A functional trait analysis of successional pathway dynamics
St. Martin, Philippe
Doctor of Philosophy
DisciplineNatural Resources Management
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The study of plant community re-assembly following disturbances in anthropogenically managed landscapes is a necessity in today’s climate. The measurement of plant functional traits is a tool that can be of great help in understanding how individual plants and entire communities respond to shifts in disturbance regimes and environmental characteristics that are directly or indirectly under human influence. In Eastern Newfoundland, two distinct successional pathways may be initiated depending on fire severity. Fires of high severity in Picea mariana-dominated forests will initiate a forest succession; fires of low severity can cause a state shift where an ericaceous heath dominated by Kalmia angustifolia will succeed where a P. mariana-dominated forest once stood. To enhance understanding of community response to varying disturbance regimes, I applied a functional trait analysis to two distinct successional pathways with the aim of (i) assessing the functional diversity (FD) of both pathways, (ii) identifying the causes of the observed FD, and (iii) using the functional traits of both communities to predict future successional pathways. Alpha functional diversity (α-FD) was calculated as functional dispersion (FDis) and beta functional diversity (β-FD) was mean pairwise distance (DPW) and mean distance to nearest neighbour (DNN). Identifying significant drivers of FD in both communities was performed by linking soil characteristics with plant traits via a combine RLQ-fourth corner approach. Finally, prediction of post-fire succession was made possible by constructing a model based on fuzzy logic that incorporated community flammability and regeneration strategy of dominant plants, along with environmental variables.