Dense understories of shade-tolerant tree species naturally develop in hardwood forests. Partial cutting practicesβfor example, select cuts, thinnings, or preparatory harvests for some regeneration practicesβcan lead to the development of shade-tolerant understory species, including red maple Acer rubrum , American beech Fagus grandifolia , blackgum Nyssa sylvatica , and black birch Betula lenta. In addition, preferential browsing by white-tailed deer favors less-desirable shade-tolerant tree species such as striped maple Acer pensylvanicum , American beech, and eastern hophornbeam Ostrya virginiana.
These species are increasing in abundance throughout Pennsylvania's forests. Dense understories of undesirable shade-tolerant trees interfere with the establishment and development of desirable regeneration such as northern red oak Quercus rubra , white oak Quercus alba , black cherry Prunus serotina , and yellow poplar Liriodendron tulipifera.
Researchers have concluded that species diversity declines as shade-tolerant reproduction continues to expand. Recognizing and treating less-desirable trees prior to a planned harvest increases the proportion of desirable species in the future stand. Removing or deadening undesirable trees is a forest management tool owners can employ to achieve their objectives. It allows the owner to favor species better suited to the site that meet future desired conditions and their objectives.
The most effective method for deadening undesirable standing trees involves using an herbicide. Hack-and-squirt, also known as frill and spray, herbicide applications offer one of the most target-specific, efficient, and economical means for controlling unwanted trees.
Hack-and-squirt applications are effective on various size stems and can be used on steep topography and on small ownerships. Hack-and-squirt applications are applicable in hardwood stands where mechanical broadcast spray treatments are not feasible or desirable.
