Ryan Jameson (M.Sc candidate)
In May of 2007 I graduated from Mount Allison University in Sackville, NB with a B.Sc. focusing on biology and geography. During this time I completed a directed studies with Dr. Colin Laroque and the Mount Allison Dendrochronology Lab using dendroclimatology to obtain a hindcast of past precipitation levels in Jasper National Park. I started my M.Sc. in the spring of 2007 under the supervision of Luise Hermanutz at Memorial University.
Seed production and limitation: A potential bottleneck to treeline advance.
Trees and shrubs rely on sexual reproduction to expand their ranges as scenarios of climate change permit. It follows that if the production of viable seed is limited, a bottleneck to northern and altitudinal migration could occur. The objective of this study is to investigate the current state of ovulate cone production and seed viability of trees and woody shrubs at the taiga-tundra ecotone of the Mealy Mountains. I also aim to assess the roles of potentially seed limiting factors (growing degree-days, predispersal insect predation, disease) on cone production and seed viability. Results from this project will also contribute important feeds to a climate-vegetation model being produced by Alvin Simms.
Field work in 2007 was conducted between late June and early August, and also included a short fall field season in mid-September. During this time, trees encountered along transects of 100 m in open and closed canopy stands were surveyed for cone presence/absence, ovulate cone load, signs of physical disturbance, and their heights and DBHs were estimated. Eight open canopy transects were completed, as well as three closed canopy transects giving a total of approximately 2200 m2 of area surveyed. Tree islands and krummholz above the treeline were surveyed individually as they were encountered along large-scale North-South transects running between the valley’s walls. Over 130 tree islands and krummholz were surveyed within the valley of study. As I was surveying, I also collected over 200 ovulate cone samples in order to inspect for insect damage, disease and for seed viability tests to be conducted at Memorial University.
28% of surveyed trees had at least one generation of ovulate cones present in the closed canopy site, compared to an average of 17% in the open canopy sites. There also seems to be a large discrepancy in cone productivity between species, as well as the rate at which they were encountered in forested stands. Black spruce accounted for over half of all cone bearing trees encountered, but only 20% of black spruce’s were actually producing ovulate cones. Larch contributed just over 25% of total forested stand cone productivity, while white spruce (under 20%) and balsam fir (approximately 5%) make up the remainder. The highest elevation at which cone production was encountered is 764 m above sea level. Six ovulate cones were found on the tallest leader (1.02 m and a basal diameter of 3 cm) of a black spruce krummholz smaller than 70 m2 in total area.
During the winter of 2008 I will be examining the ovulate cones and seeds sampled in 2007 for any evidence of insect damage or disease. I will also be testing the seed for viability. In the summer of 2008 I will be returning to the Mealy Mountains to establish more surveying transects and collect more samples to get a better representation of the valley.
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