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Climate warming is causing shifts in key life‐history events, including flowering time. To assess the impacts of increasing temperature on flowering phenology, it is crucial to understand the transcriptional changes of genes underlying the phenological shifts. Here, we conducted a comprehensive investigation of genes contributing to the flowering phenology shifts in response to increasing temperature by monitoring the seasonal expression dynamics of 293 flowering‐time genes along latitudinal gradients in the perennial herb, Arabidopsis halleri. Through transplant experiments at northern, southern and subtropical study sites in Japan, we demonstrated that the flowering period was shortened as latitude decreased, ultimately resulting in the loss of flowering opportunity in subtropical climates. The key transcriptional changes underlying the shortening of the flowering period and the loss of flowering opportunity were the diminished expression of floral pathway integrator genes and genes in the gibberellin synthesis and aging pathways, all of which are suppressed by increased expression of FLOWERING LOCUS C, a central repressor of flowering. These results suggest that the upper‐temperature limit of reproduction is governed by a relatively small number of genes that suppress reproduction in the absence of winter cold. Summary statement: This study uncovered the transcriptional changes underlying the shift in flowering phenology in response to increasing temperature in a perennial herb, Arabidopsis halleri. The key transcriptional changes were the diminished expression of floral pathway integrator genes and genes in the gibberellin synthesis and aging pathways, all of which are suppressed by increased expression of FLOWERING LOCUS C, a central repressor of flowering. [ABSTRACT FROM AUTHOR]

To evaluate the utility of a deep-learning approach for monitoring amphibian reproduction, we examined the classification accuracy of a trained model and tested correlations between calling intensity and frog abundance. Field recording and count surveys were conducted at two sites in Kyoto City, Japan. A convolutional neural network (CNN) model was trained to classify the calls of five anuran species. The model achieved 91–100% precision and 75–98% recall per species, with relatively lower performance on less abundant species. Computational experiments investigating the effects of the number and seasonality of the training samples showed that models trained on larger datasets from broader recording seasons performed better. Calling activity was high when males were abundant (Pearson’s r 5 0.45–0.66), although correlations between the calling activity and the number of pairs in amplexus were generally weaker. Our results suggest that deep learning is an effective tool for reconstructing the reproductive phenology of male anurans from field recordings. However, caution is required when applying to rare species and when inferring female reproductive activity. [ABSTRACT FROM AUTHOR]

Biological processes can be disrupted by global climate warming, causing phenological mismatching and mistiming. On Hokkaido Island (Japan), which has a cool temperate climate, warmer and shorter winters affect plant flowering phenology. Rapid changes in flowering phenology suggest that shorter winters will result in earlier flowering. Flowering phenology patterns were recorded for nine years (2013–2021), and nine species were selected for analysis. I analyzed climate variables that affect plant flowering phenology, including annual changes in aerial temperature, snow depth, and snowmelt timing. The results indicated that winters are getting shorter and that the accumulated degree hours of aerial temperature have not significantly changed over nine years for these plant species except one species. Plant responses to these changes differed between species, with the first flowering day occurring earlier (1.5–1.8 days per year) for two species, although that of the other seven not. If climate warming continues, it will have diverse, complex, and unpredictable effects on various individual organisms and biological relationships among species. Detailed studies are needed to link climate change predictions to the predicted degree of mismatch in species interactions and networks. [ABSTRACT FROM AUTHOR]

We studied local variations in temperature from winter to spring, and interpopulation variations in leaf out phenology (the day and the temperature sum for budburst and leaf expansion) of Siebold's beech (Fagus crenata) canopy trees. We focused on local topographic variation associated with the late frost regime for the canopy trees using 5–10 years of in situ observation of the temperature at 12 sites and leaf out phenology of two populations inhabiting a basin (basin populations) and 4 populations inhabiting hillside slopes (hillside slope populations) in the Hakkoda Mountains, northern Japan. The late frost regime differed between topographies; late frosts occurred during warmer periods in the basin compared to hillside slopes. The basin populations exhibited a larger temperature sum for leaf out than the hillside slope populations, regardless of altitude, suggesting that local variation in the late frost regime is an abiotic factor causing local variations in leaf out phenology. The six studied populations exhibited earlier days and smaller temperature sum of budburst in years with longer chilling duration. However, the extent of phenotypic plasticity in the temperature sum was small for the basin compared to hillside slopes. The temperature sum of leaf expansion in the hillside slope populations also negatively correlated with chilling duration, whereas that of the basin populations responded in the opposite direction. The safety margin from the last frost differed between the topographies, but not that from the last fatal frost, suggesting local adaptation to the late frost regime in each habitat. [ABSTRACT FROM AUTHOR]

Alpine and subalpine moorland ecosystems contain unique plant communities, often with many endemic and threatened species, some of which depend on insect pollination. Although alpine and subalpine moorland ecosystems are vulnerable to climatic change, few studies have investigated flower-visiting insects in such ecosystems and examined the factors regulating plant-pollinator interactions along altitudinal gradients. Here, we explored how altitudinal patterns in flower visitors change according to altitudinal shifts in flowering phenology in subalpine moorland ecosystems in northern Japan. We surveyed flower-visiting insects and flowering plants at five sites differing in altitude in early July (soon after snowmelt) and mid-August (peak growing season). In July, we found a higher visiting frequency by more variable insect orders including dipteran, hymenopteran, coleopteran, and lepidopteran species at the higher altitude sites in association with the mass flowering of Geum pentapetalum and Nephrophyllidium crista-galli. In August, such altitudinal patterns were not observed, and dipteran species dominated across the sites due to the flowering of Narthecium asiaticum and Drosera rotundifolia. Our study provides key baselines for the detection of endangered biotic interactions and extinction risks of moorland plants under ongoing climate change. [ABSTRACT FROM AUTHOR]

Mapping the expansion or reduction of rice fields is fundamental for food and water security, greenhouse gas emission accounting, and environmental management. The historical mapping of rice fields with satellite images is challenging because of the limited availability of remote sensing and training data from past decades. The use of phenology-based algorithms has been proposed for mapping rice fields because they can take advantage of rice fields' characteristic spectral signature during the transplanting phase and do not need training data. However, in order to employ phenology-based algorithms effectively for the historical rice mapping of large areas, we need to incorporate automatized methods able to deal with non-usable data (e.g., cloud cover) and with spatial inconsistencies in the number of available images for each pixel. Here we propose the combination of a pixel-based, phenological algorithm with the temporal aggregation of all available Landsat images to produce national level historical maps of rice fields in Japan from the 1980s onwards. We used temporally aggregated metrics (median, percentiles, etc.), derived from spectral indices of a large number of images within the Google Earth Engine, to minimize the issue of inconsistent image availability and reduce the effects of outliers in phenology-based algorithms. We produced seven rice field maps, for the periods 1985–89, 1990–94, 1995–99, 2000–04, 2005–09, 2010–14, and 2015–19. The overall map accuracies ranged from 83% to 95% when validated with visually interpreted aerial photography. We detected a 23% decrease in the area of rice fields at a country level, although the changes varied greatly among prefectures. Here we present the first freely available historical rice field maps of Japan from the 1980s onwards, together with the source code, and a web application that enables the exploration of the maps and data relating to the derived rice field area changes. The application of temporal aggregation is promising for dealing with the gap-filling of large amounts of satellite data, reducing the issue of data outliers and providing an effective use of the historical Landsat archive for phenology-based crop detection algorithms. Our maps could greatly help researchers, conservationists and policymakers studying the drivers and consequences of rice field changes, and our methods could be extrapolated to map rice fields at large scales in other regions of the world. [ABSTRACT FROM AUTHOR]

Recently, technological advances in UAV-mounted sensors, such as light detection and ranging (LiDAR) and multispectral sensors, have expanded the applications of unmanned aerial vehicles (UAVs) in ecosystem monitoring. LiDAR is suitable for analyzing the underlying microtopography of wetlands because it can produce a digital terrain model (DTM) with high spatial resolution. If a multispectral sensor that can also capture near-infrared wavelengths is used, it is possible to calculate the normalized difference vegetation index (NDVI), which is related to the amount of vegetation present, and the normalized difference water index (NDWI), which is related to the dryness and wetness of the soil. The purpose of this study was to understand the distribution of a disturbance-dependent species in wetlands using high spatial resolution images acquired with a consideration of phenology, and to evaluate the habitat of this disturbance-dependent species using data acquired by LiDAR and multispectral sensors. The wetland around the Omimaiko Inland Lake in Minamikomatsu, Otsu City, Shiga Prefecture, Japan, was chosen as the site for this study. I chose to examine the distribution of Euphorbia adenochlora as a disturbance-dependent species growing in the wetlands of the study area. Using high spatial resolution images acquired with a consideration of phenology, we were able to determine the distribution of the disturbance-dependent species E. adenochlora. Using the data obtained using LiDAR and multispectral sensors, we were able to evaluate its habitat and deduce its viability at six growth sites. This study aims to introduce a new way of applying UAVs in monitoring disturbance-dependent species in wetlands. [ABSTRACT FROM AUTHOR]

Hybridization is a major source of phenotypic variation and a driving force for evolution. Although novel hybrid traits can often disrupt adaptive relationships between the parental phenotypes and their environments, how new hybrid traits disrupt local adaptation remains unclear. Here, we report how a new phenotype of hybrids between two Imperata cylindrica ecotypes contributes to rapid reproductive isolation from their parents and affects hybrid fitness.We analysed 350 accessions of I. cylindrica collected from the 1980s to the 2010s throughout Japan to explore the genetic population structure of the hybrids. We surveyed the flowering periods, seed set, and germination of two ecotypes and their hybrids in both natural habitats and common gardens.Genetic analyses of population structure revealed that the hybrid populations consisted of only F1 individuals, without advanced generation hybrids. The flowering phenology of the F1 plants was delayed until autumn, 5–6 months later than the parental ecotypes. The drastic shift in flowering phenology prevents F1s from backcrossing. In addition, it changes their seed dispersal time to winter. Germination is inhibited by low temperatures, and the seeds likely decay before the next spring, resulting in the absence of an F2 generation. We identified the environmental mismatch of the F1 population as a specific mechanism for the maintenance of an only F1 population.Synthesis. We have demonstrated that this flowering phenology mismatch promotes reproductive isolation between the parents and F1s and affects various temporal components of the hybrids, resulting in a unique hybrid population consisting only of F1s. This system sheds light on the importance of hybrid traits in driving rapid reproductive isolation. [ABSTRACT FROM AUTHOR]

Autumn foliage color is an important phenological characteristic associated with climate and appeals to populations as a cultural ecosystem service (CES). Land surface phenology (LSP) analyzed using time-series remotely sensed imagery can facilitate the monitoring of autumn leaf color change (ALCC); however, the monitoring of autumn foliage by LSP approaches is still challenging because of complex spatio-temporal ALCC patterns and observational uncertainty associated with remote sensing sensors. Here, we evaluated the performance of several LSP analysis approaches in estimation of LSP-based ALCCs against the ground-level autumn foliage information obtained from 758 sightseeing (high CES) sites across Japan. The ground information uniquely collected by citizens represented ALCC stages of greening, early, peak, late, and defoliation collected on a daily basis. The ALCC was estimated using a second derivative approach, in which normalized difference vegetation index (NDVI), kernel normalized difference vegetation index (kNDVI), enhanced vegetation index (EVI), two-band enhanced vegetation index (EVI2), and green red vegetation index (GRVI) were applied based on MODerate resolution Imaging Spectroradiometer (MODIS) MOD09A1 with four (Beck, Elmore, Gu, and Zhang) double logistic smoothing methods in 2020. The results revealed inconsistency in the estimates obtained using different analytical methods; those obtained using EVI with the Beck model estimated the peak stage of the ALCC relatively well, while the estimates obtained using other indices and models had high discrepancies along with uncertainty. Our study provided insights on how the LSP approach can be improved toward mapping the CESs offered by autumn foliage. [ABSTRACT FROM AUTHOR]

This study aims to clarify the community‐wide mating systems and pollination success of alpine plants. Selfing abilities and fruit‐set success of entomophilous alpine plants were compared using a dataset of 46 species that were obtained during the last 30 years in the Taisetsu Mountains, northern Japan. Almost all species showed self‐incompatibility or weak self‐compatibility, indicating that obligate outcrossing is a common mating system in alpine plants. This mating property leads to a clear seasonal pattern of fruit‐set success responding to the seasonal dynamics of pollinator activity. Most species are visited by bumble bees and/or flies, and the seasonal trend of pollination success was shown to vary among pollinator types. Pollen limitation in bee‐pollinated plants was intense early in the season and tended to decrease as the season progressed, reflecting the colony development cycle of bumble bees. Thus, the fruit‐set success of bee‐pollinated plants increased with the delay of flowering time. In contrast, seasonal trends in the pollen limitation and fruit‐set success of fly‐pollinated species were less clear. Mixed‐type plants visited by both bees and flies showed a pattern intermediate to that of bee‐type and fly‐type plants. The flowering phenology of alpine plant communities was greatly regulated by snowmelt patterns, and the pollination success of single species varied greatly among local populations distributed in different snowmelt habitats. These heterogeneous landscape features create diverse plant–pollinator interactions in alpine ecosystems. Based on these results, the ecological and evolutionary significance of the outcrossing syndrome in alpine plants is discussed. [ABSTRACT FROM AUTHOR]

• Apple phenology models were developed based on experiments in controlled environments. • Overlap model accurately predicted apple bloom dates in warm and cold climates. • Phenology model with systematic experiments is suitable for wide regional and future temperature. Climate change affects crop phenology, and this has raised interest in phenology models. Most previous studies have determined the functions and parameters of phenology models through calibrations based on observed historical bloom dates under field conditions. However, if all the functions and parameters are determined through bud response experiments in controlled environments, it becomes possible to develop a model that is independent of observation in specific regions and has a small risk of overfitting. Hence, we grew potted 'Fuji' apple trees under fully temperature-controlled condition to quantify the temperature response of endodormancy release, flower bud development, and their interaction to determine the functions and parameters of models. The optimum temperature to release endodormancy was between –3 °C and 6 °C, and it was not released at temperatures ≥12 °C. The developmental rate of the flower bud increased with increasing chilling treatment time at 6 °C; however, it did not change over 2000 h The relationship between the temperature and developmental rate was exponential for the ecodormancy stage. The models constructed from these experimental results were validated using a dataset of historical bloom dates observed under three different climatic field conditions in Japan. The results demonstrated that, regardless of whether the region was cold or warm, the overlap model can predict bloom dates with accuracy, whereas the sequential model can predict bloom dates with accuracy only in cold regions. The overlap model in which the functions and parameters are fixed through bud response experiments in controlled environments, is expected to be applicable for predictions spanning diverse temperature conditions in global apple-growing regions, including future temperature scenarios, without succumbing to overfitting. [ABSTRACT FROM AUTHOR]

BACKGROUND: In order to better understand the population dynamics of invasive species in their native range, we developed two predictive phenological models using the ubiquitous invasive insect pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), as the model organism. Our work establishes a zero‐inflated negative binomial regression (ZINB) model, and a general additive mixed model (GAMM) based on 11 years of black light trap monitoring of H. halys at three locations in Japan. RESULTS: The ZINB model indicated that degree days (DD) have a significant effect on the trap catch of adult H. halys, and that precipitation has no effect. A dataset generated by 1000 simulations from the ZINB suggested that higher predicted trap catches equated to a lower probability of encountering a zero‐count. The GAMM produced a cubic regression smooth curve which forecasts the seasonal phenology of H. halys as following a bell‐shaped trend in Japan. Critical DD points during the field season in Japan included 261 DD for first H. halys adult detection and 1091 DD for peak activity. CONCLUSIONS: This study establishes the first models capable of forecasting native H. halys population dynamics based on DD. These robust models practically improve population forecasting of H. halys in the future and help fill gaps in knowledge pertaining to its native phenology, thus ultimately contributing to the progression of efficient management of this globally invasive species. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The effects of climate change on plant phenological events such as flowering, leaf flush, and leaf fall may be greater in steep river basins than at the horizontal scale of countries and continents. This possibility is due to the effect of temperature on plant phenology and the difference between vertical and horizontal gradients in temperature sensitivities. We calculated the dates of the start (SGS) and end of the growing season (EGS) in a steep river basin located in a mountainous region of central Japan over a century timescale by using a degree-day phenological model based on long-term, continuous, in situ observations. We assessed the generality and representativeness of the modelled SGS and EGS dates by using phenological events, live camera images taken at multiple points in the basin, and satellite observations made at a fine spatial resolution. The sensitivity of the modelled SGS and EGS dates to elevation changed from 3.29 days (100 m)−1 (−5.48 days °C−1) and −2.89 days (100 m)−1 (4.81 days °C−1), respectively, in 1900 to 2.85 days (100 m)−1 (−4.75 days °C−1) and −2.84 day (100 m)−1 (4.73 day °C−1) in 2019. The long-term trend of the sensitivity of the modelled SGS date to elevation was −0.0037 day year−1 per 100 m, but the analogous trend in the case of the modelled EGS date was not significant. Despite the need for further studies to improve the generality and representativeness of the model, the development of degree-day phenology models in multiple, steep river basins will deepen our ecological understanding of the sensitivity of plant phenology to climate change. [ABSTRACT FROM AUTHOR]

Phenological responses of plants to temperature dynamics are receiving attention due to the ongoing challenge with climate change. Most previous phenological studies have focused on flowering phenology rather than fruiting phenology. However, at mid-latitudes, the air temperature periodically changes during the growing period of plants. Hence, cool temperatures early and late in the growing period may affect reproductive success through pollination and fruit-development processes. To evaluate the linkages between reproductive phenology and success, we compared the phenologies, photosynthetic capacities, and fruit-set rates among 25 species within a cool-temperate community in northern Japan. The ambient temperature during the flowering periods of individual species increased with delays in flowering-onset time, whereas the ambient temperature during fruit-development periods was highest for species which bloomed in July. Fruit-set success among species was positively correlated with the ambient temperatures during the reproductive periods and with the photosynthetic capacity. Fruit production of early blooming species was limited by cool temperatures during the flowering period, presumably because of low pollinator activity, whereas that of late-blooming species was limited by cool temperatures during the fruit-development period because of slow fruit-development (i.e., sink limitation). Thus, limiting factors of fruit production varied depending on the flowering phenology of individual species within a community. [ABSTRACT FROM AUTHOR]

Hybrid zones between species with staggered reproductive phenology sometimes occur along elevational gradients. The maintenance of such hybrid zones may depend on elevational shift in phenology and vertical dispersal of pollen and seeds. In a hybrid zone of Cerasus leveilleana (Cl) and C. sargentii (Cs), 111 adults, 372 embryos of 65 mothers, and 133 juveniles were sampled across elevations of 900–1,400 m in central Japan. Using the hybrid index estimated from nuclear microsatellites, the samples were assigned to Cl, Cs or their hybrid taxon. Cs was in higher elevations than Cl with an overlapping range, and their hybrids were in intermediary elevations. Flowering periods were earlier in Cs than in Cl with little overlap at the same elevation and were intermediate in their hybrids. Flowering periods were delayed in higher elevations and overlapped between Cl and Cs in different elevations. Fruiting periods were slightly earlier in Cs than in Cl but were largely overlapped. Effective pollinators and seed dispersers were common among the taxa. Changes in the hybrid index from mothers to their embryos were larger in hybrid mothers than in Cl or Cs mothers, indicating mating of hybrids with diverse taxa. In Cs, juveniles were more abundant in lower elevations than embryos, indicating downhill seed dispersal. Proportions of hybrids were 19% in embryos, 17% in juveniles and 12% in adults. The findings suggest that the hybrid zone is maintained by interspecific pollination between different elevations, backcrossing with hybrids at similar elevations, vertical seed dispersal and mild selection against hybrids. [ABSTRACT FROM AUTHOR]

In Japan, the geographical distribution of the first date of flowering (FFD) of Yoshino cherry trees (Cerasus ×yedoensis) in 2020, a year when temperatures were mild during the previous December and March, was different from the average FFD, which progresses northward along a latitudinal gradient. We hypothesized that global warming may have changed the average geographical pattern of the FFD. To test this hypothesis, we examined the relationship between the observed FFD and latitude at 42 sites during the period 1953–2020. We found that the correlation between FFD and latitude had decreased since 1980. This decrease may have been caused by a rise of temperatures in winter that delayed dormancy release and the subsequent FFD in areas where the annual mean temperature is high. Our results suggest that the correlation between FFD and latitude will decrease further as the climate warms in the future. [ABSTRACT FROM AUTHOR]

We evaluated the spatial characteristics of the first day of peak leaf colouring (PLCstart) and their relationships with air temperature along latitudinal and elevational gradients in Japan from 2015 to 2017. Leaf colouring information collected from more than 740 sites via citizen science was analysed, representing elevations from 0 to 2800 m and latitudes from 32°N to 44°N. We found that locations with earlier PLCstart dates (day of year 265–294) displayed steeper slopes in elevation per degree of latitude than locations with later PLCstart dates (day of year 295–314). This statistically significant result indicates that the influence of elevation on PLCstart (vertical gradient) weakened as the leaf colouring season progressed in Japan. In addition to these spatial characteristics, the PLCstart and the warmth index (based on monthly mean air temperature) showed significant linear correlations for latitudinal and elevational gradients. This result suggests that the sensitivity of PLCstart to air temperature, as manifested in both latitudinal and elevational gradients, is constant. This study suggests that online phenological data may provide more accurate results for a regional scale (100–1000 km) than the datasets used by previous studies. [ABSTRACT FROM AUTHOR]

Spring leaf phenology has been intensively studied in temperate deciduous broad-leaved tree species, but the phenology of evergreen broad-leaved tree species has seldom been focused on. Evaluation of the difference in spring leaf phenology between coexisting deciduous and evergreen species is essential to predict their responses to climate change. In this study, spring leaf phenology was investigated for the 12 deciduous and 12 evergreen broad-leaved species coexisting in a warm-temperate forest in Japan, based on the predictions that selection pressure for earlier leaf production in spring results in less intraspecific variation in phenology at a given timing (SDmax) and a shorter duration of leaf expansion in deciduous than in evergreen species. In contrast to this prediction, SDmax did not differ between deciduous and evergreen species and was not related to leaf area or LMA. On the other hand, the duration of leaf expansion was longer in evergreen than in deciduous species, and was positively correlated with LMA. The leaves of greater LMA required longer periods of leaf expansion, probably due to a higher cost of and/or more conservative leaf development in the face of herbivory. As a consequence, the timing of full leaf expansion was delayed not only by later budburst (approximately two weeks) but also by a longer duration of leaf expansion (approximately two weeks) in evergreen than in deciduous broad-leaved species, which would probably influence the productivity of newly emerging leaves in spring. [ABSTRACT FROM AUTHOR]

This study intended to clarify whether low irradiance, high temperature or both acted as a trigger inducing summer dormancy in Daphne pseudomezereum (Dpm), a wintergreen shrub native to Japanese mixed forests. A 2-year growth chamber experiment was conducted in Otsu, Japan where, in the first year, 3 provenances of Dpm were raised in two irradiance levels by two temperature regimes to observe their effects on leaf phenology. The results showed a clear effect of temperature, but not irradiance, on leaf phenology. In the second year, the experiment was repeated using different Dpm plants and applying only the two temperature regimes. The results confirmed those obtained in the first year, where the temperature regime that tracked normal field condition induced summer dormancy similar to field populations. In both years, when plants were kept over the summer under a cool temperature regime mimicking field conditions in April, most plants did not undergo summer dormancy (i.e., becoming "evergreen"). In contrast to phenology, leaf morphology (i.e., LMA), and photosynthetic capacity (e.g., Amax) did respond to irradiance levels consistent with shade adaptive changes, but were not affected by temperature. Simulated carbon gain using previously determined parameters for Dpm and the chamber microclimate data found that only plants in the warm treatment experienced carbon deficit in mid-summer. These findings suggest that summer temperature alone and the attendant rise in respiration can alter internal carbon balance and trigger the onset of summer dormancy in Dpm. [ABSTRACT FROM AUTHOR]

The occurrence of many parasites and their hosts vary conspicuously by season due to their periodic life history events. Nematomorphs are common parasites in terrestrial‐aquatic ecotones, but it is still unknown how the nematomorphs complete their complex life cycles by using multiple hosts that are potentially seasonally variable. In this study, we examined the life history of a nematomorph (Gordionus sp.) inhabiting a mountain stream in northern Japan by the seasonal survey of their infection on aquatic and terrestrial hosts and laboratory experiments. Adults of Gordionus sp. entered into stream from early June to mid‐July. The laboratory experiment suggested that the newly hatched larvae become infective to intermediate host (aquatic insect larvae) from September to November, depending on the water temperature. The nematomorph larvae infected aquatic insect hosts with diverse emergence phenology, which result in prolonged temporal window for the trophic transmission between aquatic and terrestrial hosts. The common definitive host (Pterostichus thunbergi) seemed to survive multiple years, which would allow the nematomorph larvae to fully develop within the infected host. Trophically transmitted parasites sometimes track a specific pathway of prey–predator interactions within a food web and thus are sensitive to temporal match–mismatch between intermediate and definitive hosts. Contrary to this, the nematomorphs we studied may benefit from using temporally diverse pathways across aquatic and terrestrial food webs, which may result in maintaining the populations in their seasonal environment. [ABSTRACT FROM AUTHOR]

We investigated the spring frost risk over the main apple production areas in Japan under future climates using multiple sets of global circulation models and scenarios. Frost risk was judged by the daily minimum air temperature. Apple phenology was estimated with a phenology model under future meteorological conditions. Since spring cold hardiness of apple trees depends on the phenophase, we took the effect into consideration by decomposing the season into three phenophases. April temperatures are projected to increase by 0.5–2 °C for 2031–2050 and 1.5–6 °C for 2081–2100 relative to that of 1981–2000, depending on the climate models and scenarios. Spring phenology will advance by 10 days or more for the highest temperature increase case for 2081–2100. Frost risk will not monotonically change with the future temperature increase. For the scenario with the temperature increase by 1–2 °C in spring, corresponding to the medium temperature increase case among our simulation cases, frost risk will be maximized in the southern Tohoku region and central highlands, where frost risk is relatively high under the current climates. Frost risk will tend to decrease for the highest temperature increase case. During bud break to foliation, apple trees will be in highest frost risk under future climates. [ABSTRACT FROM AUTHOR]

A winter geometrid moth, Inurois punctigera, shows sympatric and genetically isolated seasonal populations (i.e. early- and late-winter populations) in the cold regions of Japan, whereas it shows only mid-winter populations in the warm regions. Variation in adult flight phenology on a large geographic scale along latitudinal environmental gradients has been described, but the phenological variation on a more local scale along altitudinal environmental gradients has not yet been characterized. In the present study, we assessed the flight phenology at high- and low-elevation areas in Mt. Rokko, Hyogo, Japan. First, we revealed that flight period was not disrupted in mid-winter, even at high-elevation areas (>660 m) but the population abundance was much lower in high-elevation areas than in low-elevation areas. Then, in the following two seasons, we investigated I. punctigera abundance, winter harshness (i.e. winter temperature) and their host plant abundance in nine closely located stations in Mt. Rokko. A generalized linear mixed model analysis indicated a greater effect of winter temperature on I. punctigera abundance compared to available food resources, suggesting that differences in winter harshness among elevation shapes the gradient of I. punctigera abundance along altitude. Our findings suggest that harsh conditions during winter function as selective agents on mid-winter types of I. punctigera, and this could be involved in the divergence between sympatric early- and late-winter populations of I. punctigera. [ABSTRACT FROM AUTHOR]

In Japan, farm ponds retain water throughout the year while rice fields are continuously inundated for no more than 2 months, usually from spring to early summer. Although the zooplankton fauna in artificial water bodies would be expected to vary according to differences in inundation periods, scientific confirmation of this relation is largely lacking. Due to its ubiquity, the cladoceran Moina is a suitable target for studying habitat-related differences in the planktonic fauna, but its taxonomy remains unresolved, making morphological identifications potentially uncertain. We thus applied integrative taxonomy with both morphological and genetic evaluations for reliable species delimitation to Moina samples collected primarily in Japan (with smaller collections from Taiwan). This approach increased the alpha diversity of Moina species in Japan from three (in previous studies) to seven. It also revealed different habitat preferences among Moina species, with the smaller species being distributed mostly in farm ponds (followed by natural lakes), and the larger species mostly in rice fields. We argue that the phenological match/mismatch with inundation period of rice fields was a major factor for this strong trend of spatial species turnover, with differing degrees of fish predation pressure among the habitat types being another factor. [ABSTRACT FROM AUTHOR]

To clarify the effects of crab burrows on variation in sediment CO2 flux in mangrove forest, we measured the traits of crab burrows (density and entrance area size) and the CO2 flux rate from sediment surfaces, in areas with and without burrows, in a subtropical mangrove forest on Ishigaki Island, southwestern Japan. Burrow density and entrance area showed significant differences among seasons (warm, middle, and cool) and mangrove zones (upper-, middle-, and downstream), which may have depended on crab phenology, life cycle, and species composition. The sediment CO2 flux rate was significantly higher at plots with crab burrows (B+) than at those without burrows (B−) in each zone and season. However, standardized sediment CO2 flux rate by burrow surface area at B+ plots did not differ significantly from that at B− plots. In addition, there were no significant differences in sediment temperature and sediment water content between the two types of plots. Moreover, the level of microbial respiration differed significantly between sediments collected from the deep part and those collected from either the ground surface part or burrow walls. These results suggest that crab burrows increase sediment CO2 flux from the mangrove forest floor by increasing the sediment–atmosphere interface area, thereby inducing a change to aerobic conditions in the sediments around burrows. Therefore, the seasonal and spatial effect of crab burrows on the forest floor should be considered when evaluating sediment CO2 flux and examining the role of the mangrove ecosystem as a carbon sink. [ABSTRACT FROM AUTHOR]

We investigated temporal changes in paddy rice phenology and yield under climatic and varietal changes in Shonai region, Yamagata Prefecture, northeast Japan across a period of 1982–2017. In the study region, the dominant variety shifted from Sasanishiki to Haenuki in mid 1990s. Temporal trends across the study period were significant in mean air temperatures for the months from May to July, and the temperature rise has accelerated heading, which was delayed by the varietal shift. We built models of the effects of climatic and varietal changes on phenological events and yield components: number of grains per land area, percentage ripened grains, and 1000-grain weight. Combining the yield component models, we built a yield model, with which we estimated the effect of the temperature rise from May to July on the yield. The temperature rise in May and June has reduced the yield by accelerating phenology, while that in July has increased the yield by raising 1000-grain weight. The net effect was no change in the yield across the study period, which, however, does not indicate an insensitivity of the yield to the temperature rise. Rather, the finding points to the dependency of the net change in the yield on seasonal pattern of the climate change. Climate change impacts on rice should therefore be quantified on the changes at monthly or shorter time scale rather than a seasonal mean. Our finding also points to the need to pay attention to the changes in agronomic practices such as varieties. [ABSTRACT FROM AUTHOR]

The flowering phenology of early-blooming plants is largely determined by snowmelt timing in high-latitude and high-altitude ecosystems. When the synchrony of flowering and pollinator emergence is disturbed by climate change, seed production may be restricted due to insufficient pollination success. We revealed the mechanism of phenological mismatch between a spring ephemeral (Corydalis ambigua) and its pollinator (overwintered bumblebees), and its impact on plant reproduction, based on 19 years of monitoring and a snow removal experiment in a cool-temperate forest in northern Japan. Early snowmelt increased the risk of phenological mismatch under natural conditions. Seed production was limited by pollination success over the 3 years of the pollination experiment and decreased when flowering occurred prior to bee emergence. Similar trends were detected on modification of flowering phenology through snow removal. Following snowmelt, the length of the pre-flowering period strongly depended on the ambient surface temperature, ranging from 4 days (at greater than 7°C) to 26 days (at 2.5°C). Flowering onset was explained with an accumulated surface degree-day model. Bumblebees emerged when soil temperature reached 6°C, which was predictable by an accumulated soil degree-day model, although foraging activity after emergence might depend on air temperature. These results indicate that phenological mismatch tends to occur when snow melts early but subsequent soil warming progresses slowly. Thus, modification of the snowmelt regime could be a major driver disturbing spring phenology in northern ecosystems. [ABSTRACT FROM AUTHOR]

Abstract This study introduces plant phenophase as a "bridge" to assessing the impact of climate change on autumn foliage viewing tourism in Japan. The results showed that from 1978 to 2016, the autumnal foliage colouration of four cities in Japan was delayed, the duration of the autumnal leaf discolouration was significantly shortened, and only one city experienced a significant delay in leaf-falling. The delay in the autumn foliage colouration and leaf-falling periods on average increase the December maple viewing tourism volume by 3.64% and 3.02%, respectively. The impact on autumn maple foliage viewing tourism volume also has a 1-year delay effect, and the maple foliage phenophase of different cities have significantly varied influence on maple foliage viewing tourism volume. Overall, the change in the timing of maple leaf discolouration has been advantageous to the Japanese maple tourism industry. Highlights • Using plant phenology to assess the impact of climate change on tourism. • The change in maple foliage phenology has benefit for the Japanese maple tourism. • The maple foliage phenology of different cities have varied influence on tourism. [ABSTRACT FROM AUTHOR]

The year-to-year variability of the blooming phenology of cherry trees is important as a proxy climate indicator and strongly affects cultural ecosystem services. Observation of blooming phenology at multiple points requires a simple and flexible approach. We examined changes in the canopy gap fraction extracted from binarized upward images taken periodically beneath a Cerasus × yedoensis ‘Somei-yoshino’ tree. The gap fraction decreased rapidly after the start of bloom, reached a minimum value at full bloom, and began to increase again, but then decreased rapidly during leaf flush. These changes reflect the phenology of blooming and leaf flush after flower drop of ‘Somei-yoshino’. These characteristics allow detection of the year-to-year variability of the bloom and leaf-flush phenology of cherry and other deciduous tree species that show the same patterns. [ABSTRACT FROM AUTHOR]

• Effects of winter warming on the timing of cherry bloosoms are variable across latitudes. • Accelerated blooms expected in warm spring can be overridden by strong winter warming. • Rates of change in bloom dates differ significantly between before and after 1980. • Excessive winter warming could delay blooms and this is emerging at low latitudes. Rising global temperatures are affecting plant phenology. Spring warming can lead to early flowering due to accelerated heat accumulation after dormancy. Winter warming, however, may counteract this acceleration by extending the chilling period required for endodormancy release. We tested this hypothesis with historical bloom data of a flowering cherry (Prunus x yedoensis) collected from multiple locations in Japan across a latitudinal gradient. We determined differential chilling and forcing temperature effects based on advances (-) or delays (+) of bloom dates per degree Celsius of change (temperature sensitivity, S T). We applied a chilling-forcing modeling approach to reveal and disentangle the differential temperature effects during and after dormancy on spring phenology across different latitudes over time. Our analysis showed that the effects of chilling temperatures during dormancy were variable along the latitudinal gradient, while the effect of forcing temperatures after dormancy was more consistent regardless of latitude. Notably, the elevated temperatures, and thereby reduced chilling, during endodormancy delayed the bloom dates at lower latitudes, and this trend was more pronounced in recent years. Our results support the hypothesis that the effect of winter warming during endodormancy can offset or even outweigh the effect of spring warming by extending the dormancy period, and this can manifest as an overall delay in bloom dates. While the delay in flowering phenology due to winter warming is observable only in lower latitudes currently, it is likely to expand to higher latitudes in the future climate if the warming trend continues. Our findings also highlight the value of concerted long-term phenological records that can provide insights into the mechanisms underlying plasticity in tree physiology with a unique opportunity to predict their responses in a changing climate. [ABSTRACT FROM AUTHOR]

To accurately evaluate the responses of spatial and temporal variation of ecosystem functioning (evapotranspiration and photosynthesis) and services (regulating and cultural services) to the rapid changes caused by global warming, we depend on long-term, continuous, near-surface, and satellite remote sensing of phenology over wide areas. Here, we review such phenological studies in Japan and discuss our current knowledge, problems, and future developments. In contrast with North America and Europe, Japan has been able to evaluate plant phenology along vertical and horizontal gradients within a narrow area because of the country's high topographic relief. Phenological observation networks that support scientific studies and outreach activities have used near-surface tools such as digital cameras and spectral radiometers. Differences in phenology among ecosystems and tree species have been detected by analyzing the seasonal variation of red, green, and blue digital numbers (RGB values) extracted from phenological images, as well as spectral reflectance and vegetation indices. The relationships between seasonal variations in RGB-derived indices or spectral characteristics and the ecological and CO flux measurement data have been well validated. In contrast, insufficient satellite remote-sensing observations have been conducted because of the coarse spatial resolution of previous datasets, which could not detect the heterogeneous plant phenology that results from Japan's complex topography and vegetation. To improve Japanese phenological observations, multidisciplinary analysis and evaluation will be needed to link traditional phenological observations with 'index trees,' near-surface and satellite remote-sensing observations, 'citizen science' (observations by citizens), and results published on the Internet. [ABSTRACT FROM AUTHOR]

We examined the relationship between the spatio-temporal distribution of leaf litter for each species and the seasonal patterns ofin situand satellite-observed daily vegetation indices in a cool-temperate deciduous broad-leaved forest. The timing and distribution of leaf-fall revealed spatio-temporal relationships with species and topography. Values of the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and green–red vegetation index (GRVI), measured bothin situand by satellite, and those of thein situ-measured leaf area index (LAI), rapidly declined at the peak of leaf-fall. At the late stage of leaf-fall,in situ-measured values of NDVI, EVI, and LAI declined but those of GRVI changed from decreasing to increasing. The peak timing of leaf-fall, when 50–73% of the leaf litter had fallen, corresponds to LAI = 1.80–0.81, NDVI = 0.61–0.54, EVI = 0.29–0.25, and GRVI = 0.01 ∼ ‒0.07. Although the distribution of leaf litter among species displayed spatial characteristics at the peak of leaf-fall, spatial heterogeneity of amount of leaf litter at the peak timing of leaf-fall was less than that at the beginning and end. These facts suggest that the criterion for determining the timing of leaf-fall from vegetation indices should be a value corresponding to the peak of leaf-fall rather than its end. In a high-biodiversity forest, such as this study forest, the effect of spatial heterogeneity on the timing and patterns of leaf-fall on vegetation indices can be reduced by observing only the seasonal variation in colour on the canopy surface by using GRVI, which consists of visible reflectance bands, rather than that of both leaf area and colour of the canopy surface by using NDVI and EVI, which consist of visible and near-infrared reflectance bands. [ABSTRACT FROM AUTHOR]

Understanding the drivers of phenological events is vital for forecasting species' responses to climate change. We developed flexible Bayesian survival regression models to assess a 29-year, individual-level time series of flowering phenology from four taxa of Japanese cherry trees ( Prunus spachiana, Prunus × yedoensis, Prunus jamasakura, and Prunus lannesiana), from the Tama Forest Cherry Preservation Garden in Hachioji, Japan. Our modeling framework used time-varying (chill and heat units) and time-invariant (slope, aspect, and elevation) factors. We found limited differences among taxa in sensitivity to chill, but earlier flowering taxa, such as P. spachiana, were more sensitive to heat than later flowering taxa, such as P. lannesiana. Using an ensemble of three downscaled regional climate models under the A1B emissions scenario, we projected shifts in flowering timing by 2100. Projections suggest that each taxa will flower about 30 days earlier on average by 2100 with 2-6 days greater uncertainty around the species mean flowering date. Dramatic shifts in the flowering times of cherry trees may have implications for economically important cultural festivals in Japan and East Asia. The survival models used here provide a mechanistic modeling approach and are broadly applicable to any time-to-event phenological data, such as plant leafing, bird arrival time, and insect emergence. The ability to explicitly quantify uncertainty, examine phenological responses on a fine time scale, and incorporate conditions leading up to an event may provide future insight into phenologically driven changes in carbon balance and ecological mismatches of plants and pollinators in natural populations and horticultural crops. [ABSTRACT FROM AUTHOR]

Veratrum section Veratrum comprises eight species in Korea and Japan: V. alpestre, V. dahuricum, V. dolichopetalum, V. grandiflorum var. maximum, V. oxysepalum, V. patulum, V. stamineum var. micranthum, and V. stamineum var. stamineum. However, species delimitation and taxonomic treatments have long been controversial due to their highly variable vegetative and floral morphology. We conducted maximum parsimony (MP) and Bayesian inference (BI) based on a total of 4,856 base pairs of nrDNA ITS and cpDNA coding and noncoding regions ( matK, psbA- trnH, rpL16, and trnS-G) to re-examine the taxonomic status and phylogenetic relationships within Veratrum sect. Veratrum. The MP and BI trees were poorly resolved among species within Veratrum sect. Veratrum in Korea and Japan. Veratrum stamineum, which has outward spreading, exerted stamens beyond the tepals, diverged first within Veratrum and the remaining species, which have straight shorter stamens compared to the tepals, formed a monophyletic group with poor species delimitation and phylogenetic relationships among them. The incongruent phylogenetic position of V. grandiflorum var. maximum between ITS and cpDNA (it shares its most recent common ancestor with poorly resolved sect. Veratrum species in ITS, whereas it is sister to V. stamineum in cpDNA) suggested that it represents possible ancient hybrid origin between V. stamineum and V. oxysepalum. Thus, in this study we elevated the taxonomic status of V. grandiflorum var. maximum to the species rank, V. maximum. V. alpestre, which was described as a new species by Nakai in 1937, has identical ribotype and cpDNA haplotype of V. oxysepalum and its morphological variations are within the range of V. oxysepalum. Therefore, we suggest that V. alpestre should be synomized with V. oxysepalum. A further study using fast evolving nuclear and chloroplast regions is required to resolve the phylogenetic relationships among species within Veratrum sect. Veratrum. [ABSTRACT FROM AUTHOR]

Mangroves in the subtropical area of Japan are growing to their northern limits, yet little is known of their phenology. The aim of the present study was to understand both vegetative and reproductive phenology patterns, such as leaf emergence, leaf fall, bud setting, flowering, fruiting and propagule setting, in the mangrove Kandelia obovata. The phenology of this species was assessed using litter-fall data for 5 years. Leaf and stipule litter-falls continued with a clear monthly pattern throughout the years. New leaf production and leaf fall peaked in summer, immediately after the propagules fell. Leaf and stipule litter-falls were linked to monthly sunshine hour, and monthly mean air temperature and monthly mean air relative humidity, respectively. Kandelia obovata had a distinct flowering period, with the flowering phenophase starting in spring and continuing into summer. Fruit initiation started at the end of summer and continued into autumn, whereas propagule production occurred during winter and spring. Flowering of K. obovata was influenced by monthly sunshine hour and monthly mean air temperature, whereas fruit and propagule litter-falls were not linked to any climatic factors. The present results showed that a small portion (4.4%) of flowers developed into propagules. The average development period from flower buds to mature propagules was approximately 11 months. Kendall's consistency coefficient suggested that the monthly trends in vegetative and reproductive litter-fall components, except for branches, did not change significantly among years. [ABSTRACT FROM AUTHOR]

Abstract: Scientific papers published locally in many Asian countries are often inaccessible to researchers elsewhere due to language barriers or omission from international journal databases. This paper provides the first comprehensive review of the observed and projected impacts of climate change on plant and animal species in Japan, drawing extensively from both local and international publications. There were a number of long-term data sets on phenological and distributional changes covering more than five decades. Observed phenology records showed two characteristic trends in Japan; greater shifts of plant phenology in autumn relative to spring and delays in insect appearance dates in spring. Distribution records of insect and marine species indicated poleward range expansions of 18–140km per decade. Future projections on phenology suggested varied responses between species and possible disruptions in ecosystem functions, while those on distributions indicated potential significant range reductions and changes in species assemblages and diversity. Some of these responses are not in line with the global trends while others show changes of greater magnitude than for other regions, which highlights the importance of region-specific climate change impact assessments. The research recommends that, to improve the evaluation of climate change impacts in countries where the common languages are not English, search efforts should be expanded to include locally available data and publications. This can be facilitated by using country-specific journal databases and increasing collaboration with local researchers. [Copyright &y& Elsevier]

Amorpha fruticosa L., introduced from the eastern part of North and Central America as a revegetation material for artificial slopes, has escaped into riverbeds in Japan, and its negative effects are of concern. In this study, an attempt has been made to clarify the actual extent of escape and establishment of A. fruticosa, through a case study of the Sendaigawa River, Tottori Prefecture, coupled with a survey of national distribution using the National Censuses on River Environments. The autecology of A. fruticosa, including phenology, germination, allelopathy and coppicing ability, was also studied by observation and experiments. The following conclusions were drawn: A. fruticosa preferred sunny sites; the total established area in the study site was 7,500 m; A. fruticosa showed strong coppicing ability; there was lower species diversity in and around areas populated by A. fruticosa; and A. fruticosa has been expanding its area both in the watershed of Sendaigawa River region and nationwide. The authors emphasize the importance of quick control of A. fruticosa. [ABSTRACT FROM AUTHOR]

Changes in leaf phenology lengthen the growing season length (GSL, the days between leaf budburst and leaf fall) under the global warming. GSL and the leaf phenology response to climate change is one of the most important predictors of climate change effect on plants. Empirical evidence of climatic effects on GSL remains scarce, especially at a regional scale and the latitudinal pattern. This study analyzed the datasets of leaf budburst and fall phenology in Morus bombycis (Urticales), which were observed by the agency of the Japan Meteorological Agency (JMA) from 1953 to 2005 over a wide range of latitudes in Japan (31 to 44° N). In the present study, single regression slopes of leaf phenological timing and air temperature across Japan were calculated and their spatial patterns using general linear models were tested. The results showed that the GSL extension was caused mainly by a delay in leaf fall phenology. Relationships between latitude and leaf phenological and GSL responses against air temperature were significantly negative. The response of leaf phenology and GSL to air temperature at lower latitudes was larger than that at higher latitudes. The findings indicate that GSL extension should be considered with regards to latitude and climate change. [ABSTRACT FROM AUTHOR]

Background: Recent studies have described a technique that incorporates a digital camera to observe aspects of tree phenology, such as leaf expansion and leaf fall. This technique has shown that seasonal patterns of red, green and blue digital numbers (RGB_DN) extracted from digital images differ between species. Aims: To identify the different characteristics of phenology between species by examining RGB_DN, the relationship between the seasonal patterns of RGB_DN and ecological characteristics for various species were evaluated throughout the year. Methods: The relationship between the normalised RGB_DN values extracted from digital images and in situ leaf area index (LAI) and leaf chlorophyll content (indicated by soil and plant analyser development, SPAD) was examined for three dominant species for multiple years in a cool-temperate, deciduous, broad-leaved forest in Japan. Results: The RGB_DN values in spring were not useful in detecting the different characteristics of leaf-flush patterns between species. In contrast, RGB_DN values in autumn showed differences in leaf-colouring as well as in leaf-fall patterns and timings between species. Conclusion: Differences in autumn phenology between tree species can be detected by using the normalised RGB_DN technique, while the technique cannot be applied in spring. [ABSTRACT FROM AUTHOR]

Recent studies show advancing onset of plant growing season in many regions for the last several decades. With the well-established dependence of plant phenology on temperature, these trends are interpreted as an indication of global warming. For several decades, however, other determinants of plant phenology, e.g. varieties and trends in managed systems, may have changed and confounded the phenological trends. In this study, we tested if long-term changes in phenology of apple ( Malus pumila var. domestica) are attributable to long-term changes in temperature by comparing the phenological response to long-term trend in air temperature, which is of our interest, with that to year-to-year fluctuation in air temperature, which should represent the real effect of temperature on phenology. We collected records of air temperature and phenological events (budding and flowering) in apple from 1977 to 2004 at six locations in Japan. Linear trends in flowering showed advancing rate in the range from 0.21 to 0.35 day yr−1, statistically significant at three locations ( P<0.05). We also found a warming trend in mean air temperature throughout March and April, with which flowering was closely correlated, in the range from 0.047 to 0.077 °C yr−1, statistically significant at five locations ( P<0.05). We separated the temperature time-series into two components: a long-term trend and a year-to-year fluctuation, by fitting smoothing spline to the trend and taking the residuals as the anomaly. We then fit a multiple regression model of phenological response to air temperature with separate coefficients for long-term trend and anomaly. Flowering date responded to the long-term trend at −3.8 day °C−1 and to the anomaly at −4.6 day °C−1. The temperature coefficients were not statistically different from each other or among locations, suggesting that the advance of apple phenology has predominantly been caused by the temperature increase across the locations studied. The same result was also observed with budding. [ABSTRACT FROM AUTHOR]

Abstract: Vegetation phenology such as the onset of green-up and senescence is strongly controlled by climate and other environmental factors, and in turn affects the terrestrial carbon balance. Therefore, phenological observation is important as an indicator of global warming and for estimation of the terrestrial carbon balance. Because phenological responses differ from species to species, precise monitoring from the species scale to the global scale is required. In this study, we analyzed images from digital cameras, which have proliferated in recent years, to investigate their utility as remote sensors. We collected daily images taken by digital cameras in national parks across Japan over 8years in wetland mixed deciduous forest, and evergreen broadleaved forest. Values of red, green, and blue (RGB) channels in each pixel within images were extracted, and a vegetation green excess index (2G-RBi) was calculated to detect phenology. The time series of 2G-RBi showed clear phenological patterns of each vegetation type in each year at the species or community scale. Even physiological damage due to a typhoon was detected. The dates of green-up were estimated easily and objectively from the second derivative of 2G-RBi, and a trend in yearly green-up dates of various types of vegetation was demonstrated. Furthermore, a strong correlation between interannual variations in green-up dates and local spring temperature was found, and the sensitivity of green-up date to temperature was revealed. The results suggest the utility of digital cameras for phenological observations at precise temporal and spatial resolutions, despite a year-to-year drift of color balance of camera as a technical device. As a form of near-surface remote sensing, digital cameras could obtain significant ecological information. Establishing camera networks could help us understand phenological responses at a wide range of scales. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the trends and patterns of the changes in the phenology of Gingko biloba L. in Japan and its causal factors. The study made use of phonological dataset from 1961-2000 which includes the dates of budding and leaf fall for Gingko from 60 meteorological stations in Japan. Results indicate that variations in the trends of its phenology depends more on the sensitivity to the temperature of the air than the trends of the temperature.

Abstract: Studies from throughout the world have provided evidence that climate change is already affecting the ecology and persistence of species. Japan contributes valuable insights into understanding these changes through long-term records of the timing of cherry blossoms and other phenomena of ecological and cultural interest. The wide latitudinal spread of Japan also provides an opportunity to examine species over a broad range of environmental conditions. In this review, we examine phenological studies that have taken place in Japan and summarize their significance to climate change and conservation research. In Kyoto, records of the timing of celebrations of cherry blossom festivals going back to the 9th century reconstruct the past climate and demonstrate the local increase in temperature associated with global warming and urbanization. This record is probably the longest annual record of phenology from anyplace in the world and shows that cherries are currently flowering earlier than they have at any time during the previous 1200years. Detailed mapping of cherry tree flowering times in and around Osaka and other cities in Japan show that urbanization causes plants to flower earlier within the city environs than in nearby parks and outlying suburban areas. Flowering records from a large cherry arboretum at Mt. Takao, on the outskirts of Tokyo, show that both among and within species, early flowering is associated with greater responsiveness to temperature variation. Lastly, records of phenology for a wide range of plants and animals recorded at over 100 weather stations throughout Japan show that species vary greatly in their phenological responses to climate change, and highlight ecological relationships that need to be investigated in the field. Together, these studies provide important insights into how species are responding to climate change in Japan. Further research, particularly targeted field observations and experiments, is needed to build on these findings and to improve our understanding of how climate change is altering biological communities and how it will continue to affect them in the future. [Copyright &y& Elsevier]

Abstract: To document the spatial and temporal variation of environmental signals inducing seed germination in temperate forests, we measured temporal patterns of environmental signals and seed germination of six pioneer tree species in unthinned and thinned stands of conifer forests (Cryptomeria japonica plantations) and in the understory and gaps of hardwood forests in Japan. We also conducted germination experiment in laboratory for the six pioneer species to test the effects of red:far-red (R:FR) light ratio and temperature fluctuations on the seed germination. In conifer forests, the photosynthetic photon flux density (PPFD), the R:FR ratio, and the amplitude of temperature fluctuations in thinned stands were 2, 1.5, and 3 times higher, respectively, than those of unthinned stands. The PPFD and R:FR ratios just above forest floor also increased after the removal of thick litter accumulation. As a result, higher seed germination was observed in thinned compared to unthinned stands for three photoblastic species, whereas little differences were observed for three non-photoblastic species. These findings suggest that thinning, which frequently reduces litter accumulation, can substantially affect the regeneration of pioneer species and the resultant species diversity in conifer plantations. None of the measured environmental signals changed seasonally in unthinned stands of conifer forests, but they all changed remarkably in the understory of the hardwood forests. In this system, all signals were high and nearly identical to those in the gaps in early spring prior to canopy closure. Thus, the percent germination of the three photoblastic species was enhanced by high R:FR ratios and/or large temperature fluctuations even beneath the canopy and was nearly equal to that in the thinned conifer stands where the environmental conditions were nearly identical to those in the gaps. However, all of the environmental signals decreased with the expansion of canopy leaves and reached minimums at canopy closure. Even in the thinned stands and the gaps, the PPFD and magnitude of temperature fluctuations decreased over time due to shading by growing herbs and/or emerging canopy leaves. In these temporally changing environments, the germination of all photoblastic species ceased simultaneously. This study clearly demonstrated that the environmental signals inducing seed germination of photoblastic pioneer species spatially and temporally change in temperate forests, particularly in deciduous hardwood forests. Furthermore, these signals, PPFD, R:FR ratio, and the amplitude of temperature fluctuations, appear to play a very important role in tree regeneration and subsequent species diversity. [Copyright &y& Elsevier]

A shift in a life cycle event of one species relative to other species in an ecosystem should be considered more relevant than an absolute shift in phenological dates. However, there is very little evidence regarding the differential effects of climate change on the phenologies of different trophic levels and their potential effects on ecosystem functioning. The Japan Meteorological Agency has monitored the flowering of 4 Prunus tree species and the appearance date of the butterfly Pieris rapae (a proxy for potential pollinators) in spring at Nagano, Japan, since 1953. Flowering tended to occur earlier over the last 3 decades, whereas the appearance of the butterfly was delayed. The effects of climate and the timing of the sensitive period differ between both trophic levels. The plants were strongly affected by temperature (r = -0.87) 30 to 40 d prior to flowering, whereas the butterfly was less affected by temperature (r = -0.50), and the effects mainly occurred during the 15 d prior to its appearance. The temperature during the plants' sensitive period has increased sharply since 1953, whereas the temperature during the butterfly's sensitive period has not changed significantly. The phenologies of the plants and butterfly are changing in opposite directions because they use different climatic cues with different temporal trends. This is the first documentation of differential effects of climate change between plant and insect phenology in Japan. [ABSTRACT FROM AUTHOR]

Abstract: Phenological timing of leaf budburst in plants is important for growth, since early budburst timing extends the growth period of the plant. We estimated the effect of climate change on the phenological budburst timing of four trees throughout four sites in Japan, a region with few studies on this topic. The leaf budburst date of plants has advanced or been stable during the last five decades in these four Japanese localities. This fact is due to the negative relationship between dates and temperature using multiple regression models, observed at all sites. Climate change has shifted budburst phenology in Japan with the increase of spring temperatures. However, precipitation did not show any effect on budburst timing. At two sites, budburst dates of three tree species had not remarkably changed or delayed throughout the past five decades. There were differences between localities at the same latitude. [Copyright &y& Elsevier]

To clarify mortality patterns of current-year shoots within the crown of Betula maximowicziana Regel after severe insect herbivory in central Hokkaido, northern Japan, we investigated the degree of defoliation, pattern of shoot development, shoot mortality, and leaf tissue-water relations. One hundred current-year long shoots growing in a B. maximowicziana plantation were observed for defoliation and mortality in June 2002. An outbreak of herbivorous insects ( Caligula japonica and Lymantria dispar praeterea) occurred in the stand in mid-to-late June, and the monitored shoots were defoliated to various degrees. Within 1 month of defoliation, some of the severely defoliated shoots had produced new leaves on short shoots that had emerged from axillary buds. Stepwise logistic regression revealed that the probability that current-year long shoots would put out axillary short shoots with leaves is closely related to the degree of defoliation. To evaluate the water relations of the leaves, we determined pressure–volume curves for the leaves that survived the herbivorous insect outbreak and the new leaves that emerged after defoliation. The water potential at turgor loss (Ψl,tlp) and the osmotic potential at full turgidity (Ψπ,sat) were higher for the new leaves than for the surviving leaves, indicating a lower ability to maintain leaf cell turgor against leaf dehydration in the new leaves. Of the 100 shoots, 13 died after the emergence of new leaves. Stepwise logistic regression revealed that the probability that the long shoots would die generally increased with the emergence of new leaves, with increasing shoot height. This result suggests that the combined effect of the vulnerability of newly emerged leaves and low water availability, associated with higher shoot positions within the crown, caused shoot mortality. Based on our results, some possible mechanisms for mortality in severely defoliated B. maximowicziana are discussed. [ABSTRACT FROM AUTHOR]

Climate change is affecting plant phenology worldwide. Phenological responses vary among species, but it is not clear how responses differ among closely related species. We examined a 25-yr record (1981-2005) of flowering times for 97 trees, representing 17 species and hybrids of cherry (Cerasus sp. or Prunus sp.) grown at Mt. Takao, in Tokyo, Japan. The cherry trees flowered earlier over time, by an average of 5.5 d over the 25-yr study. Earlier flowering was explained largely by a 1.8°C increase in February-March mean monthly temperatures. Most species and hybrids flowered 3-5 d earlier for each 1°C increase in temperature, but early-flowering taxa flowered as much as 9 d earlier for each 1°C increase in temperature. Flowering durations and differences in flowering times among species were greater in warm years than in cold years. Species and individual trees also flowered longer in warm years. These results show that the flowering times of closely related species may change similarly in response to climate change, but that early-flowering species may diverge from the overall trend in a predictable way. Such changes in flowering may affect gene flow and pollination as the length of the flowering season increases. [ABSTRACT FROM AUTHOR]

Although it is likely that winter flowering of various plant species has been influenced by recent climate change, previous phenological analyses have not focused on flowering phenology in winter. In Japan, the Japanese apricot Prunus mume historically flowers during the cold months of winter from January to March 1 used a continuous dataset of the flowering date at 32 sites in various regions of Japan from 1953 to 2005. Over the course of this period, the flowering date of apricots has advanced, with a notable shift in regimes between 1953 1989 and 1990-2005. The correlation results show that mean winter air temperature significantly affected the flowering date of the apricots at all of the sites, but snowfall was not correlated with the flowering date at 30 out of 32 sites. The difference between the mean flowering dates of 1953-1989 and 1990 2905 was correlated with the correlation coefficient between the flowering date and air temperature. Winter flowering of Japanese apricot has been influenced by recent climate change, especially by drastic climate-related shifts in the timing of key processes. [ABSTRACT FROM AUTHOR]

In forest ecosystems, fine roots have a considerable role in carbon cycling. To investigate the seasonal pattern of fine root demography, we observed the fine root production and decomposition processes using a minirhizotron system in a Betula-dominated forest with understory evergreen dwarf bamboo. The length density of fine roots decreased with increasing soil depth. The seasonal patterns of each fine root demographic parameter (length density of visible roots, rates of stand-total fine root production and decomposition) were almost the same at different soil depths. The peak seasons of the fine root demographic parameters were observed in the order: stand-total fine root production rate (late summer) > length density of the visible roots (early autumn) > stand-total fine root decomposition rate (autumn, and a second small peak in spring). The fine root production rate was high in the latter part of the plant growing season. Fine root production peaked in late summer and remained high until the end of the tree defoliation season. The higher stand-total fine root production rate in autumn suggests the effect of understory evergreen bamboo on the stand-total fine root demography. The stand-total fine root decomposition rate was high in late autumn. In the snow-cover period, the rates of both fine root production and decomposition were low. The fine root demographic parameters appeared to show seasonal patterns. The fine root production rate had a clearer seasonality than the fine root decomposition rate. The seasonal pattern of stand-total fine root production rate could be explained by both overstory and understory above-ground productivities. [ABSTRACT FROM AUTHOR]

Leaf-fall phenology was studied in a cool–temperate deciduous broad-leaved forest in central Japan in relation to the topographic environmental gradients that occur along a short mountain slope. Leaf-fall phenology was described quantitatively using data from leaf litter collected along the slope. In autumn, leaf fall at the study site tended to occur slightly earlier on the upper slope than on the lower slope. This pattern was found at both the stand and the species levels. Our results suggest that leaf-fall phenology may be affected by difference in microclimatic conditions, because environmental conditions are thought to be more severe on the upper slope than on the lower slope. The less intensive methods used in this study, the litter trap method, and Dixon’s model succeeded in quantifying the phenological patterns of leaf fall within stands and within species along the short mountain slope. [ABSTRACT FROM AUTHOR]