PhD Theses.Tree crown morphology and arrangement in three-dimensional space is a key driver of forest dynamics,
determining not only the competitiveness of an individual but also the competitive effect exerted on
neighbouring trees. Many theoretical frameworks aim to predict crown morphology from first principles and
assumptions of Euclidean form and ultimately infer whole forest stand structure and dynamics but paucity in
data has limited vigorous testing. Tree crowns are also not rigid in form and due to their sessile nature, must
morphologically adapt to immediate abiotic and biotic surroundings to enhance survival.
The characterisation of tree structure has been limited by the simplicity and associated error of traditional
crown measurements. This project uses Terrestrial Laser Scanning data collected from a water limited
Mediterranean forest community in Spain to highlight methodological opportunities presented by TLS in
understanding forest structure and also the various developments required to extract ecologically meaningful
metrics from these data. It then applies these novel metrics to answer questions about how tree crowns scale
with size, the effects of competition and how plasticity in shape and arrangement interacts with light capture
at the individual and plot scales.
Modification to existing code as well as bespoke development were required to segment and calculate
individual metrics from trees in this forest type. Accurate measures of crown morphology highlighted
allometric scaling deviations from theoretical predictions and intra-specific differences in response to
competition, calculated using more representative neighbourhood metrics. Inter-specific differences in crown
plasticity and significant effects of size (height) were also evident, along with trade-offs between
morphological plasticity and crown size. Light capture was positively affected by plasticity with inter-specific
differences highlighting various biomass allocations strategies species undertake to acquire light. At the plot
scale, mixed-genus plots intercepted less direct light and were structurally more complex rather than more
volume filling
