Sugar maple seedling carbon assimilation at the northern limit of its range: the importance of seasonal light

2010 ◽  
Vol 40 (2) ◽  
pp. 385-393 ◽  
Author(s):  
Matthew C. Kwit ◽  
Lesley S. Rigg ◽  
David Goldblum
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Carbon Assimilation ◽  
Frost Damage ◽  
Carbon Gain ◽  
Time Period ◽  
History Of ◽  
Short Time ◽  
Seedling Leaf

Using in situ light curves and understory seasonal light measurements the importance of canopy avoidance was evaluated for a population of sugar maple ( Acer saccharum Marsh.) seedlings living at the boreal ecotone in Lake Superior Provincial Park, Ontario, Canada. At higher latitudes, the time period associated with canopy avoidance is shorter and occurs at cooler temperatures, increasing the risk of frost damage. In 2008, leaf-out began 5 days prior to the last frost of the season. By modeling the potential carbon gain of seedlings, it is clear that the short time period prior to canopy leaf-out still contributes a disproportionate amount of carbon to the overall budget of seedlings. Of the total seasonal carbon gain, 80.6% was assimilated in the initial 15 days following sugar maple seedling leaf-out. Based on our model, by leafing out only 6 days earlier than the average seedling leaf-out date, ∼200% more carbon could be assimilated during the course of the growing season. Vegetation phenology is cued by climatic triggers — as climate changes so too will phenological responses. These mechanisms add to the overall carbon budget of seedlings; recognizing these mechanisms is essential to thoroughly understand the natural history of this species.

Short term nitrogen dynamics in a small Brazilian wetland (Lago Infernão, São Paulo)

1989 ◽  
Vol 5 (3) ◽  
pp. 323-335 ◽  
Author(s):  
Clive Howard-Williams ◽  
F. de Esteves ◽  
J. E. Santos ◽  
M. T. Downes
Keyword(s):  
N Uptake ◽  
Algal Community ◽  
Nitrifying Bacteria ◽  
Temperature Changes ◽  
Time Period ◽  
Uptake Rates ◽  
Eichhornia Azurea ◽  
Short Time ◽  
Epiphyte Community

ABSTRACTWe have studied a number of related processes of the nitrogen cycle in a Brazilian floodplain lake to identify the major pools and pathways over a short time period. The study was centred on the littoral zone dominated by the floating plantEichhornia azurea, which has a large epiphyte algal community of which heterocystous cyanobacteria were the major components. The water column was continuously undersaturated with oxygen although some elevated values (to 60% saturation) were recorded in the macrophyte beds in the afternoon. Marked diel temperature changes were documented. NH4-N dominated the dissolved N component in the water with maximal values (60 mg m−3) at lowest O2, concentrations early in the morning. Nitrogen fixation (acetylene reduction) of the epiphyte community showed marked diel changes with daily values of 5 mg N fixed m−2day−1(based on 3:1 C2H4:N2ratio). Macrophyte NH4-N uptake rates (in situincubations) were 93 mg N m−2day−1. The activities of nitrifying bacteria could not be detected with the nitrapyrin block on dark CO2fixation but denitrification (acetylene block technique) was recorded in the sediments when enhanced with NO-3. The major pathways of aquatic nitrogen involved macrophyte uptake and sediment release of NH4-N.

Leaf- and plant-level carbon gain in yellow birch, sugar maple, and beech seedlings from contrasting forest light environments

2000 ◽  
Vol 30 (3) ◽  
pp. 390-404 ◽  
Author(s):  
Marilou Beaudet ◽  
Christian Messier ◽  
David W Hilbert ◽  
Ernest Lo ◽  
Zhang M Wang ◽  
...  
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Light Availability ◽  
Fagus Grandifolia ◽  
Carbon Gain ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Significant Difference ◽  
Leaf Level ◽  
Plant Level

Leaf-level photosynthetic-light response and plant-level daily carbon gain were estimated for seedlings of moderately shade-tolerant yellow birch (Betula alleghaniensis Britton) and shade-tolerant sugar maple (Acer saccharum Marsh.) and beech (Fagus grandifolia Ehrh.) growing in gaps and under a closed canopy in a sugar maple stand at Duchesnay, Que. All three species had a higher photosynthetic capacity (Amax) in the gaps than in shade, but yellow birch and beech responded more markedly than sugar maple to the increase in light availability. The high degree of plasticity observed in beech suggests that the prediction that photosynthetic plasticity should decrease with increasing shade tolerance may not hold when comparisons are made among a few late-successional species. Unit-area daily carbon gain (CA) was significantly higher in the gaps than in shade for all three species, but no significant difference was observed between light environments for plant-level carbon gain (CW). In shade, we found no difference of CA and CW among species. In gaps, beech had a significantly higher CA than sugar maple but similar to that of birch, and birch had a significantly higher CW than maple but similar to that of beech. Sugar maple consistently had lower carbon gains than yellow birch and beech but is nevertheless the dominant species at our study site. These results indicate that although plant-level carbon gain is presumably more closely related to growth and survival of a species than leaf-level photosynthesis, it is still many steps removed from the ecological success of a species.

A Pergunta de Feuerbach a Stirner

2013 ◽  
Vol 21 (41) ◽  
pp. 97-108
Author(s):  
Adriana Veríssimo Serrão ◽  
Keyword(s):  
Short Time Period ◽  
Ludwig Feuerbach ◽  
Time Period ◽  
History Of ◽  
The Individual ◽  
Short Time ◽  
Unique Individual

A complex controversy, the debate between Max Stimer and Ludwig Feuerbach is certainly one of the most interesting in the history of Contemporary ideas and surpasses, by the fruitfulness contained therein, the short time period in which it unfolded. The article considers the controversy in a particular aspect: the understanding of the category of the individual, showing the incompatibility between Unique-individual (Stimer) and the individual as being in relation (Feuerbach).

scholarly journals The Chiari I malformation

2019 ◽  
Vol 24 (3) ◽  
pp. 217-226 ◽  
Author(s):  
Samuel G. McClugage ◽  
W. Jerry Oakes
Keyword(s):  
Surgical Intervention ◽  
Chiari I Malformation ◽  
Proper Patient Selection ◽  
Time Period ◽  
Treatment Paradigm ◽  
History Of ◽  
Chiari I ◽  
Degenerative Disorder ◽  
Short Time ◽  
Chiari Malformations

As with many pathologies, the course of our understanding of the Chiari I malformation (CIM) has developed extensively over time. The early descriptions of the Chiari malformations by Hans Chiari in 1891 opened the door for future classification and research on this topic. However, even over a long timeframe, our understanding of the pathophysiology and, more importantly, treatment, remained in its infancy. As recently as the 1970s, CIM was not discussed in popular neurology textbooks. Syringomyelia is listed as a degenerative disorder with no satisfactory treatment. Radiation therapy was considered an option in treatment, and surgery was thought to play no role. During the last 40 years, equivalent to the duration of a neurosurgical career, our understanding of the pathophysiology and natural history of CIM, coupled with modern MRI, has improved the treatment paradigm for this patient population. More importantly, it has given us evidence confirming that CIM is a disorder responsive to surgical intervention, giving patients once thought to be destined for lifelong disability a comparatively normal life after treatment. The purpose of this article is to offer a review of CIM and its important associated entities. The authors will discuss the evolution in understanding of the Chiari malformation and, importantly, distinguish between symptomatic CIM and asymptomatic tonsillar ectopia, based on imaging and presenting symptomatology. They will discuss techniques for surgical intervention, expected outcomes, and complications after surgery. Proper patient selection for surgery based on appropriate symptomatology is tantamount to achieving good surgical outcomes in this population, separating those who can be helped by surgery from those who are unlikely to improve. While our knowledge of the Chiari malformations continues to improve through the efforts of clinical and basic science researchers, surgeons, and patients, our current understanding of these entities represents a monumental improvement in patient care over a relatively short time period.

THE SEASONAL PATTERN OF NITROGEN AND CARBON MINERALIZATION IN FOREST AND PASTURE SOILS IN SOUTHERN ONTARIO

1974 ◽  
Vol 54 (1) ◽  
pp. 15-28 ◽  
Author(s):  
R. C. ELLIS
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Agricultural Soils ◽  
Seasonal Pattern ◽  
Carbon Mineralization ◽  
Calcareous Soils ◽  
C Mineralization ◽  
Old Field ◽  
Phenological Changes

Deficiency of N could be an important limitation to the establishment of sugar maple (Acer saccharum Marsh.) on former agricultural soils. Consequently a study of the seasonal pattern in N and C mineralization was conducted with calcareous soils from four similar segments of a land unit that supported maple woodlot, old field, red pine (Pinus resinosa Ait.), planted old field, and pasture, respectively. Net N mineralized was determined after incubation in situ; rate of C mineralization was measured in situ; and both net N and C mineralized were determined after incubation (perfusion) in the laboratory. All soils showed marked seasonal variation in both their content of exchangeable ionic N and the rate at which N was mineralized. The results from in situ and laboratory determinations were similar. Maxima in May-June and in September were separated by a minimum in July. Winter minima occurred in November and late April. The direction of seasonal change was little affected by short-term changes in temperature and soil moisture, and appeared to be explicable as a response to phenological changes in the vegetation. The rate at which C was mineralized in situ reached a maximum in late July and minima in May and September; it was closely correlated with soil temperature (P = 0.001). In the laboratory the rate reached a maximum in June, and a minimum in July, followed by a slow recovery thereafter until the end of November. Both in situ and in the laboratory, N was mineralized most rapidly from the maple woodlot soil. While there were large differences among soils in the rate at which N was mineralized, there were only small differences in the rate of C mineralization. Thus, per unit of C mineralized, the net amounts of N mineralized in the laboratory from pine stand, pasture, and old-field soils were only 0.29, 0.27, and 0.22, respectively, of the amount mineralized from maple woodlot soil; comparable figures from in situ measurement were 0.24, 0.59, and 0.30. These results indicate that a diminished rate of mineralization of N on former agricultural soils vis-à-vis that on uncleared forest soils is associated with little diminution in their level of biological activity. Forest trees grown on such soils can, therefore, be expected to suffer a degree of N deficiency.

GROWTH AND DEVELOPMENT OF MYCORRHIZAE OF SUGAR MAPLE (ACER SACCHARUM MARSH.)

1966 ◽  
Vol 44 (10) ◽  
pp. 1413-1425 ◽  
Author(s):  
Kenneth J. Kessler
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Soil Conditions ◽  
Root Tips ◽  
Extramatrical Mycelium ◽  
Rooting Zone ◽  
History Of ◽  
Moisture Conditions

Beaded rootlet growth in Acer saccharum is thought to be caused by intermittent growth due to alternately favorable and unfavorable moisture conditions during the season rather than by mycorrhizal infection. Both beaded and nonbeaded rootlets are mycorrhizal-infected, and rootlets growing in the deeper soil levels where moisture conditions do not fluctuate rapidly are nonbeaded. Differences found in the activity of rootlets growing in hummocks and depressions appeared to be related to soil moisture conditions found there. This paper describes (a) the anatomy of metacutinized root tips during dry soil conditions, and the relationship of this condition to the development of constrictions between beads; (b) the extrastelar anatomical characteristics of beaded and nonbeaded rootlets; (c) the morphology of the mycorrhizal fungus in its relationship to rootlet anatomy; (d) the extramatrical mycelium of the mycorrhizal fungus found in the soil of the rooting zone (the extramatrical mycelium is thought to arise from fungal hyphae and vesicles produced in live rootlets which are released to the soil from disintegrating rootlet cortical tissue); and (e) an hypothesis regarding the life history of this type of vesicular–arbuscular mycorrhizal fungus.

Diversity of saproxylic dance flies and long-legged flies (Diptera: Empidoidea) in a temperate deciduous forest in Quebec, Canada

Zootaxa ◽  
2018 ◽  
Vol 4521 (2) ◽  
pp. 287
Author(s):  
JEFFREY M. CUMMING ◽  
BRADLEY J. SINCLAIR ◽  
SCOTT E. BROOKS ◽  
JULIA Mlynarek ◽  
TERRY A. WHEELER
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Deciduous Forest ◽  
Fagus Grandifolia ◽  
Decayed Wood ◽  
Temperate Deciduous Forest ◽  
American Beech ◽  
Emergence Traps ◽  
Temperate Deciduous

A large diversity of saproxylic Empidoidea from a temperate deciduous forest in southern Quebec is documented. Adults of 43 empidoid species representing 19 genera in 12 subfamilies and three families were collected from in situ sealed emergence traps placed over decayed logs of American beech (Fagus grandifolia Ehrhart) and sugar maple (Acer saccharum Marshall). The results of this technique give a clear indication of the saproxylic larval and pupal habitat of these species. The importance of Empidoidea as larval predators in decayed wood niches is noted. 

Phytotoxicity of American beech leaf leachate to sugar maple seedlings in a greenhouse experiment

2003 ◽  
Vol 33 (5) ◽  
pp. 814-821 ◽  
Author(s):  
Elizabeth N Hane ◽  
Steven P Hamburg ◽  
Adelia L Barber ◽  
Jennifer A Plaut
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Field Experiments ◽  
Carbon Assimilation ◽  
Seedling Development ◽  
Fagus Grandifolia ◽  
Greenhouse Experiment ◽  
Ph Effects ◽  
American Beech ◽  
Leaf Leachate

In an effort to reexamine the factors that affect codominance of American beech (Fagus grandifolia Ehrh.) and sugar maple (Acer saccharum Marsh.), a greenhouse experiment was conducted to test the potential phytotoxic effects of American beech leaf leachate on sugar maple seedlings. We utilized an experimental protocol that addressed phytotoxic, nutrient, and pH effects by watering seedlings with seven treatment solutions: simulated throughfall water, average and dilute concentrations of beech leachate, average and dilute concentrations of maple leachate, and average and dilute concentrations of nutrient solutions. Sugar maple leachate had no effect on sugar maple seedling development, chemistry, or physiology. However, sugar maple seedlings exposed to average levels of beech leachate had significantly lower leaf area, fewer nodes, lower biomass, higher carbon assimilation rates, and higher stomatal conductance than seedlings exposed to the control solution. Results suggest that secondary compounds in beech leaf leachate are suppressing sugar maple seedling development and that field experiments are needed to explore the potential allelopathic relationship between these species.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

World Economy: Prospects and Barriers for Recovery

2012 ◽  
pp. 61-83 ◽  
Author(s):  
M. Ershov
Keyword(s):  
World Economy ◽  
Western World ◽  
Short Time Period ◽  
Market Segments ◽  
Junk Bonds ◽  
The Past ◽  
Time Period ◽  
The Us ◽  
Global Liquidity ◽  
Short Time

According to the latest forecasts, it will take 10 years for the world economy to get back to “decent shape”. Some more critical estimates suggest that the whole western world will have a “colossal mess” within the next 5–10 years. Regulators of some major countries significantly and over a short time‑period changed their forecasts for the worse which means that uncertainty in the outlook for the future persists. Indeed, the intensive anti‑crisis measures have reduced the severity of the past problems, however the problems themselves have not disappeared. Moreover, some of them have become more intense — the eurocrisis, excessive debts, global liquidity glut against the backdrop of its deficit in some of market segments. As was the case prior to the crisis, derivatives and high‑risk operations with “junk” bonds grow; budget problems — “fiscal cliff” in the US — and other problems worsen. All of the above forces the regulators to take unprecedented (in their scope and nature) steps. Will they be able to tackle the problems which emerge?

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