scholarly journals Could Fire Severity Promotes the Biosynthesis of Bioactive Compounds as a Strategy to Improve Plant Survival?

2020 ◽  
Vol 3 (1) ◽  
pp. 19
Author(s):  
Ana Carolina Santacruz-García ◽  
Mónica Azucena Nazareno ◽  
Sandra Bravo
Keyword(s):  
Secondary Metabolites ◽  
Fire Severity ◽  
Woody Species ◽  
Plant Response ◽  
Fire Season ◽  
Natural Environments ◽  
Spectrophotometric Methods ◽  
Chaco Region ◽  
Response To Stress ◽  
Shrubby Species

Fire has effects on diverse aspects of plant functioning and development, many of them linked to survival. However, the response of native vegetation to this disturbance possibly reveals a plant strategy to tolerate fire linked to the biosynthesis of compounds such as chlorophylls and secondary metabolites. The aim of this study was to evaluate whether fire severity could promote biochemical tolerance to fire by influencing the biosynthesis of chemical compounds. To test this, six woody species from the Chaco region were exposed to an experimental burn of medium severity at the end of fire season in the study area. In this burn, individual plots for each plant were established. Fire severity was estimated visually as the burnt biomass of each plant, which was considered as the percentage of the loss of aboveground biomass. Then, the biochemical plant response to fire was studied, through the changes in the concentration of photosynthetic pigments (chlorophyll and carotenoids), and secondary metabolites (phenolic compounds and tannins). The metabolite quantification was carried out by using spectrophotometric methods. As a result, a strong correlation was found between the biosynthesis of metabolites in response to fire and the amount of burnt biomass during the experimental burns. This correlation could be considered as an indicator of the burnt plant response to stress. In our results, shrubby species showed both the higher amount of burnt biomass and the enhanced biosynthesis of compounds in the resprouts post-fire, which could be related to the capacity of these species to be established in disturbed environments. Our study provides new insights into the understanding of the plant strategies to fire tolerance and resilience in natural environments.

scholarly journals Demographic Effects of Severe Fire in Montane Shrubland on Tasmania’s Central Plateau

Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Judy A. Foulkes ◽  
Lynda D. Prior ◽  
Steven W. J. Leonard ◽  
David M. J. S. Bowman
Keyword(s):  
Woody Species ◽  
Fire Frequency ◽  
Fire Season ◽  
Burned Area ◽  
Large Area ◽  
Seedling Regeneration ◽  
Central Plateau ◽  
Conservation Area ◽  
Severe Fire ◽  
Representative Area

Australian montane sclerophyll shrubland vegetation is widely considered to be resilient to infrequent severe fire, but this may not be the case in Tasmania. Here, we report on the vegetative and seedling regeneration response of a Tasmanian non-coniferous woody montane shrubland following a severe fire, which burned much of the Great Pine Tier in the Central Plateau Conservation Area during the 2018–2019 fire season when a historically anomalously large area was burned in central Tasmania. Our field survey of a representative area burned by severe crown fire revealed that more than 99% of the shrubland plants were top-killed, with only 5% of the burnt plants resprouting one year following the fire. Such a low resprouting rate means the resilience of the shrubland depends on seedling regeneration from aerial and soil seedbanks or colonization from plants outside the burned area. Woody species’ seedling densities were variable but generally low (25 m−2). The low number of resprouters, and reliance on seedlings for recovery, suggest the shrubland may not be as resilient to fire as mainland Australian montane shrubland, particularly given a warming climate and likely increase in fire frequency.

scholarly journals Predicting wildfire impacts on the prehistoric archaeological record of the Jemez Mountains, New Mexico, USA

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Megan M. Friggens ◽  
Rachel A. Loehman ◽  
Connie I. Constan ◽  
Rebekah R. Kneifel
Keyword(s):  
New Mexico ◽  
Fire Severity ◽  
Fire Effects ◽  
Burn Severity ◽  
Fire Season ◽  
Archaeological Sites ◽  
Archaeological Record ◽  
Human Environment ◽  
Jemez Mountains ◽  
Archaeological Materials

Abstract Background Wildfires of uncharacteristic severity, a consequence of climate changes and accumulated fuels, can cause amplified or novel impacts to archaeological resources. The archaeological record includes physical features associated with human activity; these exist within ecological landscapes and provide a unique long-term perspective on human–environment interactions. The potential for fire-caused damage to archaeological materials is of major concern because these resources are irreplaceable and non-renewable, have social or religious significance for living peoples, and are protected by an extensive body of legislation. Although previous studies have modeled ecological burn severity as a function of environmental setting and climate, the fidelity of these variables as predictors of archaeological fire effects has not been evaluated. This study, focused on prehistoric archaeological sites in a fire-prone and archaeologically rich landscape in the Jemez Mountains of New Mexico, USA, identified the environmental and climate variables that best predict observed fire severity and fire effects to archaeological features and artifacts. Results Machine learning models (Random Forest) indicate that topography and variables related to pre-fire weather and fuel condition are important predictors of fire effects and severity at archaeological sites. Fire effects were more likely to be present when fire-season weather was warmer and drier than average and within sites located in sloped, treed settings. Topographic predictors were highly important for distinguishing unburned, moderate, and high site burn severity as classified in post-fire archaeological assessments. High-severity impacts were more likely at archaeological sites with southern orientation or on warmer, steeper, slopes with less accumulated surface moisture, likely associated with lower fuel moistures and high potential for spreading fire. Conclusions Models for predicting where and when fires may negatively affect the archaeological record can be used to prioritize fuel treatments, inform fire management plans, and guide post-fire rehabilitation efforts, thus aiding in cultural resource preservation.

Spatial and temporal variations of fire regimes in the Canadian Rocky Mountains and Foothills of southern Alberta

2016 ◽  
Vol 25 (11) ◽  
pp. 1117 ◽  
Author(s):  
Marie-Pierre Rogeau ◽  
Mike D. Flannigan ◽  
Brad C. Hawkes ◽  
Marc-André Parisien ◽  
Rick Arthur
Keyword(s):  
Rocky Mountains ◽  
Fire History ◽  
Fire Severity ◽  
Ecological Integrity ◽  
Fire Regimes ◽  
Temporal Variations ◽  
Fire Season ◽  
Canadian Rocky Mountains ◽  
Southern Alberta ◽  
Fire Exclusion

Like many fire-adapted ecosystems, decades of fire exclusion policy in the Rocky Mountains and Foothills natural regions of southern Alberta, Canada are raising concern over the loss of ecological integrity. Departure from historical conditions is evaluated using median fire return intervals (MdFRI) based on fire history data from the Subalpine (SUB), Montane (MT) and Upper Foothills (UF) natural subregions. Fire severity, seasonality and cause are also documented. Pre-1948 MdFRI ranged between 65 and 85 years in SUB, between 26 and 35 years in MT and was 39 years in UF. The fire exclusion era resulted in a critical departure of 197–223% in MT (MdFRI = 84–104 years). The departure in UF was 170% (MdFRI = 104 years), while regions of continuous fuels in SUB were departed by 129% (MdFRI = 149 years). The most rugged region of SUB is within its historical range of variation with a departure of 42% (MdFRI = 121 years). More mixed-severity burning took place in MT and UF. SUB and MT are in a lightning shadow pointing to a predominance of anthropogenic burning. A summer fire season prevails in SUB, but occurs from spring to fall elsewhere. These findings will assist in developing fire and forest management policies and adaptive strategies in the future.

Plant response to stress meets dedifferentiation

Planta ◽  
2011 ◽  
Vol 233 (3) ◽  
pp. 433-438 ◽  
Author(s):  
Gideon Grafi ◽  
Vered Chalifa-Caspi ◽  
Tal Nagar ◽  
Inbar Plaschkes ◽  
Simon Barak ◽  
...  
Keyword(s):  
Plant Response ◽  
Response To Stress

The extraordinary 2019/20 Australian bushfire season: contributing processes and environmental impacts

2020 ◽  
Author(s):  
Albert van Dijk ◽  
Marta Yebra
Keyword(s):  
Fire Suppression ◽  
Fire Severity ◽  
Critical Factor ◽  
Fuel Load ◽  
Fire Season ◽  
Native Forest ◽  
Environmental Consequences ◽  
Eastern Australia ◽  
Ability To Regenerate ◽  
History Of

<p>The recent Australian summer witnessed bushfire at a scale that is without historical precedent. We analysed the scale and severity of the fires, the main processes contributing to their scale, and environmental consequences that have already become apparent.  We did this by combining satellite-derived information of vegetation cover, biomass and history, of soil and vegetation moisture content, and of fire extent and severity. More than 80,000 km2 was burnt, much of it native forest. Fire severity varied, but was overall greater than in preceding years. A critical factor contributing to fire conditions was a multi-year drought in Eastern Australia, which culminated in 2019 with the hottest and driest year in more than a century. During the fire season, fire danger conditions were further exacerbated by oceanic modes in the Indian and Southern Oceans, which limited circulation and caused excessive heating of the Australian land mass. Fuel availability in forests was unusually high. Reasons for this were several, including afforestation and regrowth as well as effective fire suppression in preceding years, while a contributing role for CO<sub>2</sub> fertilisation is also plausible. Combined with the drought and associated vegetation mortality, this created a high and flammable fuel load. The fires strongly affected Australia’s total living carbon pool, which was already depleted by several years of below-average rainfall. Greenhouse gas releases associated with drought and bushfires are not considered in official emission accounts, but are of comparable magnitude. The smoke emissions also caused direct health impacts, affecting cities like Sydney, Melbourne and Canberra for prolonged periods. Most of the burnt forests are resilient to fire and will regenerate, assuming rainfall conditions improve. The severity, scale and connectedness of some of the fire complexes suggest ecological recolonization may be very slow, while a number of threatened species may not recover. Perhaps most concerning, some of the forests affected had burnt only years before, whereas other areas contained vegetation communities not experiencing fire for centuries, raising questions about their ability to regenerate and possibly permanent ecological regime shifts.</p>

scholarly journals High Potential for Secondary Metabolite Production of Paracoccus marcusii CP157, Isolated From the Crustacean Cancer pagurus

2021 ◽  
Vol 12 ◽  
Author(s):  
Janina Leinberger ◽  
Jonas Holste ◽  
Boyke Bunk ◽  
Heike M. Freese ◽  
Cathrin Spröer ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Elevated Temperatures ◽  
Proteolytic Enzymes ◽  
Natural Habitat ◽  
Antibacterial Properties ◽  
Gene Clusters ◽  
Natural Environments ◽  
Phylogenetic Distance ◽  
Cancer Pagurus ◽  
Bioactive Secondary Metabolites

Secondary metabolites are key components in microbial ecology by mediating interactions between bacteria and their environment, neighboring species or host organisms. Bioactivities can be beneficial for both interaction partners or provide a competitive advantage only for the producer. Colonizers of confined habitats such as biofilms are known as prolific producers of a great number of bioactive secondary metabolites and are a potential source for novel compounds. We investigated the strain Paracoccus marcusii CP157, which originates from the biofilm on the carapace of a shell disease-affected Cancer pagurus specimen, for its potential to produce bioactive secondary metabolites. Its closed genome contains 22 extrachromosomal elements and several gene clusters potentially involved in biosynthesis of bioactive polyketides, bacteriocins, and non-ribosomal peptides. Culture extracts of CP157 showed antagonistic activities against bacteria from different phyla, but also against microalgae and crustacean larvae. Different HPLC-fractions of CP157 culture extracts had antibacterial properties, indicating that several bioactive compounds are produced by CP157. The bioactive extract contains several small, antibacterial compounds that partially withstand elevated temperatures, extreme pH values and exposure to proteolytic enzymes, providing high stability toward environmental conditions in the natural habitat of CP157. Further, screening of 17 Paracoccus spp. revealed that antimicrobial activity, hemolysis and production of N-acyl homoserine lactones are common features within the genus. Taking into account the large habitat diversity and phylogenetic distance of the tested strains, we hypothesize that bioactive secondary metabolites play a central role in the ecology of Paracoccus spp. in their natural environments.

scholarly journals Biogeochemical and biophysical responses to episodes of wildfire smoke from natural ecosystems in southwestern British Columbia, Canada

2021 ◽  
Author(s):  
Sung-Ching Lee ◽  
Sara H. Knox ◽  
Ian McKendry ◽  
T. Andrew Black
Keyword(s):  
Observational Studies ◽  
Natural Experiment ◽  
Fire Severity ◽  
Fire Season ◽  
Natural Ecosystems ◽  
Diffuse Fraction ◽  
Wildfire Smoke ◽  
Carbon Dioxide Co2 ◽  
Eddy Covariance Measurement

Abstract. Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified ecosystem feedbacks. However, there are few observational studies measuring the ecosystem‐scale biogeochemical and biophysical properties during smoke episodes, and hence accessing productivity effects of changes in incident diffuse photosynthetically active radiation (PAR). In this study, we leverage two long-term eddy covariance measurement sites in forest and wetland to study four smoke episodes, which happened at different times and differed in length, over four different years. We found that the highest decrease of shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on H and LE were also greatest. Smoke generally increased the diffuse fraction from ~0.30 to ~0.50 and turned both sites into stronger carbon-dioxide (CO2) sinks with increased productivity of ~18 % and ~7 % at the forest and wetland sites, respectively. However, when the diffuse fraction exceeded 0.80 as a result of dense smoke, both ecosystems became CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke‐productivity feedbacks.

scholarly journals A suffrutescent Helianthus from Los Angeles County, California

2014 ◽  
Author(s):  
Aleksi Baznekian
Keyword(s):  
Los Angeles ◽  
Los Angeles County ◽  
Woody Species ◽  
Shrubby Species

A suffrutescent individual, belonging to the genus Helianthus, and bearing resemblance to H. annuus, has been observed in Los Angeles County, California. This individual was observed to woody proximally; not a character of the herbaceous annual sunflower, H. annuus. Photographs of this woody individual and a general herbaceous representative H. annuus are presented in this article. Dr. David J. Keil, an Asteraceae (sunflower family) taxonomist, suggests that a new shrubby species of Helianthus may be present in California, and thus, this suffrutescent individual may be a representative of that woody species. It may also be a woody variety of H. annuus.

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