Gap dynamics theory proposes that forest canopy gaps provide the high light levels needed for regeneration. Little attention has been given to more gradual alternatives; however, recent studies have demonstrated declines in within-crown leaf area index with tree size in temperate forest trees. Our project builds on this previous research by assessing the prevalence of this age-related crown thinning phenomenon. We quantified crown openness for 18 dominant tree species in temperate and tropical forests (n = 1786 trees). Separate pooled groupings of tropical and temperate species showed significantly positive relationships between openness and DBH (p<0.001). Of the 9 sampled species showing positive relationships, significance (p< 0.05) was detected in 3 out of 10 tropical species and 1 out of 8 temperate species. Two temperate species showed significantly reduced canopy openness with size. These trends highlight the role that very large trees play in influencing light availability for understorey regeneration.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43309 |
| Date | 10 December 2013 |
| Creators | Quinn, Eadaoin Maria Ines |
| Contributors | Thomas, Sean C. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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