PATTERNS OF REGENERATION OF EASTERN WHITE PINE (PINUS STROBUS L.) AS INFLUENCED BY LARGE ISOLATED PINE RESERVES AND PRECOMMERCIAL THINNING

PATTERNS OF REGENERATION OF EASTERN WHITE PINE

(PINUS STROBUS L.) AS INFLUENCED BY LARGE ISOLATED

PINE RESERVES AND PRECOMMERCIAL THINNING

By Kate E. Zellers

Thesis Advisor:  Dr. Robert S. Seymour

A Lay Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Master of Science

(in Forest Resources)

August, 2010

The spruce budworm epidemic of the 1970s and 1980s led to the salvage harvesting of spruce-fir stands, serving as a release for scattered immature eastern white pine (Pinus strobus L.) trees.  These pines are now growing as large isolated reserve trees above a mixed conifer regeneration stratum.  The objectives in this study were to determine any effect that varying levels of basal area of large pine reserve trees may have on the developing regeneration, with an emphasis on eastern white pine, and to determine if any differences in pine quality exist between two-aged stands and precommercially thinned stands, relative to white pine weevil attack, blister rust infection, and branch shedding.  Thirteen forest stands throughout the spruce-fir region of Maine were chosen for this study.  Nine of these stands were two-aged stands which had no history of precommercial thinning, contained a significant component of heavily released eastern white pine trees growing above a developing mixed species matrix, and were harvested between 1984 and 1994.  Four additional forest stands that had been regenerated in the same time period as above, and had a history of precommercial thinning were also chosen for investigation in this study.  Increasing reserve pine basal area significantly increased the likelihood of pine regeneration success.  When pine regeneration was present, however, no relationship between reserve pine basal area and pine regeneration density was found.  Non-pine density in the regeneration stratum was observed to be influenced more by differences in site, rather than basal area of reserve pine trees.  Basal area of reserve pine was found to have a negative effect on mean annual height increment of pine regeneration.  No relationship was found between the basal area of pine reserves and the presence of weevil injuries in the two-aged stand type.  Pine reserve basal area was not correlated with number of weevil injuries when investigating only those plots in which weevil damage was present.  The two-aged stands with large isolated reserves were found to have lower incidence of weevil injury and less severe stem deformation caused by weevil injury.  Two-aged stands also had smaller diameter branches.  Incidence of white pine blister rust indicated caution should be used in the precommercially thinned stand type.