PS 68-122 - Modeling the distribution of eastern white pine at the beginning of the 19th century in central province of Quebec (Canada) using land survey records

Thursday, August 6, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Eduard Mauri Ortuño , Centre d'étude de la forêt, Université Laval, Québec, QC, Canada
Alison D. Munson , Centre d'étude de la forêt, Université Laval, Québec, QC, Canada
Frédérik Doyon , Informatique et ingénierie, Université du Québec en Outaouais, Gatineau, QC, Canada

Eastern white pine (Pinus strobus L.) is one of the most economically valuable conifers in eastern North America and part of our ecological heritage. In the province of Quebec, by the late 1800's, most mature specimens had been selectively logged, particularly along the St. Lawrence River and its major tributaries, leaving relic populations that are poorly representative of its pre-settlement distribution. This study aims to understand the pre-settlement distribution of white pine in southern Mauricie in central Quebec, by relating past white pine presence, as described by primeval land survey records, to environment variables. Thirteen land survey log-books, dating from before the major selective cuts took place, and covering about 7,000 km2, were retained for the analysis, from which 2,614 survey records were extracted and geo-referenced. Each record provides a list of tree species, ordered by their abundance. We then randomly surveyed 421 locations of the primeval surveys (half with and half without white pine in the 19th century) and recorded evidence of white pine presence (old stumps, seedling, saplings, and mature white pines).


We observe that frequency of mature white pine is actually about half (14%) of what it was at the time of the primeval surveys (28%). Logistic regression analysis shows that the presence of white pine in the primeval surveys was significantly associated with outwash/alluvion and thin glacial/rocky surficial deposits, south/southwest/west aspects, and top/high-slope topographic positions, while moisture and slope were not significant. The relationship between current and past white pine presence was tested using a Chi-square 2x2 Fisher exact probability test, and expresses a strong site-fidelity; current mature white pines are found where they were at the beginning of the 19th century. The most site-faithful current evidence of the past presence of white pine was the combination of old stumps and seedlings. These results suggest that the modeled distribution is similar to that expected from white pine autoecology. Moreover, although current mature white pine distribution is halved, most of the current mature specimens are observed on the same sites that the species occupied before settlement. This implies that considerable effort will be required to restore white pine on the landscape, with the possibility of using the proposed model and the presence of stumps and seedlings as guidance.

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