year-old stand

40-year-old stand

45-year-old stand

10

273

393

479

545

599

645

684

719

15

291

412

497

563

618

663

703

738

20

304

425

510

577

631

676

716

751

25

315

435

520

587

641

687

726

761

30

323

443

529

595

649

695

735

770

35

330

450

536

602

656

702

742

777

40

336

457

542

608

662

708

748

783

45

341

462

547

614

668

714

753

788

50

346

467

552

618

673

718

758

793

55

351

471

557

623

677

723

762

797

60

355

475

560

627

681

727

766

801

65

358

479

564

630

685

730

770

805

70

362

482

568

634

688

734

773

808

75

365

485

571

637

691

737

777

812

80

368

488

574

640

694

740

779

814

85

371

491

576

643

697

743

782

817

90

373

494

579

645

699

745

785

820

95

376

496

581

648

702

748

787

822

100

378

498

584

650

704

750

790

825

105

 

501

586

652

706

752

792

827

110

 

503

588

654

709

754

794

829

115

 

505

590

656

711

756

796

831

120

 

507

592

658

713

758

798

833

125

 

509

594

660

714

760

800

835

130

 

510

596

662

716

762

802

837

135

 

512

598

664

718

764

803

838

140

 

514

599

665

720

765

805

840

145

 

515

601

667

721

767

807

842

150

 

517

602

669

723

769

808

843

155

 

 

604

670

724

770

810

845

160

 

 

605

672

726

772

811

846

165

 

 

607

673

727

773

813

848

170

 

 

608

674

729

774

814

849

175

 

 

609

676

730

776

815

850

180

 

 

611

677

731

777

817

852

185

 

 

 

678

732

778

818

853

190

 

 

 

679

734

779

819

854

195

 

 

 

681

735

781

820

855

200

 

 

 

682

736

782

821

856

205

 

 

 

683

737

783

822

857

210

 

 

 

684

738

784

824

859

1Carbon is only for living trees with a dbh of 1 inch and greater and for the entire woody component of a tree, both aboveground and belowground, but excludes foliage. CBARs are calculated using CBAR = -516.321 + 45.71438 * ln(baacre) + 296.9672 * ln(Age), n = 590, Adj. R2 = 0.7107. After calculating the amount of carbon per acre in pounds based on the CBAR and basal area, divide by 2,000 for tons of carbon or 2,205 for metric tons of carbon.

 

Table 2. Metric tons of carbon per acre (2,205 pounds per metric ton) estimates based on the CBARs presented in Table 1.1

Basal area per acre (square feet)

10-year-old stand

15-year-old stand

20-year-old stand

25-year-old stand

30-year-old stand

35-year-old stand

40-year-old stand

45-year-old stand

10

1.24

1.78

2.17

2.47

2.72

2.92

3.10

3.26

15

1.98

2.80

3.38

3.83

4.20

4.51

4.78

5.02

20

2.76

3.85

4.63

5.23

5.72

6.14

6.50

6.81

25

3.57

4.93

5.90

6.65

7.27

7.79

8.23

8.63

30

4.39

6.03

7.19

8.10

8.83

9.46

10.00

10.47

35

5.24

7.15

8.51

9.56

10.42

11.14

11.77

12.33

40

6.10

8.28

9.83

11.03

12.02

12.85

13.57

14.20

45

6.97

9.43

11.17

12.52

13.63

14.56

15.37

16.08

50

7.85

10.58

12.52

14.02

15.25

16.29

17.19

17.98

55

8.75

11.75

13.88

15.53

16.88

18.03

19.02

19.89

60

9.65

12.93

15.25

17.05

18.53

19.77

20.85

21.80

65

10.56

14.11

16.63

18.58

20.18

21.53

22.70

23.73

70

11.48

15.30

18.02

20.12

21.84

23.29

24.55

25.66

75

12.41

16.51

19.41

21.66

23.51

25.06

26.41

27.60

80

13.34

17.71

20.81

23.22

25.18

26.84

28.28

29.55

85

14.28

18.93

22.22

24.77

26.86

28.63

30.15

31.50

90

15.23

20.15

23.63

26.34

28.55

30.42

32.04

33.46

95

16.18

21.37

25.05

27.91

30.24

32.21

33.92

35.43

100

17.14

22.60

26.48

29.48

31.94

34.01

35.81

37.40

105

 

23.84

27.91

31.06

33.64

35.82

37.71

39.38

110

 

25.08

29.34

32.65

35.35

37.63

39.61

41.36

115

 

26.33

30.78

34.24

37.06

39.45

41.52

43.34

120

 

27.58

32.23

35.83

38.78

41.27

43.43

45.33

125

 

28.83

33.68

37.43

40.50

43.10

45.34

47.33

130

 

30.09

35.13

39.04

42.23

44.93

47.26

49.33

135

 

31.35

36.58

40.64

43.96

46.76

49.19

51.33

140

 

32.62

38.05

42.25

45.69

48.60

51.11

53.34

145

 

33.89

39.51

43.87

47.43

50.44

53.05

55.35

150

 

35.17

40.98

45.49

49.17

52.28

54.98

57.36

155

 

 

42.45

47.11

50.91

54.13

56.92

59.38

160

 

 

43.92

48.73

52.66

55.98

58.86

61.40

165

 

 

45.40

50.36

54.41

57.84

60.80

63.42

170

 

 

46.88

51.99

56.17

59.70

62.75

65.45

175

 

 

48.37

53.63

57.92

61.56

64.70

67.48

180

 

 

49.85

55.26

59.68

63.42

66.66

69.51

185

 

 

 

56.90

61.45

65.29

68.61

71.55

190

 

 

 

58.55

63.21

67.16

70.57

73.59

195

 

 

 

60.19

64.98

69.03

72.54

75.63

200

 

 

 

61.84

66.75

70.90

74.50

77.67

205

 

 

 

63.49

68.52

72.78

76.47

79.72

210

 

 

 

65.14

70.30

74.66

78.44

81.77

1Carbon is only for living trees with a dbh of 1 inch and greater and for the entire woody component of a tree, both aboveground and belowground, but excludes foliage.

 

Other Potential Applications

Carbon estimates obtained using this CBAR approach can also be used to quickly validate carbon estimates obtained through other sampling protocols. For example, inexperienced foresters could quickly double-check their carbon estimates to ensure their estimates when using another approach is reasonable. Consulting foresters can provide a quick estimate of carbon per acre when initially meeting with landowners.

There are likely other applications of the presented average CBARs. For instance, LiDAR (light detection and ranging, a remote sensing method) often provides an acceptable estimate of basal area per acre, but the approach currently does not directly provide estimates of sufficient quality for carbon. Thus, the CBAR approach described here could be used to provide estimates of carbon per acre when using LiDAR to conduct inventories. Alternatively, for loblolly pine, the per acre values in Table 2—based upon the CBARs in Table 1—could be used along with the LiDAR basal area estimate.

 

Table 3. Average CBARs by species or species group.1

Species/Species Group

Number2

CBAR (pounds)

CBAR (metric tons) CBAR x 2,2205

CBAR (MtCO2e)

CBAR x 2,205 x 3.667

Loblolly pine

590

591

0.2679

0.0731

Hickory

37

607

0.2754

0.0751

Oak

156

658

0.2986

0.0814

Sweetgum

230

448

0.2033

0.0554

Other pine

48

610

0.2766

0.0754

Other hardwood

258

489

0.2220

0.0605

Other softwood

24

354

0.1608

0.0438

         

All hardwood species

681*

521

0.2361

0.0644

¹Carbon is only for living trees with a dbh of 1 inch and greater and for the entire woody component of a tree, both aboveground and belowground, but excludes foliage. “Other softwood” includes eastern redcedar and baldcypress.

2This refers to the sample size used to estimate the species specific CBAR (* Exceeds 590 because some FIA plots have more than one hardwood species or species group).

 

APPENDIX

Development of Carbon-Basal Area Ratios

For this publication, average CBARs were calculated using USDA Forest Inventory and Analysis (FIA) inventories of loblolly pine plantations within Mississippi. Within FIA, only those plots classified as loblolly pine (FORTYPCD = 161 within the FIA database) and a plantation (STDORGCD = 1 within the FIA database) were selected. Only plots 6 years or older were included. Plots with site indexes (base age 25) less than 45 feet and greater than 90 feet were deleted. All FIA plots with a basal area per acre (across all species) less than 10 square feet and greater than 225 square feet were deleted. Site index at base age 25 used the FIA-reported site index at base age 50 along with the appropriate equation from Schumacher and Coile (1960). After meeting these criteria, the average plantation age was 22 years old, and the oldest plantation was 43 years old.

In addition to the CBAR for loblolly pine itself, a CBAR was also calculated for all other species within these plantations. CBARs were calculated for sweetgum (Liquidambar styraciflua L.) and select groups of several species. Select groups were oaks (Quercus spp.), hickories (Carya spp.), other pine (Pinus spp.) species (“Other pine”), all other softwood species (“Other softwood”), and then all other hardwood species (“Other hardwood”). Finally, for those who just want an estimate when grouping together all hardwood species, all hardwood species were grouped together (“All hardwood species,” Table 3).

Summary of Data Used to Produce CBARs

Following is a summary of the data used to produce the CBARs presented in Tables 1 to 3. PLEASE NOTE that carbon estimates in this publication are only for the LIVING trees sampled during the basal area inventory. Additionally, the amount of carbon being sequestered is ONLY of the woody component, thus the foliage is not included in the carbon estimate. Both aboveground and belowground components are estimated. However, forests contain many more carbon pools, such as dead trees, understory vegetation, and mushrooms. For these other carbon pools, there are both the aboveground and belowground components. Thus, the carbon estimates presented in here are not exhaustive.

 

Trees Per Acre

Species/species group

Number

Mean

Min

Max

Loblolly pine

590

162

6

584

Hickory

37

8

6

24

Oak

156

15

6

102

Sweetgum

230

17

6

108

Other pine

48

15

6

72

Other hardwood

258

15

6

78

Other softwood

24

8

6

36

All species

592

180

6

590

 

Basal Area Per Acre

Species/species group

Mean

Min

Max

Loblolly pine

103

3

217

Hickory

4

1

16

Oak

8

1

76

Sweetgum

6

1

51

Other pine

9

1

36

Other hardwood

7

1

74

Other softwood

6

1

29

All species

112

1

217

 

Volume Per Acre

Species/species group

Mean

Min

Max

Loblolly pine

2,564

12

6,497

Hickory

69

5

299

Oak

176

8

1,921

Sweetgum

117

3

1,087

Other pine

248

6

990

Other hardwood

126

8

1,909

Other softwood

97

9

533

All species

2,730

4

6,497

 

Tons Per Acre

Species/species group

Mean

Min

Max

Loblolly pine

63.8

0.1

201.3

Hickory

1.7

0.1

9.0

Oak

4.7

0.2

50.8

Sweetgum

2.6

0.1

24.9

Other pine

6.6

0.2

28.8

Other hardwood

2.8

0.2

28.6

Other softwood

1.9

0.3

12.4

All species

67.7

0.1

204.5

 

The following tables summarize the USDA Forest Service Forest Inventory and Analysis (FIA) plot data for trees classified as merchantable (living trees with a minimum dbh of 5 inches). Volume and tons per acre are based on a 1-foot stump to a 4-inch top diameter outside-bark (DOB) limit. Tons per acre is based on 2,000 pounds per ton.

Below is a summary of the USDA Forest Service FIA plot data for all living trees of dbh 1 inch and greater. Carbon is measured in metric tons (2,205 pounds) per acre.

For these loblolly pine plantations, site index (base age 25) averaged 65 feet and ranged from 45 feet to 89 feet. Site index at base age 25 used the reported site index at base age 50 along with the appropriate equation from Schumacher and Coile (1960).

 

Trees Per Acre

Species/species group

Number

Mean

Min

Max

Loblolly pine

592

229

6

2,007

Hickory

82

112

6

675

Oak

294

137

6

900

Sweetgum

335

176

6

936

Other pine

52

40

6

336

Other hardwood

400

236

6

1,505

Other softwood

41

71

6

750

All species

592

579

6

3,156

 

Carbon Per Acre

Species/species group

Number

Mean

Min

Max

Loblolly pine

592

29.4

0.72

72.5

Hickory

82

0.9

0.04

5.1

Oak

294

2.1

0.04

26.0

Sweetgum

335

1.8

0.03

15.0

Other pine

52

2.8

0.10

11.3

Other hardwood

400

1.9

0.03

23.6

Other softwood

41

1.0

0.05

6.4

All species

592

33.1

1.25

74.3

 

Basal Area Per Acre 

Species/species group

Mean

Min

Max

Loblolly pine

108

18

217

Hickory

4

0

16

Oak

8

0

76

Sweetgum

11

0

63

Other pine

10

1

36

Other hardwood

11

0

90

Other softwood

7

1

34

All species

128

28

225

The information given here is for educational purposes only. References to commercial products, trade names, or suppliers are made with the understanding that no endorsement is implied and that no discrimination against other products or suppliers is intended.


Publication 3841 (POD-11-22)

By Curtis L. VanderSchaaf, Assistant Professor, Central Mississippi Research and Extension Center. Dr. Matt Russell, a biometrics consultant, and Dr. Aaron Weiskittel, University of Maine, provided several useful comments.

Department: Forestry
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Portrait of Dr. Curtis L. VanderSchaaf
Assistant Professor