Natural disturbances and masting: from mechanisms to fitness consequences

Abstract

The timing of seed production and release is highly relevant for successful plant reproduction. Ecological disturbances, if synchronized with reproductive effort, can increase the chances of seeds and seedlings to germinate and establish. This can be especially true under variable and synchronous seed production (masting). Several observational studies have reported worldwide evidence for co-occurrence of disturbances and seed bumper crops in forests. Here, we review the evidence for interaction between disturbances and masting in global plant communities; we highlight feedbacks between these two ecological processes and posit an evolutionary pathway leading to the selection of traits that allow trees to synchronize seed crops with disturbances. Finally, we highlight relevant questions to be tested on the functional and evolutionary relationship between disturbances and masting. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

Fire history and weather interact to determine extent and synchrony of mast-seeding in rhizomatous scrub oaks of Florida

“…However, while low-severity fires may occasionally increase germination of acorns cached before [57], seeds near the surface, and in shallow caches will generally be killed [58]. In contrast, when seeds arrive soon after stand-clearing disturbance, this can result in successful recruitment of seedling cohorts, resulting in spatial signatures that can sometimes be detected decades after the event [8,24]. At the study site, the recovery of the vegetation cover to pre-fire states is rapid, however, and long-term changes in species composition were only observed under fire exclusion [34][35][36].…”

“…For example, acorn production in two California oaks, Quercus lobata and Q. douglasii, varies over the entire species range, over distances as far as 745 km, in close concordance with the spatial synchrony of weather conditions that affect pollination success [20]. Even as our understanding of the mechanistic links between annual abiotic conditions and masting has improved tremendously, the role of abiotic extremes and disturbances in long-term seed production patterns is still underexplored (see [24] in this issue).…”

“…In addition to strategies that store and accumulate reproductive potential over years of disturbance, such as serotiny, fire can select for sprouting and post-fire seeding [29]. The interplay between disturbance regime and masting can therefore be a central driver of plant fitness [24].…”

The ecology and evolution of synchronized reproduction in long-lived plants

“…Moreover, in some species, interactions with disturbances such as fire, drought, flooding or windthrows drive the extent and synchrony of seed production, as found in fire-adapted scrub oaks in Florida, USA [39]. The effects of climate change on masting will, therefore, be additionally complicated by the rate of change in the relevant disturbance regime [40].…”

“…This includes beneficial changes in light regime, soil conditions, water and nutrient availability for offspring. Vacchiano et al [40] highlight how drought, heat waves and wildfires are foreshadowed by weather conditions that can also act as proximate cues of masting. Evidence suggests that changes in disturbance regimes promote eco-evolutionary feedbacks selecting for masting behaviour [83,84].…”