8. Spacing of plantings

By observing trees and shrubs growing under natural conditions, it is often found that plants grow widely apart in low rainfall areas. Therefore, wide spacing of plantings in arid zones generally should be practiced to avoid competition for soil moisture.

The amount of water available to a tree or shrub in a plantation is proportional to the stand density. On dry sites, it is necessary to plant widely apart and to remove all competing ground vegetation; this increases infiltration of rainwater and decreases water losses through transpiration by plants and evaporation from the soil. When irrigation or mechanical cultivation is practiced, it is necessary to adjust spacing to the width of the machinery used and to ensure that plants are placed in straight rows. Actual spacing varies with species, site, and the purpose of the forest plantation. In fuelwood plantations, for example, one might prefer closer spacings than employed in other kinds of plantations. Seldom can a spacing of less than 3 x 3 meters be applied, however.

The number of trees per hectare, according to the spacing between the lines in a plantation and the spacing of plants within a line, is given in Table 4.1. For example, with a spacing between lines of 3 meters and a spacing of plants within a line of 3 meters, a planting density of 1,111 trees per hectare will be required.

Figure 4.9 Illustration showing the most common type of root doiling (one lateral root and the main root)

Figure 4.10 Ten old Pinus pinea planted with the plastic container.

Table 4.1. Number of trees per hectare according to spacing

 Spacing of plants in the lines Spacing between lines 0.50 m 0.60 0.70 0.80 0.90 1.00 1.20 1.40 1.50 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 6.50 7.00 8.00 9.00 10.00 0.50 m 40,000 33,333 28,569 25,000 22,222 20,000 16,666 14,285 13,333 12,500 11,111 10,000 0.60 33,333 27,777 23,809 20,833 18,518 16,666 13,888 11,904 11,111 10,416 9,253 8,333 0.70 28,569 23,809 20,408 17,857 15,873 14,285 11,904 10,204 3,523 8,926 7,936 7,142 0.80 25,000 20,833 17,857 15,625 13,888 12,500 10,416 8,928 8,333 7,812 6,944 6,250 0.90 22,222 18,518 15,873 13,888 12,345 11,111 9,259 7,936 7,407 6,844 6,172 5,555 1.00 20,000 16,666 14,285 12,500 11,111 10,000 8,333 7,142 6,666 6,250 5,555 5,000 4,000 3,333 1.20 16,666 13,888 11,904 10,416 9,259 8,333 6,944 5,952 5,555 5,208 4,630 4,166 3,333 2,778 1.40 14,285 11,904 10,204 8,928 7,936 7,142 5,952 5,102 4,762 4,464 3,968 3,571 2,857 2,381 1.50 13,333 11,111 9,523 8,333 7,407 6,666 5,555 4,762 4,444 4,167 3,704 3,333 2,667 2,222 1.60 12,500 10,416 8,928 7,812 6,944 6,250 5,208 4,464 4,167 3,906 3,472 3,125 2,500 2,083 1.80 11,111 9,259 7,936 6,944 6,172 5,555 4,630 3,968 3,704 3,472 3,086 2,778 2,222 1,852 2.00 10,000 8,333 7,142 6,250 5,555 5,000 4,166 3,571 3,333 3,125 2,778 2,500 2,000 1,666 1,428 1,250 1,111 1,000 909 833 2.50 - - - - - 4,000 3,333 2,857 2,667 2,500 2,222 2,000 1,600 1,300 1,142 1,000 888 800 727 666 3.00 - - - - - 3,333 2,778 2,381 2,222 2,083 1,852 1,666 1,300 1,111 952 833 747 666 606 555 3.50 - - - - - - - - - - - 1,428 1,142 952 816 714 635 571 548 476 4.00 - - - - - - - - - - - 1,250 1,000 833 714 625 555 500 454 416 384 357 312 277 250 4.50 - - - - - - - - - - - 1,111 888 747 635 555 493 444 404 370 341 317 277 247 222 5.00 - - - - - - - - - - - 1,000 800 666 571 500 444 400 363 333 307 285 250 222 200 5.50 - - - - - - - - - - - 909 727 606 548 454 404 363 330 303 279 259 227 202 181 6.00 - - - - - - - - - - 833 666 555 476 416 370 333 303 277 256 238 208 185 166 6.50 - - - - - - - - - - - - - - - 384 341 307 279 256 236 219 192 170 154 7.00 - - - - - - - - - - - - - - - 357 317 285 259 238 219 204 178 158 142 8.00 - - - - - - - - - - - - - - - 312 277 250 227 208 192 178 156 138 125 9. 00 - - - - - - - - - - - - - - - 277 247 222 202 185 170 158 138 123 111 10. 00 - - - - - - - - - - - - - - - 250 222 200 181 166 154 142 125 111 100