Cuttings are exact genetic replicas of the parent tree. They commonly are used to regenerate poplars, but also can be used to regenerate willow and green ash. Cuttings are usually 8- to 12-inch lengths of tree stems about 1/4- to 3/4-inch in diameter (longer cuttings may be used on drier sites). They are cut during the late winter from the previous year’s growth of vigorous seedlings or stump sprouts. Cuttings usually have no visible roots, but when buried vertically with just an inch of the stem protruding above ground, they will form roots. Rooted cuttings also may be available for purchase. Cuttings grow best where the soil remains moist throughout the growing season.
When designing a plantation, you need to determine an appropriate spacing between mature trees. Consider the typical crown width of a tree species when individual trees reach a useful size. For example, when growing trees for timber, you’ll need to allocate enough space so the individual trees will be just beginning to crowd each other when they are large enough to support a commercial thinning. A forester can help you determine the correct spacing depending on the species and purpose for the plantation.
Table 4-1 shows the number of trees needed per acre for various spacings. To calculate the number of trees per acre for other spacings, multiply the planned spacing (in feet) within rows by the spacing (in feet) between rows and divide that number into 43,560 (the number of square feet in an acre). For example, a plantation with trees 8 feet apart within rows and 10 feet apart between rows would require 545 trees per acre:
|Table 4-1. Number of trees per acre at different spacings.|
|SPACING (IN FEET)||TREES PER ACRE|
|4 x 4||2,722|
|5 x 5||1,742|
|6 x 6||1,210|
|7 x 7||890|
|8 x 8||680|
|9 x 9||538|
|10 x 10||436|
|11 x 11||368|
|12 x 12||303|