The total dispersal kernel: a review and future directions

The distribution and abundance of plants across the world depends in part on their ability to move, which is commonly characterized by a dispersal kernel (a probability density function describing where seeds land relative to the parent plant). The total dispersal kernel (TDK) describes the combined influence of all primary, secondary, and higher-order dispersal vectors on the overall dispersal kernel for a plant individual, population, species, or community. Seeds can be dispersed by many different vectors and can be re-dispersed several times until they are deposited in their final location. Understanding the role of each vector and their influence on the TDK is critically important for being able to predict plant responses to a changing biotic or abiotic environment, yet few examples of well-characterized TDKs exist.

the total dispersal kernel workflow
Schematic representation of the modelling cycle for parameterizing and selecting total dispersal kernel models. Image credit: Rogers et al.

In a new Editor’s Choice review published in AoBP, Rogers et al. cover existing challenges and recent advances in empirical, modeling, and statistical approaches to studying the total dispersal kernal, and suggest ways forward. The authors also include two case studies of systems where the TDK has been extensively explored, specifically (i) for the noxious-weed Carduus nutans, and (ii) for the Mariana Islands in the western Pacific. They conclude the review by suggesting that finding a common language may help to overcome the challenges of characterizing the total dispersal kernel, including the use of the term “total dispersal kernel” rather than other similar terms. They hope that their review will reinvigorate the study of TDKs through integration of empirical, mathematical and statistical approaches (shown above). Identifying the factors that that determine where seeds land has been a longstanding challenge for plant and community ecology; advances in characterizing the TDK are broadly relevant for ecology and also to conservation practitioners trying to ensure ecological resilience in a changing world.

This review was published in the AoBP Special Issue: The Role of Seed Dispersal in Plant Populations: Perspectives and Advances in a Changing World. The authors would like to thank the participants of the 2016 Seed Dispersal Workshop for the initial discussions that sparked this manuscript.