Abstract
Phytomass and nutrient accumulation are reported for eight intensively managed cottonwood plantations, ranging in age from four to 16 years on good sites. The results were developed from 24 sample trees and stand populations using the mean tree technique. The early growth of cottonwood plantations was rapid, and diameter and height growth averaged 3.6 cm and 2.6 m, respectively, during the first three years. At 16 years the mean tree was 33 cm in diameter, 32 m in height and had three logs to a 20-cm merchantability limit. From four to 16 years, the phytomass of the mean tree increased 13-fold while nutrient content increased 5- to 8-fold. The plantations maximized current annual increment for the stem components at 10 tons/ha during the fifth and sixth years, while that of crown components maximized during the first three years at 7 tons/ha. The foliage of the standing crop was 4 tons/ha through nine years, after which thinning caused a gradual decline to 2 tons/ha at 16 years. Thinnings removed 53 tons/ha of stem material with a total volume of 150 m³/ha. The mean annual increment of the stem maximized from eight to nine years at 7 tons/ha and 20 m³/ha and remained within 90% of the maximum from six to 14 years. The total net primary productivity through 16 years was about 180 tons/ha, of which 60% was stem components. The phytomass and volume yields from the system of management employed in these plantations were slightly below those reported for unthinned plantations and natural stands on similar sites. The annual nutrient requirements maximized from four to six years at 100, 12, 90, 150 and 18 kg/ha for N, P, K, Ca and Mg, respectively. By 14 years, the annual nutrient requirements declined to one half of the maximum levels. About two thirds of the annual requirements were necessary for foliage production. Much of the annual requirement was supplied through nutrient cycling. The patterns of plantation development, nutrition and productivity have distinct influences on the management of these plantations.
Keywords
Dimensions,
Volume,
Phytomass,
Nutrient Content
Citation
Shelton, M. G.; Switzer, G. L.; Nelson, L. E.; Baker, J. B.; Mueller, C. W. 1982. The Development of Cottonwood Plantations on Alluvial Soils: Dimensions, Volume, Phytomass, Nutrient Content and Other Characteristics. Technical Bulletin 113. Mississippi State University, Mississippi Agricultural and Forestry Experiment Station. 46 p.
