Roots at work: Interspecific root interactions determining community processes
01 / 2009 - 12 / 2013
Plant root growth is primarily driven by the availability of nutrients and water in the soil. However, recent discoveries show that the world underground is not quite that simple: root growth is also strongly controlled by the identity of neighbour roots. It has been shown that interspecific root interactions can lead to stimulation of total root growth. This has been hypothesised to enhance resource capture which may increase community productivity. Furthermore, root interactions may lead to spatial aggregation of roots which could affect competitive relationships among plant species and, ultimately, species coexistence. Here, I will explore the consequences of interspecific root interactions for these community processes. Furthermore, I will make a first step towards unravelling the mechanisms involved.
I have already explored a proper model system consisting of common grassland perennials, including grasses and forbs. Moreover, I have developed a novel molecular method that quantifies species proportions in mixed-species root samples allowing an unprecedented look in plant species distributions belowground. Preliminary observations in this system indicate substantial stimulation of root growth and root aggregation in mixtures compared to monocultures. Building on these early exciting results, I will first investigate what mechanisms are involved in interspecific root recognition in perennial grassland species by conducting small-scale greenhouse experiments. Second, I will study if root growth and aggregation in long-established plant communities are indeed different between communities that differ in plant diversity. Finally, I will create experimental plant mixtures of the used grassland species with treatments that manipulate interspecific root interactions, to test to what extent specific recognition mechanisms are involved.
These integrative approaches together will identify the importance of newly revealed specific root interactions, as well as the nature of the underlying mechanisms, for species coexistence and community productivity.