FERNS AS FACILITATORS OF COMMUNITY RECOVERY FOLLOWING BIOTIC UPHEAVAL (Invited Presentation)

Competition of pioneer species, such as ferns, has driven hypotheses of recolonization following modern and fossil disturbance of terrestrial biospheres. The scale of devastation following modern events such as Mt. St. Helen's is drastically different than global events such as the Cretaceous-Paleogene (K-Pg; approx. 66 Ma) extinction event. The dominance of ferns following the K-Pg is recorded as a global fern spore “spike’’ lasting 1-74 thousand years. Rapid recolonization has been hypothesized to occur due to high spore production and wind dispersal, rooting our understanding within a competitive framework. This antagonistic framework is outdated and in need of re-examination as modern ecological theory has documented the importance of positive interactions within ecosystems. Facilitation, the positive influence of one species on the fitness of another, has been documented in both micro- and macro-organisms and across trophic levels. Through the amelioration of environmental variables, fundamental niche space expands. Here we propose that ferns act as facilitators of community assemblage following substantial biotic upheaval by ameliorating the environment. This framework of facilitation is then coupled with greenhouse experiments which focus on proxy K-Pg fern species, as their physiology responds to pre- and post-extinction event. By measuring the influence of abiotic environmental variables on fern species pre- and post-biotic upheaval (K-Pg) we can revisit our ideas on facilitation through the guise of how climate might limit or enhance facilitation.