These cherry blossom festivals of spring are culturally and economically important events, and successful planning requires that the cherry blossoms appear as expected within the festival period. Locations of the four cities in Table 2 are also shown. This is an open-access article distributed under the terms of the Creative Commons Attributionwhich permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Competing interests: The authors have declared that no competing interests exist. Warming associated with climate change has been shown to alter ecosystem processes including phenology — the timing of organism development . The funders had no role in study de, data collection and analysis, decision to publish, or preparation of the manuscript. Simple, thermal-time based phenology models can provide useful insights for predicting the effects of temperature on the phenology of plants, particularly in those species e. The peak bloom date is determined when R h has been satisfied past the bud-burst.
The threshold temperature T c is the base temperature below which the chill days D c are accumulated daily since the onset of dormancy until the chilling requirement R c is met. Our indicate that PBD at the Tidal Basin are likely to be accelerated by an average of five days by s and 10 days by s for these cultivars under a mid-range A1B emissions scenario projected by ECHAM5 general circulation model.
Floral buds must be exposed sequentially to long enough periods of chilling temperature R c and heating temperature R h for spring flowering.
We applied the model to forecast future cherry PBD throughout the Mid-Atlantic region surrounding the Tidal Basin including the states of Maryland, Virginia, and West Virginia in response to climate change. In addition, we estimated recent PBD at UW from the campus newspapers and other mass-media including web search as well as our own observations for nine years of data between and We acquired temperature data for these locations from the corresponding National Oceanic and Atmospheric Administration NOAA climatological observations sites e.
From a cultural viewpoint, an accurate prediction of cherry phenology is critical because many spring festivals and events around the world are timed around a specific phenological event — peak bloom dates PBD. For example, the blossom of flowering cherry species e. Similarly, it has been proposed that floral buds of deciduous trees enter dormancy in the autumn as their leaves begin to fall . ly, several studies  have shown that a thermal-time based two-step phenology model successfully predicted flowering time of temperate tree species including fruit crops and flowering cherries such as Prunus serrulata var.
Overall, the model predicted that by the s the mean PBD in these locations would take place approximately four weeks earlier than the current PBD under the A2 emission scenario Table 2.
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Our demonstrate the potential impacts of climate change on the timing of cherry blossoms and illustrate the utility of a simple process-based phenology model for developing adaptation strategies to climate change in horticulture, conservation planning, restoration and other related disciplines. The phenology of plants is sensitive to changes in temperature. Despite over 60 years of peak bloom data, no study to our knowledge has attempted to forecast the future bloom dates of the cherry trees at the Tidal Basin of Washington, DC.
These cherry trees were propagated in from scions from 12 selections from the Ekita-mura area of Japan and planted in the spring of . For example, shorter and warmer winters can reduce the cold hardening of trees, leaving them vulnerable to frost injury . This regional forecast was made in year intervals to follow the normal year method of the World Meteorology Organization . We performed an optimization process to derive a new set of parameter estimates for Yoshino and Kwanzan cherry trees in the Tidal Basin using the daily weather data from the Reagan National Airport and PBD data between and We tested the model performance against temporally and spatially independent PBD data.
Briefly, the A1B scenario represents a future world of rapid economic growth, global population that peaks in mid-century and declines thereafter, and rapid introduction of novel and efficient technologies that are balanced across various energy sources.
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ificant genetic similarities have been reported between P. These two varieties are also widely cultivated throughout the U. In the present study, we have modified the thermal-time based phenology model developed by Cesarracio et al. For its sensitivity to winter and early spring temperatures, the timing of cherry blossoms is an ideal indicator of the impacts of climate change on tree phenology. Richardson et al. Briefly, the model used in the present study divides the flowering process of deciduous trees into two stages: dormancy including rest and quiescent periods during autumn and winter, and the flowering period following bud-burst in spring Fig.
The model requires the date in autumn when temperature falls below a threshold temperature, causing floral buds to enter the rest period of dormancy, and an estimation of three parameters.
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In Japanese culture, cherry blossoms carry great spiritual ificance and their blooming has been celebrated with rituals called hanami since the 9 th century . More details on these models are provided by Roeckner et al. In this data set, PBD are defined as the days in which 70 percent of the blossoms of cherry trees that surround the Tidal Basin are open pers. The rate of D c and D h accumulation depends on the daily air temperatures — mean T amaximum T maxand minimum T min — relative to species specific temperature thresholds as detailed in Cesaraccio et al.
Flowering cherry trees are an effective indicator of the impact of climate change on phenology because their flowering time is highly sensitive to temperatures, especially during winter and early spring i. These past PBD were compared with the predicted PBD by the calibrated model using daily temperature data from two adjacent weather stations near the Tidal Basin for both cultivars: 1 the Reagan National Airport weather station and 2 the Dulles International Airport weather station.
For example, Mynei et al. It is a hybrid of unknown origin from Japan with a ificant historical, cultural, and economic importance for the region . If R c is satisfied, rest endodormancy is released and the heat or anti-chill days D h begins to accrue towards the heating requirement R h.
The spatially and temporally downscaled datasets include daily maximum and minimum temperatures at a resolution of 30 arc-seconds ca. When tested against the historical phenology records of leaf fall, budburst, and flowering, such models can be powerful tools to forecast the impacts of climate change on phenology, and to help develop effective adaptation strategies in agriculture, horticulture, forestry, conservation planning, restoration, and natural resource management.
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Cherry blossoms, an icon of spring, are celebrated in many cultures of the temperate region. The parameter optimization process yielded a set of parameter estimates that produced minimum RMSE between predicted and observed PBD during the — period in the Tidal Basin Table 1.
The past PBD predictions at Tidal Basin using the temperature data from the Dulles International Airport resulted in similar performance data not shown. During the past decades, considerable shifts in tree phenology have been reported in the temperate regions; these shifts are likely to be a response to the changing climate.
The expected changes in phenology will have a substantial effect on the reproduction, distribution and productivity of trees as the coincidence of ecosystem processes, such as flowering and the emergence of pollinators, is disrupted .
Some plants may also become less resistant to environmental challenges. In Washington, DC area, 89 of plant species surveyed, including flowering cherry trees, exhibited a ificant advance of 4. In a rapidly changing climate, predicting the flowering dates based solely on past history is likely to become less reliable; hence a more robust predictive model is needed not only for planning purposes of these cultural events but also, perhaps more importantly, for assessing the agricultural and ecological impacts of climate change.
The objectives of the study were to 1 test the model performance for predicting PBD of the two cherry cultivars at the Tidal Basin, Washington, DC against historical records and 2 apply the model to forecast future cherry PBD in Washington, DC and the surrounding Mid-Atlantic region based on future climate projections with A1B or A2 emission scenario .
The formula for these statistics can be found in . The A2 scenario assumes a very heterogeneous world with continuously increasing global population and regionally oriented economic growth that is more fragmented and slower than in other storylines . The bud-burst model by Cesaraccio et al. We chose to use this model because 1 it has been successfully used with cherries and other temperate tree species that are highly sensitive to winter and spring temperatures in other regions 2 it is a relatively simple but robust, process-oriented model based on physiological knowledge, and 3 it requires minimal input data i.
We parameterized the model with observed PBD data from to The calibrated model was tested against independent datasets of the past PBD data from to in the Tidal Basin and more recent PBD data from other locations e. For these reasons, the timing of cherry blossom engenders strong public interest and cultural attentions worldwide. Chung et al. Using these datasets, we forecasted the future PBD of Yoshino and Kwanzan trees for three 30 normal year periods: the s —s —and s — at 30 arc-seconds spatial resolution. The acceleration is likely to be much greater 13 days for s and 29 days for s under a higher A2 emissions scenario projected by CGCM2 general circulation model.
Genetically, Yoshino cherry is thought to be closely related to several varieties in P. Phenologically, the three distinct sets of parameter estimates identified between our study and Jung et al. It has been predicted that these trends will continue into the 21st century . Regionally, the spatial variability of the predicted blooming dates increased in the late 21 st century, but overall it has been predicted that the peak blooms are likely to take place on average 29 days earlier by .
The average distance between a PBD observation site and the corresponding climatological observation site was 38 km; all weather stations were located within 16 km with an exception of Bloomington, IN where the distance was km. The onset of dormancy in deciduous trees can be approximated by the date at which the temperature falls below a fixed threshold, the date that fruits are harvested from trees, or the date when the leaves begin to fall .
The estimates for both Yoshino and Kwanzan cherry trees are considerably different from the values estimated for P. Predicted PBD vs. Furthermore, the cultural and economic ificance of the flowering cherries has yielded a series of rich, long-term, phenological data sets in many cultures enabling scientists to study tree responses to climate change . We applied the model described above using the daily air temperature data from to collected by a weather station located near the Reagan National Airport 4.
We performed temporal downscaling of the monthly data into daily temperature data needed to run the phenology model by applying the harmonic analysis detailed in Chung et al. Our modeling suggest that a considerable temporal variability is likely to emerge in the mean PBD between locations see Table 2 for standard deviations between locations.
However, with the lack of data for and a standard method to estimate growth cessation, leaf fall, and dormancy induction period, we assumed that the onset of dormancy begins on October 1 in the present study. A similar approach has been used in other phenology modeling studies [e.
Gridded daily maximum and minimum temperatures from the past — and the three projected climatological normals —, the s; —, the s; —, the s have been applied to the phenology model to create mean PBD predictions for Yoshino and Kwanzan cherry trees in the Tidal Basin and the surrounding region Fig. The model predicted a more dramatic shift in PBD for the entire region in the s Fig. A similar pattern was also found for Kwanzan under both emission scenarios Table 2. Applying the new parameter estimates for Yoshino and Kwanzan cherry trees, we tested the model performance against temporally and spatially independent data sets that included PBD observations from to at the Tidal Basin, from to at the University of Washington campus in Seattle, WA, and from the Project BudBurst database recorded in at the four locations described in Methods section.