Bridging the gap from individual-based processes to joint species distributions in a forest landscape

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The distribution of plant species across a region is the cumulative result of natural and anthropogenic disturbances, environmental conditions, the reproduction and dispersal capacities of each species as well as interactions (competition, facilitation) between individuals of the same or different species. Joint species distribution models are one of the main tools used to describe how the distribution of species depend on the environment and how species ranges may shift under environmental change. Since these models are static in time, their interpretation assumes a certain steady state for species ranges, which may limit their capacity to predict how the community would respond to sudden change. Individual-based models, such as forest simulators, describe more directly the demographic, dispersal and interaction processes affecting the individuals of different species. Some of those models also incorporate the effects of disturbances (e.g. fire) at the landscape scale. However, parametrizing these models requires extensive datasets with multiple sampling times. There is thus a need for new methods to incorporate the dynamic processes through which species change their range within the framework of joint species distribution models. Within the next five years, I will pursue three projects that all share the goal of including dispersal processes into models for the distribution of multiple species, but focus on different scales, from a forest (obj. 1) to a complex forest landscape (obj. 2) to a larger region (obj. 3). 1. Develop multi-species models for the dispersal of seeds and the establishment of seedlings in a long-studied Neotropical forest. 2. Model the dynamics of communities of deadwood-inhabiting bryophytes across the boreal forest of western Québec. 3. Reconstruct the dispersal of aquatic invasive species along road and hydrological networks based on community science observations. The realization of objectives 2 and 3 in particular will provide useful information for the management of the Canadian boreal forest. The dispersal capacity of key groups of bryophytes (obj. 2) will determine in part the amount and arrangement of old growth forests to retain in a landscape to promote the return of these organisms and their associated ecosystem services following a harvest. Community-level models of invasive species spread (obj. 3) will assist in predicting the spread of new invasive species, based on similarity in traits to those already here.