Fire effects on seed relaease and the emergence and establishment of seedlings in Banksia ericifolia. L.f

1981 ◽  
Vol 29 (5) ◽  
pp. 521 ◽  
Author(s):  
RA Bradstock ◽  
PJ Myerscough
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Fire Regimes ◽  
Fire Effects ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Fire Temperature ◽  
Banksia Ericifolia ◽  
Maximum Temperatures ◽  
The Relationship

Fire intensity and seasonality affected the release of seed in Banksia ericifolia L.f, and the post-fire emergence of seedlings. Mean maximum temperatures recorded in a heathland burn in May 1977 at heights of 0.5, 2 and 3 m were about 400, 275 and 175°C respectively. Variability in maximum temperature was dependent on the age and position of B. ericifolia stands. Release of seed held on B. ericifolia bushes increased significantly after fire. The proportion of seed released on unburnt controls stayed constant. Seeds were released earlier and quicker from cones exposed to high fire temperature maxima than from those exposed to low fire temperature maxima. Up to 80% of the seed bank was released 95 days after the fire. A greater proportion of the seed bank emerged and established as seedlings 5 months after the fire in May than after a fire the previous February. Seedling emergence and mortality were broadly related to rainfall over this period. The relationship between various fire regimes and abundance in B. ericifolia populations is discussed.

A comparison of thermocouples and temperature paints to monitor spatial and temporal characteristics of landscape-scale prescribed fires

2004 ◽  
Vol 13 (3) ◽  
pp. 311 ◽  
Author(s):  
Louis R. Iverson ◽  
Daniel A. Yaussy ◽  
Joanne Rebbeck ◽  
Todd F. Hutchinson ◽  
Robert P. Long ◽  
...  
Keyword(s):  
Grid Point ◽  
Heat Index ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Temperature Sensitive ◽  
Burned Areas ◽  
Rate Of Spread ◽  
Maximum Temperatures ◽  
Highly Correlated ◽  
Fire Characteristics

A method to better monitor landscape-level fire characteristics is presented. Three study areas in southern Ohio oak-hickory (Quercus-Carya) forests were established with four treatment areas of ~20 ha each: control (C), burn only (B), thin only (T) or thin plus burn (TB). Two independent measures useful for qualitatively characterising fire intensity were established on a 50-m grid, resulting in over 120 sampling locations at each site, in the burned areas: aluminum tags painted with temperature-sensitive paints, and logger-probe units that logged probe temperature every 2 s during burns. Fires were conducted in spring 2001. The logger-probe units allowed five measures qualitatively related to fire intensity or timing to be calculated at each grid point: maximum probe temperature; duration of probe temperature above 30°C; a heat index, defined as the summed temperatures above 30°C; time of maximum temperature; and estimated rate of spread. Maximum temperatures recorded by the two measuring systems were highly correlated (r2 = 0.83). Relative to painted tags, logger-probe units provide information useful for assessing some other components of fire behaviour. The temporal recording of temperatures allowed us to prepare a web-based simulation of the fires. Heat index and rate of spread estimates provided additional fire information. The TB units consistently burned cooler than the B units, perhaps because of uncured slash and a disrupted fuel bed in those units.

Soil temperatures during and following low-intensity prescribed burning in a Eucalyptus pauciflora forest

Soil Research ◽  
1986 ◽  
Vol 24 (1) ◽  
pp. 33 ◽  
Author(s):  
RJ Raison ◽  
PV Woods ◽  
BF Jakobsen ◽  
GAV Bary
Keyword(s):  
Organic Matter ◽  
Prescribed Burning ◽  
Organic Matter Content ◽  
Heat Content ◽  
Soil Surface ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Daily Maximum ◽  
Low Intensity ◽  
Maximum Temperatures

Temperatures at the soil surface and at several soil depths were measured during, and at intervals, for 33 months after a low-intensity prescribed burn in a subalpine Eucalyptus pauciflora forest. The high organic matter content, low bulk density, and low moisture content of the surface soil caused steep soil temperature gradients to be generated during the fire. Mean maximum temperatures during the fire were 600 � 50, 450 � 52, 54 � 5 and 42 � 5�C in the litter and at 0, 2 and 5 cm soil depths respectively. The highest temperatures recorded at 0, 2 and 5 cm depths were 703, 94 and 44�C. Temperatures exceeding 200�C, which result in volatilization of N from soil organic matter, were estimated to have occurred in the upper 3 mm of the soil. Byram fire intensity tended to be negatively correlated with the maximum temperature measured at the soil surface, but was not correlated with the amount of heat absorbed by black cans (thermal integrators) or the increase in the heat content of the soil. After the burn, the mean daily maximum temperatures in the soil were markedly higher on burnt than on unburnt sites. For example, soon after burning increases were 6, 10, 4 and 4�C at 0, 2, 5 and 10 cm depths, respectively, during a 5-day summer period. Mean daily minimum temperatures on recently burnt plots were similar to or slightly lower than those on unburnt areas. Average day-time temperature in recently burnt forest in summer was elevated by up to 8 and 4�C at 0 and 10 cm soil depths.

Fire Alters Emergence of Invasive Plant Species from Soil Surface-Deposited Seeds

Weed Science ◽  
2009 ◽  
Vol 57 (3) ◽  
pp. 304-310 ◽  
Author(s):  
Lance T. Vermeire ◽  
Matthew J. Rinella
Keyword(s):  
Invasive Species ◽  
Invasive Plant ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Fire Regimes ◽  
Fire Effects ◽  
Fuel Load ◽  
Spotted Knapweed ◽  
Plant Seed ◽  
Fuel Loads

Restoration of historic fire regimes is complicated by concerns about exotic plant invasions, yet little is known of how the two may interact. Seeds of Japanese brome, spotted knapweed, Russian knapweed, and leafy spurge were subjected to fire at six fuel loads (100 to 700 g m−2) and a nonburned control. Fires were simulated with field-cured grass and time–temperature profiles were developed from thermocouples at the soil surface. Emergence was determined by species and fuel load in growth chambers. Fuel load explained 98% of variation in mean heat dosage and emergence decreased with increasing fuel load across species. Emergence was reduced 79 to 88% relative to nonburned treatment with 100 g m−2of fuel and at least 97% with 200 g m−2of fuel. Emergence probabilities were less than 0.01 for all species but spotted knapweed with a 300 g m−2fuel load. Results indicate high potential for fire to disrupt the life cycle of invasive species through direct seed mortality. The relationship between fuel load and seedling emergence provides good predictability of fire effects on surface-deposited seeds. A single fire is unlikely to eradicate many invasive species because they often produce abundant seeds and some will undoubtedly escape fire. However, abrupt reductions in seedling emergence with relatively light fuel loads indicate that fire may be an effective tool for increasing mortality of invasive plant seed across a broad range of habitats.

scholarly journals Studies in the dynamics of disinfection. X. The effect of lethal temperatures on standard cultures of Bact. coli. III. on the variation of the rate of disinfection with temperature at pH 7·0, including the calculation of a new and constant temperature coefficient

1947 ◽  
Vol 45 (3) ◽  
pp. 333-341
Author(s):  
R. C. Jordan ◽  
S. E. Jacobs ◽  
H. E. F. Davies
Keyword(s):  
Minimum Temperature ◽  
Logistic Equation ◽  
Maximum Temperature ◽  
Temperature Coefficients ◽  
The Past ◽  
Lethal Temperatures ◽  
Two Temperatures ◽  
Maximum Temperatures ◽  
The Relationship ◽  
Very High

1. The 99·99 % mortality time (t) has been used as a measure of the rate of disinfection of standard cultures of Bact. coli by heat under carefully controlled conditions, and the relationship between this rate and temperature (T) over the range 47–55° C. has been examined.2. From the form of the relationship a minimum temperature of about 44° C. for the reaction was indicated, but the formula t (T — α)b = a, which has been used for the calculation of biological temperature coefficients in the past, was quite inadequate to express the relationship when an acceptable value for the maximum temperature (α) was employed.3. The formula t × θT = A more usually employed in bacteriological work, fitted the data reasonably well except at the highest temperature. The very high value of 897 for Q10 was obtained.4. On theoretical grounds, the above formula could not apply at temperatures near the minimum, and also it appeared likely to break down when high temperatures were used.5. It was shown that the full graph of log (t — 10) against temperature should be sigmoid and asymptotic to two temperatures, a minimum and a maximum, the latter being defined as the temperature at which 99·99 % mortality would be produced in 10 min.6. The graph of the Pearl-Verhulst logistic equation is of this type and, with 44 and 56° C. as the minimum and maximum temperatures, it provided an excellent fit to the data, especially at the highest temperature used.

scholarly journals Non-native plants exert strong but under-studied influence on fire dynamics

NeoBiota ◽  
2020 ◽  
Vol 61 ◽  
pp. 47-64
Author(s):  
Clare E. Aslan ◽  
Brett G. Dickson
Keyword(s):  
Native Species ◽  
Native Plants ◽  
Meta Analysis ◽  
Fire Regimes ◽  
Fire Effects ◽  
Fire Dynamics ◽  
Feedback Cycle ◽  
Quantitative Studies ◽  
Significant Difference ◽  
The Relationship

Altered fire regimes are among the most destructive consequences of anthropogenic environmental change. Fires have increased in frequency in some regions, and invasion by fire-adapted non-native species has been identified as a major driver of this change, which results in a feedback cycle promoting further spread by the non-native species and diminishing occurrence of natives. We notice, however, that non-native species are often invoked in passing as a primary cause of changing fire dynamics, but that data supporting this claim are rarely presented. We therefore performed a meta-analysis of published literature to determine whether a significant relationship exists between non-native species presence and increased fire effects and risk, examined via various fire metrics. Our analysis detected a strongly significant difference between fire metrics associated with non-native and native species, with non-native species linked to enhanced fire effects and risk. However, only 30 papers discussing this linkage provided data to support it, and those quantitative studies examined only eight regions, five biome types, and a total of 22 unique non-native taxa. It is clear that we are only beginning to understand the relationship between non-native species and fire and that results drawn from an extremely limited set of contexts have been broadly applied in the literature. It is important for ecologists to continue to investigate drivers of changing fire regimes as factors such as climate change and land use change alter native and non-native fuels alike.

The sensitivity of fire activity to interannual climate variability in Victoria, Australia

2019 ◽  
Vol 69 (1) ◽  
pp. 146
Author(s):  
Sarah Harris ◽  
Neville Nicholls ◽  
Nigel Tapper ◽  
Graham Mills
Keyword(s):  
Climate Models ◽  
Fire Management ◽  
Fire Regime ◽  
Maximum Temperature ◽  
Area Burned ◽  
Climate Parameters ◽  
Fire Activity ◽  
Maximum Temperatures ◽  
In Fire ◽  
The Relationship

Climate change is expected to have an impact on fire activity in many regions around the globe.The extent of this can only be determined by first establishing the relationship between climate and fire activity. This study relates observed changes in fire activity in Victoria to observed changes in antecedent and concurrent climate parameters – maximum temperature, rainfall and vapour pressure, using data for 1972–2014. A first-difference approach was adopted to estimate the amount by which the observed changes in the climate parameters would have altered the fire activity in the absence of other confounding effects. This study provides a method for examining the sensitivity of fire activity to changes in climate parameters without the need to consider the complex response of fuel dynamics to future climates and changes in fire regime or fire management. We used stepwise multiple-regression to determine the months whose climate parameters explained much of the variance in the total number of fires (TNF) and area burned in a fire season. The best performing fire–climate models explained almost two-thirds of the variation in year-to-year variability of fire activity. The significant explanatory ability of the fire–climate models established in this study reveals the combination of climate parameters that closely relates to the observed year-to-year changes in fire activity, and this may provide an additional valuable resource for fire management planning. Further, we explored the role changes in climate have had on the trend in fire activity. Natural logarithm of area burned and mean fire size have not significantly increased over the study period, but the TNF has significantly increased. We find that the observed increase in maximum temperatures and decrease in rainfall account for 26% of the observed increase in TNF for the 1972–2014 period. Therefore, most of the upward trend found in fire numbers must be due to factors other than climate (i.e. changes in fire occurrence, reporting/recording, land and fire-management changes). Additionally, this study concludes that total area burned should have also increased significantly due to the observed changes in climate and that improved fire-management practicesmay be offsetting this expected increase in the area burned. Finally, using the relationship established in this study between fire numbers and climate parameters, we estimate that a 2°C increase in mean monthly maximum temperatures could be expected to lead to a 38% increase in fire numbers.

scholarly journals Studies in the dynamics of disinfection. VI. Calculation of a new and constant temperature coefficient for the reaction between phenol and Bact. coli

1946 ◽  
Vol 44 (4) ◽  
pp. 249-255 ◽  
Author(s):  
R. C. Jordan ◽  
S. E. Jacobs
Keyword(s):  
Temperature Coefficient ◽  
Constant Temperature ◽  
Point Of View ◽  
Phenol Concentration ◽  
Maximum Temperature ◽  
Threshold Temperature ◽  
Temperature Coefficients ◽  
Maximum Temperatures ◽  
Relationship Of ◽  
The Relationship

1. The virtual sterilization time (v.s.t.) has been used as a measure of the rate of disinfection of Bact. coli cultures by phenol under carefully standardized conditions. The relationship of this time to temperature at each of five phenol concentrations has been examined from a fresh point of view, since it has previously been shown (Jordan & Jacobs, 1946) that none of the commonly accepted temperature coefficients was satisfactorily constant.2. The relationship is such that a minimum or threshold temperature exists for each concentration. A corresponding ‘maximum’ temperature has been fixed, defined as the temperature at which the v.s.t. is 10 min. The value of (v.s.t. – 10) thus varies from infinity to zero between these temperature limits.3. Sigmoid curves are obtained when log (v.s.t. –10) is plotted against temperature for given phenol concentrations. These may be regarded as asymptotic to ordinates at the minimum and maximum temperatures.4. The Pearl-Verhulst logistic equation gives a curve of the required sigmoid type, and this formula has been shown to fit the curves of log (v.s.t. – 10) against temperature very satisfactorily over the range of concentrations studied.5. One of the constants of this formula partakes of the nature of a temperature coefficient, and it has, therefore, been possible to derive a truly constant temperature coefficient for each phenol concentration.6. The values of this new temperature coefficient do not vary greatly with phenol concentration within the range studied, but it is not yet possible to establish whether it is essentially constant for all phenol concentrations with which it is possible to work.

The relationship between temperature fluctuations and the softening of hard seeds of some legume species

1966 ◽  
Vol 17 (5) ◽  
pp. 625 ◽  
Author(s):  
BJ Quinlivan
Keyword(s):  
Critical Factor ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Temperature Fluctuations ◽  
Maximum Temperature ◽  
Hard Seeds ◽  
Maximum Temperatures ◽  
The Relationship ◽  
Fluctuating Temperatures ◽  
Main Factor

Hard seeds of subterranean clover (Trifolium subterraneum L.) of the Geraldton and Bacchus Marsh strains, and of West Australian blue lupin (Lupinus varius L.), were subjected to various daily fluctuating temperatures within the normal summer environmental range (15–75°C). The main factor determining the rate of softening of the hard seeds was the maxinlum temperature of the fluctuation. Provided the temperature changed by some 15°C , the amplitude of the fluctuation did not appear to be a critical factor. The softening of hard seeds of any particular species did not commence until the amplitude of the temperature fluctuation, or the maximum temperature, reached a certain level, which in turn varied with the species. Beyond this level the rate of softening increased with increasing fluctuations to a point where the rate became very rapid, and thereafter wider fluctuations or higher maximum temperatures did not give significant increases.

scholarly journals The role of Pteridium arachnoideum(Kaulf) on the seed bank of the endangered Brazilian Cerrado

2016 ◽  
Vol 76 (1) ◽  
pp. 256-267 ◽  
Author(s):  
R. O. Xavier ◽  
J. G. Alday ◽  
R. H. Marrs ◽  
D. M. S. Matos
Keyword(s):  
Seed Bank ◽  
Management Strategy ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Common Species ◽  
Ground Vegetation ◽  
Brazilian Cerrado ◽  
Invasive Grasses ◽  
The Relationship

Abstract The native bracken (Pteridium arachnoideum) often occurs in mono-specific stands in the Brazilian Cerrado, and this dominance can impact on both the above-ground vegetation and soil seed bank. This study investigated how invasion by this species over a 20-year period changed the seed bank and the relationship between the seed bank and litter mass. We extracted soil samples from three replicated invaded and uninvaded sites, and followed seedling emergence for six months. We collected the above-ground biomass and litter of P. arachnoideum in ten 1m2 plots from three invaded sites. There was no difference between invaded and uninvaded areas in seed bank richness, diversity or overall abundance. The most abundant family was the Melastomataceae, followed by the Poaceae. The Melastomataceae was more abundant in uninvaded sites, but the most common species of this family (Tibouchinastenocarpa) was not affected. The grasses were more common in invaded sites in the rainy season and were affected by heterogeneity in the litter layer. The seed bank could play a role in the recovery of these invaded areas, but the presence of weeds and invasive grasses could constrain their use as a management strategy.

scholarly journals A late-Holocene multiproxy fire record from a tropical savanna, eastern Arnhem Land, Northern Territory, Australia

The Holocene ◽  
2021 ◽  
pp. 095968362098803
Author(s):  
Emma Rehn ◽  
Cassandra Rowe ◽  
Sean Ulm ◽  
Craig Woodward ◽  
Michael Bird
Keyword(s):  
Isotope Composition ◽  
Fire Regimes ◽  
Northern Territory ◽  
Ecosystem Dynamics ◽  
Optical Methods ◽  
Fire Intensity ◽  
Tropical Savanna ◽  
Anthropogenic Fire ◽  
Pyrogenic Carbon ◽  
Arnhem Land

Fire has a long history in Australia and is a key driver of vegetation dynamics in the tropical savanna ecosystems that cover one quarter of the country. Fire reconstructions are required to understand ecosystem dynamics over the long term but these data are lacking for the extensive savannas of northern Australia. This paper presents a multiproxy palaeofire record for Marura sinkhole in eastern Arnhem Land, Northern Territory, Australia. The record is constructed by combining optical methods (counts and morphology of macroscopic and microscopic charcoal particles) and chemical methods (quantification of abundance and stable isotope composition of pyrogenic carbon by hydrogen pyrolysis). This novel combination of measurements enables the generation of a record of relative fire intensity to investigate the interplay between natural and anthropogenic influences. The Marura palaeofire record comprises three main phases: 4600–2800 cal BP, 2800–900 cal BP and 900 cal BP to present. Highest fire incidence occurs at ~4600–4000 cal BP, coinciding with regional records of high effective precipitation, and all fire proxies decline from that time to the present. 2800–900 cal BP is characterised by variable fire intensities and aligns with archaeological evidence of occupation at nearby Blue Mud Bay. All fire proxies decline significantly after 900 cal BP. The combination of charcoal and pyrogenic carbon measures is a promising proxy for relative fire intensity in sedimentary records and a useful tool for investigating potential anthropogenic fire regimes.

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