Bloom Phenology Research Articles

Abundancia de colibríes y uso de flores en un bosque templado del sureste de México

Hummingbird abundance varies with plant bloom phenology used for feeding. However, the information on hummingbird-flower interaction is limited for tropical mountain environments. We evaluated hummingbird abundance using mist nest and estimated monthly flowering phenology visited by hummingbirds in three different habitats (oak forest, cloud forest and bush) from January to August 2010 in Huitepec Ecological Reserve. We recorded four hummingbird species (Hylocharis leucotis, Lampornis amethystinus, Lamprolaima rhami and Eugenes fulgens), and their abundance varied among habitats (H3.8=14.8, p=0.001). Seven plant species were visited for hummingbirds and showed the highest number of flower species during dry season. Bush had the highest blossom. Fuchsia paniculata had the highest blossom period but only was visited by H. leucotis. Passiflora membranacea was the only species visited for all hummingbird species. The only positive association was E. fulgens abundance with P.a membranacea bloom (r(S)=0.93, p=0.02). Hummingbird abundance fluctuations in this study are determined for interactions with floral resources and their habitat distribution.

Predicting Flower Phenology and Viability of Highbush Blueberry

To maximize yield of pollination-dependent agricultural crops, farmers must ensure that sufficient pollinators are present when flowers are open and viable. We characterized and compared the lower development threshold temperature, bloom phenology, and flower viability of five common cultivars of highbush blueberry (Vaccinium corymbosum L.) to enable prediction of when flowers would be available for pollination. Threshold temperatures of all cultivars were found to be very similar and range between 7 and 8 °C. Logistic regression was used to characterize bloom phenology for all cultivars under field and greenhouse conditions. Bloom phenology under greenhouse conditions was delayed ≈100 growing degree-days when compared with field conditions. Average flower viability was determined daily from first flower opening until 5 days after flower opening for each cultivar. Results indicated declining flower viability with increasing flower age with most flowers unsuitable for pollination more than 4 days after opening. Implications of these results for planning pollination of highbush blueberry fields are discussed.

Consequences of Habitat Fragmentation for the Prairie-Endemic Weevil Haplorhynchites aeneus

Widespread destruction of tallgrass prairies in the midwestern United States has fragmented plant communities with the result that populations of endemic animal species have become geographically isolated from one another. The goal of the research summarized here was to evaluate the potential for conserving endemic prairie species of herbivorous insects by managing their host plants. Our study species was the weevil Haplorhynchites aeneus (Boehman), adults of which feed on pollen of plants in the genus Silphium (Asteraceae: Heliantheae). The female weevils clip the peduncles of flower heads and oviposit into the heads, where the larvae feed on the ovules. The research was conducted in 12 prairie sites in eastern Illinois. An allozyme analysis revealed that most populations of H. aeneus at the various prairie sites were genetically differentiated from one another, but the degree of differentiation was not associated with geographic distance between sites. Adult H. aeneus fed and oviposited on the plant species Silphium laciniatum L., S. integrifolium Michx., and S. terebinthinaceum Jacq, which differ in bloom phenology. There was no evidence of genetic differentiation of weevil populations with respect to host plant species, and adult weevils strongly preferred S. terebinthinaceum. We conclude that the oligophagous nature of the weevil assures its survival in small prairie remnants even where some of the host plant species are absent. Although H. aeneus can have a significant impact on reproduction of host plants by clipping flower heads, the perennial nature of Silphium species prevents their local extinction.

Contributions of meteorology to the phenology of cyanobacterial blooms: Implications for future climate change

Cyanobacterial blooms are often a result of eutrophication. Recently, however, their expansion has also been found to be associated with changes in climate. To elucidate the effects of climatic variables on the expansion of cyanobacterial blooms in Taihu, China, we analyzed the relationships between climatic variables and bloom events which were retrieved by satellite images. We then assessed the contribution of each climate variable to the phenology of blooms using multiple regression models. Our study demonstrates that retrieving ecological information from satellite images is meritorious for large-scale and long-term ecological research in freshwater ecosystems. Our results show that the phenological changes of blooms at an inter-annual scale are strongly linked to climate in Taihu during the past 23 yr. Cyanobacterial blooms occur earlier and last longer with the increase of temperature, sunshine hours, and global radiation and the decrease of wind speed. Furthermore, the duration increases when the daily averages of maximum, mean, and minimum temperature each exceed 20.3 °C, 16.7 °C, and 13.7 °C, respectively. Among these factors, sunshine hours and wind speed are the primary contributors to the onset of the blooms, explaining 84.6% of their variability over the past 23 yr. These factors are also good predictors of the variability in the duration of annual blooms and determined 58.9% of the variability in this parameter. Our results indicate that when nutrients are in sufficiently high quantities to sustain the formation of cyanobacterial blooms, climatic variables become crucial in predicting cyanobacterial bloom events. Climate changes should be considered when we evaluate how much the amount of nutrients should be reduced in Taihu for lake management.

Phenology of phytoplankton blooms in the Nova Scotian Shelf-Gulf of Maine region: remote sensing and modeling analysis

Remotely sensed ocean color data and numerical modeling have been used to study the phenology of both spring and fall phytoplankton blooms (FPBs) in the Nova Scotian Shelf (NSS)-Gulf of Maine (GoM) region. The ocean color data reveal a general pattern of westward progression of the spring phytoplankton bloom (SPB), and an eastward progression of the FPB in the NSS-GoM region. The spatial pattern of mean chlorophyll concentration in spring is similar to that in fall, with a lower concentration in the NSS and higher in the GoM. Interannually, there is a weak but significant tendency for years with earlier (delayed) SPBs to be followed by delayed (earlier) FPBs, but the mean chlorophyll concentrations during SPBs are not correlated with those during FPBs. The inter-annual variability of SPB timing is significantly correlated with sea surface salinity (SSS), but the FPB timing is correlated with both SSS and sea surface temperature. The process-oriented numerical modeling experiments suggest that (i) salinity is the main factor influencing the bloom timing and magnitude in the NSS-GoM region, especially for the timing of SPBs; (ii) compared to buoyancy forcing induced by vertical salinity gradients, the impact of surface heating and surface wind stress on the blooms variability is much weaker; and (iii) the nutrient level controls the bloom magnitude, but only has a minor effect on bloom timing. This study provides a quantitative estimation of relationship between changes in local/ remote environmental forcing and phytoplankton phenological shifts, thus improving our understanding on the possible impact of climate change on coastal/shelf ecosystems.

Impacts of Climate Change on Narragansett Bay

Abstract The objective of this paper is to examine the impacts of global climate change on Rhode Island's coastal ecosystems. Average annual air temperature in Rhode Island has increased by 1.7 °C since 1880, water temperatures of Narragansett Bay have increased by 1.2 °C since 1950, precipitation increased 27% between 1895 and 1999, and sea level rose 0.13 m between 1931 and 2007. We can already see the effects of these climatic changes on the Narragansett Bay ecosystem, including ecological changes in the Bay's food web from phytoplankton and Zooplankton to fish, e.g., changes in phenology of seasonal phytoplankton blooms and dominant fish species (e.g., Pseudopleuronectes americanus [Winter Flounder]). These climatic changes have increased freshwater inputs and the concomitant pollutant loads into the Bay. Rising sea level has contributed to ongoing erosion of the coast and has put waterfront homes at increased risk. It is imperative to continue monitoring these effects.

Spatial and Temporal Variability of Benthic Oxygen Demand and Nutrient Regeneration in an Anthropogenically Impacted New England Estuary

Strong benthic–pelagic coupling is an important characteristic of shallow coastal marine ecosystems. Building upon a rich history of benthic metabolism data, we measured oxygen uptake and nutrient fluxes across the sediment–water interface along a gradient of water column primary production in Narragansett Bay, RI (USA). Despite the strong gradients seen in water column production, sediment oxygen demand (SOD) and benthic nutrient fluxes did not exhibit a clear spatial pattern. Some of our sites had been studied in the 1970s and 1980s and thus allowed historical comparison. At these sites, we found that SOD and benthic fluxes have not changed uniformly throughout Narragansett Bay. In the uppermost portion of the bay, the Providence River Estuary, we observed a significant decrease in dissolved inorganic phosphorus fluxes which we attribute to management interventions. At another upper bay site, we observed significant declines in SOD and dissolved inorganic nitrogen fluxes which may be linked to climate-induced decreases in water column primary production and shifts in bloom phenology. In the 1970s, benthic nutrient regeneration supplied 50% to over 200% of the N and P needed to support primary production by phytoplankton. Summer nutrient regeneration in the Providence River Estuary and Upper bay now may only supply some 5–30% of the N and 3–20% of the P phytoplankton demand.

Continental‐scale phenology: warming and chilling

AbstractWith abundant evidence of recent climate warming, most vegetation studies have concentrated on its direct impacts, such as modifications to seasonal plant and animal life cycle events (phenology). The most common examples are indications of earlier onset of spring plant growth and delayed onset of autumn senescence. However, less attention has been paid to the implications of continued warming for plant species' chilling requirements. Many woody plants that grow in temperate areas require a certain amount of winter chilling to break dormancy and prepare to respond to springtime warming. Thus, a comprehensive assessment of plant species' responses to warming must also include the potential impacts of insufficient chilling.When collected at continental scale, plant species phenological data can be used to extract information relating to the combined impacts of warming and reduced chilling on plant species physiology. In this brief study, we demonstrate that common lilac first leaf and first bloom phenology (collected from multiple locations in the western United States and matched with air temperature records) can estimate the species' chilling requirement (1748 chilling hours, base 7.2 °C) and highlight the changing impact of warming on the plant's phenological response in light of that requirement. Specifically, when chilling is above the requirement, lilac first leaf/first bloom dates advance at a rate of − 5.0/− 4.2 days per 100‐h reduction in chilling accumulation, while when chilling is below the requirement, they advance at a much reduced rate of − 1.6/− 2.2 days per 100‐h reduction. With continental‐scale phenology data being collected by the USA National Phenology Network (http://www.usanpn.org), these and more complex ecological questions related to warming and chilling can be addressed for other plant species in future studies. Copyright © 2009 Royal Meteorological Society

Changes in Phytoplankton Biomass in the Western Scheldt Estuary During the Period 1978–2006

We investigated whether climate change results in long-term changes in phytoplankton biomass and phenology in a turbid eutrophic coastal plain estuary. Changes in annual mean chlorophyll a (chla) concentrations were studied for the period 1978–2006 in the eutrophic and turbid macro-tidal Western Scheldt estuary. Three stations were investigated: WS1, at the mouth of the estuary; station WS6, halfway up the estuary; and station WS11, near the Dutch–Belgian border near the upstream end of the estuary. No significant long-term changes in yearly averaged chla concentrations were observed in WS1 and WS6, but in WS11 the phytoplankton biomass decreased considerably. This is most likely due to an increase in grazing pressure as a result of an improvement in the dissolved oxygen concentrations. Spectral analyses revealed a possible periodicity of 7 years in the mean chla which was related to periodicity in river discharge. We also observed strong phenological responses in the timing of the spring/summer bloom which were related to a well-documented increase in the temperature in the estuary. The fulcrum, the center of gravity or the day at which 50% of the cumulative chla was reached during the year, advanced by 1–2 days/year. A similar trend was observed for the month in which the maximum bloom was observed, with the exception of station WS1. All stations showed an earlier initiation of the bloom, whereas the day at which the phytoplankton bloom was terminated also moved forward in time excepted for WS11. As a result, the bloom length decreased at station WS1, remained the same at station WS6, and increased at WS11. This complicated pattern in bloom phenology demonstrates the complex nature of ecosystem functioning in estuaries.

Gulf Stream position and winter NAO as drivers of long-term variations in the bloom phenology of the diatom Skeletonema costatum "species-complex" in Narragansett Bay, RI, USA

Bloom behavior of the Skeletonema costatum species-complex, a keystone diatom cluster, in Narragansett Bay (NBay), USA, during a 39 - year (1959-1997) time series was statistically related to variations in the path and latitudinal position of the north wall of the Gulf Stream (GSNW). Winter-spring abundance of the Skeletonema complex was ca. 10-fold greater in years when the GSNW was displaced to the south; summer abundance was 3-fold higher in years of southerly displaced GSNW flow. The relationships with the North Atlantic Oscillation (NAO), the influence of temperature on growth and grazing of Skeletonema and the advective connectivity of NBay with contiguous regional waters potentially impacted by GSNW dynamics are evaluated. The two major, regionally coupled ocean-atmosphere systems, the NAO and the GSNW, differ in their seasonal and interannual impacts and do not directly explain the specific causes of the associated variations in bloom behavior of the Skeletonema complex. Summer bloom behavior was correctly forecast in 14 of 17 years based on advanced predictions of GSNW position at its extreme northern (GSNWI > + 0.5) and southern (GSNW < - 0.5) latitudinal limits.

Copepod life cycle adaptations and success in response to phytoplankton spring bloom phenology

AbstractIn a seasonal environment, the timing of reproduction is usually scheduled to maximize the survival of offspring. Within deep water bodies, the phytoplankton spring bloom provides a short time window of high food quantity and quality for herbivores. The onset of algal bloom development, however, varies strongly from year to year due to interannual variability in meteorological conditions. Furthermore, the onset is predicted to change with global warming. Here, we use a long‐term dataset to study (a) how a cyclopoid copepod, Cyclops vicinus, is dealing with the large variability in phytoplankton bloom phenology, and (b) if bloom phenology has an influence on offspring numbers. C. vicinus performed a two‐phase dormancy, that is, the actual diapause of fourth copepodid stages at the lake bottom is followed by a delay in maturation, that is, a quiescence, within the fifth copepodid stage until the start of the spring bloom. This strategy seems to guarantee a high temporal match of the food requirements for successful offspring development, especially through the highly vulnerable naupliar stages, with the phytoplankton spring bloom. However, despite this match with food availability in all study years, offspring numbers, that is, offspring survival rates were higher in years with an early start of the phytoplankton bloom. In addition, the phenology of copepod development suggested that also within study years, early offspring seems to have lower mortality rates than late produced offspring. We suggest that this is due to a longer predator‐free time period and/or reduced time stress for development. Hence, within the present climate variability, the copepod benefited from warmer spring temperatures resulting in an earlier phytoplankton spring bloom. Time will show if the copepod's strategy is flexible enough to cope with future warming.

Diagnostic Properties of Phytoplankton Time Series from Remote Sensing

Remote sensing provides our only window into the phytoplankton community on synoptic scales, permitting the construction of spatially distributed time series of biomass indexed as chlorophyll concentration. Data from the SeaWiFS mission have accumulated to the point where they meet the criterion of a 10-year series. The seasonal phytoplankton cycle is the dominant mode of temporal variability. The time series can be used to construct a variety of ecological indicators of the pelagic system useful in ecosystem-based management. These are reviewed and examples of their implementation are presented. Phenology of phytoplankton blooms is given particular attention. Interannual variation in some of the indicators is strong, presumably a response to variation in large-scale forcing. Examination of the results in the context of a simple phytoplankton-nutrient model enhances the interpretation. Remote sensing imagery also lends itself to the retrieval of information on community structure, in addition to biomass. More information will be recovered from satellite imagery if the remote-sensing program is coupled closely to a ship program on which appropriate bio-optical observations are made. The data series can be distilled to yield concise descriptions of the unfolding of ecosystem characteristics through time.

The phenology of phytoplankton blooms: Ecosystem indicators from remote sensing

Remote sensing offers many advantages in the development of ecosystem indicators for the pelagic zone of the ocean. Particularly suitable in this context are the indicators arising from time series that can be constructed from remotely sensed data. For example, using ocean-colour radiometry, the phenology of phytoplankton blooms can be assessed. Metrics defined in this way show promise as informative indicators for the entire pelagic ecosystem. A simple phytoplankton–substrate model, with forcing dependent on latitude and day number is used to explore the qualitative features of bloom phenology for comparison with the results observed in a suite of 10-year time series of chlorophyll concentration, as assessed by remote sensing, from the Northwest Atlantic Ocean. The model reveals features of the dynamics that might otherwise have been overlooked in evaluation of the observational data.

Resilience of North Sea phytoplankton spring bloom dynamics: An analysis of long‐term data at Helgoland Roads

Analyzing one of the most extensive long‐term data series in the North Sea, the Helgoland Roads time series, we investigated the changes in the factors that potentially drive phytoplankton bloom dynamics in the German Bight. We compared the changes in these factors with the changes in the spring bloom phenology. We combined zooplankton, nutrient, weather, and phytoplankton data to analyze whether there has been a shift in trophic interactions in the North Sea affecting the spring bloom timing. The potential influence of temperature, with a mean increase of 1.5°C, was investigated. We showed that the German Bight around Helgoland is a highly dynamic system and has undergone considerable change in the last 30 yr. Nutrient levels, temperature, underwater light climate and wind speed have all changed. However, the spring bloom dynamics have hardly changed at all. We showed that the spring bloom tends to come later in warmer years but that this is not directly correlated with the overall warming trend. The known regime shift of the late 1980s is clearly visible in our data in terms of average phytoplankton winter densities and average cell size, but even so the start of the spring bloom has not changed.

Effects of immaturity on productivity and nut quality in pistachio (Pistacia vera L.)

SummaryImmature trees of pistachio (Pistacia vera L.), a dioecious species, exhibit major cropping problems; in particular, insufficient male bloom and low yields of poor quality nuts. The aims of this research were to elucidate the extent of pollen limitation and factors that affect pollination and fruit-set during this precarious period. The experiment was conducted in a 4 year-old, 57 ha orchard, in the southwest of the San Joaquin Valley, California. Female trees of the cultivar ‘Kerman’ and trees of the male cultivar ‘Peters’ were interplanted at a ratio of 1:24. Bloom phenology was recorded visually. Supplementary pollination treatments, using electrostatic and non-electrostatic methods, were applied to the female trees and compared to open-pollination. Pollen density in the air was analysed during the application of the treatments. The following results were found: male and female bloom completely overlapped, although pollen availability became a limiting factor early in the flowering period; supplementary pollination significantly increased pollen flow, while pollen levels were extremely low in open-pollination; supplementary pollination, and electrostatic pollination in particular, significantly increased pollen germination on the stigma, and reduced the level of blank nuts. In conclusion, pollination was found to be a limiting factor in immature pistachio trees. It is suggested that, in some cases, electrostatic pollination could supplement natural pollination, thereby ensuring higher yields with better nut quality. However, poor levels of pollen alone could not account for all the differences in cropping between immature and mature pistachio trees.

The Study of Pollen Development in Nine Cultivars of Hazelnut (Corylusavellana)

Pollen development is an important event in plant reproduction. Hazelnut (Corylus avellana) male flower differentiation starts in summer and pollen shed is in the winter. Hazelnut pollen shed can vary up to 3 months between early to late flowering genotypes. Microsporogenesis and microgametogenesis of hazelnut is not well understood. Pollen development and differentiation of nine genotypes, representing early to late blooming cultivars from the National Clonal Germplasm Repository in Corvallis, Ore., were studied. Catkins were collected weekly from Aug. to Nov. 2002. Tissue sections were examined under the light microscope. Microsporogenesis was divided into five stages: archesporial cells, sporogenous cells and parietal layers, pollen mother cells (PMC), tetrads, and microspores. Microgametogenesis was distinguished between young pollen grains (uninucleate) and mature pollen grains (binucleate). On 4 Aug., cultivars were at different developmental stages of microsporogenesis. Early blooming cultivars had PMCs present. Later-blooming cultivars only contained archesporial cells. PMCs were present in all cultivars by 22 Aug. Microspores were observed on 26 Sept. in all cultivars. This study contributes to a better understanding of male gametophyte development in hazelnut, which has increased our ability to correlate hazelnut pollen development with bloom phenology.

Floral biology, pollination and fertilisation in temperate zone fruit species and grape. * Kozma P, Nyeki J, Soltesz M, Szabo Z. 2003. * Budapest: Akademiai Kiado. $98 (hardback).621 pp.

The primary focus of this book is to discuss the floral biology of the fruit crops including apple, grape, Ribes, Rubus, strawberry, the stone fruits and several nut species. The emphasis is on horticultural aspects of reproductive biology and pollination ecology. The strong point of the book is the amount of information provided on the anatomy and morphology of floral structures, the different patterns of floral development and the types of crossing relationships in fruit crops. It begins with five overview chapters concerning the hormonal aspects of floral development, the morphology of pollen, stigmata and anthers, and descriptions of the types of floral injury. There is then a lengthy (150 pages) discussion of flower types in grapes, followed by a chapter on plantation design. The book then launches into a series of chapters describing individual crops, which vary somewhat in content due to multiple authors, but all provide comprehensive information on bloom phenology, levels of self-fertility and varietal compatibility groups. There is a wealth of information on types of mating systems and extensive lists are given on the fertility and inter-fertility of the common varieties grown. The book ends with a general discussion of bee pollination and the conditions that influence its effectiveness. The information provided in this book is heavily slanted towards the Hungarian and European literature on floral biology, but overall it is an excellent survey of literature not available anywhere else in English. Its English is a bit stilted as is often the case when chapters are translated, but in general it is understandable. The book is recommended to individuals interested in the planning of large-scale commercial plantations of temperate fruit crops, and those who are interested in detailed descriptions of the anatomy and morphology of plant reproductive structures.

DETECTING ENERGY-BALANCE MODIFICATIONS AT THE ONSET OF SPRING

The nature of energy-flux transitions during the onset of midlatitude spring has not been widely examined, despite their critical implications for global-scale biospheric measures and climate change. Further conventional assessment of these phenomena across multiple locations is restricted by satellite-derived data limitations, and the paucity of surface measurement sites. In this paper, we explore a new phenology-based strategy for evaluating the spring surface energy-balance shift that can address these concerns. Our technique can reflect native-species responses and atmospheric surface layer change at a variety of sites, using synoptic-scale first leaf and first bloom phenology models. We test the approach at three locations with diverse climates, and within a group of stations in the state of Oklahoma, which has moderate climate variations across an east-to-west gradient. The results show that the onset of spring in midlatitudes is a modally abrupt (rather than gradual) seasonal transition in terms of energy balance (sensible and latent heat levels) and carbon-flux change that can be linked directly to vegetation phenology. The consistent temporal pattern and magnitude of flux variations across diverse sites suggest that this technique has potential as a proxy for spring energy-balance change at many locations. [Key words: phenology, spring, energy balance, North America.]

Nectar quality in open-pollinated, pol CMS hybrid, and dominant SI hybrid oilseed summer rape

Nectar sugar composition and temporal patterns of nectar sugar production were examined in oilseed summer rape (Brassica napus L. ssp. oleifera (Metzg.)) from six open-pollinated, eight pol cytoplasmic male-sterile (CMS) hybrid and seven dominant self-incompatible (SI) hybrid cultivars at three field plot sites in Manitoba. The total sugar content of nectar samples was measured by the Dreywood anthrone reaction for total carbohydrate, and simple sugar composition was determined using an enzymatic bioanalysis for D-glucose, D-fructose and sucrose. Hybrid and open-pollinated cultivar flowers had similar sugar content. Mean total sugar content per flower also did not vary among hybrid breeding systems when compared within individual weeks of the bloom period or within daily sampling periods. However, for all cultivars, total nectar sugar content per flower was lower during the 08:00 and 11:00 h sampling periods and increased to maximum levels during the 14:00 and 16:00 h sampling periods. Significant differences in nectar sugar content were also found in relation to the bloom phenology of the cultivars. Cultivars produced the greatest amount of sugar per flower during the first 2 wk of the bloom period, then sugar production decreased in the third and fourth weeks. Nectar sugar ratios from all cultivars averaged approximately 1:1 glucose:fructose. Nectar glucose content among cultivars was similar but, among breeding systems, CMS cultivars tended to have lower amounts of glucose than SI or open-pollinated cultivars. Selecting for higher total sugar content may produce nectars more attractive to foraging honeybees (Apis mellifera L.), thereby ensuring adequate pollination of hybrid parental lines and F1 hybrid plants. Selecting for lower nectar glucose will produce honeys with more desirable granulation characteristics. Overall, the production and quality of nectar sugar in oilseed rape hybrids are similar to those of open-pollinated cultivars, and are not likely to adversely affect the pollinating activities of honeybees or their potential for honey production. Key words: oilseed summer rape, Brassica napus, honeybees, Apis mellifera, nectar, simple sugars

LAWS OF BLOOM PHENOLOGY BY APPLE

LAWS OF BLOOM PHENOLOGY BY APPLE