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Climate warming–driven phenological shifts are species‐specific in woody plants: evidence from twig experiment in Kashmir Himalaya
Abstract
Experimental evidences in support of climate warming–driven phenological shifts are still scarce, particularly from the developing world. Here, we investigated the effect of experimental warming on flowering phenology of selected woody plants in Kashmir Himalaya. We selected the twigs of four congeneric pairs of temperate woody species (Prunus, Populus, Ulmus, Viburnum)—typical spring-flowering plants in the region. Using randomised block design, we monitored these winter dormant twigs in controlled growth chambers to study the effect of different temperature regimes (9, 17, 20 and 23 °C) and species identity on the patterns of phenological shifts. We observed a significant phenological shift in all the species showing preponement in the first flower out and senescence phases ranging from 0.56 to 3.0 and 0.77 to 4.04 days per degree increase in temperature, respectively. The duration of flowering phase in all the species showed a corresponding decrease along the gradient of increasing temperature, which was more driven by preponement of the flower senescence than the start of flower- ing. The patterns of phenological shifts were highly species-specific, and the magnitude of these shifts significantly varied in all the four pairs of congeneric species despite their phylogenetic similarity. Our study provides experimental support to the previous long-term observation and herbarium-based studies showing that the patterns of phenological shifts in response to global climate warming are likely to vary between species, even those belonging to same evolutionary stock. Our findings highlight that a one-size-fits-all strategy to manage the likely impacts of climate warming–induced phenological shifts will seldom succeed, and should instead be designed for the specific phenological responses of species and regions.
... In mountainous ecosystems, plant phenology shows an intimate relationship with elevation-dependent climatic conditions (Menzel et al., 2006;Chen et al., 2018;Stucky et al., 2018). A species responds to environmental cues such as precipitation, air and soil temperature, and humidity by either preponing or postponing its phenophases (Bhattarai et al., 2021;Hassan et al., 2022). Phenological shifts is regarded as a key strategy employed by vegetation to cope with global climate change (Zohner et al. 2017; Liu and Zhang 2020). ...
... The current climate warming is inducing notable phenological shifts, either advancing spring owering in temperate ecosystems or delaying summer owering phenology in various plant species and consequently affecting crucial ecological processes and biotic interactions of these plants (Cleland et al., 2012;Iler et al., 2021;Rosbakh et al., 2021). To unravel the mechanisms behind phenological shifts and to enhance predictions of future changes in phenological events, it is crucial to gain a more comprehensive understanding of the relationship between climate warming and the associated phenological changes in species (Hassan et al., 2022). The study of phenology along elevation gradients enhances our understanding of variations in plant development under diverse temperature regimes and elucidates the potential impacts of these phenological shifts on plant-pollinator interaction (Cornelius et al., 2013;Morton and Rafferty, 2017). ...
In the era of the Anthropocene, changes in the timing of plant life cycle events serve as prominent biological markers of global environmental shifts. Major of the studies dedicated to documenting and analyzing plant phenological changes are from North America and Europe. Although few studies are available from Himalayan regions, but there is a notable scarcity of comparable studies in the developing world, particularly in regions like the Himalaya. To fill this knowledge gap, the present study aims to attempt the reveal to attempt to unravel the vegetative and reproductive phenology of Phytolacca acinosa across Kashmir Himalaya. For this, we selected and tagged 10 healthy individuals for monitoring and documenting the onset and duration of different phenological events from sprouting to senescence. Further, flowering phenology was recorded using flowering variables such as moment, intensity and duration. Our results reveal that Phytolacca acinosa completes the entire life cycle within a period 7–8 months, and the timing of phenophases varied significantly across the selected sites. Our results also reveal that the plant populations at lower elevations exhibited a clear precedence of vegetative and reproductive phases in their life cycle as compared to those growing at higher elevations. We found that all the phenophases except senescence showed an overlap with the preceding phase. We also found that the flowering variables showed significant variation across the selected sites with the maximum values at low elevations, while minimum values at high elevations. Our study is the first attempt that provides useful insights into the phenology of P. acinosa across different habits along an elevation gradient in Kashmir Himalaya. Phenological adjustments, such as advancing or delaying reproductive phases, are crucial strategies for species to optimize reproductive success. Global climate change, characterized by rapid warming and disruptions, particularly during reproductive periods, has notably impacted species at higher elevations. Understanding phenological attributes is vital in contemporary conservation biology and the phenological data from this study will assist in formulating effective strategies for the restoration and conservation of the target species.
... The ground-based observations are now supplemented with data obtained from state-ofthe-art remote sensing tools (Forkel et al., 2015;Pinzon & Tucker, 2014). The use of historical herbarium specimens and experimental approaches have also attracted wide attention of researchers (Everingham et al., 2021;Hassan et al., 2022). ...
... Thus, as expected, such studies are available only for one to few years. Several experimental studies to assess the impact of changing climate on plant phenology are available from the developed world (Ettinger et al., 2020), but such studies are still rare from the developing world (Hassan et al., 2022). Recent advances using artificial intelligence and machine learning tools to automatically extract herbarium-based data Vol.: (0123456789) offer much promise of assessing and predicting plant phenological shifts over the larger temporal scale in various regions/ecosystems across the world (Goëau et al., 2022). ...
Climate warming-driven temporal shifts in phenology are widely recognised as the foremost footprint of global environmental change. In this regard, concerted research efforts are being made worldwide to monitor and assess the plant phenological responses to climate warming across species, ecosystems and seasons. Here, we present a global synthesis of the recent scientific literature to assess the progress made in this area of research. To achieve this, we conducted a systematic review by following PRISMA protocol, which involved rigorous screening of 9476 studies on the topic and finally selected 215 studies for data extraction. The results revealed that woody species, natural ecosystems and plant phenological responses in spring season have been predominantly studied, with the herbaceous species, agricultural ecosystems and other seasons grossly understudied. Majority of the studies reported phenological advancement (i.e., preponement) in spring, followed by also advancement in summer but delay in autumn. Methodology-wise, nearly two -third of the studies have employed direct observational approach, followed by herbarium-based and experimental approaches, with the latter covering least temporal depth. We found a steady increase in research on the topic over the last decade with a sharp increase since 2014. The global country-wide scientific output map highlights the huge geographical gaps in this area of research, particularly in the biodiversity-rich tropical regions of the developing world. Based on the findings of this global synthesis, we identify the current knowledge gaps and suggest future directions for this emerging area of research in an increasingly warming world.
... The ground-based observations are now supplemented with data obtained from state-ofthe-art remote sensing tools (Forkel et al., 2015;Pinzon & Tucker, 2014). The use of historical herbarium specimens and experimental approaches have also attracted wide attention of researchers (Everingham et al., 2021;Hassan et al., 2022). ...
... Thus, as expected, such studies are available only for one to few years. Several experimental studies to assess the impact of changing climate on plant phenology are available from the developed world (Ettinger et al., 2020), but such studies are still rare from the developing world (Hassan et al., 2022). Recent advances using artificial intelligence and machine learning tools to automatically extract herbarium-based data 36 Page 10 of 19 ...
Climate warming-driven temporal shifts in phenology are widely recognised as the foremost foot- print of global environmental change. In this regard, concerted research efforts are being made worldwide to monitor and assess the plant phenological responses to climate warming across species, ecosystems and seasons. Here, we present a global synthesis of the recent scientific literature to assess the progress made in this area of research. To achieve this, we conducted a systematic review by following PRISMA protocol, which involved rigorous screening of 9476 studies on the topic and finally selected 215 studies for data extraction. The results revealed that woody species, natural ecosystems and plant phenological responses in spring season have been predominantly studied, with the herbaceous species, agricultural ecosystems and other seasons grossly understudied. Majority of the studies reported phenological advancement (i.e.,preponement) in spring, followed by also advancement in summer but delay in autumn. Methodology- wise, nearly two-third of the studies have employed direct observational approach, followed by herbarium-based and experimental approaches, with the latter covering least temporal depth. We found a steady increase in research on the topic over the last decade with a sharp increase since 2014. The global country-wide scientific output map highlights the huge geographical gaps in this area of research, particularly in the biodiversity-rich tropical regions of the developing world. Based on the findings of this global synthesis, we identify the current knowledge gaps and suggest future directions for this emerging area of research in an increasingly warming world.
... The phenological events are compromised with the advance or delay of timing of seasonal changes in plants (Piao et al., 2019). The advancement of flowering in response to increasing temperature has been substantiated by different experimental evidences (Hassan et al., 2021(Hassan et al., , 2022. The soil microbiome, an important aspect of the establishment of plant diversity is greatly imperilled by the changing climate (Classen et al., 2015). ...
Climate change-driven rapid alteration of
ecosystems globally is further complicated by grow-
ing anthropogenic pressures, especially in the eco-
logically sensitive mountainous regions. However,
these two major drivers of change have largely been
considered separately in species distribution models,
thus compromising their reliability. Here, we inte-
grated ensemble modelling with the human pressure
index for predicting distribution and mapping prior-
ity regions across a whole range of occurrences for
vulnerable species, Arnebia euchroma. Our results
identifed 3.08% of the study area as ‘highly suitable’,
2.45% as ‘moderately suitable’, and 94.45% as ‘not
suitable’ or ‘least suitable’. Compared to current cli-
matic conditions, future RCP scenarios of 2050 and
2070 showed a signifcant loss in habitat suitability
and a slight shift in the distribution pattern of the tar-
get species. By excluding the high-pressure areas of
the human footprint from the predicted suitable habi-
tats, we were able to identify the unique areas (70%
of the predicted suitable area) that need special atten-
tion for conservation and restoration. Such models, if
well implemented, may play a pivotal role in achiev-
ing the efective targets under the aegis of the current
UN decade on ecological restoration (2021–2030) in
accordance with SDG 15.4.
Climate change is one of the primary causes of species redistribution and biodiversity loss, especially for threatened and endemic important plant species. Therefore, it is vital to comprehend “how” and “where” priority medicinal and aromatic plants (MAPs) might be effectively used to address conservation-related issues under rapid climate change. In the present study, an ensemble modelling approach was used to investigate the present and future distribution patterns of Aquilegia fragrans Benth. under climate change in the entire spectrum of Himalayan biodiversity hotspot. The results of the current study revealed that, under current climatic conditions, the northwest states of India (Jammu and Kashmir, Himachal Pradesh and the northern part of Uttarakhand), the eastern and southern parts of Pakistan Himalaya have highly suitable climatic conditions for the growth of A. fragrans. The ensemble model exhibited high forecast accuracy, with temperature seasonality and precipitation seasonality as the main climatic variables responsible for the distribution of the A. fragrans in the biodiversity hotspot. Furthermore, the study predicted that future climate change scenarios will diminish habitat suitability for the species by −46.9% under RCP4.5 2050 and −55.0% under RCP4.5 2070. Likewise, under RCP8.5, the habitat suitability will decrease by −51.7% in 2050 and −94.3% in 2070. The current study also revealed that the western Himalayan area will show the most habitat loss. Some currently unsuitable regions, such as the northern Himalayan regions of Pakistan, will become more suitable under climate change scenarios. Hopefully, the current approach may provide a robust technique and showcases a model with learnings for predicting cultivation hotspots and developing scientifically sound conservation plans for this endangered medicinal plant in the Himalayan biodiversity hotspot.
Climate change is one of the main drivers for species redistribution and biodiversity loss, especially for endemic and medicinally important plant species with a restricted distributional range. For that reason, it is vital to comprehend "how" and "where" priority medicinal and aromatic plants (MAPs) might be effectively used to address conservation-related issues under rapid climate change. In the current study, we used an ensemble modelling approach to investigate the present and future potential distribution coupled with the range dynamics of the Aquilegia fragrans –a medicinally important endangered plant species in the entire spectrum of the Himalayan biodiversity hotspot. The findings of the current study revealed that, under current climatic conditions, the northwest states of India (Jammu and Kashmir, Himachal Pradesh, and the northern part of Uttarakhand); the eastern and southern parts of Pakistan Himalaya have highly suitable and optimal climatic conditions for the growth of A. fragrans. The ensemble model exhibited high forecast accuracy, with temperature seasonality (BIO4) and precipitation seasonality (BIO15) as the main climatic variables responsible for the distribution in the biodiversity hotspot. Furthermore, the study predicted that future climate change scenarios will diminish habitat suitability for the species by -46.922% under RCP4.5 2050 and − 55.052% under RCP4.5 2070. Likewise, under RCP8.5 the habitat suitability will decrease by -51.760% in 2050 and-94.351% in 2070. The current study also revealed that the western Himalayan area will show the most habitat loss. Some regions that are currently unsuitable such as the northern Himalayan regions of Pakistan will become more suitable under climate change scenarios. Hopefully, the current approach will provide a robust technique and showcases a model with learnings for predicting cultivation hotspots and devising scientifically sound conservation plans for this endangered medicinal plant in the Himalayan biodiversity hotspot.
Studying phenology is undeniably one of the most effective ways to monitor and perceive how a particular plant species interact and respond to varying environmental conditions. In this study, the shifts in flowering phenological events of 24 herbaceous species with the changing elevation and temperature were observed in Dhauladhar Mountain range of Lesser Himalaya. Five permanent plots (20 × 20 m2) were established from 2,000 m to 4,000 m elevation at each rising 500 m distance for the documentation of herbaceous flora. Abundance-based documentation of flowering phenological events (onset of flowering duration [OFD] ≥ 10% to 30%, the peak of flowering duration [PFD] > 30% to 80%, the end of flowering duration [EFD] > 80% and total flowering duration [FD] as the difference of end and onset of flowering DOY) was done in each plot. The onset, the peak, and the end of the flowering day of the year (DOY) were recorded at 20%, 55%, and 90% floral abundance, respectively, from 1st of January. Upon analyses, the Linear-mixed effects model depicted significant differences in the flowering phenological events with elevation and soil temperature. The onset of flowering DOY and peak of the flowering DOY varied significantly with soil temperature gradient, while the end of flowering DOY showed non-significant interaction. The linear model of ANOVA demonstrated that OFD, PFD, EFD and FD varied significantly with elevation at p
Siberia has undergone dramatic climatic changes due to global warming in recent decades. Yet, the ecological responses to these climatic changes are still poorly understood due to a lack of data. Here, we use a unique dataset from the Russian 'Chronicles of Nature' network to analyse long-term (1976-2018) phenological shifts in leaf out, flowering, fruiting and senescence of 67 common Siberian plant species. We find that Siberian boreal forest plants advanced their early-season (leaf out and flowering) and mid-season (fruiting) by 2.2, 0.7 and 1.6 days/decade, and delayed the onset of senescence by 1.6 days/decade during this period. These mean values, however, are subject to substantial intraspecific variability, which is partly explained by the plants' growth forms. Trees and shrubs advanced leaf out and flowering (-3.1 and-3.3. days/decade) faster than herbs (1 day/decade), presumably due to the more direct exposure of leaf and flower buds to ambient air for the woody vegetation. For senescence, we detected a reverse pattern: stronger delays in herbs (2.1 days/decade) than in woody plants (1.0-1.2 days/decade), presumably due to stronger effects of autumn frosts on the leaves of herbs. Interestingly, the timing of fruiting in all four growth forms advanced at similar paces, from 1.4 days/decade in shrubs to 1.7 days/decade in trees and herbs. Our findings point to a strong, yet heterogeneous, response of Siberian plant phenology to recent global warming. Furthermore, the results highlight that species-and growth form-specific differences among study species could be used to identify plants particularly at risk of decline due to their low adaptive capacity or a loss of synchronization with important interaction partners.
The twig method in climate chambers has been shown to successfully work as a proxy for outdoor manipulations in various experimental setups. This study was conducted to further establish this method for the investigation of allergenic pollen from tree species (hazel, alder, and birch). Direct comparison under outdoor conditions revealed that the cut twigs compared to donor trees were similar in the timing of flowering and the amount of pollen produced. Cut twigs were able to flower in climate chambers and produced a sufficient amount of pollen for subsequent laboratory analysis. The addition of different plant or tissue fertilizers in the irrigation of the twigs did not have any influence; rather, the regular exchange of water and the usage of fungicide were sufficient for reaching the stage of flowering. In the experimental setup, the twigs were cut in different intervals before the actual flowering and were put under warming conditions in the climate chamber. An impact of warming on the timing of flowering/pollen characteristics could be seen for the investigated species. Therefore, the twig method is well applicable for experimental settings in pollen research simulating, e.g., accelerated warming under climate change.
Union territory of Jammu and Kashmir, one of the leading producers of temperate fruits in India, is in the process of adopting high-density apple cultivation. Establishment of high-density apple orchard involves a very high cost which gets compensated by higher productivity during its productive life. Considering the profitability of cultivating high-density apple a need was felt to examine its quality and yield potential that could guide the Government to formulate a roadmap for its dissemination in its domain area. High-density apple (variety-Super Chief Sandidge) was recently introduced from Italy. It is reported to be very productive and quality wise, retains a high score of consumer acceptability, accordingly efforts are being made to extend its adoption in the union territory of Jammu and Kashmir. To formulate a policy for its adoption, ex-ante evaluation was carried out by employing economic surplus model on the experimental data collected from the technical expert group of scientists involved in its cultivation, assessment, evaluation and dissemination. The results reveal that productivity of apple has increased by 53.6 mt/ha and labor employment has increased by 676 man days/ha due to the adoption of high-density apple technology. The results further revealed that with an expected expansion of high-density apple orchards over 30% of the target area NPV, IRR and BC ratio would amount to 16.43 Billion US $, 62% and 98.60.
Warming climate and its impact on vegetation phenological trends have been widely investigated. However, interannual variability in temperature is considerably large in recent decades, which is expected to trigger an increasing trend of variation in vegetation phenology. To explore the interannual phenological variation across the contiguous United States (CONUS), we first detected the onset of vegetation greenup using the time series of the daily two-band Enhanced Vegetation Index (EVI2) observed from the AVHRR Long-Term Data Record (1982–1999) and the MODIS Climate Modeling Grid (2000–2016). We then calculated the interannual variation in greenup onset during four decadal periods: 1982–1989, 1990–1999, 2000–2009 and 2010–2016. Further, the trend of interannual variation in greenup onset from 1982 to 2016 was analyzed at pixel and state levels. Extreme phenological events were also determined using a greenup onset anomaly for each pixel. Similar approaches were applied to spring temperatures to detect extreme years and to the temporal trend of interannual variation to explain the phenological variation. The results revealed that 62% of pixels show an increasing interannual variation in greenup onset, and in 44% of pixels, this variation could be explained by the temperature. Although extreme phenology occurred locally in different years, three nationwide extreme phenological years were distinguished. The extreme warm spring that occurred in 2012 resulted in the occurrence of greenup onset as much as 20 days earlier than normal in large parts of the CONUS. In contrast, greenup onset was much later (up to 30 days) in 1983 and 1996 due to cool spring temperatures. These findings suggest that interannual variation in spring phenology could be much stronger in the future in response to climate variation, which could have more significant impacts on terrestrial ecosystems than the regular long-term phenological trend.
Kashmir Valley has been witnessing erratic snowfall events in recent autumns which severely impacted apple orchards and harvests. Here, we combine remotely sensed data and field observations to map snowfall distribution and snow depths during the recent snowfall events in November 2018 and November 2019. Besides, we used ERA-5 reanalysis climate datasets to investigate the causes of these erratic snowfall events, pointing to an early arrival of Western Disturbances (WD) to the area. Analysis of these untimely snowfall episodes indicates that snow depths varied from 5-122 cm and 31-152 cm during the 2018 and 2019 snowfall events, respectively. In turn, satellite data analysis reveals that the apple orchards cover roughly 9.8% (1329 km 2) of the entire surface of Kashmir Valley, out of which 32.6% were mildly to severely damaged by snow. The areas in South Kashmir suffered the most from the untimely snowfall with an area affected estimated to~264 km 2 , followed by North Kashmir (~151 km 2) and Central Kashmir (18 km 2). The snowfall caused substantial harvest losses in orchards ranging from 4-50% with an average of~35%. The geopotential analysis from the ERA-5 dataset provides insights into the synoptic weather patterns leading to the snowfall events and point to a trough in the high-troposphere (200 mb), along with a col at lower levels (850 mb) over the Kashmir Valley from November 2-5, 2018. The lower levels (850 mb) experienced intense cyclonic circulation which favored advection of moisture from the Arabian Sea during the November 6-7, 2019, snowfall event. The large economic losses related to early arrival of WD led to a virtual grounding of the horticultural sector in 2018 and 2019. Therefore, more baseline research is critically needed along with a comprehensive evaluation of the suitability of horticulture as an economically viable sector that is being promoted over the Kashmir region, also under climate change.
Research on woody plant species highlights three major cues that shape spring phenological events: chilling, forcing and photoperiod. Increasing research on the phenological impacts of climate change has led to debate over whether chilling and/or photoperiod cues have slowed phenological responses to warming in recent years. Here we use a global meta-analysis of all published experiments to test the relative effects of these cues. Almost all species show strong responses to all three cues, with chilling being the strongest and photoperiod the weakest. Forecasts from our findings for Central Europe suggest that spring phenology will continue to advance, as stalling effects of chilling generally appear above 4 °C warming in this region. Our results unify both sides of the debate over phenological cues: while all species may respond to all cues strongly in experimental conditions, in current environmental conditions the dominant signal of climate change is from increased forcing.
Low-cost phenological experiments with cut twigs are increasingly used to study bud development in response to spring warming and photoperiod. However, a broader variety of species needs to be tackled and in particular the influence of insufficient winter chilling deserves more attention. Therefore, we investigated if and how chilling requirements can be efficiently investigated by cut twigs and how this low-tech approach could be successfully implemented as a citizen science or school project. We conducted an experiment on bud burst and leaf development of Corylus avellana L. twigs, with natural chilling outdoors on a shrub (S) and another chilling treatment as cut twigs in containers (C), and subsequent forcing indoors. Subsampling of the number of cutting dates and number of twigs was used to infer minimum required sample sizes. Apart from insufficiently chilled twigs, ~80% of the twigs (both S and C) reached leaf out. For multiple definitions of chilling and forcing, a negative exponential relationship was revealed between chilling and amount of forcing needed to reach certain developmental stages. At least 5 out of 15 cutting dates or alternatively half of the 10 twig repetitions, but especially those mirroring low chilling conditions, were needed to describe the chilling-forcing relationship with some degree of robustness. In addition, for cutting dates with long chilling, i.e., from January onwards, freshly cut twigs (S) required significantly more forcing to reach bud burst than twigs from containers (C), although the effect was small. In general, chilling conditions of mature shrubs were well captured by cut twigs, therefore opening the possibility of chilling through refrigeration. We conclude that experimental protocols as outlined here are feasible for citizen scientists, school projects, and science education, and would have the potential to advance the research field if carried out on a large scale. We provide an easy-to-use Shiny simulation app to enable citizen scientists to build up a bud development model based on their own experimental data and then simulate future phenological development with winter and/or spring warming. This may encourage them to further study other aspects of climate change and the impacts of climate change.
Ecological communities consist of species that are joined in complex networks of interspecific interaction. These interactions often form and dissolve rapidly, but this temporal variation is not well integrated into our understanding of the causes and consequences of network structure. If interspecific interactions exhibit temporal flexibility across time periods over which organisms co‐occur, then the emergent structure of the corresponding network may also be flexible, something that a temporally‐static perspective will miss. Here, we use an empirical plant–pollinator system to examine short‐term (week‐to‐week) flexibility in network structure (connectance, nestedness and specialization) and in the individual species interactions that contribute to that structure across three summer growing seasons in a subalpine ecosystem. We then compared the properties of weekly networks to the properties of cumulative networks that aggregate field observations over each full summer season. As a test of the potential robustness of networks to perturbation, we also simulated the random loss of species from weekly networks. A week‐to‐week view reveals considerable flexibility in the interactions of individual species and their contributions to network structure. For example, species that would be considered relatively generalized across their entire activity period may be much more specialized at certain times, and at no point as generalized as the cumulative network may suggest. Furthermore, a week‐to‐week view reveals corresponding flexibility in network structure and potential robustness throughout each summer growing season. We conclude that short‐term flexibility in species interactions leads to short‐term variation in network properties, and that a cumulative, season‐long perspective may miss important aspects of the way in which species interact, with implications for understanding their ecology, evolution and conservation.
Background
A warmer climate has consequences for the timing of phenological events, as temperature is a key factor controlling plant development and flowering. In this study, we analyse the effects of the long-term climate change and an extreme weather event on the first flowering day (FFD) of five spring-flowering wild plant species in the United Kingdom. Citizen science data from the UK Woodland Trust were obtained for five species: Tussilago farfara (coltsfoot), Anemone nemorosa (wood anemone), Hyacinthoides non-scripta (bluebell), Cardamine pratensis (cuckooflower) and Alliaria petiolate (garlic mustard).
Results
Out of the 351 site-specific time series (≥ 15-years of FFD records), 74.6% showed significant negative response rates, i.e. earlier flowering in warmer years, ranging from − 5.6 to − 7.7 days °C⁻¹. 23.7% of the series had non-significant negative response rates, and 1.7% had non-significant positive response rates. For cuckooflower, the response rate was increasingly more negative with decreasing latitudes. The winter of 2007 reflects an extreme weather event, about 2 °C warmer compared to 2006, where the 2006 winter temperatures were similar to the 1961–1990 baseline average. The FFD of each species was compared between 2006 and 2007. The results showed that the mean FFD of all species significantly advanced between 13 and 18 days during the extreme warmer winter of 2007, confirming that FFD is affected by temperature.
Conclusion
Given that all species in the study significantly respond to ambient near-surface temperatures, they are suitable as climate-change indicators. However, the responses to a + 2 °C warmer winter were both more and less pronounced than expected from an analysis of ≥ 15-year time series. This may reflect non-linear responses, species-specific thresholds and cumulative temperature effects. It also indicates that knowledge on extreme weather events is needed for detailed projections of potential climate change effects.
The Kashmir Himalaya, nestled in the northwestern side of the Himalayan biodiversity hotspot, possesses a rich biodiversity of immense potential. Plethora of anthropogenic activities during last few decades has deleteriously affected the biodiversity of this fragile mountain ecosystem, thereby threatening its bio-security. Contextually, conservation of the biota assumes vital importance, for which inventorization and documentation of the biota is essential. Though some work has been done on different aspects of the flora but not on the bee flora of the area. Present study documents the diversity of bee flora from this biodiversity-rich part of the Himalaya. Systematic survey and field observation approach has been used to document the diversity of foraging plants of bees. During the present study, a total 228 plant species belonging to 182 genera and 58 families were recorded, which serve as food source for bees. Overall 77 foraging species were found frequently visited by bees. Annual herbs were found as potential source of pollen and nectar. Majority of plant species were both pollen and nectar-producing and grow as wild in this Himalayan region. A total 37 bee species belonging to 15 genera and 6 families were found visiting the documented flowering plants for their food. Family Apidae was found to be dominant group of bees.
Climate warming has the potential to disrupt plant-pollinator interactions or to increase competition of co-flowering plants for pollinators, due to species-specific phenological responses to temperature. However, studies focusing on the effect of temperature on solitary bee emergence and the flowering onset of their food plants under natural conditions are still rare. We studied the effect of temperature on the phenology of the two spring bees Osmia cornuta and Osmia bicornis, by placing bee cocoons on eleven grasslands differing in mean site temperature. On seven grasslands, we additionally studied the effect of temperature on the phenology of the red-list plant Pulsatilla vulgaris, which was the first flowering plant, and of co-flowering plants with later flowering. With a warming of 0.1°C, the abundance-weighted mean emergence of O. cornuta males advanced by 0.4 days. Females of both species did not shift their emergence. Warmer temperatures advanced the abundance-weighted mean flowering of P. vulgaris by 1.3 days per 0.1°C increase, but did not shift flowering onset of co-flowering plants. Competition for pollinators between P. vulgaris and co-flowering plants does not increase within the studied temperature range. We demonstrate that temperature advances plant flowering more strongly than bee emergence suggesting an increased risk of pollinator limitation for the first flowers of P. vulgaris.
Phenological mismatches due to climate change may have important ecological consequences. In a three-year study, phenological shifts due to experimental warming markedly altered trophic relationships between plants and insect herbivores, causing a dramatic decline of reproductive capacity for one of the plant species. In a Tibetan meadow, the gentian (Gentiana formosa) typically flowers after the peak larva density of a noctuid moth (Melanchra pisi) that primarily feeds on a dominant forb (anemone, Anemone trullifolia var. linearis). However, artificial warming of ;1.58C advanced gentian flower phenology and anemone vegetative phenology by a week, but delayed moth larvae emergence by two weeks. The warming increased larval density 10-fold, but decreased anemone density by 30%. The phenological and density shifts under warmed conditions resulted in the insect larvae feeding substantially on the gentian flowers and ovules; there was ;100-fold more damage in warmed than in unwarmed chambers. This radically increased trophic connection reduced gentian plant reproduction and likely contributed to its reduced abundance in the warmed chambers.
Understanding the influence of evolutionary history on species-specific phenological events of high-altitude plants and their sensitivity to the abiotic factors has gained importance mainly in the context of climate change. However, the majority of phenology studies across altitudinal gradient are carried out on flowering, whereas other reproductive phenology events are seldom considered. We tested the role of abiotic factors and evolutionary history on the reproductive phenology traits of high-altitude Rhododendron community which comprised of 10 locally aggregated species in Kyongnosla Alpine Sanctuary, Sik-kim Himalaya. The study was carried out from 2013 to 2015 across an altitude gradient of 3400-4230 m a.s.l. We generated dated phylogenetic hypotheses to test for phylogenetic signal in reproductive phenol-ogy events, and its durations across 10 Rhododendron species and also among groups of species distributed at every 100 m altitude. Comparative phylogenetic methods were used to explore the relationship between phenology traits and abiotic variables such as daylength and temperature. The early phenology events such as budding, flowering, and initial fruiting, which occurred during the favorable month of the year, exhibited strong phylogenetic signal and were mainly associated with daylength and temperature. In contrast, the later events such as immature fruiting, mature fruiting, and fruit dehiscence, which occurred during the later months of the year, showed a weak phylogenetic signal and were mostly associated with daylength. With the increase in altitude, we found a decreasing trend of phylogenetic signal for the early phenology events and later events did not show a significant trend. Our results suggest that only early events are constrained by evolutionary history; thus, the closely related species share the similar timing of the early phenology events. Also, the role of shared evolutionary history in phenological trait sensitivity to the abiotic factors reduces from early to the late phenology events. This approach can be extended to other representative plant families of the Himalayan region to better understand the response of reproductive traits to abiotic factors in deep evolutionary time.
The local weather and climate of the Himalayas are sensitive and interlinked with global-scale changes in climate, as the hydrology of this region is mainly governed by snow and glaciers. There are clear and strong indicators of climate change reported for the Himalayas, particularly the Jammu and Kashmir region situated in the western Himalayas. In this study, using observational data, detailed characteristics of long- and short-term as well as localized variations in temperature and precipitation are analyzed for these six meteorological stations, namely, Gulmarg, Pahalgam, Kokarnag, Qazigund, Kupwara and Srinagar during 1980–2016. All of these stations are located in Jammu and Kashmir, India. In addition to analysis of stations observations, we also utilized the dynamical downscaled simulations of WRF model and ERA-Interim (ERA-I) data for the study period. The annual and seasonal temperature and precipitation changes were analyzed by carrying out Mann–Kendall, linear regression, cumulative deviation and Student's t statistical tests. The results show an increase of 0.8 ∘C in average annual temperature over 37 years (from 1980 to 2016) with higher increase in maximum temperature (0.97 ∘C) compared to minimum temperature (0.76 ∘C). Analyses of annual mean temperature at all the stations reveal that the high-altitude stations of Pahalgam (1.13 ∘C) and Gulmarg (1.04 ∘C) exhibit a steep increase and statistically significant trends. The overall precipitation and temperature patterns in the valley show significant decreases and increases in the annual rainfall and temperature respectively. Seasonal analyses show significant increasing trends in the winter and spring temperatures at all stations, with prominent decreases in spring precipitation. In the present study, the observed long-term trends in temperature (∘Cyear-1) and precipitation (mmyear-1) along with their respective standard errors during 1980–2016 are as follows: (i) 0.05 (0.01) and -16.7 (6.3) for Gulmarg, (ii) 0.04 (0.01) and -6.6 (2.9) for Srinagar, (iii) 0.04 (0.01) and -0.69 (4.79) for Kokarnag, (iv) 0.04 (0.01) and -0.13 (3.95) for Pahalgam, (v) 0.034 (0.01) and -5.5 (3.6) for Kupwara, and (vi) 0.01 (0.01) and -7.96 (4.5) for Qazigund. The present study also reveals that variation in temperature and precipitation during winter (December–March) has a close association with the North Atlantic Oscillation (NAO). Further, the observed temperature data (monthly averaged data for 1980–2016) at all the stations show a good correlation of 0.86 with the results of WRF and therefore the model downscaled simulations are considered a valid scientific tool for the studies of climate change in this region. Though the correlation between WRF model and observed precipitation is significantly strong, the WRF model significantly underestimates the rainfall amount, which necessitates the need for the sensitivity study of the model using the various microphysical parameterization schemes. The potential vorticities in the upper troposphere are obtained from ERA-I over the Jammu and Kashmir region and indicate that the extreme weather event of September 2014 occurred due to breaking of intense atmospheric Rossby wave activity over Kashmir. As the wave could transport a large amount of water vapor from both the Bay of Bengal and Arabian Sea and dump them over the Kashmir region through wave breaking, it probably resulted in the historical devastating flooding of the whole Kashmir valley in the first week of September 2014. This was accompanied by extreme rainfall events measuring more than 620 mm in some parts of the Pir Panjal range in the south Kashmir.
Advancing phenology is one of the most visible effects of climate change on plant communities, and has been especially pronounced in temperature-limited tundra ecosystems. However, phenological responses have been shown to differ greatly between species, with some species shifting phenology more than others. We analysed a database of 42,689 tundra plant phenological observations to show that warmer temperatures are leading to a contraction of community-level flowering seasons in tundra ecosystems due to a greater advancement in the flowering times of late-flowering species than early-flowering species. Shorter flowering seasons with a changing climate have the potential to alter trophic interactions in tundra ecosystems. Interestingly, these findings differ from those of warmer ecosystems, where early-flowering species have been found to be more sensitive to temperature change, suggesting that community-level phenological responses to warming can vary greatly between biomes.
Premise of the Study
Climate‐driven changes in phenology are substantially affecting ecological relationships and ecosystem processes. The role of variation among species has received particular attention; for example, variation among species’ phenological responses to climate can disrupt trophic interactions and can influence plant performance. Variation within species in phenological responses to climate, however, has received much less attention, despite its potential role in ecological interactions and local adaptation to climate change.
Methods
We constructed three common gardens across an elevation gradient on Cadillac Mountain in Acadia National Park, Maine, to test population‐level responses in leaf‐out phenology in a reciprocal transplant experiment. The experiment included three native species: low bush blueberry (Vaccinium angustifolium), sheep's laurel (Kalmia angustifolia), and three‐toothed cinquefoil (Sibbaldiopsis tridentata).
Key Results
Evidence for local adaptation of phenological response to temperature varied among the species, but was weak for all three. Rather, variation in phenological response to temperature appeared to be driven by local microclimate at each garden site and year‐to‐year variation in temperature.
Conclusions
Population‐level adaptations in leaf‐out phenology appear to be relatively unimportant for these species in Acadia National Park, perhaps a reflection of strong genetic mixing across elevations, or weak differences in selection on phenological response to spring temperatures at different elevations. These results concur with other observational data in Acadia and highlight the utility of experimental approaches to understand the importance of annual and local site variation in affecting phenology both among and within plant species.
Premise of the Study
Much research has focused on plant responses to ongoing climate change, but there is relatively little information about how climate change will affect the early plant life history stages. Understanding how global warming and changes in winter snow pattern will affect seed germination and seedling establishment is crucial for predicting future alpine population and vegetation dynamics.
Methods
In a 2‐year study, we tested how warming and alteration in the snowmelt regime, both in isolation and combination, influence seedling emergence phenology, first‐year growth, biomass allocation, and survival of four native alpine perennial herbs on the southeastern Tibetan Plateau.
Key Results
Warming promoted seedling emergence phenology of all four species and biomass per plant of two species but reduced seedling survival of three species. Prolonged snow cover partly mediated the affects of warming on Primula alpicola (survival and biomass), Pedicularis fletcheri (phenology, biomass, and root:shoot ratio) and Meconopsis integrifolia (survival). For the narrowly distributed species M. racemosa, seedling growth was additively decreased by warming and prolonged snow cover.
Conclusions
Both warming and alteration of the snow cover regime can influence plant recruitment by affecting seedling phenology, growth, and survival, and the effects are largely species‐specific. Thus, climate change is likely to affect population dynamics and community structure of the alpine ecosystem. This is the first experimental demonstration of the phenological advancement of seedling emergence in the field by simulated climate warming.
In the Pacific Northwest of the USA, winter and spring temperature vary with the Pacific Decadal Oscillation, making effects of anthropogenic warming difficult to detect. We sought to detect community-level signals of anthropogenic change in a legacy plant phenology dataset. We analyzed both incomplete data from 1959 to 2016 on spring phenology of 115 species and more complete 1996–2016 data on spring and fall events for 607 plant species. We used ordination of the long-term dataset to identify two major axes of community-level change in phenology among years, with the first being a trend toward earlier spring phenology in more recent years. In contrast, for the short-term dataset, variation in spring phenology was mostly PDO-driven and did not reveal a strong trend over time. At both time scales, a second axis of phenological variation reflected summer and fall events, especially earlier appearance of fall color in recent years. In univariate analysis, more than 80% of individual species’ leaf out dates and first flower dates occurred earlier over time, for an average advance across all species of 2.5 days per decade from 1959 to 2016. While most events did not advance in the period 1996–2016, fall color advanced by 10.6 days per decade, suggesting that intensification of summer drought has continued regardless of the PDO cycle. While estimates of slope over time depended strongly on the time window chosen for the analysis, estimates of slope versus temperature were consistently negative regardless of time window, averaging 5–7 days per 1 °C for spring events.
Significance
Shifts in the timing of species interactions are often cited as a consequence of climate change and, if present, are expected to have wide-reaching implications for ecological communities. Our knowledge about these shifts mostly comes from single systems, which have provided no clear picture, thus limiting our understanding of how species interactions may be responding overall. Using a new global database based on long-term data on the seasonal timing of biological events for pairwise species interactions, we find that the relative timing of interacting species has changed substantially in recent decades. The observed shifts are greater in magnitude than before recent climate change began, suggesting that there will be widespread warming-related shifts in the synchrony of species in the future.
Spatial community reassembly driven by changes in species abundances or habitat occupancy is a well-documented response to anthropogenic global change, but communities can also reassemble temporally if the environment drives differential shifts in the timing of life events across community members. Much like spatial community reassembly, temporal reassembly could be particularly important when critical species interactions are temporally concentrated (e.g., plant-pollinator dynamics during flowering). Previous studies have documented species-specific shifts in phenology driven by climate change, implying that temporal reassembly, a process we term “phenological reassembly,” is likely. However, few studies have documented changes in the temporal co-occurrence of community members driven by environmental change, likely because few datasets of entire communities exist. We addressed this gap by quantifying the relationship between flowering phenology and climate for 48 co-occurring subalpine wildflower species at Mount Rainier (Washington, USA) in a large network of plots distributed across Mt. Rainier's steep environmental gradients; large spatio-temporal variability in climate over the 6 yr of our study (including the earliest and latest snowmelt year on record) provided robust estimates of climate-phenology relationships for individual species. We used these relationships to examine changes to community co-flowering composition driven by ‘climate change analog’ conditions experienced at our sites in 2015. We found that both the timing and duration of flowering of focal species was strongly sensitive to multiple climatic factors (snowmelt, temperature, and soil moisture). Some consistent responses emerged, including earlier snowmelt and warmer growing seasons driving flowering phenology earlier for all focal species. However, variation among species in their phenological sensitivities to these climate drivers was large enough that phenological reassembly occurred in the climate change analog conditions of 2015. An unexpected driver of phenological reassembly was fine-scale variation in the direction and magnitude of climatic change, causing phenological reassembly to be most apparent early and late in the season and in topographic locations where snow duration was shortest (i.e., at low elevations and on ridges in the landscape). Because phenological reassembly may have implications for many types of ecological interactions, failing to monitor community-level repercussions of species-specific phenological shifts could underestimate climate change impacts.
1. The warming of terrestrial high-latitude ecosystems, while increasing, will likely be asymmetric across seasons – where winter non-growing seasons will warm more than summer growing seasons. Asymmetric winter warming in temperature-sensitive ecosystems may delay spring phenological events by reducing the opportunity that a plants’ chilling requirement is met. Similarly, symmetric warming can advance spring phenology.
2. To explore the impact of asymmetric warming on plant phenology, we applied a year-round warming and a winter warming treatment to our experimental plots. Over a two-year period, we monitored leaf-out and flowering phenology for 11 plant species.
3. There was variation among species, however, both winter and year-round warming, advanced the leaf-out day and the first flowering day relative to the control treatment. Winter warming advanced leaf-out and flowering phenology by 11.1 (± 2.4) and 12.6 (± 2.9) days, respectively. However, year-round warming had less of an impact advancing leaf-out and flowering phenology by 5.1 (± 2.1) and 10.0 (± 3.0) days, respectively.
4. Our study provides direct evidence that asymmetric winter warming has a larger impact on plant phenology than symmetric year-round warming. Increasing soil temperature in the winter from below to above freezing temperatures advanced the spring phenology of alpine plants. Winter warming increased soil temperature more than year-round warming, which explains why phenology advanced under winter warming more than under year-round warming. In addition, early or mid-season flowering plant species displayed different phenology strategies in warmer winters.
5. Synthesis: Relative to other ecosystems, alpine ecosystems such as the Tibetan Plateau will likely respond to asymmetric warming given the higher amplitude of winter temperature increases due to climatic warming thus seasonal variation in warming should be considered when predicting and modelling the response of alpine ecosystems to climatic change.
The timing of the seasonal activity of organisms is a tractable indicator of climate change. Many studies in North America have investigated the role of temperature on the onset date of phenological transitions in temperate deciduous trees and found that the onset of leafing and flowering in numerous species has occurred earlier in recent years, apparently in response to higher temperatures in winter and spring.
Few studies have examined the climatic and biogeographic drivers of phenological responses in water‐limited ecosystems or explored interspecific variation in responses of phenological metrics other than the timing of onset, such as the periodicity or duration of phenological activity.
This study used phenological observations of four species of Quercus contributed to the USA National Phenology Network database from 2009 to 2014 to investigate how responses to climate (temperature and precipitation) and geographic location (latitude, longitude and elevation) varied among two western North American species ( Q. agrifolia and Q. lobata ) and two eastern and central North American species ( Q. alba and Q. rubra ).
Within years, in species in the western, water‐limited ecosystems, the phenological phases observed here (bud break, flowers or flower buds) tend to occur intermittently throughout the growing season, and each event is of longer duration than the same phenophases of the temperate‐zone species, rendering a single onset date an incomplete metric with which to track responsiveness or to compare species. By contrast, the eastern/central U.S. species were phenologically more responsive than the western species to spatial and temporal variation in winter, spring, and fall precipitation and maximum temperature.
Synthesis . Within and between regions these congeners exhibited a diversity of responses to seasonal temperature and precipitation. This indicates that for predictive model development it is critical to understand how each underlying driver influences species that are adapted to different climatic regimes. These results underscore the value of studying a range of phenological metrics and species from a variety of ecosystems to better predict phenological responses to short‐term variation and to long‐term change in climate.
The capacity of grass species to alter their reproductive timing across space and through time can indicate their ability to cope with environmental variability and help predict their future performance under climate change.
We determined the long‐term (1895–2013) relationship between flowering times of grass species and climate in space and time using herbarium records across ecoregions of the western USA .
There was widespread concordance of C 3 grasses accelerating flowering time and general delays for C 4 grasses with increasing mean annual temperature, with the largest changes for annuals and individuals occurring in more northerly, wetter ecoregions. Flowering time was delayed for most grass species with increasing mean annual precipitation across space, while phenology–precipitation relationships through time were more mixed.
Our results suggest that the phenology of most grass species has the capacity to respond to increases in temperature and altered precipitation expected with climate change, but weak relationships for some species in time suggest that climate tracking via migration or adaptation may be required. Divergence in phenological responses among grass functional types, species, and ecoregions suggests that climate change will have unequal effects across the western USA .
Phenology is an integrative science that comprises the study of recurring biological activities or events. In an era of rapidly changing climate, the relationship between the timing of those events and environmental cues such as temperature, snowmelt, water availability, or day length are of particular interest. This article provides an overview of the observer-based plant phenology sampling conducted by the U.S. National Ecological Observatory Network (NEON), the resulting data, and the rationale behind the design. Trained technicians will conduct regular in situ observations of plant phenology at all terrestrial NEON sites for the 30-yr life of the observatory. Standardized and coordinated data across the network of sites can be used to quantify the direction and magnitude of the relationships between phenology and environmental forcings, as well as the degree to which these relationships vary among sites, among species, among phenophases, and through time. Vegetation at NEON sites will also be monitored with tower-based cameras, satellite remote sensing, and annual high-resolution airborne remote sensing. Ground-based measurements can be used to calibrate and improve satellite-derived phenometrics. NEON's phenology monitoring design is complementary to existing phenology research efforts and citizen science initiatives throughout the world and will produce interoperable data. By collocating plant phenology observations with a suite of additional meteorological, biophysical, and ecological measurements (e.g., climate, carbon flux, plant productivity, population dynamics of consumers) at 47 terrestrial sites, the NEON design will enable continental-scale inference about the status, trends, causes, and ecological consequences of phenological change.
Although precipitation interannual variability is projected to increase due to climate change, effects of changes in precipitation variance have received considerable less attention than effects of changes in the mean state of climate. Interannual precipitation variability effects on functional diversity and its consequences for ecosystem functioning are assessed here using a 6-year rainfall manipulation experiment. Five precipitation treatments were switched annually resulting in increased levels of precipitation variability while maintaining average precipitation constant. Functional diversity showed a positive response to increased variability due to increased evenness. Dominant grasses decreased and rare plant functional types increased in abundance because grasses showed a hump-shaped response to precipitation with a maximum around modal precipitation, whereas rare species peaked at high precipitation values. Increased functional diversity ameliorated negative effects of precipitation variability on primary production. Rare species buffered the effect of precipitation variability on the variability in total productivity because their variance decreases with increasing precipitation variance.
High temperature affects numerous biochemical and physiological traits in plants. Primary leaves of sunflower (Helianthus annuus L.) were collected from plants grown under a control temperature (day/night regime of 23/19 degrees C) or a high temperature (day/night regime of 33/29 degrees C) for 16, 22, 28, 32 or 42 d. Leaves of sunflower plants exposed to high temperature exhibited decreased growth, as reflected by lower specific leaf mass and reduced leaf area as compared with controls. A superior decrease in soluble protein content during leaf life span in plants grown at high temperature relative to control plants (70% vs. 45%, respectively) suggests that high temperature promotes soluble protein degradation in leaves. High temperature also reduces net photosynthetic rate (P-N) possibly by decreasing the content in photosynthetic pigments and the stomatal conductance (g(s)). The activity of nitrate reductase and glutamine synthetase decreased while deaminating activity in glutamate dehydrogenase increased in leaves exposed to high temperature. Our results suggest that high temperature induced early senescence in sunflower leaves, probably as a result of an accumulation of soluble sugars and the associated decrease in starch levels. Oxidative damage resulting from increased H2O2 accumulation and a decline in antioxidant activity may have also contributed to accelerated senescence of primary leaves at high temperature.
Lidder tributary in the Upper Indus Basin (UIB) of the Himalayas, an important source of surface and ground water, is experiencing clear indications of climate change. In the basin, minimum, maximum and average temperatures are showing a significant increasing trend in all the four seasons. Precipitation is showing insignificant decrease over time in the basin. However, the proportion of snow is decreasing and correspondingly, the proportion of rains is increasing. The temperature projections also show increasing trends for the end of this century. The time series analysis of the Normalized Difference Snow Index (NDSI) shows a depletion of the snow-cover in the region. Furthermore, during the last 51 years, the glacier area in the basin has decreased from 46.09 km2 in 1962 to 33.43 km2 in 2013, a depletion of 27.47%. As a result of glacier recession in the basin, the streamflow fed predominantly by snow- and glacier-melt, is showing a statistically significant decline since the mid-nineties. The declining streamflows have potential to adversely affect agriculture, energy production, tourism and even domestic water supplies. The Snowmelt Runoff Model (SRM) was tested for estimating the runoff from this glaciated basin on an operational basis. The average simulated runoff 11.94 m3/s at the outlet is in concordance with the average measured runoff 13.51 m3/s showing R2 of 0.82. The model could thus be used for snowmelt runoff estimation, on an operational basis, for judicious utilization of the depleting water resources in the region.
Recent warming significantly advanced leaf onset in the northern hemisphere. This signal cannot be accurately reproduced by current models parameterized by daily mean temperature (T mean). Here using in situ observations of leaf unfolding dates (LUDs) in Europe and the United States, we show that the interannual anomalies of LUD during 1982–2011 are triggered by daytime (T max) more than by nighttime temperature (T min). Furthermore, an increase of 1 °C in T max would advance LUD by 4.7 days in Europe and 4.3 days in the United States, more than the conventional temperature sensitivity estimated from T mean. The triggering role of T max , rather than the T min or T mean variable, is also supported by analysis of the large-scale patterns of satellite-derived vegetation green-up in spring in the northern hemisphere (430°N). Our results suggest a new conceptual framework of leaf onset using daytime temperature to improve the performance of phenology modules in current Earth system models.
Significance
Natural events in temperate ecosystems are triggered by seasonal temperature changes. Climate change may shift the timing of these events. We use a century of herbarium collections of Himalayan rhododendrons to investigate climate-driven change in flowering time. Although increased annual temperatures are associated with earlier flowering, increased fall temperatures are associated with delayed flowering. Annual warming may advance flowering through positive effects on overwintering bud formation, whereas fall warming may delay flowering through an impact on chilling requirements. These contrasting effects have resulted in opposing changes in flowering time, even as temperatures have warmed rapidly in the past 45 y. This study demonstrates the value of natural history collections to inform ecological questions, especially regarding climate change.
Premise:
Forecasting how species will respond phenologically to future changes in climate is a major challenge. Many studies have focused on estimating species- and community-wide phenological sensitivities to climate to make such predictions, but sensitivities may vary within species, which could result in divergent phenological responses to climate change.
Methods:
We used 743 herbarium specimens of the mountain jewelflower (Streptanthus tortuosus, Brassicaceae) collected over 112 years to investigate whether individuals sampled from relatively warm vs. cool regions differ in their sensitivity to climate and whether this difference has resulted in divergent phenological shifts in response to climate warming.
Results:
During the past century, individuals sampled from warm regions exhibited a 20-day advancement in flowering date; individuals in cool regions showed no evidence of a shift. We evaluated two potential drivers of these divergent responses: differences between regions in (1) the degree of phenological sensitivity to climate and (2) the magnitude of climate change experienced by plants, or (3) both. Plants sampled from warm regions were more sensitive to temperature-related variables and were subjected to a greater degree of climate warming than those from cool regions; thus our results suggest that the greater temporal shift in flowering date in warm regions is driven by both of these factors.
Conclusions:
Our results are among the first to demonstrate that species exhibited intraspecific variation in sensitivity to climate and that this variation can contribute to divergent responses to climate change. Future studies attempting to forecast temporal shifts in phenology should consider intraspecific variation.
When a phenological shift affects a demographic vital rate such as survival or reproduction, the altered vital rate may or may not have population-level consequences. We review the evidence that climate change affects populations by shifting species’ phenologies, emphasizing the importance of demographic life-history theory. We find many examples of phenological shifts having both positive and negative consequences for vital rates. Yet, few studies link phenological shifts to changes in vital rates known to drive population dynamics, especially in plants. When this link is made, results are largely consistent with life-history theory: Phenological shifts have population-level consequences when they affect survival in longer-lived organisms and reproduction in shorter-lived organisms. However, there are just as many cases in which demographic mechanisms buffer population growth from phenologically induced changes in vital rates. We provide recommendations for future research aiming to understand the complex relationships among climate, phenology, and demography, which will help to elucidate the extent to which phenological shifts actually alter population persistence.
Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
In an age of anthropocene, shifting plant phenology is one of the most striking biological indicators of global environmental change. Majority of the studies reporting shifts in plant phenology are available from the North America and Europe and largely scarce from the developing world, including the Himalaya; and studies integrating multiple methodological approaches to investigate the climate-driven phenological shifts are too rare. Here, we report the shifts in spring flowering phenology of model plant species, Sternbergia vernalis in response to the changing climate in Kashmir Himalaya, by integrating decadal field observational records with long-term herbarium and dated-photograph data, and supported with experimental evidences. Our results revealed a significant increasing trend of 0.038, 0.016 and 0.023 °C/year in the annual mean maximum temperature (Tmax), mean minimum temperature (Tmin) and diurnal temperature range (DTR) respectively; but an insignificant decreasing trend in annual precipitation of −1.24 mm/year over the last four decades (1980–2019) in this Himalayan region. The flowering phenology of S. vernalis has significantly advanced by 11.8 days/°C and 27.8 days/°C increase in Tmax and Tmin respectively, indicating that the climate warming has led to substantial shifts in flowering phenology of the model plant species. We also observed a strong association of seasonal Tmax (December–February) and DTR on the early onset of spring flowering, however precipitation had no significant effect on the timing of flowering. The greenhouse experiment results further supported a significant effect of temperature in triggering the phenological shifts, wherein the model plant grown under different temperature treatments flowered 9–20 days earlier compared to the control. Our study showcases the integrated use of multiple methodological approaches for unravelling the long-term phenological shifts in response to climate change, and contributes in filling the knowledge gaps in the phenological research from the developing world in general and the Himalaya in particular.
Although there is abundant evidence that plant phenology is shifting with climatic warming, the magnitude and direction of these shifts can depend on the environmental context, plant species, and even the specific phenophase of study. These disparities have resulted in difficulties predicting future phenological shifts, detecting phenological mismatches, and identifying other ecological consequences. Experimental warming studies are uniquely poised to help us understand how climate warming will impact plant phenology, and meta‐analyses allow us to expose broader trends from individual studies. Here, we review 70 studies comprised of 1,226 observations of plant phenology under experimental warming. We find that plants are advancing their early‐season phenophases (bud break, leaf‐out, and flowering) in response to warming while marginally delaying their late‐season phenophases (leaf coloration, leaf fall, and senescence). We find consistency in the magnitude of phenological shifts across latitude, elevation, and habitat types, while the effect of warming on nonnative annual plants is two‐times larger than the effect of warming on native perennial plants. Encouragingly for researchers, plant phenological responses were generally consistent across a variety of experimental warming methods. However, we found numerous gaps in the experimental warming literature, limiting our ability to predict the effects of warming on phenological shifts. In particular, studies outside of temperate ecosystems in the northern hemisphere, or those that focused on late‐season phenophases, annual plants, nonnative plants, or woody plants and grasses, were underrepresented in our dataset. Future experimental warming studies could further refine our understanding of phenological responses to warming by setting up experiments outside of traditionally studied biogeographic zones, and measuring multiple plant phenophases (especially late‐season phenophases) across species of varying origin, growth form, and life cycle.
The Himalayan region, due to its fragile ecology, is extremely vulnerable to even small perturbations in climate that might not only affect the pristine ecosystems but also the socioeconomic sectors across the mountain arc. In this study, we analyzed the climate variability and trends of change in precipitation and temperature for Kashmir Himalaya between 1980 and 2017. Investigations were carried out for six meteorological stations located within Kashmir valley. The non-parametric Mann–Kendall test was used for significance of trends in precipitation and temperature data on monthly, seasonal, and annual scales, while Sen’s non-parametric estimator of the slope was used to estimate the magnitude of trend. The results obtained indicate that the Kashmir region receives about 72% annual precipitation from Western Disturbances (WD) and 28% from Indian Summer Monsoon (ISM). The influence of ISM was higher towards south Kashmir, while north Kashmir was mostly influenced by western disturbances. The contribution of ISM to total rainfall recorded a 10% increase for the time series. With noticeable inter-station variations, our results indicate statistically significant positive trends for both TMax (p
Background and aims:
Warmer temperatures and altered precipitation patterns are expected to continue to occur as the climate changes. How these changes will impact the flowering phenology of herbaceous perennials in northern forests is poorly understood but could have consequences for forest functioning and species interactions. Here, we examine the flowering phenology responses of five herbaceous perennials to experimental warming and reduced summer rainfall over three years.
Methods:
This study is part of the B4WarmED experiment located at two sites in northern Minnesota, USA. Three levels of warming (ambient, +1.6°C, +3.1°C) were crossed with two rainfall manipulations (ambient and 27% reduced growing season rainfall).
Key results:
We observed species-specific responses to the experimental treatments. Warming alone advanced flowering for four species. Most notably, the two fall blooming species showed the strongest advance of flowering to warming. Reduced rainfall alone advanced flowering for one fall blooming species and delayed flowering for the other, with no significant impact on the three early blooming species. Only one species, Solidago spp, showed an interactive response to warming and rainfall manipulation by advancing in +1.6°C warming (regardless of rainfall manipulation) but not advancing in the warmest, driest treatment. Species-specific responses led to changes in temporal overlap between species. Most notably, the two fall blooming species diverged in their flowering timing significantly. In ambient conditions, these two species flowered within the same week. In the warmest, driest treatment, flowering occurred over a month apart.
Conclusions:
Herbaceous species may differ in how they respond to future climate conditions. Changes to phenology may lead to fewer resources for insects or a mismatch between plants and pollinators.
Arboreal or woody flora, as a surrogate of biota, is immensely useful for rapid assessment and monitoring of biodiversity in a region. The present chapter provides an annotated inventory of the arboreal flora of the state of Jammu and Kashmir in India, including both native and exotic species. At the present stage of investigation, the arboreal flora of the state comprises 768 species, belonging to 362 genera in 106 families. This flora includes 382 species which are exclusively wild-growing, 323 species are cultivated for different purposes, and 63 species are cultivated and grow in the wild as well. Growth form-wise, the trees, shrubs, sub-shrubs, and woody climbers are represented by 291, 364, 39, and 74 species, respectively. The three regions – Jammu, Kashmir, and Ladakh – contribute 561, 384, and 92 species, respectively, to the total arboreal flora of this Himalayan state.
The chapter provides an updated account of angiosperm flora of the state of Jammu & Kashmir (J&K). A total of 5056 taxa, comprising 4778 species plus 278 subspecies/varieties, belonging to 1306 genera in 180 families are recorded from the state. Asteraceae with 613 species and 50 subspecies/varieties in 130 genera is the largest family, followed by Poaceae, Fabaceae, Brassicaceae, Rosaceae, Cyperaceae, Lamiaceae, Ranunculaceae, Caryophyllaceae, Boraginaceae, Apiaceae and Polygonaceae. The larger genera in the angiosperm flora include Taraxacum with 83 species and infra-specific taxa (mostly apomicts), followed by Carex (78 species), Potentilla, Astragalus, Artemisia, Ranunculus, Saussurea, Polygonum, Nepeta, Corydalis, Silene, Poa, Gentiana, Draba, Euphorbia, Berberis, Cyperus, Saxifraga, Allium, Salix, Geranium, Veronica, Persicaria, Androsace and Primula. The consolidated taxonomic checklist of angiosperms presented here reveals that the species plus infra-specific taxa recorded from J&K constitute 27.28% of all the angiosperm species in India, and 58.11% of the angiosperm flora of the Indian Himalayan region. Furthermore, many families and genera in the state contain 50% or more of their total species occurring in India. These results reveal that J&K is a mega-biodiversity state of India, rich in endemics and arboreal, aquatic, medicinal and crop plants. A good proportion of the flora, however, comprises exotic weeds, some of which have become invasive.
Accurate predictions of spring plant phenology with climate change are critical for projections of growing seasons, plant communities and a number of ecosystem services, including carbon storage. Progress towards prediction, however, has been slow because the major cues known to drive phenology – temperature (including winter chilling and spring forcing) and photoperiod – generally covary in nature and may interact, making accurate predictions of plant responses to climate change complex and nonlinear. Alternatively, recent work suggests many species may be dominated by one cue, which would make predictions much simpler.
Here, we manipulated all three cues across 28 woody species from two North American forests.
All species responded to all cues examined. Chilling exerted a strong effect, especially on budburst (−15.8 d), with responses to forcing and photoperiod greatest for leafout (−19.1 and −11.2 d, respectively). Interactions between chilling and forcing suggest that each cue may compensate somewhat for the other. Cues varied across species, leading to staggered leafout within each community and supporting the idea that phenology is a critical aspect of species' temporal niches.
Our results suggest that predicting the spring phenology of communities will be difficult, as all species we studied could have complex, nonlinear responses to future warming.
There is an increasing potential to incorporate recent advances in our understanding of molecular-genetic pathways of flowering-time regulation to forecast shifts in flowering phenology in response to rising temperature. Recent studies developed models that integrate temperature and photoperiod signals into the network of floral regulatory genes, and predicted the shortening of flowering duration under warming based on the expression dynamics of major flowering-time genes in the perennial herb Arabidopsis halleri subsp. gemmifera. Nevertheless, empirical testing of the model prediction is still lacking. We performed temperature manipulation experiments and common garden experiments to test the model predictions using plants from two distant populations of A. halleri. We also quantified expression levels of two major flowering-time genes and compared the observed and predicted gene expression patterns. Our experiments in the laboratory and the field demonstrated that flowering duration of A. halleri was significantly shortened under warming conditions. Our results also revealed that the end of flowering was more sensitive to the climate warming than the onset of flowering in A. halleri. The observed gene expression dynamics in the warming condition were predicted well by the gene regulatory model. The transplant experiment of plants from Hokkaido, the northernmost island, to the subtropical field site in Okinawa, Japan, showed that plants flowered without significant activation of FLOWERING LOCUS T, a floral integrator crucial for the accelerated flowering in long days. The study suggested that the redundancy of flowering gene regulatory network could be beneficial to the persistence of flowering ability under extreme climatic conditions.
Flowering phenology is of great importance for flower tourism planning, landscape arrangement, and pollen allergy forecast. Previous studies mainly focused on the changes in the first flowering date of plants, but rarely examined the spatiotemporal changes in flowering duration. In this study, we systematically analyzed the changes in flowering durations for 23 woody plants at 42 sites from China Phenological Observation Network (CPON) during 1963-2012. Through investigations on the spatiotemporal patterns, interspecific difference, and the forms of change in flowering durations, the following conclusions are drawn. (1) Out of all the 259-time series, flowering durations have lengthened in 159-time series (61.39%), where 21.24% have lengthened significantly. The extending trends for shrub species are found to be more significant than those for tree species. (2) Most flowering durations in the south of Northeast China, East China, and Central China exhibited trends of shortening, but those in the north of Northeast China, North China, parts of Southwest China, and South China exhibited extending trends. The strongest trend (0.94 d/a) occurred at around 20°N. The mean trend of flowering duration (0.28 d/a) in western China (87°E-112°E) was larger than that in eastern China (0.05 d/a). (3) The overall changes in flowering duration could be identified into three stages: 1963-1980 (shorter), 1981-1997 (close to multi-year average) and 2001-2012 (longer), although evident difference existed among species. (4) As for the time series with extending flowering duration, 43.39% were induced by a much earlier first flowering date than the end of flowering date. For the time series with shortening flowering duration, 62% were caused by a more advanced trend at the end of flowering date than at the first flowering date.
The timing of phenological events, such as leaf-out and flowering, strongly influence plant success and their study is vital to understanding how plants will respond to climate change. Phenological research, however, is often limited by the temporal, geographic, or phylogenetic scope of available data. Hundreds of millions of plant specimens in herbaria worldwide offer a potential solution to this problem, especially as digitization efforts drastically improve access to collections. Herbarium specimens represent snapshots of phenological events and have been reliably used to characterize phenological responses to climate. We review the current state of herbarium-based phenological research, identify potential biases and limitations in the collection, digitization, and interpretation of specimen data, and discuss future opportunities for phenological investigations using herbarium specimens.
Intuitively, interannual spring temperature variability (STV) should influence the leaf-out strategies of temperate zone woody species, with high winter chilling requirements in species from regions where spring warming varies greatly among years. We tested this hypothesis using experiments in 215 species and leaf-out monitoring in 1585 species from East Asia (EA), Europe (EU) and North America (NA). The results reveal that species from regions with high STV indeed have higher winter chilling requirements, and, when grown under the same conditions, leaf out later than related species from regions with lower STV. Since 1900, STV has been consistently higher in NA than in EU and EA, and under experimentally short winter conditions NA species required 84% more spring warming for bud break, EU ones 49% and EA ones only 1%. These previously unknown continental-scale differences in phenological strategies underscore the need for considering regional climate histories in global change models.
The relative roles of temperature and day length in driving spring leaf unfolding are known for few species, limiting our ability to predict phenology under climate warming. Using experimental data, we assess the importance of photoperiod as a leaf-out regulator in 173 woody species from throughout the Northern Hemisphere, and we also infer the influence of winter duration, temperature seasonality, and inter-annual temperature variability. We combine results from climate- and light-controlled chambers with species’ native climate niches inferred from georeferenced occurrences and range maps. Of the 173 species, only 35% relied on spring photoperiod as a leaf-out signal. Contrary to previous suggestions, these species come from lower latitudes, whereas species from high latitudes with long winters leafed out independent of photoperiod. The strong effect of species’ geographic–climatic history on phenological strategies complicates the prediction of community-wide phenological change.
A spring phenology model that combines photoperiod with accumulated heating and chilling to predict spring leaf out dates is optimized using PhenoCam observations and coupled into the Community Land Model (CLM) 4.5. In head-to-head comparison (using satellite data from 2003-2013 for validation) for model grid cells over the Northern Hemisphere deciduous broadleaf forests (5.5 million km(2) ), we found that the revised model substantially out-performed the standard CLM seasonal-deciduous spring phenology sub-model at both coarse (0.9×1.25 degree) and fine (1km) scales. The revised model also does a better job of representing recent (decadal) phenological trends observed globally by MODIS, as well as long-term trends (1950-2014) in the PEP725 European phenology dataset. Moreover, forward model runs suggested a stronger advancement (up to 11 days) of spring leaf out by the end of the 21(st) century for the revised model. Trends towards earlier advancement are predicted for deciduous forests across the whole northern hemisphere boreal and temperate deciduous forest region for the revised model, whereas the standard model predicts earlier leaf out in colder regions, but later leaf out in warmer regions, and no trend globally. The earlier spring leaf out predicted by the revised model resulted in enhanced gross primary production (up to 0.6 Pg C yr(-1) ) and evapotranspiration (up to 24 mm yr(-1) ) when results were integrated across the study region. These results suggest that the standard seasonal deciduous submodel in CLM should be reconsidered, otherwise substantial errors in predictions of key land-atmosphere interactions and feedbacks may result. This article is protected by copyright. All rights reserved.
Using Landsat data at decadal interval (1980-2013), the glacier fluctuations (glacier area, equilibrium line altitude and specific mass balance) of nine benchmark glaciers in Kashmir Himalaya was estimated. The observed changes were related with topographic and climatic variables in order to understand their influence. From the data analysis, it was observed that the glaciers have shrunk by 17%, ELA has shifted upwards (80-300 m), and SMB shows variation in glacier mass loss from -0.77 to -0.16 m.w.e. Annual air temperature showed a significant increasing trend and a slight but insignificant decrease in precipitation was observed during the period. It is evident that, in the same climatic regime, varying topography plays a key role in determining the glacier changes. It is believed that the observed changes in the glacier geometry and dynamics, if continued, shall have adverse effect on the streamflows, water supplies and other dependent sectors in the region.
Experimental data on the perception of day length and temperature in dormant temperate zone trees are surprisingly scarce.
In order to investigate when and where these environmental signals are perceived, we carried out bagging experiments in which buds on branches of Fagus sylvatica, Aesculus hippocastanum and Picea abies trees were exposed to natural light increase or kept at constant 8-h days from December until June. Parallel experiments used twigs cut from the same trees, harvesting treated and control twigs seven times and then exposing them to 8- or 16-h days in a glasshouse.
Under 8-h days, budburst in Fagus outdoors was delayed by 41 d and in Aesculus by 4 d; in Picea, day length had no effect. Buds on nearby branches reacted autonomously, and leaf primordia only reacted to light cues in late dormancy after accumulating warm days. Experiments applying different wavelength spectra and high-resolution spectrometry to buds indicate a phytochrome-mediated photoperiod control.
By demonstrating local photoperiodic control of buds, revealing the time when these signals are perceived, and showing the interplay between photoperiod and chilling, this study contributes to improved modelling of the impact of climate warming on photosensitive species.
Climate change is advancing the leaf-out times of many plant species and mostly extending the growing season in temperate ecosystems. Laboratory experiments using twig cuttings from woody plant species present an affordable, easily replicated approach to investigate the relative importance of factors such as winter chilling, photoperiod, spring warming and frost tolerance on the leafing-out times of plant communities. This Viewpoint article demonstrates how the results of these experiments deepen our understanding beyond what is possible via analyses of remote sensing and field observation data, and can be used to improve climate change forecasts of shifts in phenology, ecosystem processes and ecological interactions.
The twig method involves cutting dormant twigs from trees, shrubs and vines on a single date or at intervals over the course of the winter and early spring, placing them in containers of water in controlled environments, and regularly recording leaf-out, flowering or other phenomena. Prior to or following leaf-out or flowering, twigs may be assigned to treatment groups for experiments involving temperature, photoperiod, frost, humidity and more. Recent studies using these methods have shown that winter chilling requirements and spring warming strongly affect leaf-out and flowering times of temperate trees and shrubs, whereas photoperiod requirements are less important than previously thought for most species. Invasive plant species have weaker winter chilling requirements than native species in temperate ecosystems, and species that leaf-out early in the season have greater frost tolerance than later leafing species.
This methodology could be extended to investigate additional drivers of leaf-out phenology, leaf senescence in the autumn, and other phenomena, and could be a useful tool for education and outreach. Additional ecosystems, such as boreal, southern hemisphere and sub-tropical forests, could also be investigated using dormant twigs to determine the drivers of leaf-out times and how these ecosystems will be affected by climate change.
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