A comparison of the effects of different shelterwood harvest methods on the survival and growth of acorn-origin oak seedlings

Abstract

Timely development of newly germinated oak (Quercus spp.) seedlings into competitive-sized regeneration is an essential part of the oak regeneration process. The amount of sunlight reaching the forest floor partly governs this development, and foresters often use the shelterwood system to expose oak seedlings to varying degrees of insolation. To further understand the seedling development–sunlight–shelterwood relationships, I conducted a multiyear study at five locations in Pennsylvania. Each location had four stands either uncut or recently treated with one of three shelterwood harvest methods (preparatory cut, first removal cut, or final removal cut) resulting in four different levels of sunlight reaching the forest floor. In each stand, four 32 m2 plots were prepared, and each was planted with 400 acorns of black (Quercus velutina Lam.), chestnut (Quercus montana Willd.), northern red (Quercus rubra L.), or white oak (Quercus alba L.) and protected from wildlife. Germination success was universally high and for the next 8 years, I monitored seedling survival and measured seedling growth. The final and first removal cut treatments had higher seedling survival than the preparatory cut and uncut treatments. Oak seedling growth was positively related to sunlight availability; seedlings in the final removal cut grew the most, followed in descending order by those in the first removal cut, preparatory cut, and uncut treatments. These findings provide insight into the subtleties of regenerating oak forests with the shelterwood system.