Phenological Studies Research Articles

Phenological response of plants of different biomorphs to climate change in Western Siberia

The results of a phenology study of 78 species of perennial plants from biomorphological groups of chamaephytes, hemicryptophytes and geophytes over a 20-year period (1996—2015) are discussed. Against the background of air temperature and precipitation changes of the warm season in Novosibirsk, the timing shift in phenological events have been analyzed using calculated linear trends. It is found that the trends for species groups are multidirectional and vary significantly in magnitude. At the same time, most of the shifts in phenology are due not to trends, but to the interannual variability of climatic indicators.

Assessing the phenological state of evergreen conifers using hyperspectral imaging time series

Phenology is a reliable indicator of vegetation condition and ecological changes in the environment. Plant Spectral Phenology (PSP) offers the potential for the development of automated, rapid, and wide-area vegetation monitoring systems. The spectral characteristics of plants (vegetation) are employed as metrics of PSP, which can be sensed both proximally and remotely. A key objective is to undertake a comparative analysis of the results of PSP versus those of phenology based on visual observations. The resolution of this issue is of paramount importance for the coordination of phenological studies at diverse levels (ground, surface, and remote), thus ensuring the continuity of phenological studies conducted prior to the advent of PSP. This issue is particularly pronounced in the case of evergreen conifers. The present study focuses on four evergreen conifers: Thuja occidentalis, Platycladus orientalis, Pinus sylvestris and P. nigra subsp. pallasiana. Hyperspectral imaging was performed under laboratory conditions using a Cubert UHD-185 hyperspectral camera. Concomitantly, phenological observations were conducted. The spectral time series yielded 79 chlorophyll-sensitive and carotenoid-sensitive Vegetation Indices (VIs), which were then used to construct double logistic functions. A significant proportion of the VIs exhibited a high degree of correctness with regard to the aforementioned functions, as indicated by the value of R2 exceeding 0.7. The values of the principal stages of seasonal development of evergreen conifers, namely the Start of Season (SOS), End of Season (EOS), Position of Peak value (POP) and Length of Season (LOS), were calculated using double logistic functions. These stages were matched to the phenological phases of development of the experimental plants. The values of SOS, EOS, POP and LOS varied significantly depending on the VIs used as a metric as well as the evergreen conifers. The lowest variability by metrics is observed in SOS, while the maximum is observed in EOS and POP. The results obtained may be of importance for the choice of criterion for the comparison of PSP with phenology based on visual observations and the most suitable VIs for these purposes.

Phenology, voltinism, and brood development of Xylosandrus (Coleoptera: Curculionidae) ambrosia beetles in New York.

The ambrosia beetles Xylosandrus germanus (Blanford) and Xylosandrus crassiusculus (Motschulsky) are nonnative pests in orchards and nurseries in North America. They construct galleries in the sapwood of stressed woody hosts and culture a symbiotic fungus as food for their offspring. Preventing attacks is preferred but a better understanding of their biology may elucidate additional avenues for control. Recent phenological studies are lacking for X. germanus that is common in New York, and biological information on brood and gallery development is lacking for the less abundant X. crassiusculus. We conducted both outdoor rearing and laboratory studies to better understand the timing of key events in the maturation of their galleries, particularly associated with the symbiotic fungi. Two and a partial third summer generation were consistently observed over 2 yr for X. germanus; and thus, 3 flights of adult females (foundresses) occurred each summer from mid-April to late September. In both the field and laboratory, initial growth of the symbiotic fungus occurs within a few days of gallery initiation. The rapid development of the reproductive tract and oviposition by X. germanus appears to be stimulated by the presence of the fungus. Fungal, reproductive, and brood development are similar for the related X. crassiusculus in laboratory studies; the 2 species mainly appear to differ in size. The lag between beetle colonization and reproduction currently seems too brief to be exploited for management. Disruption of other stages in gallery development should also be explored to minimize the beetle damage if attacks cannot be prevented.

Temperature sum models in plant spring phenology studies: two commonly used methods have different fields of application.

In studies of plant spring phenology, temperature sum models are traditional tools. They are used to quantify plant development in terms of accumulation of temperature-dependent developmental units, such as Growing Degree Hours, GDHs. A key parameter in these models is the threshold (or base) temperature, Tthr, representing the lower thermal limit for the development to occur. The parameter can be either estimated when the model is fitted into the data or fixed a priori. Here we examine the limitations of both methods and identify fields of applications for each of them.

A global analysis of ice phenology for 3702 lakes and 1028 reservoirs across the Northern Hemisphere using Sentinel-2 imagery

As existing global lake ice studies have predominantly focused on medium to large lakes, and reservoir ice studies have been limited to regional scales, very few studies of ice phenology have combined both lakes and reservoirs of different sizes. This study aims to characterize the freeze-up and break-up dates of 3702 lakes and 1028 reservoirs from 1 to 31,000 km2 across the Northern Hemisphere, and to analyze spatial patterns and relationships between ice phenological dates and driving factors. The freeze-up and break-up dates of these water bodies were retrieved from Sentinel-2 imagery using an ice detection algorithm through the Google Earth Engine platform from 2019 to 2023. The algorithm was verified by comparing phenology dates with an independent database based on observations from passive microwave sensors, with a mean absolute error of 18 days for both freeze-up and break-up dates. This newly established ice phenology database along with various geographic, morphometric, and climatic characteristics of the water bodies, was used to develop a random forest model for predicting ice phenology dates. While the predictive model performance is at a fair level (mean absolute error of 12 days for both freeze-up and break-up), challenges were encountered in certain high-elevation areas where cloudy conditions as well as black ice resulted in delayed freeze-up dates. Among the variables included in the random forest model, latitude and accumulation of freezing degree days were identified as the main drivers of ice phenology dates. Despite the challenges of applying a single, straightforward method on a global scale, this study has allowed the creation of a vast and comprehensive database of lake and reservoir freeze-up and break-up dates that can be used by the community to further analyze ice patterns.

Is there variation in ten woody species reproductive phenology within the Atlantic Forest biodiversity hotspot?

ABSTRACT Understanding reproductive phenology in tropical and subtropical forests is challenging. Thus, there are scarce large-scale phenological studies for those forests. Digitized herbarium collections can provide valuable information for understanding biological rhythms, e.g. timing of reproduction. Our aim was to verify the geographical variability of flowering and fruiting patterns and the effects of local climate on the reproductive phenology of woody species in the Atlantic Forest biodiversity hotspot. We used herbarium records compiled from the Global Biodiversity Information Facility – GBIF, speciesLink, JABOT, and the “Portal de Datos de Biodiversidad Argentina” as a main source of data to assess differences in reproductive phenology for 10 species with wide geographical distribution in the Atlantic Forest. Contrary to our expectations, we observed a non-seasonal reproductive phenology of all species and relations with temperature in the northern forests and to precipitation in the southern forests. When considered individually, there was no obvious relationship between phenophases and climatic factors. We expected that species occurring in a broad geographic distribution would change their biological rhythms related to local environmental factors, but it is likely that widely distributed species are abundant exactly because they are less dependent on biophysical characteristics of the environment. This is the first study comparing species located in the northern and southern regions of the Atlantic Forest using herbarium data, highlighting its importance to understand large scale ecological rhythms in tropical biomes.

Chrono-spatial reproductive phenology of Swertia bimaculata Hook.f. & Thomson ex C.B.Clarke reveals suitability as climate-changing bio-indicator along the Sikkim Himalayan altitude

Genus Swertia under the family Gentianaceae is morphologically and taxonomically distinct with about 14 species from Sikkim Himalayan region. A Chrono-spatial floral phenology study was conducted on Swertia bimaculata from 1580 to 2400 m altitude in West Sikkim Himalayan region. The floral phenology was studied in a field nursery at 1200 m altitude and spatial floral phenology was studied over a 1580–2400 m altitudinal range in the West Sikkim Himalayan region. Detailed study on flowering pattern and seed formation in S. bimaculata revealed late flowering at 1200 m compared to 2400 m. Plants at the lower altitude showed prolonged and variable flowering from September to November and seed formation from November to December. During September to mid-October, pentamerous and bisexual flowers were observed, followed by 9–16 % tetramerous until November; and up to 24 % trimerous and 10 % bimerous until the end of flowering season in December. By the end of December, 43 % of flowers become stamen-less (monoclinous). Less than 2 % seed formation was observed in stamen-less flowers. The temporal phenological behavior reveals a successful reproductive adaptive strategy, depicting pentamerous flowers during favorable conditions, reducing to tetramerous, followed by tri- & bimerous with female (monoclinous) flowers until the end of flowering with stressful conditions, suggesting its suitability as a stress indicator to the changing climatic conditions. Along the altitudinal range floral anomalies from the usually observed pentamerous (and very rare hexamerous) flowers in favorable conditions change to tetramerous and/or trimerous, as the environmental conditions become more stressful, suggesting that the changes in this species could be used as an indicator of stress in changing climatic conditions.

Potential of Herbarium-based Phenological Studies to Predict the Climate Change Impacts

Herbarium records provide a valuable historical database for assessing plant phenology shifts in the context of global climate change. The herbarium specimens, collected from diverse locations and periods, offer comprehensive data illustrating how many plants are altering their blooming times in response to global climate change. The appropriate use and analysis of long-term herbarium records offer an additional dimension for the study of plant phenology through the application of advanced experimental methodologies such as bioinformatics and satellite imagery, statistics, and Artificial Intelligence (AI) which, coupled with field observations, will improve ecosystems evaluation. These efforts can significantly contribute to conservation strategies and climate change mitigation and further support the synchronization of scientific inputs for evaluating the impacts of climate change and its ecological implications.

A study of wheat phenology and the factors affecting the wheat yield

A study of wheat phenology and the factors affecting the wheat yield

Long-term monitoring of the columnar cactus Cipocereus minensis reveals unforeseeable reproductive phenology

Phenological studies with species of cactus have grown in recent decades but the number of species studied remains very low, considering the high species richness of this group. In addition, temporal patterns of flowering and fruiting are important to understanding the processes that govern these crucial events of plant demography and ecology. Based on a five-year study of the reproductive phenology of C. minensis we asked if there is seasonality of flowering and fruiting. Secondly, we tested which climatic variables trigger C. minensis reproductive events in the Espinhaço region. We found that not all individuals produced flowers and fruits each year and a few individuals contributed with most flowers. Flower and immature fruit production is higher during the dry months, with fruits maturing during the rainy season or just before. In general, phenological events were seasonal, except for mature fruit production in 2010 and flower production in 2011. Some phenological traits such as flower timing, frequency, duration, and timing of immature fruit production had not been reported for the genus Cipocereus and were detected only because of the long-term phenological observations. Phenological heterogeneity in cactus might be a response to annual climatic fluctuations, mainly rainfall.

Seasonal phenology and starch allocation patterns in populations of Oxycaryum cubense f. cubense and paraguayense in Mississippi, Louisiana, and Florida

Abstract Phenological studies for Cuban bulrush [Oxycaryum cubense (Poepp. & Kunth) Lye] have been limited to the monocephalous form in Lake Columbus (Mississippi). Accordingly, there is little available information on potential phenological differences among O. cubense forms (monocephalous vs. polycephalous) and populations in other geographic locations in the United States. Therefore, seasonal patterns of biomass and starch allocation in O. cubense were quantified from two populations in Lake Columbus on the Tennessee-Tombigbee Waterway in Mississippi (monocephalous), two populations from Lake Martin in Louisiana (polycephalous), and two populations from Orange Lake in Florida (polycephalous). Monthly samples of O. cubense inflorescence, emergent, and submersed tissue were harvested from two plots per state from October 2021 to September 2022. During monthly data collection, air temperature and photoperiod were recorded. Starch allocation patterns were similar among all sites, with starch storage being less than 1.5% dry weight for all plant tissues. Biomass was greatest in Lake Columbus (monocephalous; 600.7 g dry weight [DW] m−2) followed by Lake Martin (polycephalous; 392.3 g DW m−2) and Orange Lake (polycephalous; 233.85 g DW m−2). Peak inflorescence biomass occurred in the winter for the Lake Martin and Orange Lake populations and in the summer for the Lake Columbus population. Inflorescence biomass in Lake Columbus had a positive relationship (r2 = 0.53) with warmer air temperatures. Emergent and submersed biomass generally had negative relationships with both photoperiod and temperature (r2 = 0.02 to 0.77) in all sites. Peak biomass was also negatively related to temperature and photoperiod. Results from this study indicate that there are differences in biomass allocation between the two growth forms of O. cubense and that growth can occur at temperatures below freezing. Low temperature tolerance may allow this species to expand its range farther north than previously suspected.

Seed Dormancy Class and Germination Characteristics of Berberis amurensis var. latifolia Nakai, Native to Korea

Berberis amurensis var. latifolia Nakai is a plant native to the Ulleung Island in Korea. In this study, we aimed to identify seed dormancy-breaking and germination requirements of this species using water imbibition experiments, gibberellic acid (GA3) treatment (0, 10, 100, or 1000 mg/L), cold stratification (0, 2, 4, 8, or 12 weeks at 5 °C), move-along experiments, and phenological studies. In the water imbibition experiment, the seed weight increased by more than 120% after 24 h. Analysis of the internal morphological characteristics of the seeds revealed that the embryo in freshly matured seeds was fully grown and did not grow thereafter. The final germination percentages after 12 weeks of cold stratification at 5 °C were 49 ± 6.4% and 63 ± 3.4% under light and dark conditions, respectively. In move-along and phenological studies, a longer cold stratification treatment period resulted in a higher germination percentage; however, the warm stratification treatment did not affect germination significantly. The GA3 treatment had little effect on seed germination. Therefore, we concluded that B. amurensis var. latifolia seeds have intermediate physiological dormancy, and pre-treatment with cold stratification for 12 weeks and incubation in the dark are required for effective seed propagation.

Vegetative and reproductive phenology in seasonal climate vegetation: phenological complementarity between woody and herbaceous plants in the Brazilian Chaco

Plant growth and reproduction patterns may be closely associated with environmental seasonality, but the high diversity of plant strategies has revealed complex phenological patterns. Here, we evaluate the occurrence, duration, and seasonality of vegetative and reproductive phenophases of the Brazilian Chaco vegetation. In addition, we summarize the results of a systematic literature review about the phenology of herbaceous and woody plants in different types of seasonal vegetation in the South American Dry Diagonal. Woody plants have a high intense leaf fall and low leaf flush during the dry season in the Brazilian Chaco, whereas in herbaceous plants these phenophases have more fluctuations. In both types, flowering and fruiting are continuous, not uniform, and mainly concentrate during the rainy season. However, woody species present two intensity peaks independent of rainfall, mean temperature, photoperiod, or soil water availability. In turn, in herbaceous species, flowering and fruiting responded to local climatic variables and photoperiod, presenting a peak of intensity during the rainy season. The rainy season plays an important role in plant growth and reproduction in seasonal climates around the world, mainly due to the energetic demand for plants. Like other vegetation types with seasonal climates, particularly in the South American Dry Diagonal, the Brazilian Chaco presents a wide range of phenological patterns, with generally different patterns between woody and herbaceous species. Community-level phenological studies conducted in areas with a seasonal climate have globally focused only on reproduction in relation to vegetative phenology, mostly ignoring herbaceous flora. Here, we emphasize that the phenological complementarity between the woody and herbaceous components is of great importance in maintaining the availability of resources.

Ecology and Phenology of the Subtidal Brown Alga Sargassum furcatum (Ochrophyta, Fucales), a Likely Non-Indigenous Species from the Mediterranean Sea

This study provides new insights regarding the ecology and phenology of the likely non-indigenous canopy-forming species Sargassum furcatum on the central-eastern coast of Sicily (Italy, Central Mediterranean). This species was described for St. Thomas (Virgin Islands), and it was reported for the first time in the Mediterranean in 1995 in the Chafarinas islands (Spain, western Mediterranean). After the first report, this species was found in 2021 in several sites located along the eastern coast of Sicily (Italy), along the French Mediterranean coastline, in Corsica, and recently also in the Aeolian Islands (Italy). No phenological studies on this species have been ever carried out in the Mediterranean Sea. To conduct this study, a visual census activity was performed in three sites along the Ionian coast of Sicily throughout 2023, during which the length of the main axis of S. furcatum specimens was measured and the frequency of findings of the species during the year was noted. In this study, it was observed that S. furcatum shows a wide adaptability in terms of range of depth, temperature, light exposure, and type of substrate. Since the distribution of this species is mostly centralized in the western Atlantic Ocean, it is likely that S. furcatum entered the Mediterranean through the Gibraltar Strait. Consequently, the entrance of this species in this Basin could be further proof of the ongoing seawater warming and tropicalization of Mediterranean waters. From this point of view, it is important to keep monitoring the dynamics of S. furcatum in the Mediterranean Sea in order to understand its putative impacts on autochthonous communities.

Fruit and Seed Phenological studies of Rauvolfia species distributed in the Southern Western Ghats

Fruiting pattern of five Rauvolfia species in the southern Western Ghats were observed to get an insight and limitations impacting their fruiting cycles. These species displayed parallel seasonal occurrences in their flowering and fruiting. Over two continuous years, from January to December in 2011 and 2012, monthly observations highlighted discrepancies in the duration of flowering and fruiting, despite the shared seasonal aspects. The peaks and patterns of fruiting varied among these species, demonstrating differences in key factors like fruiting duration, peak times, single/double fruit ratio, and seed purity. Moreover, it was observed that annual precipitation influences the flowering and fruiting behaviors of Rauvolfia.

Phenological studies on the onion cultivar ‘Ariesana’ in the process of seed production and the main characteristics of the mother plants

Phenological studies on the onion cultivar ‘Ariesana’ in the process of seed production and the main characteristics of the mother plants

Phenology

Flowers blooming, fungi fruiting, insects biting, fish spawning, geese migrating, deer calving; our consciousness is steeped in a seasonal calendar of nature's events. Phenology is the study of these recurring, seasonal life-history events, though nowadays this term is widely applied to the events themselves. From Shakespeare's sonnet 98, "From you I have been absent in the spring", to the appearance of seasonal events and migratory species in the oral traditions of Native Americans, interest in phenology is long-standing and transcends cultures. In this primer we introduce the study of phenology, trace the development of the field, and examine the prominent role phenology has played in evidencing the widespread impacts of anthropogenic climate change on life on Earth. We will consider the potential implications of climatic change for the ability of populations to persist and the stability of species interactions.

Citizen science data on urban forageable plants: a case study inBrazil.

This paper presents two key data sets derived from the Pomar Urbano project. The first data set is a comprehensive catalog of edible fruit-bearing plant species, native or introduced to Brazil. The second data set, sourced from the iNaturalist platform, tracks the distribution and monitoring of these plants within urban landscapes across Brazil. The study includes data from the capitals of all 27 federative units of Brazil, focusing on the ten cities that contributed the most observations as of August 2023. The research emphasizes the significance of citizen science in urban biodiversity monitoring and its potential to contribute to various fields, including food and nutrition, creative industry, study of plant phenology, and machine learning applications. We expect the data sets presented in this paper to serve as resources for further studies in urban foraging, food security, cultural ecosystem services, and environmental sustainability.

Tracking Phenological Changes over 183 Years in Endemic Species of a Mediterranean Mountain (Sierra Nevada, SE Spain) Using Herbarium Specimens.

Phenological studies have a crucial role in the global change context. The Mediterranean basin constitutes a key study site since strong climate change impacts are expected, particularly in mountain areas such as Sierra Nevada, where we focus. Specifically, we delve into phenological changes in endemic vascular plants over time by analysing data at three scales: entire massif, altitudinal ranges, and particular species, seeking to contribute to stopping biodiversity loss. For this, we analysed 5262 samples of 2129 herbarium sheets from Sierra Nevada, dated from 1837 to 2019, including reproductive structure, complete collection date, and precise location. We found a generalized advancement in phenology at all scales, and particularly in flowering onset and flowering peak. Thus, plants flower on average 11 days earlier now than before the 1970s. Although similar trends have been confirmed for many territories and species, we address plants that have been studied little in the past regarding biotypes and distribution, and which are relevant for conservation. Thus, we analysed phenological changes in endemic plants, mostly threatened, from a crucial hotspot within the Mediterranean hotspot, which is particularly vulnerable to global warming. Our results highlight the urgency of phenological studies by species and of including ecological interactions and effects on their life cycles.

A Review on the Utilization of Herbarium Data in Phenological Research Addressing Climate Change Implications

In recent years, the profound impact of climate change on biodiversity has become increasingly evident, with significant consequences for critical life events in the natural world. It underscores the significant influence of climate variations on seasonal life events within the biotic environment of flora, such as blooming response, leaf growth, leaf senescence and fruit ripening. These phenological shifts, particularly in temperate and tropical ecosystems, serve as vital indicators of climatic changes. This review study delves into the intricate relationship of herbarium data for bridging the gap in plant phenological observation for the investigations on climatic change. This comprehensive literature review of 30 key research papers published in the past two decades, which focus on the utility of herbarium specimens as tools to document phenological changes, was critically analysed in this research study. Long-term observation of phenological data by various phenological observation networks has paved the way for advanced environmental analysis in climatic change studies. However, despite the importance of phenological data from field observation, its collection and long-term observation records, present challenges, emphasizing the need for spatiotemporal depth of phenological data. A noticeable gap in field data collection has hindered various studies reliant on plant phenological data. In response to these challenges, herbaria serve as invaluable repositories of plant specimens, boasting rich historical records spanning over a century, providing a deep spatiotemporal and taxonomic insight. Research findings indicate the fidelity of herbarium records to fill the gap in field observations, with no significant differences between the field observations and herbarium data, highlighting the reliability of herbarium data in capturing phenological information. Overcoming the challenges associated with extensive herbarium datasets, digitalization and the implementation of crowdsourcing platforms have emerged as effective strategies, granting researchers easy online access to these data. Moreover, it is evident that in Sri Lanka, there exists a research gap in utilizing herbarium data for phenological studies in climate change observation and the implementation of online accessibility for herbarium data, highlighting the need to address this gap in future research endeavours.
 
 Keywords: Climate change, Herbarium data, Biodiversity, Phenological data