Flowering Phenology Research Articles

Coordination of spring vascular and organ phenology in deciduous angiosperms growing in seasonally cold climates.

In seasonally cold climates, many woody plants tolerate chilling and freezing temperatures by ceasing growth, shedding leaves and entering dormancy. At the same time, transport within these plants often decreases as the vascular system exhibits reduced functionality. As spring growth requires water and nutrients, we ask the question: how much does bud, leaf and flower development depend on the vasculature in spring? In this review, we present what is known about leaf, flower and vascular phenology to sort out this question. In early stages of bud development, buds rely on internal resources and do not appear to require vascular support. The situation changes during organ expansion, after leaves and flowers reconnect to the stem vascular system. However, there are major gaps in our understanding of the timing of vascular development, especially regarding the phloem, as well as the synchronization among leaves, flowers, stem and root vasculature. We believe these gaps are mainly the outcome of research completed in silo and urge future work to take a more integrative approach. We highlight current challenges and propose future directions to make rapid progress on this important topic in upcoming years.

Shared pollinators and sequential flowering phenologies in two sympatric cactus species

Background and aims – The reproductive characteristics of sympatric Cactaceae are important because they help to understand interfering or facilitating mechanisms that allow their coexistence. Globose Cactaceae show melittophily flowers that may be attractive to a shared set of pollinators, and if the flowering events are not overlapping, flower resources could be present for the pollinators through time. Ariocarpus kotschoubeyanus and Neolloydia conoidea are two sympatric cactus species in the southern Chihuahuan Desert. The objective of this study is to describe and compare some reproductive characteristics of these species.Material and methods – Individuals of Ariocarpus kotschoubeyanus and Neolloydia conoidea (n = 231 and 212, respectively) were marked and monitored during one year, recording for each species, the floral phenology, behaviour and morphology, flower visitors, breeding and mating systems (through pollination experiments).Key results – The flowering periods of these species do not overlap. The flowers of both species are melittophily, with the same shape, colour, and similar behaviour; both are obligate xenogamous plants. The mating system of Neolloydia conoidea is outcrossing but mixed in Ariocarpus kotschoubeyanus. They share 75% of pollinators (solitary and social bees).Conclusions – The temporal blooming separation of these species could be an important factor to facilitate coexistence within the xerophyte community since they share the same set of pollinators to achieve their reproductive success.

The Impact of Microclimate on the Reproductive Phenology of Female Populus tomentosa in a Micro-Scale Urban Green Space in Beijing

The spatial variation of poplars’ reproductive phenology in Beijing’s urban area has aggravated the threat of poplar fluff (cotton-like flying seeds) to public health. This research explored the impact of microclimate conditions on the reproductive phenology of female Populus tomentosa in Taoranting Park, a micro-scale green space in Beijing (range <1 km). The observed phenophases covered flowering, fruiting, and seed dispersal, and ENVI-MET was applied to simulate the effect of the microclimate on SGS (start day of the growing season). The results showed that a significant spatial variation in poplar reproductive phenology existed at the research site. The variation was significantly affected by the microclimate factors DMT (daily mean temperature) and DMH (daily mean heat transfer coefficient), with air temperature playing a primary role. Specifically, the phenology of flowering and fruiting phenophases (BBB, BF, FF, FS) was negatively correlated with DMT (−0.983 ≤ r ≤ −0.908, p <0.01) and positively correlated with DMH (0.769 ≤ r ≤ 0.864, p < 0.05). In contrast, DSD (duration of seed dispersal) showed a positive correlation with DMT (r = 0.946, p < 0.01) and a negative correlation with DMH (r = −0.922, p < 0.01). Based on the findings, the increase in air convection with lower air temperature and decrease in microclimate variation in green space can be an effective way to shorten the seed-flying duration to tackle poplar fluff pollution in Beijing’s early spring.

Comparing the reproductive biological characteristics of the alien invasive Coreopsis lanceolata to those of the non‐invasive alien congener Coreopsis tinctoria

AbstractIt is important to determine the characteristics associated with the success of alien species. However, there is no universal syndrome of invasion reproductive characteristics to explain the success of invasiveness has not been identified. Comparative studies on congeneric successful or non‐successful alien species are beneficial for revealing the drivers of invasion success and predicting future distributions. Reproductive biological characteristics, including the mating system, phenology of flowering, floral syndrome, pollination biology and seed germination have been investigated in the invasive Coreopsis lanceolata and non‐successful congener alien species Coreopsis tinctoria. The results revealed that C. lanceolata significantly attracted insect visitors by 11.67 times more than its congener, and the corolla density of C. lanceolata was positively correlated with the number of visiting insects. The high attraction of local insect bees Apis cerana guarantees the reproductive success and high seed production of C. lanceolata. Nevertheless, there was no versatile mating system, because its congener non‐successful alien species C. lanceolata still successfully invaded due to the combination strategies of self‐compatibility and presence of rhizomes. Furthermore, the ability of seed germination of C. lanceolata was lower than that of C. tinctoria, especially under drought and Al3+ stress, suggesting that germination performance can serve as a reference indicator. However, this was not an absolute trait for invasiveness. Hence, these germination traits might slow down the invasiveness of C. lanceolata in south China. These present findings highlight that the combination of self‐incompatibility and rhizomes should be given attention in the risk assessment protocols for plant invasiveness.

The impact of micro climate on flowers development in Siam orange plant (Citrus nobilis var. microcarpa. L)

Constraints that can affect the occurrence of induction and flowering development of Siamese citrus plants are endogenous and exogenous factors. Exogenous factors include microclimate. Microclimate, especially extreme humidity, is one of the factors that can determine the physiological process of flowering of Siamese citrus plants. Siam oranges require 6-9 wet months (rainy season) and 3-6 dry months (dry) and need enough water especially in July-August (dry season). The purpose of this study was to examine and determine the role of microclimate on the phenology of flowering Siam oranges in Badung, Bangli and Gianyar. The assessment method was observed in citrus centers from 2014 to August 2018. The results showed high rainfall occurring throughout 2014, a flowering phenology disorder that had previously flowered Siamese citrus plants 1 to 3 times a year to 4 to 6 times a year. The number of flowering periods is not supported by the number of flowers formed because the flower miscarried before the fruit-set formed, the height of the deciduous flower is supported by the large number of leaves formed at the location of the garden whose height is less than 1000 meters above sea level. Location of citrus orchards which applies an integrated management system to. New potentials are good for cultivating conjoined oranges, namely dry land or dry fields and sandy soil when compared to oranges planted in faddy fields.

Flowering Phenology Adjustment and Flower Longevity in a South American Alpine Species.

Delayed flowering due to later snowmelt and colder temperatures at higher elevations in the alpine are expected to lead to flowering phenological adjustment to prevent decoupling of peak flowering from the warmest time of the year, thereby favoring pollination. However, even if flowering is brought forward in the season at higher elevations, an elevational temperature gap is likely to remain between the high- and low-elevation populations of a species at the time these reach peak flowering on account of the atmospheric reduction in temperature with increasing elevation. The negative effect of this temperature gap on pollination could be compensated by plastically-prolonged flower life spans at higher elevations, increasing the probability of pollination. In a tightly temperature-controlled study, the flowering phenology adjustment and flower longevity compensation hypotheses were investigated in an alpine species in the Andes of central Chile. The snow free period varied from 7 to 8.2 months over 810 m elevation. Temperatures were suitable for growth on 82–98% of the snow free days. Flowering onset was temporally displaced at the rate of 4.6 d per 100 m increase in elevation and flowering was more synchronous at higher elevations. Flowering phenology was adjusted over elevation. The latter was manifest in thermal sums tending to decrease with elevation for population flowering onset, 50% flowering, and peak flowering when the lower thermal limit for growth (TBASE) was held constant over elevation. For TBASE graded over elevation so as to reflect the growing season temperature decline, thermal sums did not vary with elevation, opening the door to a possible elevational decline in the thermal temperature threshold for growth. Potential flower longevity was reduced by passive warming and was more prolonged in natural populations when temperatures were lower, indicating a plastic trait. Pollination rates, as evaluated with the Relative Pollination Rate index (RPR), when weighted for differences in floral abundance over the flowering season, declined with elevation as did fruit set. Contrary to expectation, the life-spans of flowers at higher elevations were not more prolonged and failed to compensate for the elevational decrease in pollination rates. Although strong evidence for phenological adjustment was forthcoming, flower longevity compensation did not occur over Oxalis squamata’s elevational range. Thus, flower longevity compensation is not applicable in all alpine species. Comparison with work conducted several decades ago on the same species in the same area provides valuable clues regarding the effects of climate change on flowering phenology and fitness in the central Chilean alpine where temperatures have been increasing and winter snow accumulation has been declining.

Flowering Phenology and the Influence of Seasonality in Flower Conspicuousness for Bees.

Flowering patterns are crucial to understand the dynamics of plant reproduction and resource availability for pollinators. Seasonal climate constrains flower and leaf phenology, where leaf and flower colors likely differ between seasons. Color is the main floral trait attracting pollinators; however, seasonal changes in the leaf-background coloration affect the perception of flower color contrasts by pollinators. For a seasonally dry woody cerrado community (Brazilian savanna) mainly pollinated by bees, we verified whether seasonality affects flower color diversity over time and if flower color contrasts of bee-pollinated species differ between seasons due to changes in the leaf-background coloration. For 140 species, we classified flower colors based on human-color vision, and for 99 species, we classified flower colors based on bee-color vision (spectral measurements). We described the community’s flowering pattern according to the flower colors using a unique 11 years phenological database. For the 43 bee-pollinated species in which reflectance data were also available, we compared flower color diversity and contrasts against the background between seasons, considering the background coloration of each season. Flowering was markedly seasonal, peaking at the end of the dry season (September), when the highest diversity of flower colors was observed. Yellow flowers were observed all year round, whereas white flowers were seasonal, peaking during the dry season, and pink flowers predominated in the wet season, peaking in March. Bee-bluegreen flowers peaked between September and October. Flowers from the wet and dry seasons were similarly conspicuous against their corresponding background. Regardless of flowering season, the yellowish background of the dry season promoted higher flower color contrast for all flower species, whereas the greener background of the wet season promoted a higher green contrast. Temporal patterns of flower colors and color contrasts were related to the cerrado seasonality, but also to bee’s activity, visual system, and behavior. Background coloration affected flower contrasts, favoring flower conspicuousness to bees according to the season. Thus, our results provide new insights regarding the temporal patterns of plant–pollinator interactions.

Species delimitation and hybridization history of a hazel species complex.

Hybridization increases species adaptation and biodiversity but also obscures species boundaries. In this study, species delimitation and hybridization history were examined within one Chinese hazel species complex (Corylus chinensis-Corylus fargesii). Two species including four varieties have already been described for this complex, with overlapping distributions. A total of 322 trees from 44 populations of these four varieties across their ranges were sampled for morphological and molecular analyses. Climatic datasets based on 108 geographical locations were used to evaluate their niche differentiations. Flowering phenology was also observed for two co-occurring species or varieties. Four statistically different phenotypic clusters were revealed, but these clusters were highly inconsistent with the traditional taxonomic groups. All the clusters showed statistically distinct niches, with complete or partial geographical isolation. Only two clusters displayed a distributional overlap, but they had distinct flowering phenologies at the site where they co-occurred. Population-level evidence based on the genotypes of ten simple sequence repeat loci supported four phenotypic clusters. In addition, one cluster was shown to have an admixed genetic composition derived from the other three clusters through repeated historical hybridizations. Based on our new evidence, it is better to treat the four clusters identified here as four independent species. One of them was shown to have an admixed genetic composition derived from the other three through repeated historical hybridizations. This study highlights the importance of applying integrative and statistical methods to infer species delimitations and hybridization history. Such a protocol should be adopted widely for future taxonomic studies.

Genomic Architecture of Phenotypic Plasticity in Response to Water Stress in Tetraploid Wheat.

Phenotypic plasticity is one of the main mechanisms of adaptation to abiotic stresses via changes in critical developmental stages. Altering flowering phenology is a key evolutionary strategy of plant adaptation to abiotic stresses, to achieve the maximum possible reproduction. The current study is the first to apply the linear regression residuals as drought plasticity scores while considering the variation in flowering phenology and traits under non-stress conditions. We characterized the genomic architecture of 17 complex traits and their drought plasticity scores for quantitative trait loci (QTL) mapping, using a mapping population derived from a cross between durum wheat (Triticum turgidum ssp. durum) and wild emmer wheat (T. turgidum ssp. dicoccoides). We identified 79 QTLs affected observed traits and their plasticity scores, of which 33 reflected plasticity in response to water stress and exhibited epistatic interactions and/or pleiotropy between the observed and plasticity traits. Vrn-B3 (TaTF1) residing within an interval of a major drought-escape QTL was proposed as a candidate gene. The favorable alleles for most of the plasticity QTLs were contributed by wild emmer wheat, demonstrating its high potential for wheat improvement. Our study presents a new approach for the quantification of plant adaptation to various stresses and provides new insights into the genetic basis of wheat complex traits under water-deficit stress.

Stochastic flowering phenology in Dactylis glomerata populations described by Markov chain modelling

Understanding the relationship between flowering patterns and pollen dispersal is important in climate change modelling, pollen forecasting, forestry and agriculture. Enhanced understanding of this connection can be gained through detailed spatial and temporal flowering observations on a population level, combined with modelling simulating the dynamics. Species with large distribution ranges, long flowering seasons, high pollen production and naturally large populations can be used to illustrate these dynamics. Revealing and simulating species-specific demographic and stochastic elements in the flowering process will likely be important in determining when pollen release is likely to happen in flowering plants. Spatial and temporal dynamics of eight populations of Dactylis glomerata were collected over the course of two years to determine high-resolution demographic elements. Stochastic elements were accounted for using Markov chain approaches in order to evaluate tiller-specific contribution to overall population dynamics. Tiller-specific developmental dynamics were evaluated using three different RV matrix correlation coefficients. We found that the demographic patterns in population development were the same for all populations with key phenological events differing only by a few days over the course of the seasons. Many tillers transitioned very quickly from non-flowering to full flowering, a process that can be replicated with Markov chain modelling. Our novel approach demonstrates the identification and quantification of stochastic elements in the flowering process of D. glomerata, an element likely to be found in many flowering plants. The stochastic modelling approach can be used to develop detailed pollen release models for Dactylis, other grass species and probably other flowering plants.

Satellite prediction of forest flowering phenology

Knowledge of flowering phenology is essential for understanding the condition of forest ecosystems and responses to various anthropogenic and environmental drivers. However, monitoring the spatial and temporal variability in forest flowering at landscape scales is challenging (e.g. current monitoring is often highly localized and in-situ or for single dates). This study presents a method that combines drone and satellite images (PlanetScope) that can produce landscape-scale maps of flowering dynamics. This method is demonstrated in forest landscapes dominated by the eucalypt Corymbia calophylla (red gum or marri) in Western Australia. Drone-derived images of flowering eucalypt canopies, available for restricted temporal and spatial extents, are used to label satellite image pixels with the proportion of a pixel footprint that is flowering. The pixels labelled with flowering proportion, the response variable, are combined with various metrics that characterize time series of spectral indices sensitive to the presence of green vegetation and cream-colored flowers, the predictor variables. A machine learning model then predicts daily pixel-level flowering proportions. The model is trained with data from two sites and is tested with data from three sites and various dates throughout the Corymbia calophylla season. The model is able to accurately predict pixel-level flowering proportion throughout the flowering season (RMSE <4% across all sites and dates), across sites with dense to sparse canopy, different background soil covers, and is robust to not detecting false positive flowering when no flowering events are occurring. Due to the spatiotemporal coverage of satellite images, this model can be deployed to generate regional maps of flowering dynamics in forest ecosystems that can be used for monitoring forest ecosystem condition and supporting research into drivers of eucalypt forest phenology.

Warming and elevated CO2 induces changes in the reproductive dynamics of a tropical plant species

Tropical plant species are vulnerable to climate change and global warming. Since flowering is a critical factor for plant reproduction and seed-set, warming and elevated atmospheric carbon dioxide concentrations (eCO2) are crucial climate change factors that can affect plant reproductive dynamics and flowering related events in the tropics. Using a combined free-air CO2 enrichment and a free-air temperature-controlled enhancement system, we investigate how warming (+2 °C above ambient, eT) and elevated [CO2] (~600 ppm, eCO2) affect the phenological pattern, plant-insect interactions, and outcrossing rates in the tropical legume forage species Stylosanthes capitata Vogel (Fabaceae). In comparison to the control, a significantly greater number of flowers (NF) per plot (+62%) were observed in eT. Furthermore, in warmed plots flowers began opening approximately 1 h earlier (~09:05), with a canopy temperature of ~23 °C, than the control (~09:59) and eCO2 (~09:55) treatments. Flower closure occurred about 3 h later in eT (~11:57) and control (~13:13), with a canopy temperature of ~27 °C. These changes in flower phenology increased the availability of floral resources and attractiveness for pollinators such as Apis mellifera L. and visitors such as Paratrigona lineata L., with significant interactions between eT treatments and insect visitation per hour/day, especially between 09:00–10:40. In comparison to the control, the additive effects of combined eCO2 + eT enhanced the NF by 137%, while the number of A. mellifera floral visits per plot/week increased by 83% during the period of greatest flower production. Although we found no significant effect of treatments on mating system parameters, the overall mean multilocus outcrossing rate (tm = 0.53 ± 0.03) did confirm that S. capitata has a mixed mating system. The effects of elevated [CO2] and warming on plant-pollinator relationships observed here may have important implications for seed production of tropical forage species in future climate scenarios.

Testing the environmental prediction hypothesis for community‐wide mass flowering in South‐East Asia

AbstractGeneral flowering, in which hundreds of species synchronize their flowering at multi‐year intervals, is a puzzle to ecologists. It is hypothesized that species taking part in general flowering time their reproduction to meet favorable environmental conditions for seedling establishment. We tested this environmental prediction hypothesis using 14‐year weekly flower records of five Shorea species (Dipterocarpaceae) and daily meteorological data in a lowland rain forest in Malaysia. We first investigated causal inference between three potential flowering triggers (cooling, drought, and the synergistic signal of cooling and drought) and flowering. We then explored the causality between flowering triggers and moisture condition during seedling establishment. Our results demonstrated that the synergistic signal of cooling and drought causally influences flowering phenology with the highest predictability for the timing of flowering. Both drought and the synergistic signal of cooling and drought are causally linked to favorable wet conditions during seedling establishment, but the predictability of future rainfall by the synergistic signal was higher than the drought alone. These results support the environmental prediction hypothesis and raise the question as to whether climate change allows the prediction to hold for plant regeneration in the future.

Phenological synchrony between the hoary squash bee (Eucera pruinosa) and cultivated acorn squash (Cucurbita pepo) flowering is imperfect at a northern site.

The phenology of crop flowering and pollinator reproduction can become asynchronous at the edge of their respective ranges. At a northern site in Peterborough County, Ontario, we evaluated offspring emergence of Cucurbita pollen specialist hoary squash bees (Eucera pruinosa) from nests in enclosures to determine their phenological synchrony with a squash crop (Cucurbita pepo). For the crop, we evaluated the percentage of bees that emerged in time to provide pollination services during the crop pollination window. For the bees, we compared the period when both male and females were present and could mate to the whole crop flowering period. We found that fewer than half the bees had emerged by the time the crop pollination window closed and only 34.1% of the flowering period of the crop could support the reproductive activities of the bees, suggesting that phenological synchrony was imperfect from the perspective of both the crop and the pollinator at this northern site.

Differential Effects of Winter and Spring Warming on Flowering Phenology of Cherry Trees Across a Latitudinal Gradient

Differential Effects of Winter and Spring Warming on Flowering Phenology of Cherry Trees Across a Latitudinal Gradient

地果花粉供应格局成因和适生区分析

被子植物的性别表达与分配具有环境依赖性，使其性器官和雌雄功能在不同环境中趋于合理。地果雄果的花药胚珠比在不同地域间存在极大的变幅，同时呈现出不同的雄花分布格局，苞片口型（OS型）的花药胚珠比显著低于果腔散布型（SS型）。基于地果的339个实际分布点，使用最大熵模型模拟不同雄花分布类型地果的适生区，并对各适生区的环境贡献因子、区域间扩散的环境限制因子进行分析，探究地果雄花分布类型和花粉供应的地域分布格局成因。结果显示，OS型、SS型对应着不同的适生区，前者主要分布在四川盆地、后者主要分布在横断山区-云南高原、而贵州高原为多种类型的共存。各类型的环境条件有显著差异，OS型分布于低海拔、最冷月极端低温较低、温度季节变化明显的区域，而SS型分布于高海拔、强太阳辐射、温度季节变化较小的区域。环境条件的差异限制了地果在不同区域间的扩散，同时影响着地果的繁殖物候、传粉小蜂的种群动态等，这可能是地果性别分配策略变化的原因。;Plastic sex expression and allocation is common in angiosperm. Many plant species adjust their relative allocation to male and female organs in response to the environmental conditions in order to optimize sex functions in different environments. Large variation in anther-to-ovule ratios is presented among the natural populations of Ficus tikoua in the Southwest China. And it is associated with differing distributions of male flowers in the figs. Three male flower distributions occur, namely concentrated around ostiole (OS type), scattered throughout the fig cavity (SS type), and intermediate type (IS type). The anther-to-ovule ratios of OS type were significantly higher than those of SS type. We employed a maximum entropy model to simulate the potential suitable areas of F. tikoua based on 339 documented distribution sites. The key environmental factors contributing to the regional distribution of different plant phenotypes and restricting the expansion of the plant among regions were assessed. The distribution of the three phenotypes were largely allopatric, with OS type centered on Sichuan Basin, SS type concentrated on Hengduan Mountains-Yunnan Plateau, and co-occurrence on Guizhou Plateau. The environmental conditions associated with phenotype were different. OS type was associated with lower altitude, lower minimum temperature of the coldest month, and greater temperature seasonality. SS type was linked to higher altitude, stronger solar radiation, and smaller temperature seasonality. The different environmental conditions in each distribution region restricted cross-region expansion, brought about the variation of flower phenology of the plant and the population dynamics of its pollinating fig wasps, which might contribute to the divergence of sex allocation strategies of F. tikoua.

Allopatry, hybridization, and reproductive isolation in Arctostaphylos.

Hybridization plays a key role in introgressive adaptation, speciation, and adaptive radiation as a source of evolutionary innovation. Hybridization is considered common in Arctostaphylos, yet species boundaries are retained in stands containing multiple species. Arctostaphylos contains diploids and tetraploids, and recent phylogenies indicate two clades; we hypothesize combinations of these traits limit or promote hybridization rates. We statistically analyzed co-occurrence patterns of species by clade membership and ploidy level from 87 random 0.1ha plots. We sampled multiple sites to analyze for percent hybridization based on morphology. Finally, phenophases were analyzed by scoring herbarium sheets for a large number of taxa from both clades as well as tetraploids, and second, surveying three field sites over two years for divergence in phenological stages between co-occurring taxa. Most taxa in Arctostaphylos are allopatric relative to other congenerics. When two taxa co-occur, the patterns are a diploid with a tetraploid, or two diploids from different clades. When three taxa co-occur, the pattern is two diploids from different clades and a tetraploid. Field and herbarium data both indicate flowering phenology is displaced between diploids from the two clades; one of the diploid clades and tetraploids overlap considerably. The two deep clades in Arctostaphylos are genetically distant, with hybrids rare or non-existent when taxa co-occur. Reproductive isolation between clades is enhanced by displaced flowering phenology for co-occurring species. Within clades, taxa appear to have few reproductive barriers other than an allopatric distribution or different ploidy levels.

New perspective for evaluating the main Camellia oleifera cultivars in China

To assess the adaptability of Camellia oleifera for introduction in new growth locations, this study evaluated 10 representative C. oleifera cultivars from the main areas in China where this oil-producing evergreen crop is grown. Cluster analysis, correlation analysis, and membership function analysis were used to evaluate various indices of the selected C. oleifera cultivars, including flowering phenology, cold tolerance, leaf structure, pollen characteristics, and pollen viability. The correlation analysis identified the full blossoming time, leaf palisade and spongy tissue thickness, pollen deformity rate, and pollen activity as key indices for determining the adaptability of the cultivars to new areas. The membership function analysis of the 10 C. oleifera cultivars revealed the following order of adaptability: ‘XLC25’ > ‘Changlin4hao’ > ‘Ganzhouyou8hao’ > ‘Ganzhouyou6hao’ > ‘Tiechengyihao’ > ‘Eyou465’ > ‘XLC10’ > ‘Changlin3hao’ > ‘Changlin18hao’ > ‘QY235.’ When introducing C. oleifera cultivars to new regions, the higher-ranked cultivars are more likely to be successful. The results of this study may provide a new direction for the comprehensive assessment of plant introduction and domestication potential, i.e., the assessment of the vegetative and reproductive growth, adversity resistance, and blossoming time of plants.

Gender expression in Sedum praealtum A. DC. (Crassulaceae) in Central Veracruz, Mexico

Inflorescence type and design determine the position of reproductive meristems and sequence of flowers opening. I examined the gender expression over two entire flowering seasons in Sedum praealtum A. DC. (Crassulaceae) in Central Veracruz, Mexico. Specifically, I studied the floral longevity, sexual-phase duration, flower opening within an inflorescence and sex ratio in the species. I observed that the 8-days flower initiated in male-phase and then switched to female-phase. An extended time of pollen presentation by gradual anthers dehiscence caused an incomplete protandry in the species. The basal-positioned floral buds reached anthesis sooner than the distal-positioned floral buds, resembling an acropetal flowering sequence. Inflorescences production ceased in the middle of the flowering season, whereas flower opening remained constant over reproductive season of the species. The opening of flowers in successive cohorts linked to changes in the flower sexual-phase phenology caused an initial sex expression toward maleness and a balanced sexual expression from the peak to the end of reproductive season in the population sampled. This study highlights the important influence that variations in onset and duration of sexual-phase of flowers can have on sex expression in flowering plants.

Invertebrate Decline Leads to Shifts in Plant Species Abundance and Phenology.

Climate and land-use change lead to decreasing invertebrate biomass and alter invertebrate communities. These biotic changes may affect plant species abundance and phenology. Using 24 controlled experimental units in the iDiv Ecotron, we assessed the effects of invertebrate decline on an artificial grassland community formed by 12 herbaceous plant species. More specifically, we used Malaise traps and sweep nets to collect invertebrates from a local tall oatgrass meadow and included them in our Ecotron units at two different invertebrate densities: 100% (no invertebrate decline) and 25% (invertebrate decline of 75%). Another eight EcoUnits received no fauna and served as a control. Plant species abundance and flowering phenology was observed weekly over a period of 18 weeks. Our results showed that invertebrate densities affected the abundance and phenology of plant species. We observed a distinct species abundance shift with respect to the invertebrate treatment. Notably, this shift included a reduction in the abundance of the dominant plant species, Trifolium pratense, when invertebrates were present. Additionally, we found that the species shifted their flowering phenology as a response to the different invertebrate treatments, e.g. with decreasing invertebrate biomass Lotus corniculatus showed a later peak flowering time. We demonstrated that in addition to already well-studied abiotic drivers, biotic components may also drive phenological changes in plant communities. This study clearly suggests that invertebrate decline may contribute to already observed mismatches between plants and animals, with potential negative consequences for ecosystem services like food provision and pollination success. This deterioration of ecosystem function could enhance the loss of insects and plant biodiversity.