Climate change and plant reproduction: trends and drivers of mast seeding change

Abstract

Climate change is reshaping global vegetation through its impacts on plant mortality, but recruitment creates the next generation of plants and will determine the structure and composition of future communities. Recruitment depends on mean seed production, but also on the interannual variability and among-plant synchrony in seed production, the phenomenon known as mast seeding. Thus, predicting the long-term response of global vegetation dynamics to climate change requires understanding the response of masting to changing climate. Recently, data and methods have become available allowing the first assessments of long-term changes in masting. Reviewing the literature, we evaluate evidence for a fingerprint of climate change on mast seeding and discuss the drivers and impacts of these changes. We divide our discussion into the main characteristics of mast seeding: interannual variation, synchrony, temporal autocorrelation and mast frequency. Data indicate that masting patterns are changing but the direction of that change varies, likely reflecting the diversity of proximate factors underlying masting across taxa. Experiments to understand the proximate mechanisms underlying masting, in combination with the analysis of long-term datasets, will enable us to understand this observed variability in the response of masting. This will allow us to predict future shifts in masting patterns, and consequently ecosystem impacts of climate change via its impacts on masting. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

An assessment of temporal variability in mast seeding of North American Pinaceae

“…Thus while we detected no broad patterns in CVp across regions, more localized patterns may exist within species [26,64]. In addition, increasing data collection across elevational gradients at different latitudes in mountainous areas will allow for documenting mast-seeding patterns over time and testing hypotheses related to climate change (see also [34]). While temperature increases are predicted to be substantial at high latitudes, other components of climate change include frequency and severity of fires, insect attacks and extreme weather events [65], and increasing CO 2 has been shown to experimentally impact conifer seed production [66] and could impact long-term mast-seeding patterns.…”

“…Whether absolute temperature values (T) or relative temperature compared to the previous year (ΔT ) drive reproduction is critical to forecasting future mast events under a warming climate; if ΔT is the main driver then mast-seeding variability is not expected to change [21], whereas direct climate warming would lead to an increased cueing frequency that may induce a breakdown in mast-seeding patterns over time [32]. While temperature appears to play a key role, the depletion of endogenous resources by a large reproductive event diminishes the number of reproductive buds the following year even when the conditions are favourable, such that high levels of reproduction do not happen in consecutive years [26,33,34].…”

Mast seeding promotes evolution of scatter-hoarding

“…This could shift the beech-rodent interactions towards antagonism, with higher rodent abundances (predicted also by [90]), more seed consumed and fewer cached (recall that caching declines with more frequent masting: figure 3). On the other hand, a recent meta-analysis of global data suggests that masting has become more pronounced ( [91]; see also [92]). Such a change could make seed caching more profitable for granivores (higher intensity of masting promotes caching: figure 2).…”

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

“…[68,69]). In newly established forests, or those recovering from disturbance, ontogenetic changes in masting will have important implications for management [5], irrespective of any parallel changes in masting resulting from environmental change [35].…”

“…Resource dynamics, environmental variation, genetic and hormonal regulation, pollen limitation and their alignment through space and time are factors that generate variability and synchrony [3]. The specific way each of these proximate factors drives masting is highly variable among plant species and even populations [46], providing an exciting avenue for research but also creating a challenge in predicting the responses of masting to climate change [35]. For example, LaMontagne et al [36] found that in North America conifers, masting is cued by the difference between summer temperatures 2 and 3 years before seed fall, supporting the so-called ΔT model (i.e.…”