A comparative assessment of plant flammability through a functional approach: The case of woody species from Argentine Chaco region

Our objective was to assess the current fire regime of a 600 ha savanna dominated by the grass species Elionorus muticus Spreng., located in Santiago del Estero Province, north-western Chaco region, Argentina. The degree of tolerance of some native woody species to fire, the fire mean fire frequency (FF), and Weibull median probability (WMPI) were evaluated. Sampling sites were located in the ecotone between the savanna and the surrounding forests. A database was developed from fire scars found in cross sections of native tree and shrub species, cut at different heights above ground; that covered the recent 70 years of fire history (1925–1996). Results indicate that the savanna has a mean FF of 0.179 fires year–1 and an FI = 3 years. The mean height of fire scars found in trees and shrubs which indicate medium to high fireline intensities with flame lengths larger than 1 m are frequent in the savanna. Native species have different degrees of tolerance: Aspidosperma quebracho blanco (tree) and Schinopsis quebracho colorado (tree) are more tolerant to fire than Acacia furcatispina (shrub) and A. aroma (shrub). Bark thickness of the tree species (1–1.5 cm in mature individuals) allows them to withstand the frequent, high intensity fires of the savanna.

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

Environmental Sciences Proceedings ◽

10.3390/iecf2020-08083 ◽

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.

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Provenance matters: variability under saline stress in young plants of four populations of a Prosopis (mesquite) species from dry forests of Argentina

Canadian Journal of Forest Research ◽

10.1139/cjfr-2020-0130 ◽

2021 ◽

Author(s):

Paula Venier ◽

Guillermo Funes ◽

Ingrid Teich ◽

Diego López Lauenstein ◽

Ramiro Lascano

Keyword(s):

Forest Restoration ◽

Stress Condition ◽

Woody Species ◽

Growth Conditions ◽

Stem Diameter ◽

Saline Stress ◽

Dry Forests ◽

Salt Stress Condition ◽

Physiological Variables ◽

Chaco Region

Planting of native perennial woody species tolerant to variable salt concentrations can facilitate the recovery of degraded dry forests. The objective was to evaluate and compare the response to saline stress on experimentally controlled conditions of young plants from four provenances of Prosopis alba, a mesquite species useful for restoration plans. They were from different localities of the Chaco Region of Argentina (Santiago del Estero, Chaco, Formosa and Salta) and were evaluated for 45 days under greenhouse controlled growth conditions at 0, 100 and 300 mM NaCl. We measured variables associated with growth, photosynthesis and redox state. The imposed salt stress condition did not cause plant death in any provenance. However, salinity produced a strong effect on growth and physiological variables of all provenances. Salta provenance was associated to higher net values of biomass and stem diameter. Chaco registered the greatest relative values of height and stem diameter, indicating a higher salinity tolerance than the other provenances; also it produced more antioxidants, to cope with the oxidative stress associated to saline stress. Chaco and Salta could be the most promising provenances to use in restoration plans of dry forests in areas with saline soils in the Chaco region. We emphasize the importance of use different provenances in forest restoration for a more successful system recovery.

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