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Author  |
Arnott, J. T. |

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Title |
Growth Response of White and Englemann Spruce Seedlings to Extended Photoperiod Using Three Light Intensities |
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Year |
1982 |
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Technical Report: Pacific Forestry Centre |
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Plants |
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Four seedlots of white spruce (Picea glauca (Moench) Voss) and three of Engelmann spruce (Picea engelmannii Parry), covering a range of 10 degrees of latitude and a range of altitudes, were sown in BC/ CFS Styroblocks and grown in a heated greenhouse and an unheated shadehouse, using incandescent light to provide a 19-h photoperiod. Four intensities of lighting were used: 0, 100,200, and 400 Ix. A second experiment with the same seedlots was conducted in growth rooms that were programmed to evaluate the effect of low night temperature on seedling shoot growth when the photoperiod was extended to 19 h, using a light intensity of 200 Ix.
Shoot length of white and Engelmann spruce seedlings grown under an extended daylength of 100 Ix were significantly taller than the control (0 Ix). There were no significant differences in shoot length or weight among the three intensities of light used to extend the photoperiod for all seedlots except the southern latitude-low elevation population of Engelmann spruce. The more northern populations of white spruce and the high altitude populations of Engelmann spruce did not require light intensities higher than 100 Ix to maintain apical growth. Low night temperature (7°C) did produce significantly smaller seedlings than the warm night (1SoC) regime. However, terminal resting buds of seedlings grown under the cool night regime did not form any sooner than on those seedlings grown under warm nights. |
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IDA @ intern @ |
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2372 |
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Author  |
Ben-Attia, M.; Reinberg, A.; Smolensky, M.H.; Gadacha, W.; Khedaier, A.; Sani, M.; Touitou, Y.; Boughamni, N.G. |

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Title |
Blooming rhythms of cactus Cereus peruvianus with nocturnal peak at full moon during seasons of prolonged daytime photoperiod |
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Journal Article |
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Year |
2016 |
Publication |
Chronobiology International |
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Chronobiol Int |
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33 |
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4 |
Pages |
419-430 |
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Plants; Moonlight |
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Abstract |
Cereus peruvianus (Peruvian apple cactus) is a large erect and thorny succulent cactus characterized by column-like (cereus [L]: column), that is, candle-shaped, appendages. For three successive years (1100 days), between early April and late November, we studied the flowering patterns of eight cacti growing in public gardens and rural areas of north and central Tunisia, far from nighttime artificial illumination, in relation to natural environmental light, temperature, relative humidity and precipitation parameters. Flower blooming was assessed nightly between 23:00 h and until at least 02:00 h, and additionally around-the-clock at ~1 h intervals for 30 consecutive days during the late summer of each year of study to quantify both nyctohemeral (day-night) and lunar patterns. During the summer months of prolonged daytime photoperiod, flower blooming of C. peruvianus exhibited predictable-in-time variation as “waves” with average period of 29.5 days synchronized by the light of the full moon. The large-sized flower (~16 cm diameter) opens almost exclusively at night, between sunset and sunrise, as a 24 h rhythm during a specific 3-4-day span of the lunar cycle (full moon), with a strong correlation between moon phase and number and proportion of flowers in bloom (ranging from r = +0.59 to +0.91). Black, blue and red cotton sheets were used to filter specific spectral bands of nighttime moonlight from illuminating randomly selected plant appendages as a means to test the hypothesis of a “gating” 24 h rhythm phenomenon of photoreceptors at the bud level. Relative to control conditions (no light filtering), black sheet covering inhibited flower bud induction by 87.5%, red sheet covering by 46.6% and blue sheet covering by 34%, and the respective inhibiting effects on number of flowers in bloom were essentially 100%, ~81% and ~44%. C. peruvianus is a unique example of a terrestrial plant that exhibits a circadian flowering rhythm (peak ~00:00 h) “gated” by 24 h, lunar 29.5-day (bright light of full moon) and annual 365.25-day (prolonged summertime day length) environmental photoperiod cycles. |
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e Departement des Sciences de la Vie, Faculte des Sciences de Bizerte , Universite de Carthage , Zarzouna , Tunisie |
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0742-0528 |
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PMID:27030087 |
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LoNNe @ kyba @ |
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1411 |
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Bennie, J.; Davies, T.W.; Cruse, D.; Gaston, K.J. |

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Title |
Ecological effects of artificial light at night on wild plants |
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Journal Article |
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2016 |
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Journal of Ecology |
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J Ecol |
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104 |
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3 |
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611-620 |
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Plants; wild plants; photobiology; Circadian; Ecophysiology; light cycles; light pollution; photoperiodism; photopollution; physiology; sky glow; urban ecology |
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1.Plants use light as a source of both energy and information. Plant physiological responses to light, and interactions between plants and animals (such as herbivory and pollination), have evolved under a more or less stable regime of 24-hour cycles of light and darkness, and, outside of the tropics, seasonal variation in daylength.
2.The rapid spread of outdoor electric lighting across the globe over the past century has caused an unprecedented disruption to these natural light cycles. Artificial light is widespread in the environment, varying in intensity by several orders of magnitude from faint skyglow reflected from distant cities to direct illumination of urban and suburban vegetation.
3.In many cases artificial light in the nighttime environment is sufficiently bright to induce a physiological response in plants, affecting their phenology, growth form and resource allocation. The physiology, behaviour and ecology of herbivores and pollinators is also likely to be impacted by artificial light. Thus, understanding the ecological consequences of artificial light at night is critical to determine the full impact of human activity on ecosystems.
4.Synthesis. Understanding the impacts of artificial nighttime light on wild plants and natural vegetation requires linking the knowledge gained from over a century of experimental research on the impacts of light on plants in the laboratory and greenhouse with knowledge of the intensity, spatial distribution, spectral composition and timing of light in the nighttime environment. To understand fully the extent of these impacts requires conceptual models that can (i) characterise the highly heterogeneous nature of the nighttime light environment at a scale relevant to plant physiology, and (ii) scale physiological responses to predict impacts at the level of the whole plant, population, community and ecosystem. |
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Environment and Sustainability Institute, University of Exeter, Penryn, United Kimgdom; j.j.bennie(at)exeter.ac.uk |
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Wiley |
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0022-0477 |
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IDA @ john @ |
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1350 |
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Bennie, J.; Davies, T.W.; Cruse, D.; Inger, R.; Gaston, K.J. |

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Cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem |
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Journal Article |
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2015 |
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Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |
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Philos Trans R Soc Lond B Biol Sci |
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2015 |
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20140131 |
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Ecology; light pollution; photopollution; artificial light at night; biotic interactions; community-level; bottom-up effects; grasslands; herbivores; invertebrates; pea aphid; Acyrthosiphon pisum; plants; insects |
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Artificial light at night has a wide range of biological effects on both plants and animals. Here, we review mechanisms by which artificial light at night may restructure ecological communities by modifying the interactions between species. Such mechanisms may be top-down (predator, parasite or grazer controlled), bottom-up (resource-controlled) or involve non-trophic processes, such as pollination, seed dispersal or competition. We present results from an experiment investigating both top-down and bottom-up effects of artificial light at night on the population density of pea aphids Acyrthosiphon pisum in a diverse artificial grassland community in the presence and absence of predators and under low-level light of different spectral composition. We found no evidence for top-down control of A. pisum in this system, but did find evidence for bottom-up effects mediated through the impact of light on flower head density in a leguminous food plant. These results suggest that physiological effects of light on a plant species within a diverse plant community can have detectable demographic effects on a specialist herbivore. |
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Environment and Sustainability Institute, University of Exeter, Penryn TR10 9FE, UK; k.j.gaston@exeter.ac.uk |
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Royal Society |
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The biological impacts of artificial light at night: from molecules to communities |
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IDA @ john @ |
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1128 |
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Author  |
Bennie, J.; Davies, T.W.; Cruse, D.; Inger, R.; Gaston, K.J.; Lewis, O. |

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Title |
Artificial light at night causes top-down and bottom-up trophic effects on invertebrate populations |
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Journal Article |
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2018 |
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Journal of Applied Ecology |
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J Appl Ecol |
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55 |
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6 |
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2698-2706 |
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Ecology; Animals; Plants |
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Globally, many ecosystems are exposed to artificial light at night. Nighttime lighting has direct biological impacts on species at all trophic levels. However, the effects of artificial light on biotic interactions remain, for the most part, to be determined.
We exposed experimental mesocosms containing combinations of grassland plants and invertebrate herbivores and predators to illumination at night over a 3‐year period to simulate conditions under different common forms of street lighting.
We demonstrate both top‐down (predation‐controlled) and bottom‐up (resource‐controlled) impacts of artificial light at night in grassland communities. The impacts on invertebrate herbivore abundance were wavelength‐dependent and mediated via other trophic levels.
White LED lighting decreased the abundance of a generalist herbivore mollusc by 55% in the presence of a visual predator, but not in its absence, while monochromatic amber light (with a peak wavelength similar to low‐pressure sodium lighting) decreased abundance of a specialist herbivore aphid (by 17%) by reducing the cover and flower abundance of its main food plant in the system. Artificial white light also significantly increased the food plant's foliar carbon to nitrogen ratio.
We conclude that exposure to artificial light at night can trigger ecological effects spanning trophic levels, and that the nature of such impacts depends on the wavelengths emitted by the lighting technology employed.
Policy implications. Our results confirm that artificial light at night, at illuminance levels similar to roadside vegetation, can have population effects mediated by both top‐down and bottom‐up effects on ecosystems. Given the increasing ubiquity of light pollution at night, these impacts may be widespread in the environment. These results underline the importance of minimizing ecosystem disruption by reducing light pollution in natural and seminatural ecosystems. |
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0021-8901 |
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NC @ ehyde3 @ |
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2086 |
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