Functional traits and demography: how can they address global environmental change challenges in plant communities?

Global environmental change is having widespread effects on ecosystem functioning. For plant communities, climate change, introduction of non-native species and deforestation are some major threats, resulting in the extinction risk of 1 in 5 plant species globally (Royal Botanic Gardens, 2016). Understanding how plant communities respond to environmental stressors is a major scientific and societal concern. Being able to predict responses would greatly help to efficiently allocate financial and human resources to manage plant communities. A method that has gained great interest for predicting changes in plant community dynamics is the use of functional traits. These are measurable features of an individual organism that can be morphological, phenological or physiological in nature (Violle et al. 2007). For plants, examples include height above ground, leaf area or average mass of seeds. Functional traits have been adopted across the ecological and environmental sciences to explain phenomena like biological invasions (van Kleunen et al. 2010), or testing for species coexistence mechanisms (Adler et al. 2013). However, rarely is the use of traits linked to individual fitness through its contributions to the population through important life processes: survival, growth and reproduction (Salguero-Gómez et al. 2018; Middleton et al. in prep). This decoupling of the "functionality" in functional traits, has resulted in mixed results in empirical studies in terms of their explanatory and predictive power (Yang et al. 2018).