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Premise of the Study:Herbarium specimens provide a robust record of historical plant phenology (the timing of seasonal events such as flowering or fruiting). However, the difficulty of aggregating phenological data from specimens arises from a lack of standardized scoring methods and definitions for phenological states across the collections community. Methods and Results:To address this problem, we report on a consensus reached by an iDigBio working group of curators, researchers, and data standards experts regarding an efficient scoring protocol and a data-sharing protocol for reproductive traits available from herbarium specimens of seed plants. The phenological data sets generated can be shared via Darwin Core Archives using the Extended MeasurementOrFact extension. Conclusions:Our hope is that curators and others interested in collecting phenological trait data from specimens will use the recommendations presented here in current and future scoring efforts. New tools for scoring specimens are reviewed.

Phenological events - defined points in the life cycle of a plant or animal - have been regarded as highly plastic traits, reflecting flexible responses to various environmental cues. The ability of a species to track, via shifts in phenological events, the abiotic environment through time might dictate its vulnerability to future climate change. Understanding the predictors and drivers of phenological change is therefore critical. Here, we evaluated evidence for phylogenetic conservatism - the tendency for closely related species to share similar ecological and biological attributes - in phenological traits across flowering plants. We aggregated published and unpublished data on timing of first flower and first leaf, encompassing ̃4000 species at 23 sites across the Northern Hemisphere. We reconstructed the phylogeny for the set of included species, first, using the software program Phylomatic, and second, from DNA data. We then quantified phylogenetic conservatism in plant phenology within and across sites. We show that more closely related species tend to flower and leaf at similar times. By contrasting mean flowering times within and across sites, however, we illustrate that it is not the time of year that is conserved, but rather the phenological responses to a common set of abiotic cues. Our findings suggest that species cannot be treated as statistically independent when modelling phenological responses. Synthesis. Closely related species tend to resemble each other in the timing of their life-history events, a likely product of evolutionarily conserved responses to environmental cues. The search for the underlying drivers of phenology must therefore account for species' shared evolutionary histories. Closely related species tend to resemble each other in the timing of their life-history events, a likely product of evolutionarily conserved responses to environmental cues. The search for the underlying drivers of phenology must therefore account for species' shared evolutionary histories. © 2013 British Ecological Society.

Phenological studies are rarely reported from arctic and subarctic regions, but are essential to evaluate species' response to climate change in these rapidly warming ecosystems. Here, we present a phylogenetic analysis of flowering phenology across an elevational gradient in the Canadian subarctic. We found that the timing of first flower was best explained by a combination of snowmelt, elevation, and growing degree-days. We also show that early flowering species have demonstrated lower intraspecific variability in their response to climate cues in comparison with late flowering species, such that individual flowering times of early species are more closely tied to environmental predictors. Previous work has suggested that early flowering species are more variable in their phenology. However, these studies have mostly examined variation in phenology over time, whereas we examined variation in phenology over space. We suggest that both patterns can be explained by the tighter coupling between phenology and climate cues for early flowering species. Thus, early flowering species have low intraspecific variance in flowering times within a single growing season as individuals respond more uniformly to a common set of cues in comparison with late flowering species. However, these same species may show large variance between years reflecting interannual variation in climate. Key words: first flowering day, variability, snowmelt, temperature sum, phylogenetics. Des etudes phenologiques a partir de regions arctiques et subarctiques sont rarement rapportees, mais elles sont essentielles pour evaluer la reponse des especes aux changements climatiques dans ces ecosystemes qui se rechauffent rapidement. Les auteurs presentent ici une analyse de la phenologie florale a travers un gradient d'altitude dans le subarctique canadien. Ils ont trouve que la combinaison de la fonte des neiges, de l'altitude et des degres-jour de croissance expliquait le mieux le moment de la premiere floraison. Ils ont aussi montre que les especes a floraison hative ont presente une variabilite intra-specifique plus faible sur le plan de leur reponse aux signaux climatiques comparativement aux especes a floraison tardive, de telle sorte que les moments de floraison individuels des especes hatives sont plus etroitement lies aux predicteurs environnementaux. Des travaux precedents ont suggere que les especes a floraison hative sont davantage variables sur le plan de la phenologie. Cependant, ces etudes ont principalement examine la variation de la phenologie en fonction du temps, alors que les auteurs ont examine la variation de la phenologie en fonction de l'espace. Ils suggerent que les deux patrons peuvent etre expliques par une detection sensible aux signaux climatiques pour le declenchement de la phenologie chez les especes a floraison hative. Alors, les especes a floraison hative ont une variance intra-specifique faible sur le plan du moment de la floraison lors d'une seule saison de croissance car les individus repondent de maniere plus uniforme a un ensemble commun de signaux comparativement aux especes a floraison tardive. Cependant, ces memes especes peuvent montrer une variance importante en fonction des annees, refletant la variation interannuelle du climat. [Traduit par la Redaction] Mots-cles: premier jour de floraison, variabilite, fonte des neiges, somme des temperatures, phylogenetique., Plants have responded to the harsh arctic and alpine environment with a high degree of specialization in structure and function (Korner 2003). In the short growing season in these ecosystems, [...]

Arctic plants are adapted to climatic variability, but their long‐term responses to warming remain unclear. Responses may occur by range shifts, phenological adjustments in growth and reproduction, or both. Here, we compare distribution and phenology of 83 arctic and boreal mountain species, sampled identically in the early 20th (1917–1919) and 21st centuries (2017–2018) from a region of northern Sweden that has warmed significantly. We test two compensatory hypotheses to high‐latitude warming—upward shifts in distribution, and earlier or extended growth and reproduction. For distribution, we show dramatic upward migration by 69% of species, averaging 6.1 m per decade, especially boreal woodland taxa whose upward expansion has reduced arctic montane habitat by 30%. Twenty percent of summit species showed distributional shifts but downward, especially moisture‐associated snowbed flora. For phenology, we detected wide inter‐annual variability in the onset of leafing and flowering in both eras. However, there was no detectable change in growing‐season length, relating to two mechanisms. First, plot‐level snow melt data starting in 1917 demonstrated that melt date, rather than vernal temperatures, better predicts plant emergence, with snow melt influenced by warmer years having greater snowfall—warmer springs did not always result in earlier emergence because snowbeds can persist longer. Second, the onset of reproductive senescence between eras was similar, even when plant emergence was earlier by a month, possibly due to intensified summer heat stress or hard‐wired 'canalization' where senescence occurs regardless of summer temperature. Migrations in this system have possibly buffered arctic species against displacement by boreal expansion and warming, but ongoing temperature increases, woody plant invasion, and a potential lack of flexibility in timing of senescence may foreshadow challenges. [ABSTRACT FROM AUTHOR]

Temperature sums are widely used to predict the seasonal timing of yearly recurring biological events, such as flowering, budburst, and hatching. We use a classic energy allocation model for annual plants to compare a strategy for reproductive timing that follows a temperature sum rule (TSR) with a strategy that follows an optimal control rule (OCR) maximizing reproductive output. We show that the OCR corresponds to a certain TSR regardless of how temperature is distributed over the growing season as long as the total temperature sum over the whole growing season is constant between years. We discuss such scenarios, thus outlining under which type of variable growth conditions TSR maximizes reproductive output and should be favored by natural selection. By providing an ultimate explanation for a well‐documented empirical pattern this finding enhances the credibility of temperature sums as predictors of the timing of biological events. However, TSR and OCR respond in opposite directions when the total yearly temperature sum changes between years, representing, for example, variation in the length of the growing season. Our findings have implications for predicting optimal responses of organisms to climatic changes and suggest under which conditions natural selection should favor photoperiod versus temperature control. [ABSTRACT FROM AUTHOR]

1. Variation in spring phenology – like tree budburst – affects the structure of insect communities, but impacts of autumn phenology have been neglected. Many plant species have recently delayed their autumn phenology, and the timing of leaf senescence may be important for herbivorous insects. 2. This study explored how an insect herbivore community associated with Quercus robur is influenced by variation in autumn phenology. For this, schools were asked to record, across the range of oak in Sweden, the autumn phenology of oaks and to conduct a survey of the insect community. 3. To tease apart the relative impacts of climate from that of tree phenology, regional tree phenology was first modelled as a function of regional climate, and the tree‐specific deviation from this relationship was then used as the metric of relative tree‐specific phenology. 4. At the regional scale, a warmer climate postponed oak leaf senescence. This was also reflected in the insect herbivore community: six out of 15 taxa occurred at a higher incidence and five out of 18 taxa were more abundant, in locations with a warmer climate. Similarly, taxonomic richness and herbivory were higher in warmer locations. 5. Trees with a relatively late autumn phenology had higher abundances of leaf miners (Phyllonorycter spp.). This caused lower community diversity and evenness on trees with later autumn phenology. 6. The findings of the present study illustrate that both regional climate‐driven patterns and local variation in oak autumn phenology contribute to shaping the insect herbivore community. Community patterns may thus shift with a changing climate. [ABSTRACT FROM AUTHOR]

Plant phenology - the timing of plant life-cycle events, such as flowering or leafing out - plays a fundamental role in the functioning of terrestrial ecosystems, including human agricultural systems. Because plant phenology is often linked with climatic variables, there is widespread interest in developing a deeper understanding of global plant phenology patterns and trends. Although phenology data from around the world are currently available, truly global analyses of plant phenology have so far been difficult because the organizations producing large-scale phenology data are using nonstandardized terminologies and metrics during data collection and data processing. To address this problem, we have developed the Plant Phenology Ontology (PPO). The PPO provides the standardized vocabulary and semantic framework that is needed for large-scale integration of heterogeneous plant phenology data. Here, we describe the PPO, and we also report preliminary results of using the PPO and a new data processing pipeline to build a large dataset of phenology information from North America and Europe. [ABSTRACT FROM AUTHOR]

Phenological changes among plants due to climate change are well documented, but often hard to interpret. In order to assess the adaptive value of observed changes, we study how annual plants with and without growth constraints should optimize their flowering time when productivity and season length changes. We consider growth constraints that depend on the plant's vegetative mass: self-shading, costs for nonphotosynthetic structural tissue and sibling competition., We derive the optimal flowering time from a dynamic energy allocation model using optimal control theory. We prove that an immediate switch (bang-bang control) from vegetative to reproductive growth is optimal with constrained growth and constant mortality., Increasing mean productivity, while keeping season length constant and growth unconstrained, delayed the optimal flowering time. When growth was constrained and productivity was relatively high, the optimal flowering time advanced instead. When the growth season was extended equally at both ends, the optimal flowering time was advanced under constrained growth and delayed under unconstrained growth., Our results suggests that growth constraints are key factors to consider when interpreting phenological flowering responses. It can help to explain phenological patterns along productivity gradients, and links empirical observations made on calendar scales with life-history theory. [ABSTRACT FROM AUTHOR]

Premise of the Study Herbarium specimens provide a robust record of historical plant phenology (the timing of seasonal events such as flowering or fruiting). However, the difficulty of aggregating phenological data from specimens arises from a lack of standardized scoring methods and definitions for phenological states across the collections community. Methods and Results: To address this problem, we report on a consensus reached by an iDigBio working group of curators, researchers, and data standards experts regarding an efficient scoring protocol and a data‐sharing protocol for reproductive traits available from herbarium specimens of seed plants. The phenological data sets generated can be shared via Darwin Core Archives using the Extended MeasurementOrFact extension. Conclusions: Our hope is that curators and others interested in collecting phenological trait data from specimens will use the recommendations presented here in current and future scoring efforts. New tools for scoring specimens are reviewed.

Long-term phenology monitoring has documented numerous examples of changing flowering dates during the last century. A pivotal question is whether these phenological responses are adaptive or not under directionally changing climatic conditions. We use a classic dynamic growth model for annual plants, based on optimal control theory, to find the fitness-maximizing flowering time, defined as the switching time from vegetative to reproductive growth. In a typical scenario of global warming, with advanced growing season and increased productivity, optimal flowering time advances less than the start of the growing season. Interestingly, increased temporal spread in production over the season may either advance or delay the optimal flowering time depending on overall productivity or season length. We identify situations where large phenological changes are necessary for flowering time to remain optimal. Such changes also indicate changed selection pressures. In other situations, the model predicts advanced phenology on a calendar scale, but no selection for early flowering in relation to the start of the season. We also show that the optimum is more sensitive to increased productivity when productivity is low than when productivity is high. All our results are derived using a general, graphical method to calculate the optimal flowering time applicable for a large range of shapes of the seasonal production curve. The model can thus explain apparent maladaptation in phenological responses in a multitude of scenarios of climate change. We conclude that taking energy allocation trade-offs and appropriate time scales into account is critical when interpreting phenological patterns. [ABSTRACT FROM AUTHOR]

Forecasting how species and ecosystems will respond to climate change has been a major aim of ecology in recent years. Much of this research has focused on phenology - the timing of life-history events. Phenology has well-demonstrated links to climate, from genetic to landscape scales; yet our ability to explain and predict variation in phenology across species, habitats and time remains poor. Here, we outline how merging approaches from ecology, climate science and evolutionary biology can advance research on phenological responses to climate variability. Using insight into seasonal and interannual climate variability combined with niche theory and community phylogenetics, we develop a predictive approach for species' reponses to changing climate. Our approach predicts that species occupying higher latitudes or the early growing season should be most sensitive to climate and have the most phylogenetically conserved phenologies. We further predict that temperate species will respond to climate change by shifting in time, while tropical species will respond by shifting space, or by evolving. Although we focus here on plant phenology, our approach is broadly applicable to ecological research of plant responses to climate variability. [ABSTRACT FROM AUTHOR]

This study tested the monophyly of the previously proposed genera Alaternus, Frangula, Oreoherzogia, and Rhamnus s.str., and the phylogenetic relations suggested by Grubov (1949), within the Rhamnus s.1. clade. Based on a global sample of 22 species, we derived phylogenetic hypotheses using parsimony analysis of variation in trnL-F (chloroplast) and ITS (nuclear) DNA regions. Both Alaternus, Frangula, and Oreoherzogia gained strong support, and our results further support recognition of Frangula as a monophyletic genus. The resolution between Alaternus, Oreoherzogia, and the rest of Rhamnus s.str, was less clear, and the mainly Mediterranean Oreoherzogia was strongly grouped with the American R. crocea. Therefore, we consider it as unjustified to split the rest of Rhamnus into smaller genera. Regarding Grubov's phylogenetic hypothesis, our study could only support the dichotomy between Frangula and the rest of Rhamnus. [ABSTRACT FROM AUTHOR]

The study of plant phenology is concerned with the timing of plant life-cycle events, such as leafing out, flowering, and fruiting. Today, thanks to data digitization and aggregation initiatives, phenology monitoring networks, and the efforts of citizen scientists, more phenologically relevant plant data is available than ever before. Until recently, combining these data in large-scale analyses was prohibitively difficult because no standardized plant phenology terms and concepts were available to facilitate data interoperability. We have recently completed the first public release of The Plant Phenology Ontology (PPO), the result of a collaborative effort to develop the terminology, definitions, and term relationships that are needed for large-scale data integration and machine reasoning. We are currently using the PPO to join disparate plant phenology datasets into a single data resource. In this talk, I will give an introduction to the PPO, including the design of the ontology and examples with real phenological data, and I will present preliminary results of our initial experiments with integrating plant phenology data. [ABSTRACT FROM AUTHOR]