Corrigendum

This article refers to:

What proportion of the costs of urban trees can be justified by the carbon sequestration and air-quality benefits they provide?

Sunderland, T., Rogers, K., and Coish, N. (2012). What proportion of the costs of urban trees can be justified by the carbon sequestration and air-quality benefits they provide? Arboricultural Journal: The International Journal of Urban Forestry, 34(2), pp. 62–82. http://dx.doi.org/10.1080/03071375.2012.701416

The above article was published online and in print with a significant error. The formula for the calculation of the discount rate was stated and applied incorrectly. This reduced the flow of benefits from the trees, in some cases significantly. Correcting this error required changes to the results for the illustrative analysis for the individual trees. The correction to the discount rate formula and explanation are given below.

The incorrect formula was:

The correct formula is:

Table 2

End of life removal costs for Maritime Pine and Oak should be £1080 and not £2000.

Table 7 Results for individual trees at Green Book discount rate (3.5% and then declining step-wise according to Green Book schedule).

Tree	Location	Low			Central			High
		Costs (£)	Benefits (£)	Cost: Benefit ratio	Costs (£)	Benefits (£)	Cost: Benefit ratio	Costs (£)	Benefits (£)	Cost: Benefit ratio
Lime	Street	2287.59	176.65	1: 0.08	2287.59	841.90	1: 0.37	2287.59	2133.92	1: 0.93
Cherry	Street	2152.80	4.63	1: 0.00	2152.80	14.66	1: 0.01	2152.80	31.88	1: 0.01
Pine	Park	626.54	65.11	1: 0.10	626.54	291.23	1: 0.46	626.54	720.30	1: 1.15
Oak	Park	667.85	294.17	1: 0.44	667.85	1396.69	1: 2.09	667.85	3521.52	0: 5.27

Table 8 Results for individual trees at sensitivity discount rate (2.1%).

Tree	Location	Low			Central			High
		Costs (£)	Benefits (£)	Cost: Benefit ratio	Costs (£)	Benefits (£)	Cost: Benefit ratio	Costs (£)	Benefits (£)	Cost: Benefit ratio
Lime	Street	2341.99	372.73	0.16	2341.99	1788.09	0.76	2341.99	4535.33	1.94
Cherry	Street	2170.13	5.66	0.00	2170.13	17.67	0.01	2170.13	38.11	0.02
Pine	Park	715.80	125.24	0.17	715.80	562.42	0.79	715.80	1390.46	1.94
Oak	Park	680.61	678.50	1.00	680.61	3258.15	4.79	680.61	8237.61	12.10