CypFire. Dr. Gianni DELLA ROCCA. Interaction between Cypress and Wildfires: Scientific achievements

Transcription

1 CypFire Interaction between Cypress and Wildfires: Scientific achievements Dr. Gianni DELLA ROCCA Institute for Sustainable Plant Protection CNR, Italy

2 WHAT FLAMMABILITY MEANS? Flammability: general ability of vegetation (fuel) to burn Distinct aspects of combustion: White & Zipperer (2010) Ignitability ease to ignition. Sustainability how well combustion will proceed. Combustibility velocity or intensity of combustion. Consumability amount of combusted fuel. Combustion phases: Pre-heating Pre-Ignition (smoke) Pyrolisis (red spots) Flaming Smoldering Glowing

3 TO BE MORE FLAMABLE OR LESS FLAMMABLE A TWIST In previous studies, crown samples of C. sempervirens was classified as: low or moderate flammable (Valette,1990; Neyisci and Intini, 2006), not very flammable (Ganteaume et al., 2013), highly flammable (Dimitrakopoulos and Papioannou, 2001; Liodakis et al., 2002) Dimensions of plant flammability: individual plant portions, whole plant, set of plants (woodland). Methods & Devices for flammability characterization and its setting. Lack of standardization! Traits influencing the Flammability: i) physical properties (morphology, surface/volume ratio, architecture), ii) primary chemical traits (water content, percentage in lignin, mineral/ash content), and iii) presence/abundance of secondary flammable metabolites (isoprenoids), iv) the vegetation/fuel structure (e.g., fuel loading, arrangement, packing ratio, porosity, dead : live ratio). Ranking: comparison among whom?

4 Cupressus sempervirens var. sempervirens (sin. var. horizontalis) Cupressus sempervirens var. pyramidalis (sin. var. fastigiata, var. stricta) 4 4

5 Assumptions C. sempervirens var. horizontalis: widespread and naturalized (throughout the Mediterranean); marked tolerance to drought and to high temperatures; ability to go dormant during summer and; to vegetate in highly-deteriorated and rocky soils; cypress is adapted to the typical xero-med climate and can grow in conditions that are extremely unsuitable (even lethal) for most tree species. For these reasons, cypress can be properly compared only to other Mediterranean species which have similar ecological characteristics (grow in similar ecological conditions).

6 Characterization of C. sempervirens var. horizontalis FUELS: In collaboration with the: Wildfire Laboratory INIA, Madrid (external and indipendet institution) live fine fuel (Crown) Ø < 0.6 cm (FMC=96-120%) Litter (FMC=10-12%)

7 DEVICES PHRR HRR TTI EPIRADIOMETER (Valette, 1990) C Time to smoke Time to pyrolisis Time to ignition Flame duration Flame high Smouldering duration Glowing duration RMF MASS LOSS CALORIMETER (Madrigal et al., 2012) kw/m 2 MOISTURE ANALYZER FMC% - Moisture to extintion

8 Fuel bed ignition test, simulating a fire brand / ember fall BURNING TABLE Surface fire propagation test

9 specie; LS Means Current effect: F(5, 684)=187,32, p=0,0000 Effective hypothesis decomposition Vertical bars denote 0,95 confidence intervals Time of pyrolis (sec) Results on stabilized litters just few examples tempo incandesc Cupressus glabra Pinus halepensis Cupressus sempervirens Pinus pinaster specie Pinus pinea Quercus ilex specie; LS Means Current effect: F(5, 661)=188,21, p=0,0000 Effective hypothesis decomposition Vertical bars denote 0,95 confidence intervals Time to Ignition (sec) specie; LS Means Current effect: F(5, 26)=,47254, p=,79323 Effective hypothesis decomposition Vertical bars denote 0,95 confidence intervals Ignition frequency (%) inizio fiamma freq fiamma Cupressus glabra Pinus halepensis Cupressus sempervirens Pinus pinaster Pinus pinea Quercus ilex 60 Cupressus glabra Pinus halepensis Cupressus sempervirens Pinus pinaster Pinus pinea Quercus ilex specie specie

10 Results on stabilized litters Flame height (cm) 23 specie; LS Means Current effect: F(5, 661)=36,192, p=0,0000 Effective hypothesis decomposition Vertical bars denote 0,95 confidence intervals H fiamma Ash content (gr/gr) 14 Cupressus glabra Pinus halepensis Cupressus sempervirens Pinus pinaster Pinus pinea Quercus ilex 0,14 specie; LS Means Current effect: F(5, 691)=174,90, p=0,0000 Effective hypothesis decomposition Vertical bars denote 0,95 confidence intervals specie 0,12 0,10 peso ceneri 0,08 0,06 0,04 0,02 0,00 Cupressus glabra Pinus halepensis Cupressus sempervirens Pinus pinaster specie Pinus pinea Quercus ilex

11 MLC: Heat Release Rate (HRR) High combustion delay

12 Cupressus sempervirens var. horizontalis No surface fire propagation! No litter ignition! Bulk density effect > 60 kg/m 3 (threashold)

13 Quercus ilex subsp. ilex and Quercus faginea

14 Pinus pinea

15 MAIN RESULTS Comparison among species belonging to the same vegetation belt and climate zone Cypres adopts a water saving strategy faced to the drought. In summer time its leaves have a higher water content than those of many other strictly Mediterraneran tree species. Cypress leaves and litter are slow to ignite (low ignitability) but release an high amount of energy during the combustion (high combustibility). Litter is dense (compact), retains humidity and allow an low oxygen circulation, consequently it is really hard to catch fire. Cypress leaves have a high mineral content that essentially indicates that there is less mass to burn (low consumability). The flammable isoprenoids (expecially MT) are stored superficially in leaf glands in cypress. During the thermal decomposition of the fuel, are early dispersed, poorly contributing to the flammability phases.

16 For further details (Scientific papers)

17 Brief remarks on the cypress at the plant level and at stand level Absence of understory in cypress stands i) mulching action exerted by the thick layer of the litter; ii) supposed acidity and the allelopathic effect of the litter, which prevent the germination of other plants; iii) marked shading, which reduces the amount of light reaching the soil. Cypresses can limit the risk of surface fires involving litter or understory, compared to other tree species which, instead, allow the development of a continuous layer of understory vegetation.

18 reduced circulation of air within the crowns; maintenance of a humidity inside (both these factors reduces flammability) Thickness of the crown The flames develop easily and rapidly in a tree with a crown that is not very dense and well-aired. Common cypresses (var. horizontalis) has a rather thick crown compared to other conifers (e.g. pines). Cypress crowns are also capable to retaining part of the radiating heat of the fire that delay the loss of humidity of the surrounding vegetation, thus slowing down the advance of the fire.

19 How to realize an effective multi-row cypress barrier? It is a still empirical task. Previous and consolidated experiences are based on windbreaks Cypress barrier Woodland 2,50 m 2,50 m Cypress plantation strategy 2,50 m 2,50 m

20 Cypress plantation realized in Siena 7 Cypress 7 Cypress 8 m Variabile rows rows 8 m Woodland Forest Track Service Trail the width depends on the topography Forest Track Woodland

21 Cypress plantation realized in Siena

22 CONCLUSIONS Selected C. sempervirens var. horizontalis have a good potential as effective complementary means to control low-medium intense wildfire in the Mediterranean environment and can really contribute to the reduction of the initial fire risk. Cypress may be planted along the access roads to the woodlands, among the plantations of other highly flammable species, to make green low-ignitable barriers, to slow down or prevent the quick spread of fire making easier its control.

23 THE IMPORTANCE OF A CORRECT COMMUNICATION WITH MASS MEDIA IGNIFUGO UNINFLAMMABLE???? Popular Science CAUTION!!!!!!! On this topic a lively debate (partially unjustified) arose

24 Responsible declarations

25 «Sciences et Avenir» April 2017

26 THANK YOU FOR YOUR ATTENTION Dr. Gianni DELLA ROCCA