Survival to prescribed fire of plantation-grown Corsican black pine in northern Portugal

Abstract

Context: The current fire regime threatens black pine (Pinus nigra Arn.) persistence in the Mediterranean Basin, which recommends larger-scale fuel treatments. Prescribed burning is an option for stand protection but its use in young stands (which are particularly at risk) is hindered by the scarce knowledge on post-fire tree survival. Aims: The objectives were to characterize bark thickness as a fire-resistance trait in P. nigra, and to describe how post-fire tree survival responds to tree size and fire effects in a 16-year old plantation. Methods: Bark thickness was related to diameter at breast height and height in the stem. Metrics describing tree size and stem and crown damage were measured 1-year after prescribed burning in 259 trees. Tree survival was modelled with logistic regression and CART analysis. Results: Bark thickness increased linearly with dbh and decreased with height in the stem. Tree survival was primarily a function of crown injury. Stem damage was an influent factor in small trees. Conclusion: Due to thinner bark and lower tolerance to crown damage, young P. nigra trees are less fire-resistant than other Mediterranean pines, e.g. P. pinaster. Prescribed fire should not be attempted if dbh <10 cm. Mechanical clearing is the treatment of choice in young stands with a significant shrub layer.

Forest management for adaptation to climate change in the Mediterranean basin: A synthesis of evidence

“…This may result, for instance, in a trade-off between the short-term resistance and the long-term resilience to drought, as the beneficial effect of thinning at reducing drought vulnerability can reverse as the stands mature due to greater physiological constraints associated with larger trees (D'Amato et al, 2013). The second example focuses on the reported negative impacts of prescribed burning on the subsequent survival, growth and physiological performance of trees (Fernandes et al, 2012;Lavoir et al, 2013;Valor et al, 2015).…”

Bark thickness and fire regime

“…For ontogenetic reasons, bark may also be thick in the upper part of the bole or in the branches. However, there is evidence that bark can be disproportionately thicker at the lower bole (Wiant & Koch 1974;Fernandes, Fernandes & Loureiro 2012;Odhiambo, Meincken & Seifert 2014;Graves, Rifai & Putz in press). It is possible that the lack of differences in bark thickness between ecosystems with different fire regimes reported by could be because bark thickness was measured on branches (1 m from the tip) and not on the main stem.…”

Influence of tree size, reduced competition, and climate on the growth response of Pinus nigra Arn. salzmannii after fire

“…Another factor driving the reduction in growth of smaller trees affected by high BCH may be related to their bark thickness. Smaller trees are more expose to suffer cambial injuries, especially at higher stem heights, as there is reduction on bark thickness as the diameter of the stem decreases (Fernandes et al 2012). In the case of large trees, the effect of fire on crown consumption and cambium damage was found to be of lesser significance than for smaller trees due to their higher crown base height and thicker bark.…”