| 1. |
- Bolmgren, Kjell, et al.
(author)
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Are mismatches the norm? Timing of flowering, fruiting, dispersal and germination and their fitness effects in Frangula alnus (Rhamnaceae)
- 2015
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In: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 124, s. 639-648
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Journal article (peer-reviewed)abstract
- The close morphological and temporal links between phases of plant growth and reproduction call for integrated studies incorporating several reproductive phases from flowering to recruitment, and associated plant-animal interactions. Phenological strategies, as well as plastic phenological response to climate change, incorporate complex interactions between developmental constraints, pollination and seed dispersal. Relationships between reproductive phenology and components of fitness were studied for two years in the north-temperate, self-incompatible, insect-pollinated, and bird-dispersed shrub Frangula alnus (Rhamnaceae). Fruit set, dispersal, germination and juvenile survival, as well as seed mass and juvenile size were measured in relation to flowering, fruiting and germination time. The results suggest that effects of flowering and fruiting time prevailed in subsequent phases, to some extent as far as to the juvenile phase, but effects of timing were complex and had partly opposing effects on different fitness components. Early flowers had higher fruit-set and experiments indicated that synchronous peak flowering increased fruit-set, but later flowers had higher seed mass. Peak fruiting was not associated with peak dispersal. Late fruits derived from late flowers promoted dispersal. Juvenile recruitment was enhanced by increasing seed size. We conclude that the phenology of flowering and fruiting in F. alnus comprises several features, each with different and sometimes counteracting effects on fitness components. From a general perspective, this result implies that we should not expect to find finely tuned matches in timing specifically between flowering and pollinators, and fruiting and seed dispersing birds.
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| 2. |
- Bolmgren, Kjell
(author)
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Digitization protocol for scoring reproductive phenology from herbarium specimens of seed plants
- 2018
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In: Applications in plant sciences. - : Wiley. - 2168-0450. ; 6
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Journal article (peer-reviewed)abstract
- 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.
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| 3. |
- Bolmgren, Kjell
(author)
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Pan European Phenological database (PEP725): a single point of access for European data
- 2018
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In: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 0020-7128 .- 1432-1254. ; 62, s. 1109-1113
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Journal article (peer-reviewed)abstract
- The Pan European Phenology (PEP) project is a European infrastructure to promote and facilitate phenological research, education, and environmental monitoring. The main objective is to maintain and develop a Pan European Phenological database (PEP725) with an open, unrestricted data access for science and education. PEP725 is the successor of the database developed through the COST action 725 "Establishing a European phenological data platform for climatological applications" working as a single access point for European-wide plant phenological data. So far, 32 European meteorological services and project partners from across Europe have joined and supplied data collected by volunteers from 1868 to the present for the PEP725 database. Most of the partners actively provide data on a regular basis. The database presently holds almost 12 million records, about 46 growing stages and 265 plant species (including cultivars), and can be accessed via . Users of the PEP725 database have studied a diversity of topics ranging from climate change impact, plant physiological question, phenological modeling, and remote sensing of vegetation to ecosystem productivity.
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| 4. |
- Bolmgren, Kjell
(author)
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The Plant Phenology Ontology: A New Informatics Resource for Large-Scale Integration of Plant Phenology Data
- 2018
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In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
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Journal article (peer-reviewed)abstract
- 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 non-standardized 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.
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| 5. |
- Ekholm, Adam, et al.
(author)
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The forgotten season : the impact of autumn phenology on a specialist insect herbivore community on oak
- 2019
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 44:3, s. 425-435
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Journal article (peer-reviewed)abstract
- 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 warmerclimate. 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.
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| 6. |
- Eriksson, Ove, et al.
(author)
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Historic hay cutting dates from Sweden 1873-1951 and their implications for conservation management of species-rich meadows
- 2015
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In: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 184, s. 100-107
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Journal article (peer-reviewed)abstract
- Semi-natural hay meadows are species rich habitats, formed by a long history of management and they have experienced a drastic decline all over Europe. There is a vast literature on conservation and species diversity of semi-natural hay-meadows, but very limited information on historic timing of hay cutting. We analyzed data collected between 1873 and 1951 on hay cutting dates and phenology of six plant species from farms distributed across Sweden. The data set comprised 16,015 observations from 175 sites. Results show that date of start and end of hay cutting varied across Sweden. The start of hay cutting was generally delayed by 2.2 days per latitudinal degree and 1.5 days per 100 m altitude, while the end of hay cutting was generally delayed by 2.9 days per latitudinal degree and 2.5 days per 100 m altitude. The average hay cutting period was 18.5 +/- 6.6 days, and became slightly shorter northwards. Site-specific factors had a great impact on when hay cutting was performed, as indicated by a significant correlation between flowering (and leafing) phenology in other species and start date of hay cutting. Today, management for conservation is usually related to a calendar date (e.g. regulated in eligibility criteria and requirements for payment in agri-environment programs in EU). In order to mimic historic management that formed this habitat, management should instead account for latitude and altitude, between-year variation in timing of hay cutting, variation in both start and end dates of hay cutting and if possible local phenological conditions.
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| 7. |
- Jin, Hongxiao, et al.
(author)
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Disentangling remotely-sensed plant phenology and snow seasonality at northern Europe using MODIS and the plant phenology index
- 2017
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In: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257 .- 1879-0704. ; 198, s. 203-212
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Journal article (peer-reviewed)abstract
- Land surface phenology is frequently derived from remotely sensed data. However, over regions with seasonal snow cover, remotely-sensed land surface phenology may be dominated by snow seasonality, rather than showing true plant phenology. Overlooking snow influences may lead to inaccurate plant phenology estimation, and consequently to misinterpretation of climate-vegetation interactions. To address the problem we apply the recently developed plant phenology index (PPI) to Moderate Resolution Imaging Spectroradiometer (MODIS) data for estimating plant phenology metrics over northern Europe. We compare PPI-derived start and end of the growing season with ground observations by professionals (6 sites) and nonprofessional citizens (378 sites), with phenology metrics derived from gross primary productivity (GPP, 18 sites), and with data on the timing of snow cover. These data are also compared with land surface phenology metrics derived from the normalized difference vegetation index (NDVI) using the same MODIS data. We find that the PPI-retrieved plant phenology agrees with ground observations and GPP-derived phenology, and that the NDVI-derived phenology to a large extent agrees with the end-of-snowmelt for the start-of-season and the start-of-snowing for the end-of-season. PPI is thereby useful for more accurate estimation of plant phenology from remotely sensed data over northern Europe and other regions with seasonal snow cover.
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| 8. |
- Johansson, Jacob, et al.
(author)
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Is timing of reproduction according to temperature sums an optimal strategy?
- 2019
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:20, s. 11598-11605
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Journal article (peer-reviewed)abstract
- 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.
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| 9. |
- Kharouba, Heather M., et al.
(author)
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Global shifts in the phenological synchrony of species interactions over recent decades
- 2018
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:20, s. 5211-5216
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Journal article (peer-reviewed)abstract
- Phenological responses to climate change (e.g., earlier leaf-out or egg hatch date) are now well documented and clearly linked to rising temperatures in recent decades. Such shifts in the phenologies of interacting species may lead to shifts in their synchrony, with cascading community and ecosystem consequences. To date, single-system studies have provided no clear picture, either finding synchrony shifts may be extremely prevalent [Mayor SJ, et al. (2017) Sci Rep 7:1902] or relatively uncommon [Iler AM, et al. (2013) Glob Chang Biol 19:2348-2359], suggesting that shifts toward asynchrony may be infrequent. A meta-analytic approach would provide insights into global trends and how they are linked to climate change. We compared phenological shifts among pairwise species interactions (e.g., predator-prey) using published long-term time-series data of phenological events from aquatic and terrestrial ecosystems across four continents since 1951 to determine whether recent climate change has led to overall shifts in synchrony. We show that the relative timing of key life cycle events of interacting species has changed significantly over the past 35 years. Further, by comparing the period before major climate change (pre-1980s) and after, we show that estimated changes in phenology and synchrony are greater in recent decades. However, there has been no consistent trend in the direction of these changes. Our findings show that there have been shifts in the timing of interacting species in recent decades; the next challenges are to improve our ability to predict the direction of change and understand the full consequences for communities and ecosystems.
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| 10. |
- Kullberg, Cecilia, et al.
(author)
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Change in spring arrival of migratory birds under an era of climate change, Swedish data from the last 140 years
- 2015
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In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. S69-S77
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Journal article (peer-reviewed)abstract
- Many migratory bird species have advanced their spring arrival during the latest decades, most probably due to climate change. However, studies on migratory phenology in the period before recent global warming are scarce. We have analyzed a historical dataset (1873-1917) of spring arrival to southern and central Sweden of 14 migratory bird species. In addition, we have used relative differences between historical and present-day observations (1984-2013) to evaluate the effect of latitude and migratory strategy on day of arrival over time. There was a larger change in spring phenology in short-distance migrants than in long-distance migrants. Interestingly, the results further suggest that climate change has affected the phenology of short-distance migrants more in southern than in central Sweden. The results suggest that the much earlier calculated arrival to southern Sweden among short-distance migrants mirrors a change in location of wintering areas, hence, connecting migration phenology and wintering range shifts.
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