Variation of Live and Dead Fine Fuel Moisture in Pinus radiata Plantations of the Australian-Capital-Territory

1993 ◽  
Vol 3 (3) ◽  
pp. 155 ◽  
Author(s):  
EW Pook ◽  
AM Gill
Keyword(s):  
Moisture Content ◽  
Pinus Radiata ◽  
Dry Weight ◽  
Pine Plantations ◽  
Fuel Moisture ◽  
Atmospheric Conditions ◽  
Needle Age ◽  
Moisture Contents ◽  
Highly Correlated ◽  
Mean Differences

A study was made of the variation in moisture content of fine dead fuel (FFM) in relation to 1) differences of fuel type (needles, leaves, twigs, bark), 2) different fuel locations (dead canopy and surface litter), 3) contrasting management of plantations (unthinned-unpruned vs thinned-pruned) and 4) environmental factors (air temperature (T) and relative humidity (H); moisture content of duff (D) and topsoil (S)). The variation of live (green needle) fine fuel moisture content (LFMC) in relation to needle age, canopy location (shaded vs unshaded) and season was also studied in Pinus radiata D. Don plantations over 2 years. Mean differences of moisture content between the several types of fuel exposed to the same atmospheric conditions were generally significant and ranged from 0.6% (pine twigs vs eucalypt twigs) up to 2.8% oven dry weight (ODW) (eucalypt bark vs recently cast pine needles). T and H were highly correlated between study sites in pine plantations and an official meteorological station at Canberra airport, 15 km away. In the pine plantations, mid afternoon moisture contents of pine needle litter (litter FFMs) were mostly higher than moisture contents of dead needles in canopies (aerial FFMs); the mean differences between litter FFMs and aerial FFMs were statistically significant. FFMs in the unthinned-unpruned plantation were also generally higher than those in the thinned-pruned plantations. Regression analyses of relationships between FFM and environmental variables showed that T and H in combination explained a large proportion of the variation in aerial FFM but much less of the variation in litter FFM. However, the inclusion of either D or S in multiple regression models accounted for significant amounts of the variation in litter FFM. LFMC decreased with needle age and, for full-grown needles, was up to 25% (ODW) higher in shaded compared to unshaded canopy locations. Seasonal patterns of change in LFMC of full-grown needles were not well defined. Variation in the parameters and the precision of FFM regression relationships between fuel locations and stands with contrasting management demonstrate the site specificity and limitations of empirical FFM models. The results suggest that for prediction of aerial FFM, models based on a combination of T and H are most appropriate; while, models that include a soil moisture variable may predict FFM of litter fuels more accurately. However, the intrinsic variation in FFM revealed in this study indicates that such models, although providing a useful guide, may not predict FFM with the accuracy required for fire behaviour models during high fire danger weather - when fuel moistures are low.

Leek (Allium porrum L.) seed development and germination

1992 ◽  
Vol 2 (2) ◽  
pp. 89-95 ◽  
Author(s):  
D. Gray ◽  
J. R. A. Steckel ◽  
L. J. Hands
Keyword(s):  
Moisture Content ◽  
Seed Development ◽  
Developmental Stages ◽  
Dry Weight ◽  
Allium Porrum ◽  
Seed Moisture Content ◽  
Subsequent Performance ◽  
Moisture Contents ◽  
Seed Moisture ◽  
Seed Growth

AbstractThe effects of development of leek seeds at 20/10°, 25/15° and 30/20°C (day/night) and drying of seed harvested at different developmental stages on subsequent performance were examined in each of 3 years. An increase in temperature from 20/10° to 30/20°C reduced mean seed weight from 2.90 to 2.55 mg as a result of a reduction in the duration of seed growth from 80 to 55 days; seed growth rate was unaffected. Seed moisture content reached a minimum, up to 35 days after the attainment of maximum seed dry weight and 115, 90 and 70 days after anthesis at 20/10°, 25/15° and 30/20°C, respectively. The curves relating seed moisture to time for each temperature regime were mapped onto a single line accounting for >90% of the variation in moisture content, using accumulated day-degrees >6°C instead of chronological time. Seeds were capable of germinating when seed moisture contents were >60% (fresh weight basis), but maximum viability and minimum mean time to germination were not attained until seed moisture contents at harvest had fallen to 20–30%. Germination was little affected by temperature of seed development. Drying immature seeds increased percentage germination. Growing seeds at 30/20°C and drying at 35°C and 30% RH raised the upper temperature limit of germination compared with growing at 20/10°C and drying at 15°C and 30% RH.

Fuelbed ignition potential and bark morphology explain the notoriety of the eucalypt messmate 'stringybark' for intense spotting

2011 ◽  
Vol 20 (7) ◽  
pp. 897 ◽  
Author(s):  
P. F. M. Ellis
Keyword(s):  
Moisture Content ◽  
Pinus Radiata ◽  
Laboratory Tests ◽  
Flight Behaviour ◽  
Outer Bark ◽  
Ignition Probability ◽  
Loss Of Life ◽  
Moisture Contents ◽  
Eastern Australia ◽  
Probability Weight

In south-eastern Australia, bark of the ‘stringybark’ eucalypt group, and notably that of messmate (Eucalyptus obliqua L’Hér.), is notorious for intense spotting and it is likely that firebrands of this type contribute significantly to loss of life and property during major wildfires. The fuelbed ignition potential by glowing samples was laboratory tested on excised sections of Pinus radiata D. Don litterbed at moisture contents between 2 and 8% and for ‘no-wind’ or for ‘wind’ of 1 m s–1. Prepared samples of outer bark between 0.5 and 1.6 g were combusted until they attained ~20% of initial mass before placement. For ‘no-wind’, flaming ignition did not occur and the probability of glowing ignition appeared to depend on the chance of contact with needles. For ‘wind’, the probability of flaming ignition was a function of sample glowing mass and fuelbed moisture content. Its ignition probability, weight-for-weight, appears to exceed that reported for other forest firebrands, including bark of E. globulus Labill. However, it is likely that the notoriety of messmate bark is also due, in part, to its morphology and in-flight behaviour. It is argued that firebrand laboratory tests to date may poorly reflect the ignition potential of similar samples after flight.

A comparison of two methods for estimating conifer live foliar moisture content

2012 ◽  
Vol 21 (2) ◽  
pp. 180 ◽  
Author(s):  
W. Matt Jolly ◽  
Ann M. Hadlow
Keyword(s):  
Moisture Content ◽  
Mean Absolute Error ◽  
Absolute Error ◽  
Fuel Moisture ◽  
Oven Drying ◽  
Moisture Contents ◽  
Content Determination ◽  
Rapid Moisture ◽  
Live Fuel Moisture ◽  
Moisture Content Determination

Foliar moisture content is an important factor regulating how wildland fires ignite in and spread through live fuels but moisture content determination methods are rarely standardised between studies. One such difference lies between the uses of rapid moisture analysers or drying ovens. Both of these methods are commonly used in live fuel research but they have never been systematically compared to ensure that they yield similar results. Here we compare the foliar moisture content of Pinus contorta (lodgepole pine) at multiple sites for an entire growing season determined using both oven-drying and rapid moisture analyser methods. We found that moisture contents derived from the rapid moisture analysers were nearly identical to oven-dried moisture contents (R2 = 0.99, n = 68) even though the rapid moisture analysers dried samples at 145°C v. oven-drying at 95°C. Mean absolute error between oven-drying and the rapid moisture analysers was low at 2.6% and bias was 0.62%. Mean absolute error was less than the within-sample variation of an individual moisture determination method and error was consistent across the range of moisture contents measured. These results suggest that live fuel moisture values derived from either of these two methods are interchangeable and it also suggests that drying temperatures used in live fuel moisture content determination may be less important than reported by other studies.

Changes in seed quality during seed development and maturation in tomato

1992 ◽  
Vol 2 (2) ◽  
pp. 81-87 ◽  
Author(s):  
I. Demir ◽  
R. H. Ellis
Keyword(s):  
Lycopersicon Esculentum ◽  
Moisture Content ◽  
Developmental Stage ◽  
Seed Development ◽  
Seed Quality ◽  
Seed Viability ◽  
Dry Weight ◽  
Seed Filling ◽  
Moisture Contents ◽  
Seed Moisture

AbstractChanges in tomato (Lycopersicon esculentumMill.) seed quality were monitored during seed development and maturation in glasshouse experiments in 2 years. The end of the seedfilling period (mass maturity) occurred 35–41 d after anthesis (differing among trusses) in 1989 and 42 d after anthesis in 1990. Seed moisture contents at this developmental stage were 53–72% (wet basis), while the onset of ability to germinate (during 21-d tests at 20°/30°C) and the onset of tolerance to rapid enforced desiccation occurred just before (1990) or just after (1989) mass maturity. In 1989, seed quality was assessed primarily by seedling size in a glasshouse experiment; maximum mean seedling dry weight 25 d after sowing was not achieved until 24–40 d after mass maturity. In 1990, seed quality was assessed primarily by germination following storage; maximum normal germination after 35 d in storage at 40 °C with 14 ± 0.5% moisture content was attained 23 d after mass maturity, but with little difference among seed lots harvested 10 d earlier or up to 30 d later. The results contradict the hypothesis that maximum seed quality is attained at the end of the seed-filling period and that seed viability and vigour begin to decline immediately thereafter.

The influence of fuel moisture content on the combustion of Eucalyptus foliage

2013 ◽  
Vol 22 (3) ◽  
pp. 343 ◽  
Author(s):  
Malcolm Possell ◽  
Tina L. Bell
Keyword(s):  
Moisture Content ◽  
Dry Weight ◽  
Co2 Concentration ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Fuel Moisture ◽  
Time To Ignition ◽  
Fuel Moisture Content ◽  
Co Concentrations

Leaves from three species of Eucalyptus were combusted in a mass-loss calorimeter to characterise the effect of fuel moisture on energy release and combustion products for this genus. Increasing moisture content reduced peak heat release and the effective heat of combustion in a negative exponential pattern while simultaneously increasing time-to-ignition. Estimates of the probability of ignition, based upon time-to-ignition data, indicated that the critical fuel moisture content for a 50% probability of ignition ranged from 81 to 89% on a dry-weight basis. The modified combustion efficiency of leaves (the ratio of CO2 concentration to the sum of the CO2 and CO concentrations) decreased exponentially as fuel moisture increased. This was because CO2 concentrations during combustion declined exponentially while CO concentrations increased exponentially. However, CO2 mixing ratios were always greater by at least one order of magnitude. Emission factors for CO2 declined exponentially with increasing fuel moisture content while CO emission factors increased exponentially to a maximum. The emission factors for volatile organic compounds increased in a pattern similar to that for CO with increasing fuel moisture content. The empirical relationships identified in this study have implications for fire-behaviour modelling and assessing the effect of fire on air quality and climate.

The effect of moisture content and prechill duration on dormancy breakage of Douglas fir seeds (Pseudotsuga menziesiivar.menziesii[Mirb.] Franco)

2003 ◽  
Vol 13 (3) ◽  
pp. 239-246 ◽  
Author(s):  
Peter G. Gosling ◽  
Yvonne Samuel ◽  
Andrew Peace
Keyword(s):  
Moisture Content ◽  
Weighting Function ◽  
Dry Weight ◽  
Germination Percentage ◽  
Douglas Fir ◽  
Germination Capacity ◽  
Moisture Contents ◽  
Bivariate Spline ◽  
Food Reserves ◽  
Seed Respiration

AbstractSeeds of Douglas fir (Pseudotsuga menziesiivar.menziesii[Mirb.] Franco) were initially germinated at six constant temperatures (10–35°C), following 0–48 weeks incubation under moist conditions at 4°C, i.e. prechill or stratification. The best, single germination temperature was 15°C for determining the efficacy of subsequent dormancy breakage treatments. Seeds from the same seedlot were then adjusted to 10, 15, 20, 25, 30, 35 and 40% moisture contents (mcfw, fresh weight basis), prechilled for 0, 2, 4, 8, 16, 32, 64 and 128 weeks and transferred to 15°C. A smoothed bivariate spline was used to model the results and showed that virtually all combinations of moisture content and prechill duration significantly stimulated germination capacity, but that the optimal germination percentage (≥93%) was stimulated only by various combinations of between 30 and 35% mcfw and 25 and 48 weeks prechill. At optimal moisture contents (30 and 35%) , extending the prechill duration beyond 48 weeks led to a decrease in germination capacity. This was not due to dormancy reintroduction, but was caused largely by seed death. Regression models using a weighting function, to account for differences in standard deviations, demonstrated significant increases in the mean moisture content of individual seeds at higher moisture contents (≥25%) and longer prechill durations (≥64 weeks) that were concomitant with significant decreases in dry weight. The most likely explanation for this was seed respiration. The combined results suggest that dormancy breakage in Douglas fir seeds requires a hydration level sufficient for respiration to take place, and that, after maximal dormancy release, seeds at the highest mc (35–40%) exhaust their food reserves and begin to deteriorate.

Relationships between the moisture content of fine woody fuels in lodgepole pine slash and the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System

1988 ◽  
Vol 18 (1) ◽  
pp. 128-131 ◽  
Author(s):  
R. Trowbridge ◽  
M. C. Feller
Keyword(s):  
Moisture Content ◽  
Forest Fire ◽  
Index System ◽  
Lodgepole Pine ◽  
Fire Season ◽  
Fire Weather ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Moisture Contents

Unsuccessful attempts to ignite slash resulting from the mechanical knocking down of lodgepole pine in west central British Columbia led to a short-term investigation of the relationship between the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System and the moisture content of various fine fuel components <1 cm in diameter. Of the types of fuel sampled, the moisture contents of B.C. Forest Service fuel moisture sticks and aged slash were similar to, and well correlated (r = 0.79 and 0.81, respectively) with, the equivalent moisture content calculated from the Fine Fuel Moisture Code. The Fine Fuel Moisture Code was not designed to relate to the moisture content of uncured fuels. Thus, the moisture contents of fresh living slash (material from knocked down trees still attached to living roots) and of fresh dead slash (material unattached to living trees that had not yet experienced a complete fire season in which to fully cure) were poorly correlated with moisture content (r = 0.16 and 0.42, respectively). The moisture content of the progressively curing, needle-bearing fresh dead slash was relatively high at the beginning of the fire season, but became similar to the moisture content during the first half of July. This suggests that the Fine Fuel Moisture Code can also be used to predict the moisture content of such fine slash after these fuels have cured for approximately 3 months during the snow-free period.

The softening of hard seeds of san-plain lupin (Lupinus varius)

1968 ◽  
Vol 19 (4) ◽  
pp. 507 ◽  
Author(s):  
BJ Quinlivan
Keyword(s):  
Moisture Content ◽  
Temperature Fluctuations ◽  
Dry Weight ◽  
Summer Temperature ◽  
Weight Basis ◽  
Humid Atmosphere ◽  
Moisture Contents ◽  
Hard Seeds ◽  
Sand Plain ◽  
Daily Temperature Fluctuations

Two types of impermeability were found in hard seeds of sand-plain lupin. Hard seeds with a moisture content above 10% (dry weight basis) are conditionally hard. They soften slowly when placed in a humid atmosphere or moist soil, the rate of softening varying directly with the moisture content. Moisture penetration occurs at random sites over the testa, but not normally at the hilum or strophiole. Hard seeds with a moisture content below 8.5%, on the other hand, are absolutely hard, and will not soften as a result of exposure to moist conditions. They will soften, however, if exposed to daily temperature fluctuations between 15 and 65°C, which fracture the impermeable coat at the strophiole. This type of softening does not occur in seeds with a moisture content above 8.5%. It is concluded that under field conditions the autumn germination pattern of the species, which has no physiological seed dormancy, would depend on the degree to which the seeds become desiccated during the summer. Where moisture contents remain above l0%, the seeds would give a scattered germination over several months. With moisture contents below 8.5% the only seeds capable of germinating would be those with a fracture at the strophiole resulting from summer temperature fluctuations. These would all germinate within a few days following moistening of the soil.

scholarly journals Análise do conteúdo de umidade foliar de fitofisionomias do Cerrado com uso de imagens do multispectral instrument do satélite Sentinel 2

2020 ◽  
Vol 13 (07) ◽  
pp. 3315
Author(s):  
Leidiane De Paula Rezende ◽  
Ricardo Vicente Ferreira
Keyword(s):  
Moisture Content ◽  
Dry Weight ◽  
Short Wave ◽  
Fuel Load ◽  
Fuel Moisture ◽  
Reflectance Analysis ◽  
Short Wave Infrared ◽  
Atmospheric Variations ◽  
Fuel Moisture Content ◽  
Sentinel 2

O estudo realizou uma análise comparativa entre o índice de reflectância de duas fitofisionomias (Macega e Cerradão) do Cerrado nas bandas de imagens do Instrumento Multiespectral (MSI) do satélite Sentinel 2 das bandas Short-wave infrared (SWIR) 1 e 2 e Near Infra-Red (NIR) de duas fitofisionomias do Cerrado em consonância com os dados in situ de Fuel Moisture Content (FMC) afim de contribuir com técnicas de Sensoriamento Remoto para monitorar combustíveis vegetais e perigos de incêndio. Dados adicionais de variáveis ambientais como temperatura e umidade do ar, e de satélites como precipitação e conteúdo de umidade de solo foram consideradas neste estudo. A análise dos dados foi feita com a aplicação de correlação linear e de regressão múltipla. No FMC, os resultados ficaram acima de 100% para o Cerradão e para a Macega atingiu valor mínimo de 20%. Na análise de correlação, a banda NIR se correlacionou positivamente (R² = 0,32) ao FMC do Cerradão, enquanto na Macega, a melhor correlação foi identificada nas bandas do SWIRs (R² = 0,36) inversamente ao FMC. Na análise de regressão, o FMC do Cerradão indicou correspondência à umidade de solo. Conclui-se que vegetais vivos tendem a recorrer a umidade do solo, enquanto que os vegetais mortos são mais afetados por variáveis atmosféricas e, por isso, são mais propensos a incêndios, como a Macega. O monitoramento do FMC por Sensoriamento Remoto requer maior amostragem em relação ao bioma Cerrado, cuja fisiologia complexa mostra ser influenciada por variáveis ambientais e climáticas que deverão ser levadas em conta em análises e estudos posteriores.  Leaf moisture content analysis of Cerrado phytophysiognomies using Sentinel 2 satellite multispectral instrument images   A B S T R A C T Moisture content of living or dead plant material is a fundamental element in the characterization of the fire's fuel load in wildfire episodes. Satellite imagery and field surveys can help to estimate Fuel Moisture Content (FMC) in different environments. FMC is computed as wet weight over dry weight of vegetation samples. In this study, 24 FMC samples of Brazilian Savana vegetation were collected between May and October 2019 in two phytotypes: Cerrado Típico and Campo Limpo, in the municipality of Sacramento / MG. We applied an statistic correlation to reflectance of the Sentinel-2 MSI spectral bands (Multispectral Instrument). Data on soil moisture, temperature, precipitation and air humidity were tested in a Multiple Linear Regression to verify possible impacts of these elements on FMC results. SWIR 1 band had a better correlation (R² = 0.33) with Campo Limpo samples, the reflectance increases as the plant's humidity decreases, turning to dead leaves. In Cerrado Típico, FMC increased during the period, keeping leaves alive. Dead leaves are affected by atmospheric variations and are more prone to burning. The risk of fire is imminent in Campo Limpo and reflectance analysis of short wave infrared (SWIR) is a strategy to predict risk of fires in this environment.Keywords:  wildfire risk; fuel moisture content; reflectance

scholarly journals The Regulatory Mechanism of 2-Acetyl-1-Pyrroline Biosynthesis in Fragrant Rice (Oryza sativa L.) Under Different Soil Moisture Contents

2021 ◽  
Vol 12 ◽  
Author(s):  
Haowen Luo ◽  
Meiyang Duan ◽  
Leilei Kong ◽  
Longxin He ◽  
Yulin Chen ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Growth Parameters ◽  
Oryza Sativa L ◽  
Dry Weight ◽  
Transcript Level ◽  
Fragrant Rice ◽  
Moisture Contents ◽  
Significant Difference

2-acetyl-1-pyrroline (2-AP) is the key compound of rice aroma. However, the responses of 2-AP biosynthesis in fragrant rice under different soil moisture and the corresponding mechanism are little known. The present study evaluated the effects of different soil moisture on 2-AP biosynthesis through a pot experiment. Four soil moisture contents, that is, 50% (SM50), 40% (SM40), 30% (SM30), and 20% (SM20), were adopted, and SM50 treatment was taken as control. The pots were weighed and watered to maintain the corresponding soil moisture content. The results showed no significant difference in growth parameters (plant height, stem diameter, and plant dry weight) among all treatments. Compared with SM50, SM40, SM30, and SM20 treatments significantly (p&lt;0.05) increased 2-AP content by 32.81, 23.18, and 53.12%, respectively. Between 20 to 90% higher proline content was observed in SM40, SM30, and SM20 treatments than in SM50. Enzymes including proline dehydrogenase, ornithine transaminase, and 1-pyrroline-5-carboxylate synthetase exhibited lower activities with soil moisture declined. Higher diamine oxidase activity was observed in SM40, SM30, and SM20 treatments compared with SM50, and real-time PCR analyses showed that transcript level of DAO1 was greatly increased under low soil moisture treatments, especially in SM20 treatment. Transcript levels of PRODH, DAO2, DAO4, DAO5, OAT, P5CS1, and P5CS2 decreased or maintained in SM40, SM30, and SM20 treatments compared with SM50. We deduced that low soil moisture content enhanced 2-AP biosynthesis mainly by upregulating the expression of DAO1 to promote the conversion from putrescine to 2-AP.

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