Photosynthate Allocation Patterns Along a Fire-Induced Age Sequence in Two Shrub Species From the California Chaparral

1993 ◽  
Vol 3 (1) ◽  
pp. 21 ◽  
Author(s):  
SR Sparks ◽  
WC Oechel ◽  
Y Mauffette
Keyword(s):  
Prescribed Burning ◽  
Physiological Basis ◽  
Defense Compounds ◽  
Adenostoma Fasciculatum ◽  
Free Interval ◽  
Standing Dead ◽  
Allocation Patterns ◽  
Photosynthate Allocation ◽  
Age Sequence ◽  
Prolonged Absence

In the prolonged absence of fire, shrubs of the California chaparral have sometimes been reported to demonstrate an increase in the proportion of standing dead biomass and a decrease in productivity (''senescence''). To investigate the possible physiological basis of this phenomenon, seasonal patterns of the allocation of 14C-labeled photosynthate were studied in leaves of two chaparral species, Adenostoma fasciculatum H. & A. and Ceanothus greggii var. perplexans (Trel.) Jeps., along a fire-induced age sequence. Harvested leaves labeled with 14C were analyzed for percent of 14C in storage, structural, metabolic, and defense compounds. No age-specific trends in photosynthate allocation were found except in the spring. During spring, when demands on photosynthate for growth were high, shrubs in older stands allocated a much lower proportion ot their photosynthate to storage compounds compared to shrubs in younger stands. Older shrubs are apparently less able to meet the concurrent demands of storage and growth during spring than younger shrubs. This observation is consistent with the notion of physiological senescence in older shrubs, and has implications for questions about the optimum length of the fire-free interval for stands managed with prescribed burning.

Biochemical composition and photosynthate distribution in sea ice microalgae of McMurdo Sound, Antarctica: evidence for nutrient stress during the spring bloom

1992 ◽  
Vol 4 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Michael P. Lizotte ◽  
Cornelius W. Sullivan
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
Natural Populations ◽  
Nutrient Status ◽  
Microalgal Biomass ◽  
Mcmurdo Sound ◽  
Nutrient Influx ◽  
Allocation Patterns ◽  
Photosynthate Allocation ◽  
Photosynthate Distribution

The nutrient status of microalgae inhabiting sea ice in McMurdo Sound, Antarctica was evaluated during the peak and decline of the spring bloom in November and December. Natural populations of microalgae were analysed for C, N, chlorophyll a, protein, lipid, polysaccharide, and low-molecular-weight carbohydrate content, and for the distribution of 14C-labelled photosynthate into macromolecular fractions. Ratios of N:C and protein to carbohydrate (PR:CHO) were similar to values reported for nutrient-limited phytoplankton. Biochemical ratios and 14C-photosynthate allocation patterns suggest that microalgae from congelation ice habitats may be more nutrient-stressed than those from underlying platelet ice habitats. This trend would be consistent with the presumed gradient of seawater nutrient influx through the platelet layer to the bottom congelation ice habitat. Microalgae from congelation ice subjected to an experimental depletion of nutrients (particularly nitrate) showed decreased N:C, PR:CHO, and allocation of 14C-photosynthate to proteins. This evidence suggests that sea ice microalgae are nutrient-stressed during the peak and decline of the spring bloom in McMurdo Sound, which presumably begins when microalgal biomass concentrations and demands for growth reach or exceed the rate of nutrient supply from underlying seawater.

CHEMICAL PROPERTIES OF SOIL AS AFFECTED BY A SINGLE BURN OF ALFALFA STUBBLE TO CONTROL INSECTS

1985 ◽  
Vol 65 (2) ◽  
pp. 357-361 ◽  
Author(s):  
J. F. DORMAAR ◽  
B. D. SCHABER
Keyword(s):  
Organic Matter ◽  
Pest Management ◽  
Prescribed Burning ◽  
Chemical Properties ◽  
Fire Regimes ◽  
Early Spring ◽  
Management Program ◽  
Long Term Effects ◽  
Southern Alberta ◽  
Standing Dead

Southern Alberta growers often burn fields of seed alfalfa (Medicago sp.) prior to initiation of growth in the spring as apart of an Integrated Pest Management Program. The present study examined the effect of a single burn of the standing dead growth and debris of a 4-yr-old alfalfa crop in early spring, late spring, or autumn on various chemical properties of the upper 50 mm of soil. Burning led to small but significant increases in organic matter, NO3-N, NH4-N, available P, extractable K, EC, and pH levels immediately after the fire. The only measurable impact 1 year later was slightly higher (P < 0.05) organic matter, but after 2 years there were no differences in these levels. Even though this study portrayed a single burn event, thereby precluding predictions of the long-term effects of different fire regimes, the changes observed were only measurable for less than 1 year. If the burning of the alfalfa stubble is done every third year it is unlikely that this practice would be detrimental to the soil characteristics examined. Key words: Fire, pest management, organic matter, prescribed burning

Prescribed burning of thinning slash in regrowth stands of jarrah (Eucalyptus marginata) following bauxite mining in south-west Australia

2010 ◽  
Vol 19 (6) ◽  
pp. 737 ◽  
Author(s):  
Andrew H. Grigg ◽  
Melanie A. Norman ◽  
Carl D. Grant
Keyword(s):  
Prescribed Burning ◽  
Fire Risk ◽  
Moderate Intensity ◽  
Eucalyptus Marginata ◽  
Bauxite Mining ◽  
Thinning Intensity ◽  
Fuel Loads ◽  
Fuel Layer ◽  
Standing Dead ◽  
Dead Vegetation

Prescribed burning of regrowth jarrah stands established after bauxite mining is key to their integration into standard jarrah forest management, but fire management in thinned regrowth stands has not been studied. Fuel loads in 10- to 13-year-old thinned regrowth increased exponentially with thinning intensity, doubling from 18 t ha–1 in untreated stands (1500–2500 stems ha–1) to 37.4 t ha–1 in the heaviest treatment (400 stems ha–1 retained); however, litter and standing dead vegetation were concentrated within 60 cm of the ground. Intensities of subsequent autumn prescribe-burns increased with increasing fuel loads, but all burns were typically of low to moderate intensity <1800 kW m–1. Three months post-burn, total fuel loads averaged 5 t ha–1, recovering after 4.5 years to 75% of pre-burn levels across all thinning treatments owing mostly to dense understorey regeneration. Where no burning occurred after thinning, total fuel loads declined to be comparable to the unthinned control after 4.5 years, averaging 20 t ha–1. Prescribed burns in autumn following thinning are not recommended because a dense well-aerated and elevated fuel layer is reinstated, posing a future fire risk. Burning 1–2 years before thinning may be an appropriate alternative strategy.

Biosynthesis and photosynthate allocation patterns of arctic ice algae

1989 ◽  
Vol 34 (3) ◽  
pp. 591-605 ◽  
Author(s):  
Ralph E. H. Smith ◽  
Pierre Clement ◽  
Erica Head
Keyword(s):  
Ice Algae ◽  
Allocation Patterns ◽  
Photosynthate Allocation ◽  
Arctic Ice

Changes of mercury concentrations in streamwater after a destructive wildfire (Camp Fire 2018) and a prescribed burning in northern California

2020 ◽  
Author(s):  
Alex Chow ◽  
Jackson Webster ◽  
Hunter Robinson ◽  
Robert rhew ◽  
Martin Tsz-Ki Tsui ◽  
...  
Keyword(s):  
Prescribed Burning ◽  
Northern California

How to Psychologically Minimize Scratching Impulses

2014 ◽  
Vol 222 (3) ◽  
pp. 140-147 ◽  
Author(s):  
Ariane Sölle ◽  
Theresa Bartholomäus ◽  
Margitta Worm ◽  
Regine Klinger
Keyword(s):  
Cognitive Processes ◽  
Placebo Effect ◽  
Psychological Factors ◽  
Pharmacological Treatments ◽  
Physiological Basis ◽  
Psychological Mechanisms ◽  
Physical Complaints ◽  
Factors Influencing ◽  
The Impact ◽  
Placebo Model

Research in recent years, especially in the analgesic field, has intensively studied the placebo effect and its mechanisms. It has been shown that physical complaints can be efficiently reduced via learning and cognitive processes (conditioning and expectancies). However, despite evidence demonstrating a large variety of physiological similarities between pain and itch, the possible transfer of the analgesic placebo model to itch has not yet been widely discussed in research. This review therefore aims at highlighting potential transfers of placebo mechanisms to itch processes by demonstrating the therapeutic issues in pharmacological treatments for pruritus on a physiological basis and by discussing the impact of psychological mechanisms and psychological factors influencing itch sensations.

Hepatitis-Free Interval After Clotting Factor Therapy in First Infused Haemophiliacs

1986 ◽  
Vol 56 (03) ◽  
pp. 268-270 ◽  
Author(s):  
M Morfini ◽  
D Rafanelli ◽  
G Longo ◽  
A Messori ◽  
P Rossi Ferrini
Keyword(s):  
Life Table ◽  
Lower Risk ◽  
Clotting Factor ◽  
Rank Test ◽  
Life Table Method ◽  
Table Method ◽  
Log Rank Test ◽  
Free Interval ◽  
Post Infusion ◽  
Clotting Factor Concentrates

SummaryPost-infusion hepatitis is known to occur very frequently in haemophiliacs after treatment with unheated commercial clotting factor concentrates, obtained from large plasma donation pool. On the contrary, single-donor cryoprecipitate is likely to carry a lower risk of transmitting hepatitis.To evaluate this hypothesis, we retrospectively reviewed the medical records of 25 first infused haemophiliacs (from 1981 to 1984) treated with unheated commercial clotting factor concentrates (n = 19) or cryoprecipitate (n = 6).The hepatitis-free interval after the beginning of therapy was expressed as exposure days. The end point of each patient, i.e. the hepatitis occurrence, was defined as an increase of aminotransferases (ALT and AST) and/or the seroconversion of HBV-markers, which were checked every three months.The life-table method and log-rank test showed that cryo-precipitates had a significantly longer hepatitis-free interval (p = 0.0131, log-rank test) and a lower risk of transmitting hepatitis (p = 0.01-0.05, life-table method) than the commercial concentrates. However, the safety of cryoprecipitate therapy was shown to cover only a few exposure days, and so the real advantage of this product depends on the bleeding frequency of the patient concerned.We believe that these methods and our findings may be useful to assess and compare the safety of the new “heat-treated” clotting factor concentrates.

SOYBEAN AND FLAX SELECTION METHODS

1970 ◽  
pp. 19-23
Author(s):  
V. М. Lukomets ◽  
S. V. Zelentsov
Keyword(s):  
High Resistance ◽  
Fungal Pathogens ◽  
Selection Process ◽  
Pathogenic Fungi ◽  
Cultivated Plants ◽  
Practical Implementation ◽  
Physiological Basis ◽  
Oil Crops ◽  
Soybean Genotypes ◽  
Genetically Determined

To improve the effectiveness of the soybeans and oil flax breeding, research to improve existing and develop new breeding methods are conducting in all-Russia Research institute of Oil Crops (Krasnodar). One of the improved methods for the soybean breeding, based on the use of sources of complexes of compensatory genes, is the CCG technology, which allows to create varieties with an increased yield of a heterotic level transmitted along the progeny for the entire life cycle of the variety. For the purpose of non-transgenic production of new traits, a theory of polyploid recombination of the genome (TPR) was formulated, which models the mechanism of the natural formation of polymorphism in the centers of origin of cultivated plants. On the basis of this theory, a method of breeding (TPR-technology) has been developed, which makes it possible to obtain recombinant reploids of soybeans and oil flax with an extended spectrum of traits. Of these reploids, the soybean lines with increased sucking force of the roots, providing high drought resistance, were distinguished; cold-resistant soybean lines, which stand in the phase of shoots of freezing to minus 5 °С; lines of oil flax with complete resistance to flax sickness of soil and high resistance to Fusarium; winter-hardy flax lines that withstand winter frosts down to minus 20–23 °С and ripen one and a half months earlier than spring sowings. Another original developed method is the ODCS-technology for isolating and selecting soybean genotypes with high resistance to fungal pathogens. The physiological basis of ODCS-technology is the blocking of osmotic nutrition of pathogenic fungi due to genetically determined increased osmotic pressure in the tissues of host plants. The practical implementation of CCG-, TPR- and ODKS-technologies in the selection process, allowed to create a whole series of soybean and oil flax varieties with improved or new traits.

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