Date of Award

2002

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

William H. Livingston

Second Committee Member

Alan S. White

Third Committee Member

Reeser Manley

Abstract

Throughout southern Maine there was a noticeable decline and mortality of white pine (Pinus sfrobus) from 1997 through 2000 in dense pole-size stands. The decline was widespread, scattered, and happened simultaneously indicating that it was incited by an abiotic stress. Because only isolated stands showed decline and mortality, site factors likely predisposed trees to injury. Site factors are likely related to the widespread field abandonment that took place throughout southern and central Maine, and led to establishment of pure white pine stands in many areas. Although white pine can regenerate on many sites, some locations will have soil limitations, such as plow plans and lithological discontinuities that cause white pine roots to spread more horizontally. A shallow root system would result in less water being available to a tree during a drought. The first hypothesis is that soil rooting restrictions predisposed the white pine to water stress inciting decline and mortality. The second hypothesis follows that the drought event occurred prior to 1997-2000, the period of white pine mortality. Paired sites, consisting of one high and one low mortality site, were evaluated in nine locations in Maine south of 45" N latitude in the towns of Wells, Lebanon, Hollis, Limington, Casco, Nobleboro, Massabesic, New Gloucester and Oxford. Tree species, crown class, crown condition, and diameter at breast height (DBH) were recorded at each stand. Two cores were removed from each dominant and codominant white pine, including dead trees, for dendrochronological analysis. Crossdating of cores was used to calculate the percentage of dead trees with the last growth ring in a given calendar year. Average annual increments between dead and surviving trees were compared on each high mortality site using mean ring widths. Potential rooting depth was measured in each site. Stream flow, precipitation, temperature, and Palmer Drought Severity Index (PDSI) were used with the program PRECON to look at long tern relationships between climate and growth.

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