The Effects Of Pruning Type On Wind Loading Of Acer Rubrum

E. Thomas Smiley; Brian Kane

doi:10.48044/jauf.2006.005

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Figure 1.
Truck setup used for testing wind loading.
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Figure 2.
Scatter plot and best fit line for the relationship between wind load on unpruned trees and velocity.
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Figure 3.
Scatter plot and best fit lines for the relationship between reduction in wind load at 20 m/sec (45 mph) and reduction in weight (unpruned tree weight minus pruned tree weight) for three pruning types. P-values relate to the comparison of line slopes for pruning types listed.
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Figure 4.
Mean reduction in bending moment (M_B) at three velocity levels (11, 16, and 20 m/sec (25, 35, and 45 mph]) for each of three pruning types and with all of the foliage stripped off.

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Table 1.

Mean reduction in wind load at three velocity levels (11, 16, and 20 m/sec [25, 35, and 45 mph]) for each pruning type or for trees with all of the foliage stripped off of the branches.

Pruning type	Velocity (m/sec)	Velocity (mph)	Reduction in wind load^{^z} (N)	P-value
Lion tailed	11	25	78	< 0.01^*
Lion tailed	16	35	140	< 0.01^*
Lion tailed	20	45	200	< 0.01^*
Reduced	11	25	96	< 0.01^*
Reduced	16	35	130	< 0.01^*
Reduced	20	45	144	< 0.01^*
Stripped	11	25	136	< 0.01^*
Stripped	16	35	209	< 0.01^*
Stripped	20	45	270	< 0.01^*
Thinned	11	25	45	< 0.01^*
Thinned	16	35	78	< 0.01^*
Thinned	20	45	103	< 0.01^*

↵^z Reduction in wind load (measured in newtons, N) is the difference between wind load before pruning and wind load after pruning.
↵* Highly significant difference in wind load before and after pruning or stripping foliage.

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Table 2.

Mean difference in wind-load reduction between specified pruning types.

Velocity (m/sec)	Velocity (mph)	Pruning comparison^{^z}	Mean wind load reduction difference (N)	P-value
11	25	Lion tailed vs. reduced	−18	0.99
16	35	Lion tailed vs. reduced	10	1.00
20	45	Lion tailed vs. reduced	56	0.06
11	25	Lion tailed vs. thinned	32	0.73
16	35	Lion tailed vs. thinned	62	0.02^*
20	45	Lion tailed vs. thinned	97	< 0.01^*
11	25	Reduced vs. thinned	51	0.11
16	35	Reduced vs. thinned	52	0.09
20	45	Reduced vs. thinned	41	0.37

↵^z Mean difference was calculated by subtracting the wind load reduction of the second pruning type listed in the pruning comparison column from the wind load reduction of the first pruning type. Negative differences indicate that the first listed pruning type did not reduce wind load as much as the second listed pruning type. Reduction in wind load is the difference between wind load before pruning and wind load after pruning.
↵* Highly significant difference between pruning types.

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Table 3.

Mean difference in bending moment reduction between specified pruning types.

Velocity (m/sec)	Velocity (mph)	Pruning comparison^{^z}	Mean bending moment difference (N*m)	P-value
11	25	Lion tailed vs. reduced	−66	0.77
16	35	Lion tailed vs. reduced	−39	0.99
20	45	Lion tailed vs. reduced	−18	1.00
11	25	Lion tailed vs. thinned	11	1.00
16	35	Lion tailed vs. thinned	48	0.96
20	45	Lion tailed vs. thinned	90	0.29
11	25	Reduced vs. thinned	77	0.51
16	35	Reduced vs. thinned	87	0.31
20	45	Reduced vs. thinned	108	0.07

↵^z Mean difference was calculated by subtracting the bending moment reduction (before-pruning bending moment minus after-pruning bending moment) of the second pruning type listed in the pruning comparison column from the bending moment reduction of the first pruning type. Negative differences indicate that the first listed pruning type did not reduce bending moment as much as the second listed pruning type.