Measurement of tree seedlings and herbaceous vegetation from 499 sample locations across Pennsylvania revealed that advance tree-seedling regeneration is inadequate for new stand establishment across most of the State. The samples were located in stands from 40% to 75% stocked to focus on stands with ample light and growing space for establishment of abundant advance regeneration. A range of regeneration adequacy criteria was applied to the measurements. Using the least stringent criterion, a low density of stems of any tree species, resulted in 40% of the sample locations being adequately stocked. Applying the most stringent criterion, a high density of stems of desirable species, resulted in only 4% of the sample locations being adequately stocked. With the exception of forest-type group, no significant relationship was found between the adequacy of regeneration and other variables tested at the broad level of geographic scale of this study. Levels of fern and grass sufficient to hamper tree-seedling development were found at 54% of the sample locations. Fern species that propagate primarily by spreading rhizomes accounted for 70% of the total fern sample. North. J. Appl. For. 12(4):187-191.
Growth of northern red oak (Quercusrubra L.), white ash (Fraxinusamericana L.), and white pine (Pinusstrobus L.) seedlings was evaluated for 2 years after germination in 12 environments that consisted of four levels of herbaceous interference (fern, fern free, grass, grass free) crossed with three levels of light intensity (100, 45, and 20% full sun), at two clear-cuts in central Pennsylvania. Grass and fern interference reduced soil moisture content and reduced height or diameter growth of all species. Shading ameliorated soil moisture, reduced herbaceous growth, generally reduced growth of all tree species in interference-free environments, and had no effect on growth of any tree species in fern and grass environments. Reduction in growth due to herbaceous interference was lower for northern red oak and white pine than for white ash, while shading had similar effects on growth of all species. Results suggest that stresses induced by shading alone have little short-term effect on the establishment of these species under conditions of heavy herbaceous interference.
Cuttings of Populus hybrid clone NE-388 (Populusmaximowiczii Henry × Populustrichocarpa Torr & Gray) were inoculated with mycelium of Septoriamusiva Peck at three potential infection courts. Cankers resulting from inoculations at stipule – petiole excision wounds and bud excision wounds developed within 17–30 and 18–22 days, respectively. Only one canker resulted from 30 nonwound lenticel inoculations. Young trees (15 and 16 weeks from planting date) developed more cankers than older trees (18 weeks from planting date). Trees atomized with conidia of S. musiva did not develop cankers; however, leaf spots developed 18–23 days after inoculation.
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