<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Sutherland, Elaine Kennedy</style></author></authors><tertiary-authors><author><style face="normal" font="default" size="100%">Zwolwski, M.</style></author></tertiary-authors></contributors><titles><title><style face="normal" font="default" size="100%">The Effect of Prescribed Burning on Southwest Ponderosa Pine Growth</style></title><secondary-title><style face="normal" font="default" size="100%">School of Renewable Natural Resources</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Watershed Management</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1989</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=746080281&amp;sid=4&amp;Fmt=2&amp;clientId=43922&amp;RQT=309&amp;VName=PQD</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">University of Arizona</style></publisher><volume><style face="normal" font="default" size="100%">PhD</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Study objectives included determining whether prescribed burning affected ponderosa pine growth; mathematically modeling the growth response to burning; and determining whether forest management history affected growth response. I sampled 188 trees from two areas near Flagstaff, Arizona; one area (Brannigan Flat) had been logged and thinned, and the other (Chimney Spring) had not; both were burned in 1976. Within each study area, control and burned plots were of similar age, vigor, height, and competition index. Trees at Chimney Spring were older, less vigorous, and taller, and had a higher competition index than at Brannigan. For each tree, periodic basal area increment (PBAI) was calculated for the years 1974-1984. To determine which variable would best model growth, postfire PBAI (individual years, 1977-1984) was correlated with previous growth (average PBAI 1974-1976); crown ratio; competition index; thinning index; and diameter. Two models of growth response were developed; one oriented toward satisfying theoretical and research goals, and the other, toward management applications. Growth was modeled using stepwise multiple linear regression, and the dependent variable was postfire PBAI. Research Model independent variables were previous growth, years (climate), and treatment-year interaction, and 72% of total variance was explained. Fire affected growth significantly and negatively for two years, and then burned trees grew similarly to control trees. Management Model independent variables were crown ratio, competition index, crown ratio, subject tree diameter, year, and treatment, and 52% of total variance was explained. This model, too, indicated a slight negative effect of burning on growth. Management history was not a significant determinant of growth response. Both models validated well; the ratio of observed-to-predicted residual mean square was 1.04 and 0.91 (Research and Management Models, respectively). Thinning index was not significantly related to postfire growth, but a change in carbohydrate allocation from stem wood to crown and root expansion could have resulted in observed burning effects. Management implications include (1) short-term growth decline may result from burning, (2) management history did not affect growth response, and (3) burning impact is greatest in dense stands of small trees.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Swetnam, T.</style></author></authors><tertiary-authors><author><style face="normal" font="default" size="100%">Zwolwski, M.</style></author></tertiary-authors></contributors><titles><title><style face="normal" font="default" size="100%">A Dendrochronological Assessment of Western Spruce Budworm, Choristoneura Occidentalis Freeman, in the Southern Rocky Mountains</style></title><secondary-title><style face="normal" font="default" size="100%">School of Renewable Natural Resources</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Watershed Management</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1987</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=753027921&amp;sid=16&amp;Fmt=2&amp;clientId=43922&amp;RQT=309&amp;VName=PQD</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">University of Arizona</style></publisher><volume><style face="normal" font="default" size="100%">PhD</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Tree-ring chronologies from ten mixed conifer stands in the Colorado Front Ranges and New Mexico Sangre de Cristo Mountains were used to reconstruct timing, duration, and radial growth impacts of past outbreaks of western spruce budworm, Choristoneura occidentalis Freeman. Graphical and statistical comparisons of tree-ring chronologies from host and non-host tree species, in conjunction with Forest Service records of outbreaks during the twentieth century, revealed that outbreaks were identifiable only in the host chronologies as sharply reduced growth periods. These comparisons also showed that host and non-host tree-ring chronologies were generally similar between outbreaks and that both were responding in a similar manner to climatic variation. A study of defoliation and insect population data that was available for the New Mexico stands demonstrated that host radial growth from 1978 to 1983 was highly correlated with budworm activity. The non-host chronologies from each stand were used to correct the host chronologies for climatic and other non-budworm environmental variations by a differencing procedure. The corrected chronologies were then used to estimate the dates and radial growth effects of past budworm outbreaks. Tree-ring characteristics of twentieth century documented outbreaks were used as criteria for inferring the occurrence of outbreaks in previous centuries. At least nine periods of increased budworm activity were identified in the region from 1700 to 1983. The mean duration of reduced growth periods caused by known and inferred budworm outbreaks was 12.6 years, and the mean interval between initial years of successive outbreaks was 34.9 years. The mean maximum radial growth loss was 50 percent of expected growth, and the mean periodic growth loss was 21.6 percent. There was an unusually long period of reduced budworm activity in the first few decades of the twentieth century, and since that time outbreaks have been markedly more synchronous between stands. Increased synchroneity of outbreaks in the latter half of the twentieth century suggests that areal extent of outbreaks has increased. This phenomenon may be due to changes in the age structure and species composition of forests following harvesting and fire suppression in the late nineteenth and early twentieth centuries.&lt;/p&gt;</style></abstract></record></records></xml>