scholarly journals Early spring warming may hasten leaf emergence in Erythronium americanum

2019 ◽  
Vol 106 (10) ◽  
pp. 1392-1396
Author(s):  
Jack T. Tessier
Keyword(s):  
Early Spring ◽  
Spring Warming ◽  
Leaf Emergence ◽  
Erythronium Americanum

scholarly journals Depletion of gaseous polycyclic aromatic hydrocarbons by a forest canopy

2008 ◽  
Vol 8 (14) ◽  
pp. 4105-4113 ◽  
Author(s):  
S.-D. Choi ◽  
R. M. Staebler ◽  
H. Li ◽  
Y. Su ◽  
B. Gevao ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Forest Canopy ◽  
Sampling Site ◽  
High Volume ◽  
Early Spring ◽  
Eastern United States ◽  
Leaf Emergence ◽  
Deposition Velocities ◽  
Polycyclic Aromatic

Abstract. Rapid uptake of gaseous polycyclic aromatic hydrocarbons (PAHs) by a forest canopy was observed at Borden in Southern Ontario, Canada during bud break in early spring 2003. High volume air samples were taken on 12 individual days at three different heights (44.4, 29.1, and 16.7 m) on a scaffolding tower and on the forest floor below the canopy (1.5 m). Concentrations of PAHs were positively correlated to ambient temperature, resulting from relatively warm and polluted air masses passing over the Eastern United States and Toronto prior to arriving at the sampling site. An analysis of vertical profiles and gas/particle partitioning of the PAHs showed that gaseous PAHs established a concentration gradient with height, whereas levels of particulate PAHs were relatively uniform, implying that only the uptake of gaseous PAHs by the forest canopy was sufficiently rapid to be observed. Specifically, the gaseous concentrations of intermediate PAHs, such as phenanthrene, anthracene, and pyrene, during budburst and leaf emergence were reduced within and above the canopy. When a gradient was observed, the percentage of PAHs on particles increased at the elevations experiencing a decrease in gas phase concentrations. The uptake of intermediate PAHs by the canopy also led to significant differences in gaseous PAH composition with height. These results are the most direct evidence yet of the filter effect of forest canopies for gaseous PAHs in early spring. PAH deposition fluxes and dry gaseous deposition velocities to the forest canopy were estimated from the concentration gradients.

Primordia and leaf production in winter wheat, triticale, and rye under field conditions

1986 ◽  
Vol 64 (9) ◽  
pp. 1972-1976 ◽  
Author(s):  
L. A. Hunt ◽  
Anne-Marie Chapleau
Keyword(s):  
Winter Wheat ◽  
Triticum Aestivum L ◽  
Early Spring ◽  
Field Conditions ◽  
Late Winter ◽  
Winter Rye ◽  
Degree Days ◽  
Leaf Production ◽  
Winter Triticale ◽  
Leaf Emergence

Primordia production and leaf emergence were investigated in winter wheat (Triticum aestivum L. em Thell.) and two related species, winter rye (Secale cereale L.) and winter triticale (× Triticosecale Wittmack), under field conditions in Southern Ontario, a region with a humid continental climate. Primordia initiation could be adequately described by a linear regression of primordia number on accumulated degree-days in the 1st year of study, 1981 – 1982. In the 2nd year, however, a linear relationship was noticed only in the late winter and early spring, with the rate of primordia production being distinctly lower earlier in the season. The rate of primordia initiation was faster in the ryes than in the wheats, a superiority which was associated with greater spikelet production. Triticale had an intermediate rate of primordia initiation but was closer to wheat in the timing of double ridge and terminal spikelet formation. Leaves emerged at a constant rate (degree-days base) which was similar in most of the cultivars.

Elevational and spatial variation in daytime ozone concentrations in the Virginia Blue Ridge Mountains: implications for forest exposure

1989 ◽  
Vol 19 (4) ◽  
pp. 422-426 ◽  
Author(s):  
F. S. Gilliam ◽  
J. T. Sigmon ◽  
M. A. Reiter ◽  
D. O. Krovetz
Keyword(s):  
Deciduous Forest ◽  
Canopy Structure ◽  
Elevational Gradient ◽  
Early Spring ◽  
Early Summer ◽  
Deciduous Trees ◽  
Blue Ridge ◽  
Canopy Development ◽  
Leaf Emergence ◽  
Blue Ridge Mountains

Ozone (O3) concentrations before and during the early growing season were monitored continuously at two closely located areas in the Virginia Blue Ridge Mountains: a deciduous forest watershed (Shaver Hollow) and a predominantly open grassy meadow (Big Meadows). In addition, O3 concentrations and canopy development (percent leaf emergence) were measured simultaneously at three sites along the elevational gradient of the Shaver Hollow watershed. When the canopy at Shaver Hollow was leafless, patterns of O3 concentration were similar between the forest and meadow, increasing steadily toward early spring, with low variability of hourly daytime measurements. Greater differences in O3 concentration between forest and meadow and higher variability occurred during the period May-June, a time when the canopy changed from 15 to 100% leaf emergence. Several factors varying along the elevational gradient, related to both canopy structure and meteorological conditions, appeared to be important in affecting absolute O3 concentrations as well as the variability of daytime means in Shaver Hollow. The high metabolic activity of new leaves may act as a sink for O3; the canopy itself may act as a physical barrier to O3 transport, restricting mixing of O3 to intermittent bursts. The coincidence of seasonal increases in O3 concentration in late spring and early summer with the development of new leaves of dominant deciduous trees in this watershed suggests that O3 may represent a potential problem for eastern hardwood forests.

scholarly journals Depletion of gaseous polycyclic aromatic hydrocarbons by a forest canopy

2008 ◽  
Vol 8 (1) ◽  
pp. 2359-2380 ◽  
Author(s):  
S.-D. Choi ◽  
H. Li ◽  
Y. Su ◽  
B. Gevao ◽  
T. Harner ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Forest Canopy ◽  
Sampling Site ◽  
High Volume ◽  
Early Spring ◽  
Eastern United States ◽  
Leaf Emergence ◽  
Deposition Velocities ◽  
Polycyclic Aromatic

Abstract. Rapid uptake of gaseous polycyclic aromatic hydrocarbons (PAHs) by a forest canopy was observed at Borden in Southern Ontario, Canada during bud break in early spring 2003. High volume air samples were taken on 12 individual days at three different heights (44.4, 29.1, and 16.7 m) on a scaffolding tower and on the forest floor below the canopy (1.5 m). Concentrations of PAHs were positively correlated to ambient temperature, resulting from relatively warm and polluted air masses passing over the Eastern United States and Toronto prior to arriving at the sampling site. An analysis of vertical profiles and gas/particle partitioning of the PAHs showed that gaseous PAHs established a concentration gradient with height, whereas levels of particulate PAHs were relatively uniform, implying that only the uptake of gaseous PAHs by the forest canopy was sufficiently rapid to be observed. Specifically, the gaseous concentrations of intermediate PAHs, such as phenanthrene, anthracene, and pyrene, during budburst and leaf emergence were reduced within and above the canopy. When a gradient was observed, the percentage of PAHs on particles increased at the elevations experiencing a decrease in gas phase concentrations. The uptake of intermediate PAHs by the canopy also led to significant differences in gaseous PAH composition with height. These results are the most direct evidence yet of the filter effect of forest canopies for gaseous PAHs in early spring. PAH deposition fluxes and dry gaseous deposition velocities to the forest canopy were estimated from the concentration gradients.

BULB AND INFLORESCENCE DEVELOPMENT IN NERINE SARNIENSIS

1997 ◽  
Vol 45 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Jane Vishnevetsky ◽  
Hannah Lilien-Kipnis ◽  
Nazilia Azizbekova ◽  
Meira Ziv
Keyword(s):  
Leaf Growth ◽  
Rest Period ◽  
Early Spring ◽  
Annual Life Cycle ◽  
Inflorescence Development ◽  
Leaf Emergence ◽  
The Family ◽  
Bulbous Plant ◽  
Growing Conditions ◽  
Autumn Flowering

Nerine is an autumn flowering perennial bulbous plant native to southern Africa belonging to the family Amaryllidaceae. Irregular flowering is often encountered in commercial flower production. The annual life cycle ofNerine sarniensisis characterized by flowering in autumn prior to leaf emergence, active leaf growth during winter and early spring, followed by leaf senescence and a rest period during the hot dry summer. The objective of this study was to follow the ontogeny ofN. sarniensiscv. ‘Autumn Glory’ with special emphasis on differentiation and development of vegetative and generative apices under outdoor growing conditions in Israel. It was found that leaf development lasted approximately eleven months, with active leaf growth of up to five months, depending on the onset of high temperatures in late spring. For most of the year the bulb contains two inflorescences at different stages of development. Inflorescence development from initiation to anthesis lasted 21–22 months, i.e., active development occurred in the bulb during its rest period. Development was only arrested for approximately two months at the end of summer, just prior to flowering.

scholarly journals Transgenerational response to early spring warming in Daphnia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kenji Toyota ◽  
Maria Cambronero Cuenca ◽  
Vignesh Dhandapani ◽  
Antonio Suppa ◽  
Valeria Rossi ◽  
...  
Keyword(s):  
Early Spring ◽  
Spring Warming

scholarly journals The Species-Specific Responses of Freshwater Diatoms to Elevated Temperatures Are Affected by Interspecific Interactions

2018 ◽  
Vol 6 (3) ◽  
pp. 82 ◽  
Author(s):  
Yun Zhang ◽  
Chengrong Peng ◽  
Zhicong Wang ◽  
Jinli Zhang ◽  
Lijie Li ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Interspecific Interactions ◽  
Seasonal Succession ◽  
Early Spring ◽  
Mixed Cultures ◽  
Specific Response ◽  
Diatom Species ◽  
Interspecies Interactions ◽  
Spring Warming ◽  
Temperature Ranges

Numerous experimental simulations with different warming scenarios have been conducted to predict how algae will respond to warming, but their conclusions are sometimes contradictory to each other. This might be due to a failure to consider interspecific interactions. In this study, the dominant diatom species in a seasonal succession were isolated and verified to adapt to different temperature ranges by constant temperature experiment. Both unialgal and mixed cultures were exposed to two fluctuant temperature treatments that simulated the temperature variations from early spring to summer, with one treatment 4 °C higher (warming scenario) than the other. We found that the specific response of diatoms to warming was affected by interspecific interactions. Spring warming had no significant effect on eurythermal species and had a positive effect on the abundance of warm-adapted diatom species, but interspecific interactions reduced this promotional effect. Cold-adapted species had a negative response to spring warming in the presence of other diatom species but had a positive response to early spring warming in the absence of interspecific interactions. In addition, warming resulted in the growth of all diatom species peaking earlier in unialgal cultures, but this effect could be weakened or amplified by interspecies interactions in mixed cultures. Our results suggest that the specific diatom species with different optimal growth temperature ranges responding to warming were expected if there were no interspecific interactions. However, in natural environments, the inevitable and complex interspecific interactions will influence the responses of diatoms to warming. This important factor should not be ignored in the prediction of organism responses to climate warming.

Early spring mycobiota of pine litter needles.

2011 ◽  
Vol 63 (2) ◽  
pp. 153-161 ◽  
Author(s):  
Ondřej Koukol
Keyword(s):  
Early Spring
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