Effects of fire frequency on prescribed fire behaviour and soil temperatures in dry dipterocarp forests

2011 ◽  
Vol 20 (1) ◽  
pp. 35 ◽  
Author(s):  
Kobsak Wanthongchai ◽  
Johann G. Goldammer ◽  
Jürgen Bauhus
Keyword(s):  
Ground Level ◽  
Flame Height ◽  
Temperature Threshold ◽  
Fire Behaviour ◽  
The Past ◽  
Fuel Loads ◽  
Dipterocarp Forests ◽  
Soil Temperatures ◽  
Burned Site ◽  
Duration Of Heating

This study investigated how fire frequencies and fuel loads influence fire behaviour and soil heating in dry dipterocarp forests of the Huai Kha Khaeng Wildlife Sanctuary, Thailand. Fire behaviour and soil temperatures during burning were measured on a series of plots with different past fire frequencies ranging from unburned control, to rarely, infrequently and frequently burned, representing fire occurrences in 0, 1, 2 and 7 out of the past 10 years respectively. The pre-burning loads of fine fuel including grasses, herbs, shrubs, seedlings, saplings and litters increased with the length of the previous fire-free interval. The rate of spread, flame height, fireline intensity and maximum soil temperatures at any soil depths were not significantly different between the past burning regimes, so fires were classed as low-intensity and low-severity surface fire. The longest duration of heating with temperatures >60°C at ground level occurred at the rarely burned site (~14 min), followed by the infrequently burned site (~12 min) and the frequently burned site (~8 min). However, the duration of heating above any given critical temperature threshold at 2- and 5-cm soil depths was less than 1 min across all regimes. From a fuel management perspective, there does not appear to be a need to carry out prescribed burns more frequently than every 6–7 years, because fine fuel loads did not continue to accumulate substantially beyond 7 years after a fire.

Fuel properties and fire behaviour characteristics of prescribed fire in pine-dominated forests at Nam Nao National Park, Thailand

2013 ◽  
Vol 22 (5) ◽  
pp. 615 ◽  
Author(s):  
K. Wanthongchai ◽  
V. Tarusadamrongdet ◽  
K. Chinnawong ◽  
K. Sooksawat
Keyword(s):  
Prescribed Fire ◽  
National Park ◽  
Forest Type ◽  
Pine Forest ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Temperature Changes ◽  
Fuel Loads ◽  
Soil Temperatures ◽  
Fuel Components

Anthropogenic burning has become a common phenomenon throughout Thailand’s pine-dominated ecosystems. This study investigated fuel loads and experimental fire behaviour characteristics in a degraded pine forest (PF) and a pine–oak forest (O-PF), at Nam Nao National Park, Thailand in three replicate 50 × 50-m plots of each forest type. Pre-burn fuel loads, fire behaviour descriptors, fire and soil temperature, the residues left after burning and post-burn fuel recovery for 1 year were investigated. The aboveground fuel load in PF (1.29 kg m–2) was significantly higher than in O-PF (0.87 kg m–2). The main fuel components in the PF stand were grass (45%) and litter (44%), whereas leaf litter was the predominant fuel in the O-PF stand (55%). The fire behaviour characteristics in the PF stand were significantly greater than those in the O-PF stand. Burning at the O-PF and the PF was respectively classified as low (48 kW m–1) and medium intensity (627 kW m–1). During the burning experiment, the surface soil temperatures at all sites were higher than 250°C. However, fire did not cause temperature changes in the deeper soil layers. In the pine forest the post-burn fuel loads 1 year after the fire remained lower than the pre-burn level. These results may imply that a pine forest at Nam Nao National Park requires more than 1 year of fire-free period to recover back to the pre-burn conditions.

scholarly journals Mechanical Mastication Reduces Fuel Structure and Modelled Fire Behaviour in Australian Shrub Encroached Ecosystems

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 812
Author(s):  
Madeleine A. Grant ◽  
Thomas J. Duff ◽  
Trent D. Penman ◽  
Bianca J. Pickering ◽  
Jane G. Cawson
Keyword(s):  
Native Species ◽  
Ecological Impact ◽  
Fold Increase ◽  
Weather Conditions ◽  
Fuel Properties ◽  
Flame Height ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Fuel Loads ◽  
The Impact

Shrub encroachment of grassland and woodland ecosystems can alter wildfire behaviour and threaten ecological values. Australian fire managers are using mechanical mastication to reduce the fire risk in encroached ecosystems but are yet to evaluate its effectiveness or ecological impact. We asked: (1) How does fuel load and structure change following mastication?; (2) Is mastication likely to affect wildfire rates of spread and flame heights?; and (3) What is the impact of mastication on flora species richness and diversity? At thirteen paired sites (masticated versus control; n = 26), located in Victoria, Australia, we measured fuel properties (structure, load and hazard) and floristic diversity (richness and Shannon’s H) in 400 mP2 plots. To quantify the effects of mastication, data were analysed using parametric and non-parametric paired sample techniques. Masticated sites were grouped into two categories, 0–2 and 3–4 years post treatment. Fire behaviour was predicted using the Dry Eucalypt Forest Fire Model. Mastication with follow-up herbicide reduced the density of taller shrubs, greater than 50 cm in height, for at least 4 years. The most recently masticated sites (0–2 years) had an almost 3-fold increase in dead fine fuel loads and an 11-fold increase in dead coarse fuel loads on the forest floor compared with the controls. Higher dead coarse fuel loads were still evident after 3–4 years. Changes to fuel properties produced a reduction in predicted flame heights from 22 m to 5–6 m under severe fire weather conditions, but no change in the predicted fire rate of spread. Reductions in flame height would be beneficial for wildfire suppression and could reduce the damage to property from wildfires. Mastication did not have a meaningful effect on native species diversity, but promoted the abundance of some exotic species.

scholarly journals Long-term O<sub>3</sub>–precursor relationships in Hong Kong: field observation and model simulation

2017 ◽  
Vol 17 (18) ◽  
pp. 10919-10935 ◽  
Author(s):  
Yu Wang ◽  
Hao Wang ◽  
Hai Guo ◽  
Xiaopu Lyu ◽  
Hairong Cheng ◽  
...  
Keyword(s):  
Hong Kong ◽  
Model Simulation ◽  
Ground Level ◽  
Effective Control ◽  
Photochemical Pollution ◽  
Mixing Ratios ◽  
The Past ◽  
Total Volatile Organic Compounds

Abstract. Over the past 10 years (2005–2014), ground-level O3 in Hong Kong has consistently increased in all seasons except winter, despite the yearly reduction of its precursors, i.e. nitrogen oxides (NOx =  NO + NO2), total volatile organic compounds (TVOCs), and carbon monoxide (CO). To explain the contradictory phenomena, an observation-based box model (OBM) coupled with CB05 mechanism was applied in order to understand the influence of both locally produced O3 and regional transport. The simulation of locally produced O3 showed an increasing trend in spring, a decreasing trend in autumn, and no changes in summer and winter. The O3 increase in spring was caused by the net effect of more rapid decrease in NO titration and unchanged TVOC reactivity despite decreased TVOC mixing ratios, while the decreased local O3 formation in autumn was mainly due to the reduction of aromatic VOC mixing ratios and the TVOC reactivity and much slower decrease in NO titration. However, the decreased in situ O3 formation in autumn was overridden by the regional contribution, resulting in elevated O3 observations. Furthermore, the OBM-derived relative incremental reactivity indicated that the O3 formation was VOC-limited in all seasons, and that the long-term O3 formation was more sensitive to VOCs and less to NOx and CO in the past 10 years. In addition, the OBM results found that the contributions of aromatics to O3 formation decreased in all seasons of these years, particularly in autumn, probably due to the effective control of solvent-related sources. In contrast, the contributions of alkenes increased, suggesting a continuing need to reduce traffic emissions. The findings provide updated information on photochemical pollution and its impact in Hong Kong.

scholarly journals Archiving Metaxourgio

2021 ◽  
pp. 167-184
Author(s):  
Thomais Kordonouri
Keyword(s):  
Urban Area ◽  
21St Century ◽  
Ground Level ◽  
The Past ◽  
The Future ◽  
Relationship Of ◽  
The Relationship ◽  
Selection Of ◽  
The Way

‘Archive’ is a totality of records, layers and memories that are collected. A city is the archive that consists of the conscious selection of these layers and traces of the past and the present, looking towards the future. Metaxourgio is an area in the wider historic urban area of Keramikos in Athens that includes traces of various eras, beginning in the Antiquity and continuing all the way into the 21st century. Its archaeological space ‘Demosion Sema’ is mostly concealed under the ground level, waiting to be revealed. In this proposal, Metaxourgio is redesigned in light of archiving. Significant traces of the Antiquity, other ruins and buildings are studied, selected and incorporated in the new interventions. The area becomes the ‘open archive’ that leads towards its lost identity. The proposal aims not only to intensify the relationship of architecture with archaeology, but also to imbue the area’s identity with meanings that refer to the past, present and future.

Soil temperatures and seed burial in relation to the performance of Heteropogon contortus and Themeda australis in burnt native woodland pastures in Eastern Queensland

1969 ◽  
Vol 17 (2) ◽  
pp. 269 ◽  
Author(s):  
JC Tothill
Keyword(s):  
Ground Cover ◽  
Ground Level ◽  
Maximum Temperature ◽  
Seed Burial ◽  
Ambient Temperatures ◽  
Seasonally Dry ◽  
Heteropogon Contortus ◽  
Average Maximum ◽  
Soil Temperatures ◽  
Native Pastures

The factors underlying the increasing dominance of Heteropogon contortus (bunch or black spear grass) as a result of regularly burning native pastures in eastern Queensland have been investigated. In the subtropical environment of this experiment the removal of ground cover by burning or other means significantly increased the average maximum temperature of the surface soil. Burning favoured the germination of buried H. contortus seed at a time when ambient temperatures were too low for this to occur in unburnt situations. In late seasons and in the seasonally dry tropics insufficient soil moisture would tend to limit growth and germination until ambient temperatures are high, in which case the burning effect would be less pronounced. The efficient seed burial mechanism of H. contortus places it at an establishment advantage over other commonly associated species such as blue grasses (Bothriochloa, Dichanthium) and others whose seeds remain largely in the surface litter. Fire destroys much of this litter, the microhabitat for seed germination at ground level, and some of the weaker perennial plants. The implications of these results in relation to the increased dominance of either H. contortus or Themeda australis (kangaroo grass) are discussed.

Methods of clearing and woody weed control in the Poplar Box (Eucalyptus populinea) lands.

1981 ◽  
Vol 3 (1) ◽  
pp. 39
Author(s):  
JA Robertson ◽  
GR Beeston
Keyword(s):  
Soil Moisture ◽  
Weed Control ◽  
Ground Level ◽  
Shrub Species ◽  
Economical Method ◽  
Fuel Loads ◽  
Injection Treatment ◽  
Treat Ment ◽  
Moisture Conditions ◽  
Eucalyptus Populnea

Eucalyptus populnea Eucalj'ptus populnea (poplar or bimble box) can be controlled by ringbarking, mechanical pulling and by direct chemical appiication; fire alone has little effect. The initial ringbarking usually kills only a small percentage of trees, but repeated removal of the coppice growth leads to a complete kill. Mechanical pulling under favourable soil moisture conditions can remove many of the fignotubers from the ground and Little regrowth occurs, but in dry soils the trees break off at or near ground level and profuse re- growth occurs from the broken stumps. Chemical injection treatment, using the picloram compounds or 2,4,5-T, is probably the most economical method and high percentage kills can be obtained under all seasonal conditions. Of the shrub associates of poplar box, Eremophila mitchellii can be effectively controlled by basal stem sprays of 1.0% butyl 2,4,5-T in diesel distillate, whilst shrubs such as Cassia nemophila, C. artemisioides and Acacia deanei have been shown to be suscep- tible to fie under suitable fuel loads. Other important shrub species have reacted in varying degrees to both chemical and fue treat- ment.

Forest fuels and potential fire behaviour 12 years after variable-retention harvest in lodgepole pine

2016 ◽  
Vol 25 (6) ◽  
pp. 633 ◽  
Author(s):  
Justin S. Crotteau ◽  
Christopher R. Keyes ◽  
Elaine K. Sutherland ◽  
David K. Wright ◽  
Joel M. Egan
Keyword(s):  
Lodgepole Pine ◽  
Structural Complexity ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Forest Fuels ◽  
Fuel Loads ◽  
Variable Retention ◽  
Harvesting Technique ◽  
Trade Offs ◽  
Variable Retention Harvesting

Variable-retention harvesting in lodgepole pine offers an alternative to conventional, even-aged management. This harvesting technique promotes structural complexity and age-class diversity in residual stands and promotes resilience to disturbance. We examined fuel loads and potential fire behaviour 12 years after two modes of variable-retention harvesting (dispersed and aggregated retention patterns) crossed by post-harvest prescribed fire (burned or unburned) in central Montana. Results characterise 12-year post-treatment fuel loads. We found greater fuel load reduction in treated than untreated stands, namely in the 10- and 100-h classes (P = 0.002 and 0.049 respectively). Reductions in 1-h (P < 0.001), 10-h (P = 0.008) and 1000-h (P = 0.014) classes were greater in magnitude for unburned than burned treatments. Fire behaviour modelling incorporated the regenerating seedling cohort into the surface fuel complex. Our analysis indicates greater surface fireline intensity in treated than untreated stands (P < 0.001), and in unburned over burned stands (P = 0.001) in dry, windy weather. Although potential fire behaviour in treated stands is predicted to be more erratic, within-stand structural variability reduces probability of crown fire spread. Overall, results illustrate trade-offs between potential fire attributes that should be acknowledged with variable-retention harvesting.

The Water Turbine Competition: A Hands-On Approach to Teaching Conservation Principles

2004 ◽  
Author(s):  
Bret Van Poppel ◽  
Michael D. McKay ◽  
A. O¨zer Arnas ◽  
Daisie Boettner
Keyword(s):  
Ground Level ◽  
The United States ◽  
United States Military Academy ◽  
United States Military ◽  
Military Academy ◽  
The Past ◽  
Hands On ◽  
Water Turbine ◽  
Approach To Teaching ◽  
Conservation Principles

For the past five semesters, the Water Turbine Competition has added significant excitement and motivation to the historically dreaded Fluid Mechanics course offered in the Department of Civil and Mechanical Engineering at the United States Military Academy. The Water Turbine Competition is an adaptation of the national Hydropower Contest. Teams of two or three students build a water turbine that will lift a weight using only the potential energy stored in a tank of water that is suspended above ground level. The water turbine project has proven to be an exciting and beneficial educational tool.

Field Observations on Adults of the Wheat Bulb Fly (Leptohylemyia coarctata (Fall.)).

1958 ◽  
Vol 49 (1) ◽  
pp. 77-94 ◽  
Author(s):  
D. B. Long
Keyword(s):  
Ground Level ◽  
Early Morning ◽  
Temperature Threshold ◽  
Field Observations ◽  
Emergence Period ◽  
Temperature Rhythm ◽  
Population Peak ◽  
Late Evening ◽  
Number Of Males ◽  
Active Return

A study of adult populations of Wheat Bulb Ply, Leptohylemyia coarctata (Fall.), has been carried out in the field by routine sweeping at Rothamsted. It has been observed that the males emerge slightly before the females and that the emergence period may cover at least three weeks in late June and early July. Although the number of males may exceed the number of females at first, the females predominate later in the season due to the shorter life span of the males.The numbers of flies on the wheat have been found to fluctuate appreciably throughout the day. During the first week of the emergence period the number of flies taken increased steadily throughout the day. After the date of population peak, however, the maximum numbers occurred in the crop in the very early morning and the late evening, which suggested a daily flight dispersion followed by a general or localised return of the flies to the crop. Further study of the data showed that the daily temperature rhythm was only partly responsible for this daily flight dispersion, and that there appeared to be an active return flight to the crop in the evening. Generally the males were more active than the females and did not settle so deeply in the crop.The temperature threshold for flight was observed to be 12 to 13°C. Winds up to 8 m.p.h. did not appear to affect flight activity, but higher winds, e.g., 15 m.p.h., markedly reduced flight, the flies remaining deep in the crop near ground level. Gale-force winds, however, were observed to produce a permanent depletion in the number of flies infesting Broadbalk field, indicating that the population was probably localised.Although portions of the populations dispersed fairly rapidly from the emergence sites, recaptures of radioactive flies labelled with 32P indicated that the extent of the dispersions was not very great. The females dispersed more than the males, and were influenced to some extent by the occurrence of wheat in flower. Frequently the flies were found to have congregated on the lee edge of the crop, but other preferred regions have been observed which could not be attributed to the influence of the wind.

scholarly journals Trends in emissions and concentrations of air pollutants in the lower troposphere in the Baltimore/Washington airshed from 1997 to 2011

2013 ◽  
Vol 13 (15) ◽  
pp. 7859-7874 ◽  
Author(s):  
H. He ◽  
J. W. Stehr ◽  
J. C. Hains ◽  
D. J. Krask ◽  
B. G. Doddridge ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Lower Troposphere ◽  
Ground Level ◽  
Lower Atmosphere ◽  
Aircraft Measurements ◽  
Near Surface ◽  
Ozone Precursors ◽  
The Past ◽  
Penalty Factor

Abstract. Trends in the composition of the lower atmosphere (0–1500 m altitude) and surface air quality over the Baltimore/Washington area and surrounding states were investigated for the period from 1997 to 2011. We examined emissions of ozone precursors from monitors and inventories as well as ambient ground-level and aircraft measurements to characterize trends in air pollution. The US EPA Continuous Emissions Monitoring System (CEMS) program reported substantial decreases in emission of summertime nitrogen oxides (NOx) from power plants, up to ∼80% in the mid-Atlantic States. These large reductions in emission of NOx are reflected in a sharp decrease of ground-level concentrations of NOx starting around 2003. The decreasing trend of tropospheric column CO observed by aircraft is ∼0.8 Dobson unit (DU) per year, corresponding to ∼35 ppbv yr−1 in the lower troposphere (the surface to 1500 m above ground level). Satellite observations of long-term, near-surface CO show a ∼40% decrease over western Maryland between 2000 and 2011; the same magnitude is indicated by aircraft measurements above these regions upwind of the Baltimore/Washington airshed. With decreasing emissions of ozone precursors, the ground-level ozone in the Baltimore/Washington area shows a 0.6 ppbv yr−1 decrease in the past 15 yr. Since photochemical production of ozone is substantially influenced by ambient temperature, we introduce the climate penalty factor (CPF) into the trend analysis of long-term aircraft measurements. After compensating for inter-annual variations in temperature, historical aircraft measurements indicate that the daily net production of tropospheric ozone over the Baltimore/Washington area decreased from ∼20 ppbv day−1 in the late 1990s to ∼7 ppbv day−1 in the early 2010s during ozone season. A decrease in the long-term column ozone is observed as ∼0.2 DU yr−1 in the lowest 1500 m, corresponding to an improvement of ∼1.3 ppbv yr−1. Our aircraft measurements were conducted on days when severe ozone pollution was forecasted, and these results represent the decreasing trend in high ozone events over the past 15 yr. Back trajectory cluster analysis demonstrates that emissions of air pollutants from Ohio and Pennsylvania through Maryland influence the column abundances of downwind ozone in the lower atmosphere. The trends in air pollutants reveal the success of regulations implemented over the past decades and the importance of region-wide emission controls in the eastern United States.

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