Fire Severity Influences Ecophysiological Responses of Pinus pinaster Ait.

Francesco Niccoli,Assunta Esposito,Giovanna Battipaglia,Simona Altieri

doi:10.3389/fpls.2019.00539

Francesco Niccoli, Assunta Esposito + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2019.00539

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Abstract

The effect of fire severity on Pinus pinaster growth and ecophysiological responses was evaluated in four burned sites of Vesuvio National Park, Southern Italy. After the wildfire of 2017, when over 1300 hectares of vegetation, mainly P. pinaster woods, were destroyed, four sites were selected according to the different degree of fire severity and a multidisciplinary approach based on tree rings, stable isotopes and percentage of crown scorched or consumed was applied. All the sampled trees in the burned sites showed a decrease in tree growth in 2017, in particular in the latewood at high-severity site. The dendrochronology analyses showed that several individuals experienced and endured higher fire severity in the past compared to 2017 fire. Further δ13C and δ18O underlined the ecophysiological responses and recovery mechanisms of P. pinaster, suggesting a drastic reduction of photosynthetic and stomata activity in the year of the fire. Our findings demonstrated that P. pinaster growth reduction is strictly linked to the percentage of crown scorch and that even trees with high level of crown scorched could survive. In all the burned sites the high temperatures and the time of exposure to the flames were not sufficient to determine the death of the cambium and all the trees were able to complete the 2017 seasonal wood formation. This data can contribute to define guidelines to managers making post-fire silvicultural operations in pine forest stands in the Mediterranean Basin.

Highlights

Forest fires are a critical issue in the Mediterranean basin, experiencing increasing frequency and intensity in the last decades (IPCC, 2014).The impact of fire on trees can cause damage to the canopy, trunk, and root system (Ducrey et al, 1996)
The Park, is characterized by a large plantation forest: while the Northern slope is covered by tall deciduous trees, the Southern side presents a large plantation dominated by P. pinaster Aiton and P. pinea L, with the presence of Pinus halepensis Mill, Pinus nigra Arnold (Picariello et al, 2000) and scattered patches of typical Mediterranean macchia vegetation
The good synchronization of the chronologies of the study areas is confirmed by the expressed population signal (EPS) value > 0.85 (Table 2)

Summary

Introduction

Forest fires are a critical issue in the Mediterranean basin, experiencing increasing frequency and intensity in the last decades (IPCC, 2014).The impact of fire on trees can cause damage to the canopy, trunk, and root system (Ducrey et al, 1996). The single or combined effect of these damages can reduce the vigor of the plant and trigger a temporary reduction in growth (Battipaglia et al, 2014a) or can lead to tree mortality if the fire is destructive (Brown, 2000). Understanding post-fire responses of trees is a crucial issue in planning forest management actions of burned area in the short term (Bovio et al, 2017) and fire risk reduction at the medium and long term (Battipaglia et al, 2017). Several plant species are able to tolerate forest fires of medium and low severity, thanks to their adaptive traits that guarantee their survival: very thick bark and needles, deep root system, self-pruning capacity and particular structure of the crown

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