Clonal traits can improve predictions of plant community response to climate change: Evidence from a turf transplant experiment in southern Norway
Ecologists have gradually settled on a “common core” of plant species traits that are easily measured and putatively represent meaningful axes of variation in plant strategy. Generally, these traits focus on plant characteristics relating to individuals or ramets – e.g. leaves, stems, flowers, and seeds – and ignore traits relating to clonality – e.g. clonal architecture, rate of lateral spread, persistence of ramet connectivity. The lack of attention to clonal traits is unfortunate as clonality is extremely common in plant communities and can affect processes relating to community assembly, community response to disturbance, and ecosystem functioning. Here, we use an ongoing turf transplant experiment in southern Norway to investigate the influence of clonal traits on community dynamics, both in comparison to and in conjunction with commonly used individual-level plant traits and data on seed rain. Intact alpine and subalpine turfs were transplanted to warmer, wetter, or warmer and wetter climates. We compared observed changes in the community composition of transplanted turfs to neutral expectations based on model simulations to understand the roles of ramet-level and clonal traits in community response to climate change.
Our consideration of clonal growth led to improved predictions of community dynamics in both control turfs and transplanted turfs. Community composition in adjacent cells was a better predictor of immigrant identity than seed rain or overall site community composition. In addition, specific types of clonal growth architecture showed differential rates of per capita immigration success following transplantation to new climates, illustrating the influence clonal traits can have on short term community dynamics. We hypothesize a colonization-competition trade-off in clonal growth strategy, wherein species capable of rapid vegetative spread arrive more readily to newly available high quality sites but are ultimately displaced by “clumping” species which are better competitors for resources once established. Our results highlight the potential value of including clonal plant ecology into models of community response to climate change.