A Mechanistic Framework for Understanding the Effects of Climate Change on the Link Between Flowering and Fruiting Phenology

Phenological shifts are a widely studied consequence of climate change. Little is known, however, about certain critical phenological events, nor about mechanistic links between shifts in different life-history stages of the same organism. Among angiosperms, flowering times have been observed to advance with climate change, but, whether fruiting times shift as a direct consequence of shifting flowering times, or respond differently or not at all to climate change, is poorly understood. Yet, shifts in fruiting could alter species interactions, including by disrupting seed dispersal mutualisms. In the absence of long-term data on fruiting phenology, but given extensive data on flowering, we argue that an understanding of whether flowering and fruiting are tightly linked or respond independently to environmental change can significantly advance our understanding of how fruiting phenologies will respond to warming climates. Through a case study of biotically and abiotically dispersed plants, we present evidence for a potential functional link between the timing of flowering and fruiting. We then propose general mechanisms for how flowering and fruiting life history stages could be functionally linked or independently driven by external factors, and we use our case study species and phenological responses to distinguish among proposed mechanisms in a real-world framework. Finally, we identify research directions that could elucidate which of these mechanisms drive the timing between subsequent life stages. Understanding how fruiting phenology is altered by climate change is essential for all plant species but is particularly critical to sustaining the large numbers of plant species that rely on animal-mediated dispersal, as well as the animals that rely on fruit for sustenance.

Flowering and fruiting phenology of jackfruit (Artocarpus heterophyllus Lam.) from Sumatra landraces in ex situ conservation area in Karangmojo, Yogyakarta

This study aimed to determine the flowering and fruiting phenology of jackfruit originated from Sumatra landraces planted in ex situ conservation in Yogyakarta within the 2018 and 2019 flowering periods. Flowering ontogeny and phenology were observed following Owens and Pushpakumara methods. Results found five developmental stages of male inflorescences, which last in 64-101 days, ended by the drought and abscissed of the males. Female inflorescences undergo five stages which take 92-160 days in total. Differences in rainfall and the dry season period resulted in different onset and duration of flowering. In 2018, which has more rainfall and a shorter dry season, flowering initiates lately (February-June) with a longer duration (6 months). In 2019, the less rainfall and more extended dry season resulted in early flowering (January-April) with a shorter duration (4 months). The Medan landrace flowered later and longer. Flowering synchrony occurred between sexes within the same tree, but there was asynchronous flowering among individual trees. Water availability is crucial in flowering and fruit production. Flowering stimulation and pollination management may also be conducted to increase flower production, pollinating agents, and fruit production and synchronize the flowering.

Taxonomy of the wild species of genus Crataegus (Rosaceae): An updated review for the flora of Nakhchivan Autonomous Republic (Azerbaijan)

We clarified the current state of genus Crataegus L. in the flora of the Nakhchivan Autonomous Republic (Azerbaijan) using a comparative analysis of herbarium specimens from the Azarbaijan herbariums and data collected during the expeditions in 2004–2018. We succeed in adding some important data on the flora of Nakhchivan Autonomous Republic and Azerbaijan, we also enhanced the previous research with chromosome and morphological analysis. We identified 17 wild species of Crataegus genus in the Nakhchivan Autonomous Republic (C. pentagyna Waldst. et Kit. ex Willd., 1800, C. zangezura Pojark., 1939, C. orientalis Pall. ex Bieb., 1808, C. pojarkoviae Kossych, 1964, C. tournefortii Griseb., 1843, C. szovitsii Pojark., 1939, C. pontica C. Koch, 1853, C. meyeri Pojark., 1939, C. eriantha Pojark., 1939, C. atrosanguinea Pojark., 1939, C. caucasica C. Koch, 1853, C. pallasii Griseb., 1843, C. rhipidophylla Gand. (С. curvisepala Lindm.; C. kyrtostyla Pojark.) 1871, C. pseudoheterophylla Pojark., 1939, C. monogyna Jacq., 1775, C. x armena Pojark., 1939, and C. x cinovskisii Kassumova), which will contribute to five introduced cultural species used in the greenery. We also clarified the status of interserial and intersection hybrids using the chromosome and morphological analysis. The article includes the complete list of Crataegus L. species with information about synonyms of the species, patterns of distribution, habitat, latitude and elevation, flowering and fruiting phenology.

The effects of an experimental drought on the ecophysiology and fruiting phenology of a tropical rainforest palm

Aims Anthropogenic climate change is predicted to increase mean temperatures and rainfall seasonality. How tropical rainforest species will respond to this climate change remains uncertain. Here, we analysed the effects of a 4-year experimental throughfall exclusion (TFE) on an Australian endemic palm (Normambya normanbyi) in the Daintree rainforest of North Queensland, Australia. We aimed to understand the impact of a simulated reduction in rainfall on the species’ physiological processes and fruiting phenology. Methods We examined the fruiting phenology and ecophysiology of this locally abundant palm to determine the ecological responses of the species to drought. Soil water availability was reduced overall by ~30% under a TFE experiment, established in May 2015. We monitored monthly fruiting activity for 8 years in total (2009–2018), including 4 years prior to the onset of the TFE. In the most recent year of the study, we measured physiological parameters including photosynthetic rate, stomatal conductance and carbon stable isotopes (δ 13C, an integrated measure of water use efficiency) from young and mature leaves in both the dry and wet seasons. Important Findings We determined that the monthly fruiting activity of all palms was primarily driven by photoperiod, mean solar radiation and mean temperature. However, individuals exposed to lower soil moisture in the TFE decreased significantly in fruiting activity, photosynthetic rate and stomatal conductance. We found that these measures of physiological performance were affected by the TFE, season and the interaction of the two. Recovery of fruiting activity in the TFE palms was observed in 2018, when there was an increase in shallow soil moisture compared with previous years in the treatment. Our findings suggest that palms, such as the N. normanbyi, will be sensitive to future climate change with long-term monitoring recommended to determine population-scale impacts.