Date of Award

8-2010

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Robert S. Seymour

Second Committee Member

Robert G. Wagner

Third Committee Member

William H. Livingston

Abstract

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 of varying levels of basal area (m2 ha-1) of large pine reserve trees may have on (1) the densities (stems ha-1) of both eastern white pine and non-pine species in the developing regeneration stratum, and (2) the height growth of eastern white pine in the developing regeneration stratum (3) incidence of white pine weevil injury of eastern white pine in the developing regeneration stratum, and (4) determine if any differences in quality exist between the two-aged stand type and the pre-commercially thinned stand type, relative to white pine weevil attack, blister rust infection, and branch shedding. Our null hypotheses were that large pine reserves have no effect on the density (stems ha-1) and height growth of the regenerating understory pine, or the density (stems ha-1) of the regenerating non-pine species, and also that large pine reserves have no effect on the frequency of white pine weevil injury of the regenerating understory pine, and that there were no differences in pine regeneration quality aspects between stand type. Thirteen forest stands throughout the spruce-fir region of Maine were chosen for this study. Nine of these stands were two-aged stands that were regenerated prior to 1995, have no history of pre-commercial thinning, and contain a significant component of heavily released eastern white pine trees growing above a developing mixed species matrix. These nine stands were harvested between the years of 1984 and 1994, and have soils ranging from somewhat poorly drained to very poorly drained. Four forest stands throughout the spruce-fir region of Maine that had been regenerated in the same time period as above, and also had a history of pre-commercial thinning that favored eastern white pine were also chosen for investigation in this study. One of these four stands contained a component of heavily released eastern white pine trees growing above the developing mixed species matrix. Soils ranged from poorly drained to very poorly-drained. Reserve pine basal area (m2 ha-1) was found to be positively correlated with the presence versus absence of pine in the regeneration stratum (p = 0.0398). The odds ratio of this model indicated that an increase of one square meter of reserve pine basal area increases the odds of pine regeneration success by 72 percent. This is true regardless of where reserve pine basal area (m2 ha-1) is held. Basal area (m2 ha-1) of reserve pine was not correlated with pine regeneration density (stems ha-1) when investigating only those plots in which pine regeneration was present (p = 0.2246). Non-pine density (stems ha-1) in the regeneration stratum was observed to be influenced more by differences in site, rather than basal area (m2 ha-1) of reserve pine trees. Reserve tree basal area (m2ha-1) was not significant in the model. Basal area of reserve pine (m ha") had a negative (p = 0.0886) effect on mean annual height increment of pine regeneration. Basal area (m2 ha-1) of pine reserves was not correlated (p = 0.3721) with the presence versus absence of weevil injuries in the two-aged stand type. Likewise, pine reserve basal area (m2 ha-1) was not correlated with number of weevil injuries (p = 0.6950) when investigating only those plots in which weevil injuries were present. The two-aged stands with large isolated reserves were found to have lower incidence of weevil injury (p = 0.0055), with smaller weevil caused stem offsets (p = 0.0449). Two-aged stands also had smaller diameter branches (p = 0.0136). Incidence of white pine blister rust indicated caution should be used in the pre-commercially thinned stand type.

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