Figure - available from: New Phytologist
This content is subject to copyright. Terms and conditions apply.
Phenological shifts and climatic sensitivities. (a) Changes to the beginning of flowering from 1940 to 2010 (ΔDOY10,Y). (b) Mean spring temperature sensitivity of the beginning of flowering (ΔDOY10,T). (c) Total spring precipitation sensitivity of the beginning of flowering (ΔDOY10,P). (d) Changes to the ending of flowering from 1940 to 2010 (ΔDOY90,Y). (e) Mean spring temperature sensitivity of the ending of flowering (ΔDOY90,T). (f) Total spring precipitation sensitivity of the ending of flowering (ΔDOY90,P). In each panel, points give the mean of the posterior distribution, thick lines give the 50% CI, and thin lines give the 80% CI. Dark colors indicate a > 90% probability, light colors a > 75% probability, and gray a ≤ 75% probability of phenological shifts (gold) and sensitivities to mean spring temperature (red) and total spring precipitation (blue). Species are arranged in each panel by ΔDOY10,Y (top) or ΔDOY90,Y (bottom) in descending order.
Source publication
Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly).
We combined long‐term field (1937–2012) and herbarium records (1850–2017) of 68 species in a flowering plant community in central North America...
Citations
... In the case of flowering season, our study detected a median increase of 0.023 d yr -1 and a median absolute change of 0.138 d yr -1 . Increases in flowering seasons or flowering durations have been reported across the literature, mostly from field studies, meta-analyses, and warming experiments in the field (Høye et al., 2013;Zhou et al., 2022;Chen et al., 2023;Austin et al., 2024). Similarly to changes in flowering date, the reported magnitude of change in flowering season duration varies greatly between study systems and species. ...
Flowering phenology is an indicator of the impact of climate change on natural systems. Anthropogenic climate change has progressed over more than two centuries, but ecological studies are mostly short in comparison. Here we harness the large‐scale digitization of herbaria specimens to investigate temporal trends in flowering phenology at a global scale.
We trained a convolutional neural network model to classify images of angiosperm herbarium specimens as being in flower or not in flower. This model was used to infer flowering across 8 million specimens spanning a century and global scales. We investigated temporal trends in mean flowering date and flowering season duration within ecoregions.
We found high diversity of temporal trends in flowering seasonality across ecoregions with a median absolute shift of 2.5 d per decade in flowering date and 1.4 d per decade in flowering season duration. Variability in temporal trends in phenology was higher at low latitudes than at high latitudes.
Our study demonstrates the value of digitized herbarium specimens for understanding natural dynamics in a time of change. The higher variability in phenological trends at low latitudes likely reflects the effects of a combination of shifts in temperature and precipitation seasonality, together with lower photoperiodic constraints to flowering.
Background
The frequency and intensity of droughts are expected to increase under global change, driven by anthropogenic climate change and water diversion. Precipitation is expected to become more episodic under climate change, with longer and warmer dry spells, although some areas might become wetter. Diversion of freshwater from lakes and rivers and groundwater pumping for irrigation of agricultural fields are lowering water availability to wild plant populations, increasing the frequency and intensity of drought. Given the importance of seasonal changes and extremes in soil moisture to influence plant reproduction, and because the majority of plants are flowering plants and most of them depend on pollinators for seed production, this review focuses on the consequences of drought on different aspects of reproduction in animal-pollinated angiosperms, emphasizing interactions among drought, flowering and pollination.
Scope
Visual and olfactory traits play crucial roles in attracting pollinators. Drought-induced floral changes can influence pollinator attraction and visitation, together with pollinator networks and flowering phenology, with subsequent effects on plant reproduction. Here, we review how drought influences these different aspects of plant reproduction. We identify knowledge gaps and highlight areas that would benefit from additional research.
Conclusions
Visual and olfactory traits are affected by drought, but their phenotypic responses can vary with floral sex, plant sex, population and species. Ample phenotypic plasticity to drought exists for these traits, providing an ability for a rapid response to a change in drought frequency and intensity engendered by global change. The impact of these drought-induced changes in floral traits on pollinator attraction, pollen deposition and plant reproductive success does not show a clear pattern. Drought affects the structure of plant–pollinator networks and can modify plant phenology. The impact of drought on plant reproduction is not always negative, and we need to identify plant characteristics associated with these more positive responses.
