An investigation of natural hybridization between jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta var. latifolia) in northern British Columbia.

摘要

This study was conducted in order to find evidence of hybridization between jack pine (Pinus banksiana) and lodgepole pine ( Pinus contorta var. latifolia) in Northeast British Columbia (BC) through genetic identification of paternity and maternity of each sample, while relating differences in morphology, wood and fibre traits, and chemical makeup to genetic identity. Adding to this, an attempt was made to determine if wood and fibre traits can be used as distinguishing features between jack pine, lodgepole pine, and their hybrids, and to determine if a "chemical extractive footprint" can be used to differentiate between species groups.;Thirty samples of pure lodgepole pine, 30 of pure jack pine, and 30 potential hybrid samples were collected from the Prince George area of BC, the Smoky Lake area of Alberta, and the Fort Nelson region of BC, respectively. Data was analyzed by comparing characteristics in order to establish trends and interactions between characteristics, site conditions, and differences among samples.;Needles from foliar regions and inner cambial layers were harvested for DNA analysis. Chloroplast DNA and mitochondrial DNA were used to determine hybridization between lodgepole pine and jack pine by restriction fragment length polymorphism (RFLP). Gross morphological characteristics of each tree were measured from collected cone and needle samples, including, cone length and orientation, and needle length and position. Tree height and diameter at breast height (DBH) were recorded at time of sampling. Two 10 mm cores (bark to bark) were taken from each tree and analyzed for fibre length and coarseness through Fibre Quality Analysis, and for microfibril angle, basic density, earlywood:latewood ratios, modulus of elasticity (MOE), and cell wall configuration using SilviScan technology. Chemical extractive makeup of each sample was determined using gas chromatography - mass spectroscopy.;Based on the genetic evidence, 16 out of 24 samples from the introgression zone clearly show hybridization, with lodgepole pine maternity and jack pine paternity, occurring in the Fort Nelson region. Morphological characteristics that have been identified to distinguish among species groups include: needle V width/length, cone angle of attachment, cone curvature, cone length, and DBH/age. Cell and fibre traits that best differentiated between pure jack pine, lodgepole pine, and hybrids were moisture content (MC), MOE, cell wall thickness, and fibre coarseness, while only MC and MOE displayed hybrid intermediacy clearly.;Preliminary chemical analysis of the samples indicates that quantitative variability does exist between jack pine, lodgepole pine, and hybrid sample wood extractives; however, a clear "chemical extractive footprint" can not be determined. Further manipulation of chromatography and more extensive investigation of mass spectra are required.;Revealing how natural hybrids are different from pure species, and what this means to the scientific and industrial communities as well as forest managers is of primary importance. Supportive evidence of hybridization and introgression in the Fort Nelson region of British Columbia will provide information for proper management of forests in this region, with regard to silvicultural practices and tree breeding, and aid in optimization of processing and manufacturing to improve wood and product quality.