| Popis: |
Survival, height and diameter for the first four year rotation were measured on two intensively cultured Populus hybrid plantations in central Pennsylvania. Treatments of control, irrigation, fertilization and fertilization/irrigation were installed on two sites and in two establishment years. Overall treatment survival was not affected by site but values were lower for 1980 planted trees (83%) than 1981 planted trees (90%). Survival values among the treatments were similar until the later ages of the first rotation. Treatments with fertilizers had lower four-year-old survival (78%) than the treatments without fertilizers (86%). The four-year-old control trees averaged 5.3 and 6.8 m in height, and 3.4 and 4.2 cm in diameter for the 1980 and 1981 establishment years, respectively. Fertilization, with or without irrigation, consistently increased annual height and diameter over the control. Fertilization/irrigation did not result in tree size values that were greater than fertilization. In general, there were inconsistent increases in annual height and diameter from irrigation. |
