Effect of experimental fire on seedlings of Australian and Gondwanan trees species from a Tasmanian montane vegetation mosaic

2018 ◽  
Vol 66 (7) ◽  
pp. 511 ◽  
Author(s):  
Lynda D. Prior ◽  
Ben J. French ◽  
David M. J. S. Bowman
Keyword(s):  
Fire Intensity ◽  
Strongly Correlated ◽  
Seedling Size ◽  
Montane Vegetation ◽  
Recovery Mechanisms ◽  
Large Fires ◽  
Experimental Approaches ◽  
World Heritage Area ◽  
In Fire ◽  
Resprouting Ability

The montane area of the Tasmanian Wilderness World Heritage Area was recently burnt by large fires ignited by lightning, and such fires are predicted to become more frequent with climate change. The region has a mix of fire-sensitive and fire-tolerant vegetation, but there is little information available on resprouting ability of seedlings of the dominant species of these mosaics. We predicted that seedlings of species found in fire-prone locations would exhibit more post-fire resprouting than seedlings of Gondwanan relictual species, which typically occur in fire-protected locations. To test this hypothesis we compared topkill and resprouting ability of seedlings from five tree species characteristic of the montane vegetation mosaics by exposing them to a propane burner flame for 0, 15, 30, 45 and 60s, simulating a fire intensity of 33 kW m–1. Overall, 93 of 100 flame-exposed plants were topkilled. Topkill was related to duration of flame exposure and seedling size rather than species. By contrast, resprouting of topkilled seedlings was strongly correlated with species rather than seedling size, and was not affected by duration of flame exposure. Contrary to expectations, the rainforest plant Nothofagus cunninghamii was the strongest resprouter, whereas few of the topkilled eucalypt seedlings resprouted. Our study shows the commonly held association between palaeoendemic Gondwanan species and low fire tolerance versus Australian species and high fire tolerance is overly simplistic. We need to better understand fire recovery mechanisms in the Tasmanian flora using a combination of field observation and experimental approaches.

scholarly journals An assessment of the implementation and outcomes of recent changes to fire management in the Kruger National Park

Koedoe ◽  
2008 ◽  
Vol 50 (1) ◽  
Author(s):  
Brian W. Van Wilgen ◽  
Navashni Govender ◽  
Sandra MacFadyen
Keyword(s):  
National Park ◽  
Fire Management ◽  
Fire Regime ◽  
Kruger National Park ◽  
Fire Intensity ◽  
Target Area ◽  
Large Fires ◽  
Sufficient Degree ◽  
Burnt Areas ◽  
In Fire

This paper reviews recent changes in fire management in the Kruger National Park, and assesses the resulting fire patterns against thresholds of potential concern. In 2002, a lightning-driven approach was replaced by an approach that combined point ignitions with unplanned and lightning fires. The approach aimed to burn an annual target area, determined by rainfall and fuel conditions, in point-ignition fires of different sizes. Most of the original fire-related thresholds of potential concern (TPCs) were incorporated into the new approach. The annual target area to be burnt ranged from 12 to 24% of the park between 2002 and 2006. The total area burnt generally exceeded the targets each year, and management fires accounted for less than half of the total area burnt. The fire regime was dominated by very large fires (> 5 000 ha) which accounted for 77% of the total area burnt. New TPCs were developed to assess whether the fire regime encompassed a sufficient degree of variability, in terms of fire intensity and the spatial distribution of burnt areas. After assessment and adjustment, it appears that these TPCs have not yet been exceeded. The point-ignition approach, and its evaluation in terms of variability and heterogeneity, is based on the untested assumption that a diverse fire regime will promote biodiversity. This assumption needs to be critically assessed. We recommend that the practice of point ignitions be continued, but that greater efforts be made to burn larger areas earlier in the season to reduce large and intense dry-season fires.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

scholarly journals Tropical Dry Forest Resilience to Fire Depends on Fire Frequency and Climate

2021 ◽  
Vol 4 ◽  
Author(s):  
Maximilian Hartung ◽  
Geovana Carreño-Rocabado ◽  
Marielos Peña-Claros ◽  
Masha T. van der Sande
Keyword(s):  
Tropical Forests ◽  
Tropical Dry Forest ◽  
Remote Sensing Data ◽  
Fire Frequency ◽  
Dry Forest ◽  
Fire Disturbance ◽  
Fire Intensity ◽  
Forest Resilience ◽  
Landsat Satellite ◽  
In Fire

Wildfires are becoming increasingly frequent and devastating in many tropical forests. Although seasonally dry tropical forests (SDTF) are among the most fire-threatened ecosystems, their long-term response to frequent wildfires remains largely unknown. This study is among the first to investigate the resilience in response to fire of the Chiquitano SDTF in Bolivia, a large ecoregion that has seen an unprecedented increase in fire intensity and frequency in recent years. We used remote sensing data to assess at a large regional and temporal scale (two decades) how fire frequency and environmental factors determine the resilience of the vegetation to fire disturbance. Resilience was measured as the resistance to fire damage and post-fire recovery. Both parameters were monitored for forested areas that burned once (F1), twice (F2), and three times (F3) between 2000 and 2010 and compared to unburned forests. Resistance and recovery were analyzed using time series of the Normalized Burn Ratio (NBR) index derived from Landsat satellite imagery, and climatic, topographic, and a human development-related variable used to evaluate their influence on resilience. The overall resilience was lowest in forests that burned twice and was higher in forests that burned three times, indicating a possible transition state in fire resilience, probably because forests become increasingly adapted during recurrent fires. Climatic variables, particularly rainfall, were most influential in determining resilience. Our results indicate that the Chiquitano dry forest is relatively resilient to recurring fires, has the capacity to recover and adapt, and that climatic differences are the main determinants of the spatial variation observed in resilience. Nevertheless, further research is needed to understand the effect of the higher frequency and intensity of fires expected in the future due to climate change and land use change, which may pose a greater threat to forest resilience.

Fire effects on the spatial patterns of soil resources in a Nicaraguan wet tropical forest

2005 ◽  
Vol 21 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Brent C. Blair
Keyword(s):  
Leaf Litter ◽  
Tropical Forests ◽  
Forest Fires ◽  
Soil Heterogeneity ◽  
Fire Effects ◽  
Fire Intensity ◽  
Vegetative Cover ◽  
Soil Resources ◽  
In Fire ◽  
The Impact

Anthropogenic wildfires are becoming increasingly frequent in wet tropical forests. This trend follows that of other anthropogenic disturbances, which are now acute and widespread. Fires pose a potentially serious threat to tropical forests. However, little is known about the impact of unintended forest fires on below-ground resources in these ecosystems. This study investigated the influence of fires on the distribution and variability of soil resources on two sets of 50×50-m burned and unburned plots in a Nicaraguan rain forest. Samples were collected at 5-m intervals throughout each plot as well as subsamples at 50-cm intervals. Geostatistical techniques as well as univariate statistics were used to quantify the spatial autocorrelation and variability of selected nutrients (N, P and K), carbon and standing leaf litter. Most variability in this forest was spatially dependent at a scale of 30 m or less. However the average range of autocorrelations varied greatly between properties and sites. Burning altered soil heterogeneity by decreasing the range over which soil properties were autocorrelated. Overall the average patch size (range) for nitrogen was reduced by 7%, phosphorus by 52%, potassium by 60% and carbon by 43%. While phosphorus and leaf litter increased in the burned plots compared to unburned plots, potassium was not different. Nitrogen and carbon did not display a consistent pattern between burning regimes and this may be explained by variation in fire intensity. Leaf litter measurements did not correlate with measured soil nutrients within plots. Observed changes in the burned forest were likely a result of both the intensity of burning and change in vegetative cover between the time of the fires and soil sampling.

scholarly journals Differential herbivore occupancy of fire-manipulated savannas in the Satara region of the Kruger National Park, South Africa

Koedoe ◽  
2020 ◽  
Vol 62 (1) ◽  
Author(s):  
Thobile B. Dlamini ◽  
Brian K. Reilly ◽  
Dave I. Thompson ◽  
Deron E. Burkepile ◽  
Judith M. Botha ◽  
...  
Keyword(s):  
South African ◽  
National Parks ◽  
Fire Regimes ◽  
Strongly Correlated ◽  
Climate Conditions ◽  
Surrounding Matrix ◽  
History Of Research ◽  
History Of ◽  
Using Data ◽  
In Fire

The Kruger National Park’s (KNP) long-running experimental burn plots (EBPs) have a history of research projects, which improve the understanding of fire in savanna ecosystems. Using data from KNP’s aerial censuses (2005–2016) and in situ dung count data (2008–2017), this study assessed (1) herbivore densities on the Satara, N’Wanetsi and Marheya EBPs, on annual, triennial and no-burn treatments and across pre-, during and post-drought climate conditions; (2) herbivore densities of these EBPs relative to their non-manipulated surroundings and (3) the extent to which distance to water and rainfall influence ungulate densities. The results revealed that herbivore mean density differed significantly between the three EBPs of Satara and across their fire treatments. N’Wanetsi showed the highest density (0.30 animals/ha), whilst the lowest was found at Marheya (0.12 animals/ha). Overall, pre-drought density was higher on the annual plots (0.56 animals/ha), whilst higher post-drought density was evidenced on the triennial plots (0.80 animals/ha). On average, there were significantly higher herbivore densities on the EBPs (2.54 animals/ha) compared to the surrounding matrix at the larger scales of the Satara management section (0.15 animals/ha) and the central KNP (0.18 animals/ha). A positive correlation between herbivore mean density estimate and distance to water was shown. However, grazer mean density across fire treatments was strongly correlated to rainfall.Conservation implications: Given the variation in fire regimes and their application, and the non-uniform and elevated herbivore densities of the EBPs, inferences from the EBPs cannot be made to the larger KNP. The trials should rather be viewed as an isolated, fire herbivory experiment. It is also recommended to align the experiment with South African National Parks’ mandate by including biodiversity parameters like small mammals and insects in the monitoring of the plots.

scholarly journals Vegetation geographical patterns as a key to the past, with emphasis on the dry vegetation types of South Africa

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 405-410 ◽  
Author(s):  
M. J. A. Werger
Keyword(s):  
Southern Africa ◽  
Woody Species ◽  
Dwarf Shrub ◽  
Strongly Correlated ◽  
Cam Plants ◽  
Winter Rainfall ◽  
Geographical Patterns ◽  
The Past ◽  
Montane Vegetation ◽  
Cape Fynbos

Southern Africa is characterized by a highly diversified vegetational cover with extremes as contrasting as desert, tropical forest, alpine grassland, or mediterranean type scrub, and many other types in between. This vegetational pattern is strongly correlated to the climatological pattern. It is therefore likely that past changes in climate can still be partly traced in the vegetational pattern, particularly in geographical anomalies, and that study of these patterns provides complementary evidence to palynological research. The following anomalies in the vegetational pattern are briefly discussed: 1. island-wise occurrence of Afro-montane vegetation on mesic, sheltered sites in the southern Sudano- Zambezian Region, in particular in the Highveld grassland/False Karoo transition area; 2. similar westward occurrence of Sudano-Zambezian scrub patches in the Karoo-Namib Region near the Orange/Vaal confluence; 3. scattered occurrence of Sudano-Zambezian woody species in a matrix of Karoo-Namib vegetation in the marginal Karoo-Namib Region; 4. island-wise occurrence of frost-tolerant, dry, karroid dwarf shrub vegetation of predominantly C,-plants on isolated peaks in the winter rainfall area of Namaqualand; 5. peculiar patchy distribution of some succulents in wide areas of climatically rather homogeneous, succulent dwarf shrub vegetation of predominantly CAM-plants in the escarpment area of Namaqualand. a pattern reminiscent of that in many Cape fynbos species. Interpretation of these patterns logically leads to the conclusion that these result from a previously wetter, a previously cooler, or a previously wetter and cooler climate, respectively, over the parts of southern Africa under discussion. This conclusion is compared with published palynological views.

scholarly journals Exploring spatial-temporal dynamics of fire regime features at mainland Spain

2017 ◽  
Author(s):  
Adrián Jiménez-Ruano ◽  
Marcos Rodrigues Mimbrero ◽  
Juan de la Riva Fernández
Keyword(s):  
Temporal Dynamics ◽  
Fire Regime ◽  
Fire Frequency ◽  
Change Point Detection ◽  
Burnt Area ◽  
Temporal Behaviour ◽  
Sen’S Slope ◽  
Large Fires ◽  
The Mediterranean ◽  
In Fire

Abstract. This paper explores spatial-temporal dynamics in fire regime features, such as fire frequency, burnt area, large fires, and natural- and human-caused fires, as an essential part of fire regime characterisation. Changes in fire features are analysed at different spatial–regional and provincial/NUTS3 levels, together with summer and winter temporal scales, using historical fire data from Spain for the period 1974–2013. Temporal shifts in fire features are investigated by means of change point detection procedures – Pettitt test, AMOC (At Most One Change), PELT (Pruned Exact Linear Time) and BinSeg (Binary Segmentation) – at regional level to identify changes in the time series of the features. A trend analysis was conducted using the Mann–Kendall and Sen's slope tests at both regional and NUTS3 level. Finally, we applied a Principal Component Analysis (PCA) and Varimax Rotation to trend outputs – mainly Sen's slope values – to summarize overall temporal behaviour, also to explore potential links in the evolution of fire features. Our results suggest that most fire features show remarkable shifts between the late 1980s and the first half of the 1990s. Mann–Kendall outputs revealed negative trends in the Mediterranean region. Results from Sen's slope suggest high spatial and intra-annual variability across the study area. Fire activity related to human sources seems to be experiencing an overall decrease in the north-west provinces, particularly pronounced during summer. Conversely, the hinterlands and the Mediterranean coast are gradually becoming less fire-affected. Finally, PCA enabled trends to be synthesized into four main components: winter fire frequency (PC1), summer burnt area (PC2), large fires (PC3) and natural fires (PC4).

An Inverse Fire Modeling Methodology for the Determination of Fire Size, Fire Location, and Soot Deposition in a Compartment

2012 ◽  
Author(s):  
Kristopher J. Overholt ◽  
Ofodike A. Ezekoye
Keyword(s):  
Gas Phase ◽  
Solid Phase ◽  
Fire Modeling ◽  
Fire Intensity ◽  
Intermediate Step ◽  
Fire Size ◽  
Fire Models ◽  
Input Parameters ◽  
In Fire ◽  
Fire Location

Fire models are routinely used in life safety design projects and are being used more often in fire and arson investigations as well as reconstructions of firefighter line-of-duty deaths (LODDs) and injuries. In all of these applications, the fire heat release rate (HRR), location of a fire in a compartment, gas-phase soot concentration, and solid-phase soot accumulation are important parameters that govern the evolution of thermal conditions within the fire compartment. These input parameters can be a large source of uncertainty in fire models, especially in scenarios in which experimental data or detailed information on fire behavior are not available, such as fire investigations and LODD reconstructions. Various methods have been reported in literature to determine the size and location of a fire in a compartment using ceiling-mounted detectors [1–4]. A previous study by the authors developed an inverse fire modeling technique to determine the time-varying HRR of fire in a compartment using measured thermocouple data [5]. The work presented in this paper extends the inverse HRR methodology by developing a technique to determine the location of a fire using wall-mounted heat flux sensors or a surrogate such as degradation characteristics of enclosure boundaries that can be collected during post-fire assessments. Additionally, the presence of soot modifies the radiative transfer field in the hot gas layer (gas phase) as well as radiative heat transfer to surfaces (condensed phase). As a detailed history of compartment conditions becomes less available, there is a need for an inversion methodology to accurately recover governing input parameters such as fire size, fire location, and fire burning properties while maintaining an adequate level of accuracy. As an intermediate step using measured fire test data, we can begin to construct an approach to use rich data to invert for fire intensity, fire location, and fire properties such as the amount of soot produced by the fire.

scholarly journals Changes in fire intensity have carry-over effects on plant responses after the next fire in southern California chaparral

2012 ◽  
Vol 24 (2) ◽  
pp. 395-404 ◽  
Author(s):  
José M. Moreno ◽  
Iván Torres ◽  
Belén Luna ◽  
Walter C. Oechel ◽  
Jon E. Keeley
Keyword(s):  
Southern California ◽  
Fire Intensity ◽  
Plant Responses ◽  
Carry Over ◽  
In Fire

Relationships between fire danger and the daily number and daily growth of active incidents burning in the northern Rocky Mountains, USA

2015 ◽  
Vol 24 (7) ◽  
pp. 900 ◽  
Author(s):  
Patrick H. Freeborn ◽  
Mark A. Cochrane ◽  
W. Matt Jolly
Keyword(s):  
Fire Danger ◽  
Burned Area ◽  
Final Size ◽  
Temporal Window ◽  
Daily Growth ◽  
Northern Rocky Mountains ◽  
History Of ◽  
Large Fires ◽  
Us Forest Service ◽  
In Fire

Daily National Fire Danger Rating System (NFDRS) indices are typically associated with the number and final size of newly discovered fires, or averaged over time and associated with the likelihood and total burned area of large fires. Herein we used a decade (2003–12) of NFDRS indices and US Forest Service (USFS) fire reports to examine daily relationships between fire danger and the number and growth rate of wildfires burning within a single predictive service area (PSA) in the Northern Rockies, USA. Results demonstrate that daily associations can be used to: (1) extend the utility of the NFDRS beyond the discovery date of new fires; (2) examine and justify the temporal window within which daily fire danger indices are averaged and related to total burned area; (3) quantify the probability of managing an active incident as a function of fire danger; and (4) quantify the magnitude and variability of daily fire growth as a function of fire danger. The methods herein can be extended to other areas with a daily history of weather and fire records, and can be used to better inform fire management decisions or to compare regional responses of daily fire activity to changes in fire danger.

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