Why incorporate plant architecture into trait-based ecology?

Trait-based ecology has improved our understanding of the functioning of organisms, communities, ecosystems, and beyond. However, its predictive ability remains limited as long as phenotypic integration and temporal dynamics are not considered. We highlight how the morphogenetic processes that shape the 3D development of a plant during its lifetime affect its performance. We show that the diversity of architectural traits allows us to go beyond organ-level traits in capturing the temporal and spatial dimensions of ecological niches and informing community assembly processes. Overall, we argue that consideration of multilevel topological, geometrical, and ontogenetic features provides a dynamic view of the whole-plant phenotype and a relevant framework for investigating phenotypic integration, plant adaptation and performance, and community structure and dynamics.

Are inter- and intraspecific variations of sapling crown traits consistent with a strategy promoting light capture in tropical moist forest?

Background and Aims Morphological variation in light-foraging strategies potentially plays important roles in efficient light utilization and carbon assimilation in spatially and temporally heterogeneous environments such as tropical moist forest understorey. By considering a suite of morphological traits at various hierarchical scales, we examined the functional significance of crown shape diversity and plasticity in response to canopy openness. Methods We conducted a field comparative study in French Guiana among tree saplings of 14 co-occurring species differing in light-niche optimum and breadth. Each leaf, axis or crown functional trait was characterized by a median value and a degree of plasticity expressed under contrasting light regimes. Key Results We found divergent patterns between shade-tolerant and heliophilic species on the one hand and between shade and sun plants on the other. Across species, multiple regression analysis showed that relative crown depth was positively correlated with leaf lifespan and not correlated with crown vertical growth rate. Within species displaying a reduction in crown depth in the shade, we observed that crown depth was limited by reduced crown vertical growth rate and not by accelerated leaf or branch shedding. In addition, the study provides contrasting examples of morphological multilevel plastic responses, which allow the maintenance of efficient foliage and enable effective whole-plant light capture in shaded conditions under a moderate vertical light gradient. Conclusions This result suggests that plastic adjustment of relative crown depth does not reflect a strategy maximizing light capture efficiency. Integrating and scaling-up leaf-level dynamics to shoot- and crown-level helps to interpret in functional and adaptive terms inter- and intraspecific patterns of crown traits and to better understand the mechanism of shade tolerance.