Recent changes to fire regimes in many regions of the world have led to renewed interest in plant flammability experiments to understand and predict the consequences of such changes. These experiments require the development of practical and standardised flammability testing protocols. The research aims were (i) to compare plant flammability assessments carried out using two different approaches, namely functional trait analysis and testing with a shoot‐level device; and (ii) to evaluate the effect of disturbances and seasonal variability on flammability. The study area was located in the Western Chaco region, Argentina, and 11 species were selected based on their representativeness in forests. We studied six functional traits related to flammability, growth habit and foliar persistence, in forests without disturbances over the three last decades as well as in disturbed forests. The seasonal variation of these functional traits was evaluated over two consecutive years. Functional trait flammability index (FI) and shoot‐level measurements followed standard protocols. Sixty per cent of the species measured presented a high to very high FI. The results of both assessment methods were significantly correlated. Both methods identified the same species as having medium flammability, but differed in regards to the most flammable species. Senegalia gilliesii was identified as the most flammable species when using functional trait analysis, whereas shoot‐level assessments found Larrea divaricata and Schinus johnstonii to be the most flammable. There were no disturbance effects on the FI but there was seasonal variation. Our results validate the use of functional traits as a predictive method of flammability testing and represent the first global effort comparing flammability obtained through functional trait analysis with empirical measurements. The significant correlation between both methods allows the selection of the one that is more appropriate for the size of the area to be evaluated and for the availability of technical resources.Abstract in Spanish is available with online material.

Resprouting is one of the main regeneration strategies in woody plants that allows post-fire vegetation recovery. However, the stress produced by fires promotes the biosynthesis of compounds which could affect the post-fire resprouting, and this approach has been poorly evaluated in fire ecology. In this study, we evaluate the changes in the concentration of chlorophylls, carotenoids, phenolic compounds, and tannins as a result of experimental burns (EB). We asked whether this biochemical response to fire could influence the resprouting responses. For that, we conducted three EB in three successive years in three different experimental units. Specifically, we selected six woody species from the Chaco region, and we analyzed their biochemical responses to EB. We used spectrophotometric methods to quantify the metabolites, and morphological variables to estimate the resprouting responses. Applying a multivariate analysis, we built an index to estimate the biochemical response to fire to EB per each species. Our results demonstrate that photosynthetic pigment concentration did not vary significantly in burnt plants that resprout in response to EB, whereas concentrations of secondary metabolites (phenolic compounds and tannins) increased up to two years after EB. Our main results showed that phenolic compounds could play a significant role in the resprouting responses, while photosynthetic pigments seem to have a minor but significant role. Such results were reaffirmed by the significant correlation between the biochemical response to fire and both resprouting capacity and resprouting growth. However, we observed that the biochemical response effect on resprouting was lower in tree species than in shrubby species. Our study contributes to the understanding of the biochemical responses that are involved in the post-fire vegetation recovery.

The objectives of this work were to estimate the ABB (Aerial Bud Bank) size in small individuals of four native woody species and its relationship with structural changes of plants after disturbances. Study area was located in dry forests from Western Chaco region, Argentina. Three tree species: Aspidosperma quebracho-blanco (Apocynaceae), Schinopsis lorentzii (Anacardiaceae), Sarcomphalus mistol (Rhamnaceae) and a shrubby species, Schinus fasciculatus (Anacardiaceae) were selected for this study. Twenty (20) juvenile individuals (below 6 cm diameter) were randomly sampled from each species and plant height (m), diameter (cm) and plant cover (%) were recorded. ABB was estimated by counting of all growth modules (shoots/branches and thorns) identified in a 1 m length segment of main stem. Results of an ANOVA (Analysis of Variance) showed significant effects of species (p < 0.0001), number of shoots/branches (p < 0.05) and number of thorns (p < 0.05) on ABB. Schinopsis lorentzii and S. fasciculatus were categorized as high ABB species, S. mistol and A. quebracho-blanco as medium and low ABB species, respectively. ABB size diminished in all species studied when plant height (p = 0.0006) and plant cover (p < 0.0001) increased which could be related to most allocation of resources towards height growth and elongation of growth modules rather than to the differentiation of new shoots. A correspondence analysis of ABB size, growth habit, number of sprouts/resprouts, presence of thorns in studied species growing in forests with different disturbances history, showed that perturbations increased number of resprouts, shrubby growth habit but spinescence was only trait with significant association with disturbed areas. These results enhance the knowledge of resprouting pattern after disturbances of native woody species and open new research lines for futures studies.