Divergence of reproductive phenology under climate warming

Abstract

Because the flowering and fruiting phenology of plants is sensitive to environmental cues such as temperature and moisture, climate change is likely to alter community-level patterns of reproductive phenology. Here we report a previously unreported phenomenon: experimental warming advanced flowering and fruiting phenology for species that began to flower before the peak of summer heat but delayed reproduction in species that started flowering after the peak temperature in a tallgrass prairie in North America. The warming-induced divergence of flowering and fruiting toward the two ends of the growing season resulted in a gap in the staggered progression of flowering and fruiting in the community during the middle of the season. A double precipitation treatment did not significantly affect flowering and fruiting phenology. Variation among species in the direction and magnitude of their response to warming caused compression and expansion of the reproductive periods of different species, changed the amount of overlap between the reproductive phases, and created possibilities for an altered selective environment to reshape communities in a future warmed world.climate change ͉ global warming ͉ precipitation P henology is a sensitive biosphere indicator of climate change (1, 2). Long-term surface data and remote sensing measurements indicate that plant phenology has been advanced by 2-3 days in spring and delayed by 0.3-1.6 days in autumn per decade (3-6) in the past 30-80 years, resulting in extension of the growing season. An extended growing season leads to increased production in terrestrial and marine ecosystems (7,8), widens amplitudes of the annual CO 2 cycle in the atmosphere (9), and prolongs production of allergic pollens (10). Although changes in vegetative phenology have considerable consequences for ecosystem functioning, we lack information on responses of reproductive phenology due to climate change, especially in a community setting (11,12). Reproductive events usually determine population and community dynamics in future generations, affecting evolutionary processes. Because the flowering and fruiting phenology of plants is very sensitive to environmental cues such as temperature, moisture, and photoperiod (13), it is imperative to understand the impact of climate change on reproductive phenology.Reproductive phenology of assembled species in a plant community is often staggered in an unbroken progression over the growing season (14-17). This temporal distribution of community-level reproductive events is largely generated by the different developmental trajectories and life forms of the different species and may be shaped by their resource needs during reproduction and ecological sorting (18). Phenological differences in reproductive events among species over the growing season may reduce competition by spreading primary resource use over different temporal pools (19)(20)(21). Differential changes in phenology and growth between species in response to climate change could lead to new patterns of spec...

Elevated CO2 further lengthens growing season under warming conditions

“…We demonstrate that warming fairly consistently leads to earlier growth in spring and elevated CO 2 to later senescence in autumn, with both mechanisms leading to a longer growing season. The stature of grasslands and their ability to encompass thousands of individual plants, many species, and different growth forms within a relatively small area make them ideal ecosystems in which to conduct global change experiments 9,12,23 . For example, in our experiment, the varied responses of the three cool-season grasses, K. macrantha, H. comata and Pascopyrum smithii, a species that did not affect growing or reproductive season length in any year, suggest that different species, even within a growth form, respond in unique ways to warming and elevated CO 2 (Figs 3 and 4) .…”

“…However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods [6][7][8][9][10] . A conceptual model to explain this apparent contradiction 11 , and an analysis of the effect of elevated CO 2 -which can delay annual life cycle events 12-14 -on changing season length, have not been tested.…”

Relatively stable response of fruiting stage to warming and cooling relative to other phenological events

“…2011;Cook et al 2012;Wolkovich et al 2012;Wang et al 2014a). Plants may face trade-offs between the adjustment of one phenological event to temperature and the timing of subsequent events during the growing season (Post et al 2008;Sherry et al 2007Sherry et al , 2011 Haggerty and Galloway 2011; Dorji et al, 2013;CaraDonna et al 2014;Wang et al 2014b). This is illustrated by Fig.…”

“…Changes of flowering dates may alter the timing of fruit maturation, whereas fruit phenology in turn determines seed maturation and dispersal, which further feeds back on the diversity of species in an ecosystem (Primack 1987). The response of timing of fruiting to warming relative to other phenological events is still unclear because of inconsistent results from different plant species (Post et al 2008; Haggerty and Galloway 2011;Sherry et al 2007) and because few studies have analyzed the effects from both warming and cooling at the same location.The timing of fruit set is closely related to production of offspring, survival and reproductive success (Primack 1987; Miller-Rushing and Primack 2008). The response of timing of fruit set to changes in temperature in alpine grassland communities has received little attention, either from direct observations or manipulative experiments (Dorji et al 2013;Wang et al 2014b).…”

Effects of climate warming on plant autotoxicity in forest evolution: a case simulation analysis for Picea schrenkiana regeneration

“…At least for some plants, it appears that seed traits could evolve relatively fast to catch up with climate change (Sherry et al. 2007). For the plasticity/adaptations of tree species, however, we know very little about their germination behavior in response to environmental changes (Hedhly et al.…”