Active or passive? Specific-leaf-area plasticity responses

Liu et al. conducted a meta-analysis to test the hypothesis that shade-induced increases in specific-leaf-area (SLA) indicate an adaptive plant response to optimizing light capture.

Mean effect sizes (log response ratio) describing the overall responses of biomass and SLA to shading
Mean effect sizes (log response ratio) describing the overall responses of biomass and SLA to shading, and how these responses depend on whether the species are woody or non-woody, and whether the study was done in a glasshouse or garden, used the same genetic material in the different light treatments, and used neutral or canopy shading. Error bars represent bias-corrected bootstrapped 95 % confidence intervals around the mean effect size estimates derived from the phylogenetically corrected meta-analytical model. The sample sizes (i.e. the number of studies) are given in parentheses. The dashed line indicates zero effect of shading.

They conclude that species with greater SLA phenotypic plasticity were less able to maintain biomass under shade. Some of the plastic changes that are frequently thought to be adaptive may simply reflect passive responses to the environment, or occur as by-products of adaptive plastic responses in other traits.

Reference List

Liu, Y., Dawson, W., Prati, D., Haeuser, E., Feng, Y., & van Kleunen, M. (2016). Does greater specific leaf area plasticity help plants to maintain a high performance when shaded? Annals of Botany, 118(7), 1329–1336. https://doi.org/10.1093/aob/mcw180