No abstract

Annual ring widths and ring areas from 131 even-aged, natural, well-stocked stands of loblolly pine (Pinustaeda L.) in the Piedmont region were analyzed to reveal possible causes of a previously reported decline in radial growth. A linear aggregate model was used to separate independent factors that are known to contribute to radial growth variation in this species. Stand, site, and climatic conditions were reconstructed for each stand for the 36-year period 1949–1984 from previous inventories and from weather records at appropriately located stations. Within each of six 5-year age-classes, the model identified declines in both ring width and ring area associated with stand density, climate changes, and the passage of time. Regional climate first ameliorated this decline as pine stands passed from droughty conditions early in the 36-year period to a favorable climate during the middle of the period, and the decline accelerated later with the return of dry conditions toward the end of the period. The tree-ring model simulates a decline in radial increment in trees in natural pine stands between the ages of 20 and 45 years in the Piedmont which has averaged 1% per year since 1950. Part of the downward trend was attributed to increased competition, part to regional drought, and a considerable part to unidentified factors, possibly regional atmospheric deposition.

Planting has been considered to be one solution to the problem of inadequate natural oak regeneration following harvesting in the Central Hardwood Region. Two types of tree shelters were used in two separate 3-year studies to determine their effects on the growth and survival of northern red oak seedlings planted in recently harvested forest openings, and to characterize shelter influence on microenvironmental factors. Sheltered seedlings planted in both trials exhibited significantly greater 3-year height growth as compared to the controls. There were no significant differences in survival rates. Relative humidity and carbon dioxide concentrations were increased significantly inside both types of shelters, while there were no differences between shelter exterior and interior daytime temperatures. Interior light intensities differed for the two shelter types and varied according to vertical location within shelters. Recommendations are given for using tree shelters as a possible means for improving oak planting success in recently harvested forest openings. North. J. Appl. For. 9(2):58-63.

Methods for deer browse protection are becoming a necessary aspect of hardwood silviculture, particularly with practices such as artificial regeneration of oaks. This study tested the effectiveness of two types of deer protection for aiding the rehabilitation of a failed northern red oak planting in southern Indiana. Tree shelters, bar soap repellent, and no protection (control) treatments were applied to 1 yr old, coppice-origin oak shoots arising from 8 yr old root-stocks of an unsuccessful 1980 old-field research planting. Oaks in tree shelters exhibited significantly greater early shoot growth than did unsheltered oaks. This height advantage was maintained, but not increased once tree crowns emerged from the shelter environment. After 5 growing seasons, oaks receiving the soap repellent treatment began to increase their rate of height growth. Continuation of this trend could negate early growth advantages of tree shelters. The use of tree shelters may improve the success of attempts to regenerate preferred browse species such as oaks, but concerns of practicality and economics remain. North. J. Appl. For. 13(1):24-29.

The impoundment of Richard B. Russell Lake resulted in the inundation of 3490 ha of forested area or 33 percent of the total area of the lake. Estimates of the total inundated leaf litter biomass were combined with a leaf litter decomposition study to determine the nutrient load and dissolved oxygen demand to the reservoir. Hickory leaf bags broke down most rapidly at the 3‐m and 28‐rn depths, followed by short‐needle pine, white oak, a hardwood litter mixture, beech, and red oak. Leaf bags incubated at the 3‐m depth exhibited significantly higher breakdown rates than those at the 28‐m depth for most leaf types, due to differences in dissolved oxygen and temperature. Respiration rates of litter were also higher at the 3‐m depth. Most leaf types accumulated nitrogen and phosphorus and lost organic carbon after an initial leaching period. Richard B. Russell Lake exhibited extensive anoxia and the buildup of total organic carbon, nitrogen, and phosphorus during summer stratification. Leaf litter breakdown accounted for 64 percent of the organic carbon increase but acted as a sink for nitrogen and phosphorus. The dissolved oxygen demand of the litter accounted for over 50 percent of the demand incurred in the lake.