Flowering Strategies Research Articles

Myrtaceae flowering strategies in a gallery forest, Chapada Diamantina, Brazil

Abstract Tropical plants exhibit virtually all known phenological responses, which can range from near-continuous to brief events, and from complete synchrony to complete asynchrony. This wide variety of phenological patterns is related to high tropical biodiversity and complex interactions with diverse abiotic and biotic factors, such as plant-pollinator interactions. Changes in these factors will therefore influence plant phenology, and differences in those phenological responses can impact reproductive success and plant fitness. We report here interspecific variations in the reproductive ecology (flowering phenology, floral biology, reproductive systems, and pollination) of 10 Myrtaceae species in a gallery forest in northeastern, Brazil. We evaluated flowering patterns and strategies, considering the frequency and duration of each phenophase from monthly observations, using the semi-quantitative Fournier scale. We also analyzed floral biology, recorded floral visitors, conducted pollination experiments (autonomous self-pollination, hand self-pollination, hand cross-pollination, and natural/open pollination), and calculated sefl-incompatibility (SII) and autogamy (AI) indices. Most species exhibited synchronous and annual flowering lasting between 1 and 5 months, with a “pulsed bang” strategy (i.e., mass flowering concentrated within just a few days, with intervals). These patterns were repeated among congeneric species, except in Myrcia, in which half of the species accompanied were classified as having a “pulsed bang” and the other half a “big bang” strategy. The flowering strategies appeared to be associated with distinct patterns of inflorescence development, bud production, flowering duration, and the timing of flowering in individual plants. Bee species were considered pollinators. Most species studied were self-incompatible and allogamous. In general, the species produced large quantities of flowers during short temporal intervals, favoring crosses between individuals having precise synchrony.

A Spray Chrysanthemum Cultivar ‘Pinky Lang’ with Pink Petal, Single Type, and Stable Flowering Strategy in High Temperature Period

A Spray Chrysanthemum Cultivar ‘Pinky Lang’ with Pink Petal, Single Type, and Stable Flowering Strategy in High Temperature Period

Cost-effective and accurate monitoring of flowering across multiple tropical tree species over two years with a time series of high-resolution drone imagery and deep learning

Detection of flowering and quantification of flowering phenology are key to monitoring the reproduction of tropical trees and their response to global change. However, effective monitoring of flowering over various scales from individuals to forest ecosystem levels is lacking due to the relatively small sizes of flowers, diverse flowering strategies across species, and the short duration of flowering, making accurate flower detection difficult. Drone-based surveys require less time and human resources than traditional ground-based flower surveys and thus may be able to help address this in a cost-effective manner but remain underexplored in species-rich tropical forest ecosystems. Here, we developed a method that integrated the Residual Networks 50 (ResNet50) deep learning algorithm with high resolution imagery (c. 0.05 m) from monthly drone surveys done in a 50-ha tropical forest plot on Barro Colorado Island (BCI), Panamá, over 2018–2020 to detect a diversity of flowering species in this tree community and to track the timing of flowering throughout the year. We built a comprehensive training library of canopy components (flower, leaf, branch, and shade) from this forest plot throughout the study period, trained a single deep learning model across all drone imagery, and validated it using five-fold cross validation at the pixel scale. We further generated image- and tree-crown-specific supervised classifications to evaluate the deep learning model at the tree-crown scale. Our deep learning method accurately classified flowers (User’s accuracy = 95.3 %, Producer’s accuracy = 85.8 %) while maintaining high predictive power for the other three classes (Overall accuracy = 98.4 %). Our results also demonstrated high consistency against tree-crown-specific supervised classifications for flower (r2 = 0.85), leaf (r2 = 0.84), and branch (r2 = 0.92) components, with lower agreement observed for the shade component (r2 = 0.59). These results demonstrate the effectiveness of our method in advancing fine-scale flower monitoring in the tropics, with potential to be extended to other regions or other remote sensing platforms with frequent high-resolution monitoring. The method will allow us to better monitor flowering in tropical forests and improve our understanding of how phenology and reproductive success may be affected by climate change.

Influence of Climatic Factors on the Phenology of Chokeberry Cultivars Planted in the Pedoclimatic Conditions of Southern Romania

This paper aimed to study the adaptation of a crop to the specific climatic conditions of southern Romania, Pitești-Mărăcineni, Romania, in terms of the phenology of two chokeberry (Aronia melanocarpa) cultivars (‘Melrom’ and ‘Nero’). The BBCH (Biologische Bundesantalt, Bundessortenamt and Chemische Industrie) scale was used for phenological observations. The recorded data were statistically processed, calculating the average onset time and duration of fruiting phenophases and dormancy duration, average air temperatures, total solar radiation, and the cold and heat accumulation. Bud swelling was registered between 28 January and 8 February, budburst occurred starting on 3 March, while flowering began in stages, between 15 April and 1 May, and was completed between 27 April and 14 May. During the 154 days of 53–87 BBCH, the average air temperature, 16.1 °C, ranged between the extremes of −6.1 and 36.8 °C. The onset data and spring–summer phenophases were mainly related to the minimum air-temperature oscillations. The flowering timing shortened as the maximum temperature and total solar radiation increased. The relation between the environmental factors and the flowering strategy indicates the A. melanocarpa as a species adapted to the temperate continental climate of southern Romania.

FLORAL BIOLOGY AND BEEKEEPING POTENTIAL OF Croton heliotropiifolius KUNTH (EUPHORBIACEAE) AT SEMI ARID REGION, BRAZIL1

ABSTRACT The aim of the present study was to determine the beekeeping potential of Croton heliotropiifolius Kunth (Euphorbiaceae) based on flowering strategy, floral characteristics, available floral resources, and the individuals frequencies and foraging activities of Apis mellifera L. on its flowers in Fazenda Ingazeira, Brazil. Each C. heliotropiifolius plant possessed inconspicuous diclinous flowers clustered into 560 ± 60 dense terminal inflorescences containing 59 ± 12 pistillate and 160 ± 26 staminate flowers. Although both types of flowers produced nectar (pistillate: 2.8 ± 0.8 μL ; staminate: 0.3 ± 0.06 μL ), A. mellifera workers mostly visited staminate flowers (98%) during the peak visitation period (08:00-11:00 h). Moreover, during the foraging period, each plant produced approximately 5.376 × 10 8 pollen grains, ensuring approximately 33 visitation cycles from a colony of A mellifera workers that picked up an average of 405 pollen grains per visit per flower. Further, C. heliotropiifolius showed an annual cornucopia flowering strategy with high flower production for five months, which is an important characteristic that ensures floral resource availability in the environment. These findings suggest that C. heliotropiifolius has a great potential for apiculture in this region.

Temporal organization among pollination systems in a tropical seasonal forest.

Temporal constancy of pollination systems is essential for the maintenance of pollinators through time. Community-level assessment of flowering phenology allows understanding variations across seasons and years and the risks of decoupling flowering and pollinators' activity. We evaluated flowering patterns and temporal diversity of pollination systems in a tropical seasonal forest. We asked whether the temporal organization of flowering times differs among pollination systems; if there is a constancy of pollination systems through the year, since climate and phylogenies constraint flowering time; if there is a prevalent flowering pattern by pollination system, and if the temporal organization of pollination systems by modularity analyses is coherent with grouping by pre-defined seasons. We characterized 10 pollination systems, examined flowering strategies, climate cues and phylogenetic constraints. Pollination by large-to-medium bees dominated (49.2%), followed by diverse insects (22.1%) and flies (14.7%). The remaining systems represented 14% of species. Flowering occurred year-round for most pollination systems, predominating the seasonal flowering strategy. Flowering patterns ranged from aggregated to nested, and random. Climate affected the flowering of most pollination systems, but there was no phylogeny constraint. Modularity grouped pollination systems differently than rainfall seasonality. Contrasting the expectations of reduced temporal constancy, most systems were present year-round, facilitating the exploitation of floral resources by pollinators. Diversity of pollination systems remained constant despite climate seasonality, indicating that several factors influence the optimum flowering time for pollination in seasonally dry vegetations. Global warming may disrupt phenological patterns and the temporal organization of plant communities, a matter for future studies.

Nocturnal Bees as Crop Pollinators

Bees are typically diurnal but around 1% of described species have nocturnal activity. Nocturnal bees are still poorly studied due to bias towards studying diurnal insects. However, knowledge concerning their biology and role as crop pollinators has increased. We review the literature on nocturnal bees’ traits and their host plants, and assess the crop pollination effectiveness of this neglected group. Nocturnal bees have visual adaptations to cope with low light intensities, and floral scents are a key sensory cue used to find their host flowers. Nocturnal bees generally show high flower constancy, the ability to vibrate flowers, and high transfer rates of pollen grains to stigmas. The flowers visited by nocturnal bees range from small radial and zygomorphic flowers to large brush blossoms; moreover, they visit plants with different flowering strategies. Nocturnal bees are effective pollinators of regional fruit crops in Brazil, such as cambuci (Campomanesia phaea), guaraná (Paullinia cupana), cajá (Spondias mombin), and in North America of cultivated pumpkins (Cucurbita species). However, they most likely are pollinators of several other crops. Strategies to host high numbers of nocturnal bees around cropping areas should be taken, such as preserving adjacent native forests, restricting soil management, providing food resources beyond crop flowers, and avoiding light pollution.

Ongoing Evolution in the Genus Crocus: Diversity of Flowering Strategies on the Way to Hysteranthy.

Species of the genus Crocus are found over a wide range of climatic areas. In natural habitats, these geophytes diverge in the flowering strategies. This variability was assessed by analyzing the flowering traits of the Spanish collection of wild crocuses, preserved in the Bank of Plant Germplasm of Cuenca. Plants of the seven Spanish species were analyzed both in their natural environments (58 native populations) and in common garden experiments (112 accessions). Differences among species observed in the native habitats were maintained under uniform environmental conditions, suggesting a genetic basis for flowering mechanisms. Two eco-morphological types, autumn- and spring-flowering species, share similar patterns of floral induction and differentiation period in summer. The optimal temperature for this process was 23 °C for both types. Unlike Irano-Turanian crocuses, spring-flowering Spanish species do not require low winter temperatures for flower elongation. Hysteranthous crocuses flower in autumn prior to leaf elongation. We conclude that the variability in flowering traits in crocuses is related to the genetic and environmental regulation of flower primordia differentiation and elongation prior to emergence above the soil surface. The elucidation of the physiological differences between eco-morphological types of crocuses: synanthous with cold requirements and synanthous and hysteranthous without cold requirements, unlocks a new approach to the flowering evolution of geophytes in Mediterranean regions. Crocus species can serve both as a new model in the study of the molecular basis of hysteranthy and for the purposes of developing the molecular markers for desirable flowering traits.

Fire‐triggered flowering is the dominant post‐fire strategy in a tropical savanna

AbstractQuestionsIn fire‐prone ecosystems, fire can enhance the flowering and fruiting of many species, a strategy assumed to be well represented in savanna. Despite this, there are surprisingly few studies assessing how prevalent fire‐stimulated flowering is. Thus, we asked: (a) are there differences in the reproductive phenology of Cerrado plants between recently burned and unburned areas; (b) how does fire affect the speed of flowering and how does this differ between growth forms; and (c) what are the post‐fire flowering (PFF) strategies of Cerrado species and is there evidence for high proportions of obligate PFF?LocationOpen savannas (campo sujo in the Cerrado) in Central Brazil (Reserva Natural Serra do Tombador — RNST, 13°35–13°38' S and 47°45'–47°51' W).MethodsWe established six plots, three recently and frequently burned (FB) and three excluded from fire for six years (E). In all treatments, the number of species flowering and fruiting was counted every 15 days for three months, and then at six, nine and 12 months after fire. We also counted the number of reproductive and vegetative shoots in 10 subplots (1 m × 1 m) per plot.ResultsApproximately 66% of species studied were fire‐stimulated, with half of these only flowering after fire (obligate PFF). Fire‐enhanced flowering was rapid, with the clearest differences between burned and unburned plots seen in the first 30 days, and up to three months after fire, where there were up to two times more species flowering in the FB than E areas.ConclusionsThe extremely high proportion of PFF species, at least five times that reported for heathlands and other shrub communities, highlights the role that short‐interval fire regimes have in savanna ecosystems, selecting for resprouting life forms and PFF dominance, particularly in herbaceous species. Rapid post‐fire reproduction may be a strategy to disperse large quantities of seed into an environment with a small recruitment window.

Functional traits modulate plant community responses to alien plant invasion

It is well known that alien plant invasion modifies the composition and diversity of resident plant communities, yet our ability to predict patterns of vegetation responses to invasion is hampered by a poor understanding of which functional traits make some resident plants more or less vulnerable to invader impacts. For example, resident species may be more likely to persist and coexist with the invader if they display different strategies of resource use (i.e. high niche differences) or if they share similar highly competitive traits (i.e. competitive hierarchy). Here, we used a trait-based approach to 1) specifically test whether species changes in abundance following plant invasion is random or depends on specific functional trait values, 2) identify which functional strategies allow resident species to coexist with the invader and 3) assess to what extent communities where the invader has been removed return to a reference state. To do so, we applied a semi-experimental approach with the annual vine Humulus japonicus, an invasive species in riparian habitats of Southern France. We monitored plant communities seven times over two years in non-invaded reference plots, invaded plots and removal plots in which the invader had been removed at the seedling stage. We quantified species richness and functional richness as well as mean community trait values of seven traits. The comparison of invaded and removal plots highlighted a strong impact of Humulus japonicus on both species and functional richness of riparian communities. Resident species that had a distinct flowering onset from the invader faced less pronounced declines. Specifically, species that flowered before the invader reached high cover, and species that had a short flowering duration had lower risk of declining. In addition, species coexisting with the invader when it reached its maximum cover displayed high stature and high seed mass. These results suggest that both niche differentiation (in terms of flowering strategy) and competitive hierarchies (in terms of height and regeneration strategy) play a role in explaining plant community responses to plant invasion. Finally, while species richness recovered rapidly in removal plots, functional richness remained lower than in non-invaded plots, pointing to a state-shift that would otherwise go undetected. Overall, our study highlights that the analysis of the functional traits of both invaders and resident species, combined with regular monitoring over time of non-invaded reference plots, invaded and removal plots can greatly improve our understanding of the impact of plant invasion on resident communities.

A Multi-platform Mobile Application to Collect Citizen Science Data for Bignoniaceae Phenological Research

The implementation of Citizen Science in biodiversity studies has led the general public to engage in environmental actions and to contribute to the conservation of natural resources (Chandler et al. 2017). Smartphones have become part of the daily lives of millions of people, allowing the general public to collect data and conduct automatic measurements at a very low cost. Indeed, a series of Citizen Science mobile applications have allowed citizens to rapidly record specimen observations and contribute for the development of large biodiversity databases around the World. Citizen Science applications have a multitude of purposes, as well as target a variety of taxa, biological questions and geographical regions. Brazil is a megadiverse country that includes many threatened species and Biomes. Conversation efforts are urgent and the engagement of the civil society is critical. Brazilian dry and wet forests are dominated by members of the plant family Bignoniaceae, all of which are characterized by beautiful trumpet-shaped flowers and a big-bang flowering strategy. Species of the Neotropical Bignoniaceae trees are popularly known in Brazil as “Ipê” and are broadly cultivated throughout the country due to the showy flowers and strong wood. Different species have different flower colors, making its identification relatively easy. The showy and colorful flowers are extremely admired by the local population and the media. Flowering of “Ipês” is triggered by dry climate, lower temperatures and increasing day-light, making this group an excellent model for phenological and climatic studies involving Citizen Science. Here, we developed a multi-platform mobile application focused on the plant family Bignoniaceae that allows users to contribute phenological data for species from this plant family. More specifically, through this application the user is able to provide data about specimen locations, phenology and date, all of which can be validated by a photograph. This platform is based on React Native, a hybrid app framework that helps the developers to reuse the code across multiple mobile platforms, a development much more efficient and with efforts focused on the user experience. This technology uses Javascript as programming language and Facebook React as a basis for development. The system is similar to other CS apps such as iNaturalist. Namely, the overall observations improve the quality of the ranking through positive feedback from the community, strengthening the network of interactions between users and encouraging active participation. On the other hand, the application allows users to access all previously stored observations, which, in turn, can suggest improvements to that particular observation. Furthermore, observations without a correct ID can be stored until others can suggest a correct identification, maximizing the value of individual observations and data gathered. An important aspect of this mobile application is the participation of a network of experts on this plant family, allowing a rapid and accurate verification of individual observations. This team of Bignoniaceae experts is also able to make full use of the data gathered by correlating climate and phenological patterns. Results from these analyses are provided to the citizens gathering the data which will, in turn, stimulate the collection of new data, especially in poorly sampled locations. This is a very dynamic mobile application, that aims to engage the civil society with true scientific research, stimulating the management of natural resources and conservation efforts. Through this mobile app, we hope to engage the general public into biodiversity studies by improving their knowledge on an iconic group of Brazilian plants, while contributing data for scientific studies. The system is expected to be released in May and will be available at ipesdobrasil.org.br.

Temporal variation in reproductive costs and payoffs shapes the flowering strategy of a neotropical milkweed, Asclepias curassavica

AbstractA central goal of evolutionary ecology is to understand the factors that select for particular life history strategies, such as delaying reproduction. For example, environmental variation and reproductive costs to survival and growth often select for reproductive delays in semelparous and iteroparous species. In this study, we examine how variation in reproductive cost, which we define as a reduction to growth, survival, or future reproduction after a reproductive event, may select for reproductive delay in an iteroparous Neotropical milkweed with no obvious reproductive season. We analyzed demographic data collected every 3 months for 3 years from four populations of Asclepias curassavica in Monteverde, Costa Rica. We detected costs of flowering to survival and growth that varied in magnitude between our 12 transition periods without a seasonal pattern. The populations also exhibited temporal variation in reproductive payoffs measured as seedling establishment. We incorporated these reproductive costs into demographic projection models, which predicted a delayed flowering strategy only when we included temporal variation in costs and payoffs. Temporal variation in reproductive costs and payoffs is an important selective force in the evolution of delayed flowering in iteroparous species. Further, a lack of predictable seasonal pattern to reproductive costs and payoffs may contribute to the lack of seasonal reproductive patterns observed in our study species and other Neotropical species.

The roles of rainfall, soil properties, and species traits in flowering phenology along a savanna-seasonally dry tropical forest gradient

We investigated flowering phenology in a semiarid macroclimate along an environmental gradient encompassing neotropical savanna, transition, and seasonally dry tropical forest (SDTF) areas in the Chapada Diamantina Mountains, northeastern Brazil. We expected to find divergence in flowering patterns between the plant communities studied that would be explained by distinct functional traits selected by differences in rainfall volumes and soil properties. Bud and flower productions were monitored in 809 individuals between January 2010 and March 2012. The savanna exhibited a continuous flowering pattern, while the transition and SDTF areas showed seasonal flowering associated with rainfall. Environmental variables and plant traits (wood densities, water potentials, and water storage capacities) were related to the observed flowering strategies of woody species. The high diversity of functional groups in the savanna was determined by higher plant water potentials that were related to low wood densities and the availability of soil water. The role of rainfall, especially the rainfall volumes during the dry season, is critical in defining different flowering patterns at the community level. The physical properties of the soil selected the presence of species with distinct water-use strategies (low wood density species in savanna areas, and high wood density species in the transition zone and forest), which in turn affected their flowering.

Alterations in flowering strategies and sexual allocation of Caragana stenophylla along a climatic aridity gradient.

Plant can alter reproductive strategies for adaptation to different environments. However, alterations in flowering strategies and sexual allocation for the same species growing in different environments still remain unclear. We examined the sexual reproduction parameters of Caragana stenophylla across four climatic zones from semi-arid, arid, very arid, to intensively arid zones in the Inner Mongolia Steppe, China. Under the relatively favorable climatic conditions of semi-arid zone, C. stenophylla took a K-strategy for flowering (fewer but bigger flowers, and higher seed set). In contrast, under the harsher climatic conditions of intensively arid zone, C. stenophylla took an r-strategy for flowering (more but smaller flowers, and lower seed set). In arid and very arid zones, C. stenophylla exhibited intermediate flowering strategies between K- and r-strategies. In semi-arid, arid and very arid zones, sexual allocation and sexual allocation efficiency (SAE) of C. stenophylla were high, and the population recruitment might be mainly through sexual reproduction; in intensively arid zone, however, sexual allocation and SAE were very low, seed production was very limited, and clonal reproduction might compensate for the decrease in sexual reproduction. Our results suggested that C. stenophylla adapted to the climatic aridity gradient by alterations in flowering strategies and reproductive allocation.

Pair-approximation analyses of evolutionarily stable strategies for flowering time in clonal monocarpic plants

Clonal plants can employ two distinct reproductive strategies, clonal and sexual reproduction. Bamboos are monocarpic clonal plants that flower after a long-term clonal reproduction, and then die after seed production. To explore the effect of spatial structure formed through clonal reproduction on the evolution of such long flowering intervals, we developed a model for population growth of clonal plants on a regular lattice. We applied the pair-approximation that enables us to obtain a closed form of the dynamics. We derived the condition that an infinitely long flowering interval (a pure clonal strategy) or annual flowering strategy became an evolutionarily stable strategy. We demonstrate that localized dispersal broadens the region in which finite flowering interval evolves. Our finding highlights the importance to take into account the spatial structure on the studies of life history strategy in clonal plants.

Strategies of flowering in dioecious plants in tropical coastal vegetation, Brazil

Dioecious species are dependent on pollen vectors for sexual reproductive success. Male and female plants can express different blooming strategies, which respectively favour pollen donation and reception. This study characterised the flowering phenology of ten dioecious species, with different floral resources and pollination systems. The study focused on an area of sandy coastal plain in southeastern Brazil. We evaluated flowering events of male and female plants, in addition to the distribution of species flowering periods over 2 years. Regardless of the dependence upon biotic pollinators, all species shared the following traits: a single or a more expressive flowering event per year, with a duration ranging from intermediate to long, a high percentage of activity and intensity and high synchronism rates for intra- and inter-sexual morphs. In most species, males flowered first and more intensely following a sex allocation perspective. The flowering periods of dioecious species were randomly distributed throughout the year, preventing the identification of phenological drivers. The results suggest that the biotic (floral resources, pollen vector), abiotic (temperature, precipitation, day length) and phylogenetic factors do not seem to explain the observed flowering strategies. Since the restinga is a geologically recent tropical environment, the phenological attributes of the dioecious species possibly reflect the individual patterns of colonising species more than it does the interactions among them and with the environment.

The evolution of flowering strategies in US weedy rice.

• Local adaptation in plants often involves changes in flowering time in response to day length and temperature. Many crops have been selected for uniformity in flowering time. In contrast, variable flowering may be important for increased competitiveness in weed species invading the agricultural environment. Given the shared species designation of cultivated rice (Oryza sativa) and its the invasive conspecific weed, weedy rice, we assessed the extent to which flowering time differed between these groups. We further assessed whether genes affecting flowering time variation in rice could play a role in the evolution of weedy rice in the United States.• We quantified flowering time under day-neutral conditions in weedy, cultivated, and wild Oryza groups. We also sequenced two candidate gene regions: Hd1, a locus involved in promotion of flowering under short days, and the promoter of Hd3a, a locus encoding the mobile signal that induces flowering.• We found that flowering time has diverged between two distinct weedy rice groups, such that straw-hull weeds tend to flower earlier and black-hull awned weeds tend to flower later than cultivated rice. These differences are consistent with weed Hd1 alleles. At both loci, weeds share haplotypes with their cultivated progenitors, despite significantly different flowering times.• Our phenotypic data indicate the existence of multiple flowering strategies in weedy rice. Flowering differences between weeds and ancestors suggest this trait has evolved rapidly. From a weed management standpoint, there is the potential for overlap in flowering of black-hull awned weeds and crops in the United States, permitting hybridization and the potential escape of genes from crops.

Flowering phenology in Solidago altissima: adaptive strategies against temporal variation in temperature

The evolution of flowering phenology is the result of a trade-off that balances many factors, including growth, reproductive capacity, and temporal overlap with pollinators. When there is large temporal variation in temperature, particularly in the onset of frost, the optimum flowering strategy will vary from year to year. In Duluth, MN, USA, the end of the growing season can vary by more than 30 days. In this study, we observed flowering phenology and pollinator abundance on 15 genotypes of Solidago altissima in Duluth, MN. We predicted that temporal variation in temperature would lead to a range of flowering strategies in the S. altissima population; some genotypes flower early and in synchrony, some ‘hedge their bets’ by flowering over a range of dates, and others have an intermediate strategy. Our results indicate that genotypes vary in mean flowering date and duration of flowering and, for the two observed years, pollinator abundance was highest for early-flowering genotypes.

Abiotic and biotic changes due to spread ofBrachypodium genuense(DC.) Roem. & Schult. in sub-Mediterranean meadows

The present research deals with the impact of the invasive species Brachypodium genuense in central Apennine meadows. The study compares meadows under different management types (mown versus abandoned). B. genuense spread in the abandoned condition alters the ecological status of the site. It lowers soil temperature, moisture and pH, while it increases soil C/N ratio and litter production. In terms of biotic features, phenological analysis indicated that the abandoned condition is less rich in flowering species and individuals in each analysed date. We observed a less affected temporal niche (during the first phase of B. genuense leaf growth) and two strongly influenced phases (in early spring and in correspondence with phases when B. genuense flowers and has full growth of leaves). Functional trait analysis indicated that species with runners, ability to form patches, and late flowering strategies benefit from B. genuense spread, whereas species marked by storage organs, small size, and early flowering s...

Size‐dependent flowering and costs of reproduction affect population dynamics in a tuberous perennial woodland orchid

Summary 1. In woodland herbs, the probability of flowering and costs associated with reproduction may strongly depend on environmental context (shade vs. light habitats) and on plant size. This may be particularly true for tuberous orchids that inhabit woodlands, as the amount of incoming radiation and total leaf area strongly determine photosynthetic capacity and hence the amount of carbohydrates that can be relocated to below‐ground storage organs that form next year’s rosette and flowering stalk. 2. To fully comprehend the impact of size‐dependent reproduction on population dynamics under varying light conditions, life cycle models should therefore include plant size in a continuous manner. In this study, annual changes in plant size and demographic behaviour of the tuberous perennial orchid Orchis purpurea were monitored during seven consecutive years (2003–2009) in open and shaded woodland. Integral projection models (IPMs) and life table response experiments (LTRE) were used to investigate the extent to which variation in plant size affected the overall population dynamics of this species and to decompose differences in population growth rates between populations of open and shaded woodland into contributions from growth, survival and reproduction. 3. Both plants in shaded and light environments needed to be a certain size to initiate flowering, but this threshold size was almost three times as large in shaded environments as in light environments. Plants in open woodlands flowered more frequently over the years, showed less size regression after flowering and produced significantly more fruits than plants in shaded environments, resulting in significantly larger population growth rates. 4. Our life cycle models revealed that costs of reproduction, measured at the population‐level, were small in the light environment, and more than buffered by the increase in survival of flowering plants compared to non‐flowering plants. In the shade environment, however, the costs of reproduction were significant and made the difference between a stable (current) and a growing (without reproduction costs) population. 5. Synthesis. Light penetration to the soil is a key variable determining population dynamics of woodland orchids. Our analyses show that differences in vital rates related to size‐dependent reproduction (flowering) and growth are essential drivers of changes in orchid population dynamics in different light environments. The combination of IPMs and LTREs thus proves to be very useful when studying the fitness consequences of size‐ and context‐dependent phenomena like flowering strategies and costs of reproduction.