Root diversity

Prof. Dr. Alexandra Weigelt, Leipzig, Germany
Prof. Dr. Liesje Mommer, Wageningen, The Netherlands

This subproject will study the importance of plant functional traits, especially root traits, and the effect of trait identity and diversity on drought resistance and recovery. We will build on the framework of plant form and function, and deepen our understanding of the integration of (1) hydrological traits into the framework and (2) biomass allocation to roots as a mediating factor of plant-drought responses. In addition, we will test the importance of trait identity, diversity and similarity for seasonal and long-term plant responses to drought stress.

We plan five working packages (WPs) for this subproject. In WP1, the PIs will lead an international workshop with renowned experts from ecological and physiological backgrounds, to discuss the multiple mechanisms linking functional traits to drought responses as outlined above. In WP2, we will quantify species-specific drought responses and traits in individual plants in a greenhouse experiment (TraitCoMic), to improve our understanding of trait relationships to drought responses in the herbaceous species of the Jena Experiment. Given the multitude of mechanisms of how individual traits or trait gradients may support drought resistance and recovery, more functionally diverse communities should maintain a higher stability of ecosystem functioning during drought. WP3 will test this hypothesis in the ResCUE Experiment using the data from WP2 together with community measures of root biomass allocation during drought. Finally, we will apply our trait data to test temporal stability in the Main Experiment in two distinct ways. In WP4, we will quantify seasonal variation of root growth in close collaboration with physiological and structural measurements aboveground in SP01 and SP02, to test if trait identity or diversity explains short-term responses to moderate droughts in dominance patterns of differently diverse communities. Finally, in WP5, we will test how different measures of functional diversity explain long-term drought resistance and recovery from severe droughts in the 20-year sequence of the Main Experiment.