History is not the past: exploring historical contingency in ecological theory, community assembly, and post-disturbance recovery

Abstract

It has long been recognized that a species’ arrival timing in a community can shape its interactions with other species, resulting in alternate community states. Timing of disturbances can also have enduring impacts on ecological communities due to “legacy effects,” which result in community structure that is contingent on the history of recent disturbance. So-called historically contingent processes can alter species abundances and eventual community composition. Still, these processes remain understudied. This may be because they seem idiosyncratic and difficult to generalize into meaningful patterns. Historically contingent species interactions, for example, can alter assembly outcomes, posing a quandary for the study of competitive coexistence. In a global change context, however, understanding how timing of past events influences future community dynamics is crucial; disturbances like fire are becoming more frequent, and the timing of life history events like germination and flowering in plants is shifting in response to altered environmental cues. With this motivation, my dissertation research focuses on the role of history in three discrete contexts. First, using insights from feminist science and technology studies, I interrogate the emergence and persistence of competition theory in ecology and its limitations for the study of coexistence, arguing that a baseline expectation of multispecies communities could generate new lines of inquiry and testable frameworks. Second, in longleaf pine understory, I explore the role of fire history, finding that communities vary both in their composition and in their response to future fire based on the timing of last exposure to fire. Finally, I use common old field grasses to explore impacts of relative germination timing between competing species on survival and growth, finding that early-arrival advantages can vary with seasonal conditions. Together, these studies show that historical legacies can exert strong effects on community structure and function and that interdisciplinary analysis can be an asset to ecological researchers.