Variation in reproductive characteristics of lodgepole pine (Pinus contorta var. latifolia) in British Columbia

Date

2014-01-09

Authors

Berland, Anne

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Abstract

Lodgepole pine (Pinus contorta var. latifolia) is the most wide-ranging pine in North America. Populations in British Columbia vary widely in phenotypic and genotypic characteristics. The effect of climate on variation in reproductive characteristics has never been examined, yet is vital to the production of seed necessary for reforestation. This study aims to determine the relationship between the climate in B.C and variation in female cone and seed characteristics. The study makes use of the Illingworth provenance trial, sixty common garden plots that are distributed throughout British Columbia. Female cones from six provenances were collected at 21 sites during the summer of 2012. The number of scales was counted and maximum length was measured for each cone. Seed was extracted and counted. Variables were pooled for each tree. The climate at each site was described using data from ClimateWNA. Principal components analysis was used to reduce the highly correlated data set to the first two principal components (PC1 and PC2), which together described 76.7% of the variation in the data. PC1 was most closely aligned with variables related to temperature, the number of frost-free days, and degree-days above 5°C or below 0°C. PC2 was most closely aligned with precipitation and moisture variables. The reproductive variables were moderately positively correlated with one another. Analysis of variance indicated that average cone length and the average number of seeds per cone were significantly affected by both site and provenance, however the average number of seeds per cone was not. Average values of each reproductive trait for each site were modelled against the first two principal components using multiple analysis of variance and univariate linear modelling. The best-fit model for the average number of scales per cone included PC1 and PC2, however the model only described 4.9% of the variation in the data. The best-fit model for the number of seeds included only PC1, and iv the model only explained 4.1% of the variation in the data. The model for average cone length had the strongest results, with a model that included PC2 and explained 18.7% of the data. The results of the study indicate that climate is not the most important factor in predicting reproductive characteristics such as cone length, and the number of scales and seed per cone. The significant effect of moisture on average cone length was the strongest relationship identified in the study. The reproductive traits were best described by their stability across the climates of the test sites. High genetic variation in lodgepole pine populations may be contributing to the stability of reproductive traits. Lodgepole pine female cone and seed traits were stable for mature trees over a wide range of provenances and climate regions.

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Keywords

forest biology, forestry, lodgepole pine, reproduction biology, conifer reproduction, climate, British Columbia

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