ill.; Thesis (M.S.)--Saint Joseph's University, 2003; Includes bibliographical references (leaves 71-78)
Abstract In this study, dendrochronological methods were used to understand how whitebark pine responds to climate in the Pacific Northwest. Whitebark pine cores were extracted, dated and their growth patterns were correlated with monthly temperature and precipitation to determine the short-term effects of climate at 27 sites at Crater Lake, Mount Rainier, and North Cascades National Parks. Six of the 27 sites showed no significant correlation between climate and whitebark growth. The short-term analysis revealed that whitebark pine growth is limited by growing season length. Negative correlations between previous December and March precipitation and positive correlations were observed between January and March temperature at sites in both North Cascades and Mount Rainier suggesting that winter precipitation in the form of snowpack limits growth while warm winter temperatures promoted growth by decreasing the snowpack in the two northern parks. Whitebark pine growth cannot begin until soil temperatures rise above freezing allowing new roots to grow. June temperatures positively correlated with growth at Crater Lake suggesting most growth occurs in the late spring. Growth is presumed to cease in the summer when high summer temperatures cause respiration costs to exceed carbon gains from photosynthesis, however July precipitation may allow whitebark pine at Crater Lake to once again resume, allowing for storage of carbon, as evidenced by a positive correlation of previous July precipitation with growth at Crater Lake. Warm fall temperatures lead to productive growing seasons the following year at Crater Lake and Mount Rainier, presumably by increasing carbon stores. Using factor analysis on 20 mean basal area increment chronologies from 20 sites, four factors were extracted which account for 88% of the variability in the whitebark pine growth patterns. The first factor, which accounted for 35% of the variance, showed a growth increase in whitebark pine since the late 1950's. We believe a combination of increasing temperatures and carbon dioxide fertilization best explain this growth increase, however the effects of increasing nitrogen deposition cannot be completely ruled out. Factor 1 is significantly positively correlated with C02 ( r=0.668, p<0.001) and annual temperature from the three climate divisions representing Mt. Rainer, North Cascades, and Crater Lake National Parks(r=0.569, p<0.001 for WA division 5, r=0.275, p=0.005 for WA division 6, r=0.495, p<0.001 for OR division 5; Figure 3.2a-c). The second major factor showed a strong negative correlation with winter Pacific Decadal Oscillation (PDO) index(r=-0.2916, p=0.006), with the time period of 1941 to 1970 the most strongly correlated (r= -0.391, p=0.005) suggesting that PDO is partially responsible for the trends observed in the growth. The third and fourth extracted factors correlated with the same climate variables that limited growth of whitebark pine in the short-term implying that their effects are seen in the long-term. IV
Abstract In this study, dendrochronological methods were used to understand how whitebark pine responds to climate in the Pacific Northwest. Whitebark pine cores were extracted, dated and their growth patterns were correlated with monthly temperature and precipitation to determine the short-term effects of climate at 27 sites at Crater Lake, Mount Rainier, and North Cascades National Parks. Six of the 27 sites showed no significant correlation between climate and whitebark growth. The short-term analysis revealed that whitebark pine growth is limited by growing season length. Negative correlations between previous December and March precipitation and positive correlations were observed between January and March temperature at sites in both North Cascades and Mount Rainier suggesting that winter precipitation in the form of snowpack limits growth while warm winter temperatures promoted growth by decreasing the snowpack in the two northern parks. Whitebark pine growth cannot begin until soil temperatures rise above freezing allowing new roots to grow. June temperatures positively correlated with growth at Crater Lake suggesting most growth occurs in the late spring. Growth is presumed to cease in the summer when high summer temperatures cause respiration costs to exceed carbon gains from photosynthesis, however July precipitation may allow whitebark pine at Crater Lake to once again resume, allowing for storage of carbon, as evidenced by a positive correlation of previous July precipitation with growth at Crater Lake. Warm fall temperatures lead to productive growing seasons the following year at Crater Lake and Mount Rainier, presumably by increasing carbon stores. Using factor analysis on 20 mean basal area increment chronologies from 20 sites, four factors were extracted which account for 88% of the variability in the whitebark pine growth patterns. The first factor, which accounted for 35% of the variance, showed a growth increase in whitebark pine since the late 1950's. We believe a combination of increasing temperatures and carbon dioxide fertilization best explain this growth increase, however the effects of increasing nitrogen deposition cannot be completely ruled out. Factor 1 is significantly positively correlated with C02 ( r=0.668, p<0.001) and annual temperature from the three climate divisions representing Mt. Rainer, North Cascades, and Crater Lake National Parks(r=0.569, p<0.001 for WA division 5, r=0.275, p=0.005 for WA division 6, r=0.495, p<0.001 for OR division 5; Figure 3.2a-c). The second major factor showed a strong negative correlation with winter Pacific Decadal Oscillation (PDO) index(r=-0.2916, p=0.006), with the time period of 1941 to 1970 the most strongly correlated (r= -0.391, p=0.005) suggesting that PDO is partially responsible for the trends observed in the growth. The third and fourth extracted factors correlated with the same climate variables that limited growth of whitebark pine in the short-term implying that their effects are seen in the long-term. IV