The effect of mesh shelters and nitrogen fertilzer on growth for bigtooth aspen wildlife plantings
Bigtooth aspen (Populus grandidentata) is a good species for use in conservation plantings in the agricultural landscape of Central Wisconsin. The buds and twigs are utilized as forage by a range of species in winter. The species is easy to manage with coppice and the resulting pulpwood finds a ready market. Early establishment of plantings can, however, be plagued by excessive browse damage. Our objective was to determine if nitrogen fertilization, poultry mesh tree shelters or a combination of both would increase aspen seedling growth rate. We planted 8 split plots of 12 bigtooth aspen seedlings (1-0 stock) (96 total seedlings). Four of the plots were fertilized with polymer coated urea at a rate of 90 Kg N per hectare and four were controls. Half of the trees in each split-plot were caged with 5 foot tall poultry mesh shelters (5 inch diameter) and half were uncaged. The poultry mesh shelters increased seedling growth. Overall, sheltered seedlings averaged 91 cm while unsheltered averaged 51 cm, with or without fertilization. However, the combination of both shelters and fertilization (107 cm) had a much greater impact than either fertilizer alone (54 cm) or shelter alone (75 cm) or the control (47 cm). At this point, all seedlings are still within the browse height of deer; however, it appears that the impact of fertilization alone is not sufficient to help the trees outgrow deer browsing although the addition of fertilizer with the use of tree shelters results in significantly increased growth.