Case Study Discussion

It was concluded in Chapter 3 that payments should only be made for carbon actually sequestered, as verified by tree measurement or by models, such as in the NCAS toolbox, in conjunction with measurement. A case study in north Queensland illustrated both the direct physical

Table 5.1 Additionally of carbon sequestered in reforestations of mixed native rainforest species in north Queensland

Site number

Years since

C t-1 ha

C t-1 ha

C t-1 ha

planting

in treesa

in soilb

additional

1

5

9

-5

4

2

7

46

-6

40

3

9

91

-7

84

4

10

83

-8

75

5

11

134

-9

125

6

12

85

-10

75

7

13

86

-11

75

8

14

112

-12

100

9

15

126

-13

113

10

17

120

-14

106

11

18

127

-15

a Tree carbon is by measurement. b Soil carbon is by NCAS toolbox forecast.

Notes:

a Tree carbon is by measurement. b Soil carbon is by NCAS toolbox forecast.

Source: Author's own data.

Table 5.2 Value of CO2e removed from the atmosphere by reforestation plantations

Site number

Ct-1 ha

CO2e t-1 ha

US$/ha at

US$/ha/year

additional

(C*3.67)

US$10/tonne

1

4

15

147

29

2

40

147

1468

210

3

84

308

3083

343

4

75

275

2753

275

5

125

459

4588

417

6

75

275

2753

229

7

75

275

2753

212

8

100

367

3670

262

9

113

415

4147

276

10

106

389

3890

229

11

112

411

4110

228

Source: Author's own data.

Source: Author's own data.

Table 5.3 Carbon sequestered and CO2e removal and value, old growth rainforest, north Queensland

Site number

C t-1 ha

CO2e t-1 ha

US$/ha at

(C*3.67)

US$10/tonne

12a

277

1017

10166

13b

308

1130

a Site 12 had suffered relatively high cyclone damage which could explain the lower level of C measured compared with site 13. b The source of Site 13 tree measurement data (DBH) is Jensen (personal communication, 2007).

Notes:

a Site 12 had suffered relatively high cyclone damage which could explain the lower level of C measured compared with site 13. b The source of Site 13 tree measurement data (DBH) is Jensen (personal communication, 2007).

Source: Author's own data.

measurement of rainforest trees in plantations of different ages and the application of an allometric equation to the estimation of biomass and hence carbon sequestered per hectare. The carbon in old growth tropical rainforests was measured in the same way. These results were then compared with results obtained by the use of CAMFor in the NCAS toolbox (Australian Government, 2007) that is designed to forecast carbon sequestration in sites anywhere where trees can grow in Australia. The research thus provides an indication of net rate of accumulation of C in plantations and the value of carbon in plantations and old growth forests, and tests the relationship between results by allometric measurement and by using CAMFor.

Future forecasts of estimates of carbon in forests of different ages and the standard deviation of these forecasts are very useful for governments for the purposes of carbon accounting and for the purposes of payments for CO2e removals. They are also invaluable for developers in making investment decisions with respect to forestry projects. However, the periodic ground-level measurement of plantations is also indispensible in verifying their carbon content. Forestry projects designed with the aid of the NCAS and verified by measurement at five-year intervals are eligible to qualify under the Australian government's voluntary offset program and will also qualify under its carbon pollution reduction scheme.

The measurement of plantations gave higher results than toolbox estimates. Part of the difference is explained by the fact that the measured plots were all fertilized, whereas the toolbox estimates were for unfertilized plantations. A second reason may be the choice of plantations with reasonable growth for measurement and the rejection of two poor plantations for inclusion in the comparison.

An additional factor that may lead to the over-estimation of the carbon

Case Study Kyoto
Note: At harvest the carbon in trees falls to zero. Prunings and thinnings are left on the forest floor, reducing the carbon in trees and increasing the carbon in debris which decays over time.

Source: Author's compilation using The National Carbon Accounting System (Australian Government, 2007).

Figure 5.8 Tonnes of carbon forecast to be sequestered per hectare in a 2008 reforestation by a monoculture of hoop pine ( Araucaria cunninghamii) that is harvested and replanted after harvest in plantations that are measured is the result of the adoption of a general practice in the study area of including a higher percentage of pioneer trees in mixed plantings than would be found in an old growth forest. This practice allows the canopy to develop quickly and to suppress weed growth. Pioneer species are usually less dense and contain less carbon than slower growing species. A refinement would be the tailoring of biomass estimates by the identification of species and their densities in measured plantations.

Case Study Kyoto
Note: Hoop pine is either i) unharvested ii) harvested (and replanted after harvest), or iii) where the product is sequestered after harvest.

Source: Author's compilation using The National Carbon Accounting System (Australian Government, 2007).

Figure 5.9 Total tonnes of onsite carbon forecast to be sequestered per hectare in a 2008 reforestation by a monoculture of hoop pine (Araucaria cunninghamii)

Errors in the application of allometric equations have been estimated by Chave et al. (2004: 416), concluding that measurement uncertainty of 5 percent could be added to an uncertainty of 10 percent with respect to wood density. A conservative estimate of additional carbon could be thus obtained by deducting 15 percent from the estimates of the annual additional increment of carbon at each site in Table 5.1.

The measurement of trees and soils in forests is labor-intensive and involves travel to sites and accommodation of professional personnel. One estimate of the costs of measurement based on a study in 325 hectares of plantation in northern New South Wales, Australia, is US$240 per hectare. This cost approximates the annual incremental value of carbon sequestered per hectare in this study; see Table 5.1. The costs may be able to be reduced, however, by the pooling of smaller plantations which would allow higher confidence limits to be achieved at a lower sampling level (Specht and West, 2003).

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