The importance of nutrient loading to improve early performance of tree seedlings is well established. However, the potentiality of nutrient loading has only been examined in monoculture. I examined the nutrient loading effects on early performance of black spruce (Picea mariana (Mill.) BSP) seedlings in pure and mixed plantings with white spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana Lamb.) seedlings on a fertility gradient. Seedlings were planted in soil bioassays from a mixed wood boreal site and grown for one season in a greenhouse. Fertilization increased height, dry mass and N uptake. Response of loaded seedlings was superior than that of non-loaded seedlings. In contrast interplanting reduced black spruce growth somewhat because of competition from companion species. Study results confirmed the importance of nutrient loading as an immediate nutrient source for seedlings, and suggest that fertilization prior to outplanting may benefit initial plantation establishment.
Despite the presence of handbooks for the production of containerized tree seedlings, the determination of appropriate rates of fertilization remains an inexact science, since the rate and timing of fertilization can be affected by factors such as local variation in water chemistry, growing media, and the environment in each greenhouse. This report presents the results of semi-operational trial of fertilizer rates and growing media to assess for black spruce and jack pine container seedlings; the range of fertilizer concentrations and seedling nutrient contents resulting in best seedling growth; and the effect of fertilization on bud development and fall freezing damage. Black spruce and jack pine seedlings were grown at the Swastika Tree Nursery according to operational greenhouse practices, at 0, 1/3, 1, 3 or 9X the operational fertilization rates for each species in three growing media.
Seedlings raised under steady-state nutrient loading conditions in the nursery may out-perform conventional seedlings in early growth after out-planting. This study estimates the long-term potential of enhanced reforestation using nutrient-loaded seedlings to increase carbon sequestration using black spruce plantations in northern Ontario as a case study. The study involved mathematical stand modelling procedures. Published early-growth data of out-planted nutrient-loaded & conventional seedlings were pooled to calibrate & select the fittest model for predicting growth of maturing plantations. Tree height estimates were converted to biomass & carbon content to express post-planting response of nursery nutrient loading on future plantation productivity & carbon sequestration.
Traditional nursery culture of containerized black spruce ('Picea mariana' [Mill.] B.S.P.) seedlings involves a late-season hardening period when irrigation and fertilization are withheld to stress seedlings and promote frost-hardiness. Nutrient uptake is limited without supplemental fertilization, hence growth during hardening results in severe dilution of internal nutrients. The main objective of this study was to promote nutrient uptake and avert N dilution by fertilizing seedlings during the hardening period. Growth continues during this time (15-weeks), but gradually declines at the end of the rotation. Hence, nutrient supplementation progressively diminished with time to match seedling growth rate. Fertilization initially increased N uptake and elevated N concentration above initial pre-hardening status, but uptake declined after 6 weeks when fertilization ceased, causing growth dilution and N concentration decline. Based on these findings, fertilization dosages were increased and delivery schedules were prolonged in a follow-up experiment. Prolonged high-dose regimes promoted N uptake and prevented dilution, as reflected by a sustained increase of N concentration with time. When transplanted for 12-weeks on Boreal forest soil substrates to test outplanting performance, seedlings that received prolonged high-dose fertilization during hardening resulted in 115% more biomass and 350% more N than conventionally reared seedlings. The results demonstrate that fertilization during the hardening period improves early outplanting performance of seedlings, and may benefit future reforestation in northern forests.
1998 contains proceedings for: Southern Forest Nursery Association Conference; Northeastern Forest Nursery Association Conference; and the combined Forest Nursery Association of British Columbia/Western Forest and Conservation Nursery Association meeting.
This manual offers foresters information to help them understand the performance of spruce seedlings after being planted on a reforestation site. It was written for university students taking a regeneration silviculture class, and foresters and researchers who work with spruce species.
Explains some of the factors that affect the response of seedlings to fertilization, including soil and aerial microclimate, seedling morphology and physiology, and soil nutrient availability. Also identifies areas where additional research is required.