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5th International Conference of Fire Effects on Soil

Properties

University College Dublin

14th – 17th July 2015

Poster Abstracts

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Sponsorship

The 5th International Conference of Fire Effects on Soil Properties acknowledge all our sponsors, without whose help the event would not have been possible.

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Poster Titles and Corresponding Authors Theme: Combining computational methods and experimental data . 7 1A Combining computational methods with spectroscopic and pyrolytic analyses for the

semi-‐quantitative assessment of pyrogenic structures in fire affected soils ....................... 7 Almendros, G.1 ([email protected]), ....................................................... 7

Theme: Fire effects on soil properties ................................................. 8 2A Influence of fire on different soil physical properties in andic soils of the Garajonay

National Park (La Gomera, Canary Islands, Spain) .............................................................. 8 Notario del Pino, J.S.1 ([email protected]), ................................................ 8

3A Fire effect against conservation agriculture ........................................................................... 9 Ayodeji, A.1 ([email protected]), ................................................ 9

4A Effects of a wildfire on soil properties – a case study in North Sardinia ................................. 10 Canu, A.1 ([email protected]), ............................................................... 10

5A The impact of fire on soil water repellency after wildfires in recently abandoned citrus orchards in the Cànyoles river watershed ......................................................................... 11

Cerdà, A.1 ([email protected]), ............................................................. 11

6A Composition of soil lipids as semi-‐quantitative fire severity proxy ..................................... 12 Almendros, G.1 ([email protected]), ..................................................... 12

7A Effect of repeated prescribed burning on soil microbial community of a Pinus halepensis Mill. plantation in the National Park of Cilento and Vallo di Diano (Southern Italy) ................................................................................................................ 13

Giuditta, E.1 ([email protected]), .............................................. 13

8A Fire effects on soil after an experimental burnt .................................................................... 14 Bento-‐Gonçalves, A.1 ([email protected]), ................................ 14

Theme: Ash properties and effects on soils ...................................... 15 9A Impact of ash wettability on splash erosion and runoff rates in the postfire ......................... 15

Jordán, A.1 ([email protected]), ...................................................................... 15

10A The contrasted response of white and black ash covers to wetting. A laboratory rainfall simulation approach ............................................................................................. 16

Cerdà, A. 1 ([email protected]), ............................................................. 16

Theme: New methodologies to study fire effects on soil properties 17 11A Soil depth affected by fire: a laboratory approach to measure temperature variations ...... 17

Antonio, G-‐G. 1 ([email protected]), ................................... 17

12A Effect of different pretreatments on soil samples for estimation of maximum temperature reached by NIR spectroscopy ....................................................................... 18

Jordán, A.1 ([email protected]), ...................................................................... 18

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13A Metal silt fences to measure sediment transport along the slopes .................................... 19 Cerdà, A. 1 ([email protected]), ............................................................. 19

14A Post-‐fire scenario in central Portugal through the Landscape Function Analyses methodology (LFA) ........................................................................................................... 20

Cancelled .................................................................................................... 20

15A O-‐Revealer: Novel technology for humanitarian demining in peatlands by controlled smouldering combustion .................................................................................................. 21

Rein, Guillermo 1 ([email protected]), .................................................. 21

Theme: Global aspects and fire management ................................... 22 16B The frequency and intensity of very large forest fires -‐ the study-‐case of Barcelos

municipality (NW Portugal) ............................................................................................... 22 Ferreira-‐Leite, F. 1 ([email protected]), ..................................... 22

Theme: Fire effects on hydrology ...................................................... 23 17B Evaluation of the impacts of log check dams applied to drainage channels, after

forest fires, in the northwest of Portugal. ......................................................................... 23 Vieira, A.1 ([email protected]), ................................................... 23

18B Soil water repellency changes after wildfires at the Serra de Grossa, La Costera, Eastern Spain .................................................................................................................... 24

Cerdà, A.1 ([email protected]), .............................................................. 24

19B Effects of repeated fires on soil nutrients and on its mobilization ...................................... 25 Santos, L.1 ([email protected]), ................................................................................ 25

Theme: Fire effects in organic soils and carbon dynamics ................ 26 20B Free and aggregate-‐occluded soil organic matter in two forest soils as affected by

wildfires of different severity ............................................................................................ 26 Mastrolonardo, G.1 ([email protected]), ...................... 26

21B Latitudinal effects on the intrinsic flammability of peat ..................................................... 27 Belcher, C.M.1 ([email protected]), ................................................... 27

22B Fire severity effects on peat carbon dynamics .................................................................... 28 Grau-‐Andres, R.1 (r.grau-‐[email protected] ), ........................... 28

23B Soil C-‐sequestration mechanisms driven by wildfires ......................................................... 29 Almendros, G.1 ([email protected]), ..................................................... 29

24B Fire effects on soil organic carbon content and stability in calcareous and gypseous soils .................................................................................................................................. 30

Mora, J.L.1 ([email protected]), ................................................................ 30

Theme: From fire intensity to fire severity ........................................ 31 25B Use of soil properties for assessing fire severity in fire prone ecosystems .......................... 31

Marcos, E.1 ([email protected]), .................................................... 31

26B A post-‐burn assessment of four tussock tundra wildfires in Alaska ..................................... 32

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Hudspith, V.1 ([email protected]), ................................................ 32

27B Influence of a step-‐change increase of peat moisture content on the horizontal propagation of smouldering fires ...................................................................................... 33

Prat-‐Guitart, N.1 (nuria.prat-‐[email protected]), ................................ 33

28B Soil heating and impact of prescribed burning in Dutch heathland ..................................... 34 Stoof, Cathelijne1 ([email protected]) .............................................. 34

Theme: Soil recovery after fires ........................................................ 35 29B Application of remote sensing techniques and GIS analysis to the study of post-‐fire

vegetation recovery and soil erosion implications after 22-‐years (Rio Verde, South of Spain) ............................................................................................................................... 35

Martínez-‐Murillo, J.F.1 ([email protected]), ............................................ 35

30B Short-‐term monitoring of clearance techniques and their consequences in post-‐fire erosion (South of Spain) ................................................................................................... 36

Martínez-‐Murillo, J.F.1 ([email protected]), ............................................ 36

31B Soil erosion rates after forest fires on terraced and non-‐terraced slopes in Eastern Spain. A field rainfall simulation experimental approach .................................................. 37

Cerdà, A.1 ([email protected]), .............................................................. 37

Theme: Combining computational methods and experimental data

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Poster Sessions All posters will be displayed in the atrium outside the main conference auditorium for all the days of the conference.

Corresponding authors are invited to give a 3 minute oral presentation (and 1 minute for questions) infront of their poster.

Their are two sessions for these oral presentations:

Session A 15:00 – 16:00 Wednesday 15th July

Session B 14:45 – 15:45 Friday 17th July

The letter at the end of each poster’s number indicates the session.

Instructions for preparing posters Your poster should be no larger than A0 portrait (841mm wide and 1189 mm high). Each poster board is 900mm wide and 1200mm high. The boards have a felt covering that will allow posters to be attached using a velcro fastener.

Posters will be on display for the entire conference.

Session A Theme: Combining computational methods and experimental data

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Poster Abstracts Theme: Combining computational methods and experimental data

1A Combining computational methods with spectroscopic and pyrolytic analyses for the semi-‐quantitative assessment of pyrogenic structures in fire affected soils Almendros, G.1 ([email protected]), González-‐Vila, F.J.2, Knicker, H.2, González-‐Pérez, J.A.2

1. MNCN -‐ CSIC. Serrano 115B, E-‐28006 Madrid, Spain 2. IRNAS -‐ CSIC. Avda. Reina Mercedes, 10, E-‐41012-‐Seville, Spain

Chemometric approaches applied to data from destructive (analytical pyrolysis) and non-‐destructive (nuclear magnetic resonance, C-‐13 NMR) techniques were explored to characterize soil organic matter fire-‐induced alterations.

Direct determination of pyrogenic organic matter (e.g., black carbon or polycyclic (>3-‐ring) compounds) by the above techniques, is limited, either because these structures remain ‘invisible’ under the usual spectral acquisition conditions, or to non-‐stoichiometric pyrolytic yields. Here, both approaches were used to find surrogates for pyrogenic structures defined as those which are in excess compared to fire-‐unaffected soils. Humic acids from two forest soils under Pinus halepensis or Pinus sylvestris were studied in unaltered or burned sites affected by medium-‐intensity or severe fires.

Dipolar dephasing (DD) C-‐13 NMR spectra displayed significant differences as compared with conventional CPMAS C-‐13 NMR, mainly in signals ascribed to rigid and mobile alkyl structures, those for tannins or carbohydrates. An index of fire-‐induced transformation was calculated as the extent to which the signal intensity in the non-‐substituted aromatic region (110–140 ppm) remains unchanged irrespective to proton decoupling conditions.

Concerning analytical pyrolysis, the compounds were represented in 3D plots after sorting out their atomic ratios in chemical spaces, i.e., the classical van Krevelen’s method showing the positioning of various classes of molecules onto 2 axes representing H/C and O/C atomic ratios and z axis the compound yield. Comparisons of these yields as 3D surfaces, directly reveal fire-‐induced changes in molecular assemblages with similar stoichiometry (i.e., ‘clusters’ of saturated and unsaturated hydrocarbons, methoxyphenols, alkylbenzenes, polycyclic aromatics…). Best correlations between pyrolytic and DD C-‐13 NMR results can be used for quantifying damage levels based on the fire effects on soil HA properties.

Session A Theme: Fire effects on soil properties

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Theme: Fire effects on soil properties

2A Influence of fire on different soil physical properties in andic soils of the Garajonay National Park (La Gomera, Canary Islands, Spain) Notario del Pino, J.S.1 ([email protected]), Suarez Mendez, N.1, Rodriguez, R.A., Rodriguez, A., Carmen, D.

1. University of La Laguna, Spain

A set of soil physical properties (particle size fractions, water holding capacity, aggregate stability and soil water repellency) were determined in 20 locations at the Garajonay National Park (La Gomera, Canary Islands, Spain) under humid, evergreen (heather and laurel) forest that had undergone a severe wildfire in summer 2012, and compared with values measured at the same locations in 2004. The main soil types in the area of interest were Andosols (either melanic, umbric or leptic), as well as andic or lithic leptosols (approximately 60% of the burned area). The results show a decrease in the clay content, water holding capacity at 33 kPa and aggregate stability (measured by the slaking test). Conversely, the sand content and the intensity of soil water repellency (MED test) increased after the passage of fire. Only the variations for the clay content proved to be statistically significant (Student’s t test, p < 0.05). The intensity of soil water repellency kept no relationship with the type of forest. Multivariate analysis (PCA) showed that the variations can be related to the particle size fractions (sand vs. clay and silt, main axis 45.4% of variance explained) or the water holding capacity (33 kPa, second axis, 31.4% of variance explained). MED values related to the first axis, more closely to the sand content. These data suggest that the impact of fire, at least at the locations surveyed in this study and as far as the studied soil properties are concerned, could not be as severe as expected after the initial evaluations in the affected area, and point towards moderate, post-‐fire water erosion after the autumn rains.


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3A Fire effect against conservation agriculture Ayodeji, A.1 ([email protected]),

Adebesin, A.1

1. Ondo State Polytechnic, Nigeria Fire affects nutrients cycling and the physical, chemical and biological properties of the soil. Combustion of litter and soil organic matter (OM) increases the availability of some nutrients Fire significantly affects soil properties because (OM) located on or near surface is rapidly combusted. It maintains the nutritional quality and moist-‐holding capacity of forest soil which can never be attain in the presence of fire. It also has capacity to retain many of the metals. It helps in soil aggregation, it improves soil structures, it improves soil aeration, it equally has high infiltration rates. OM presence are critical for maintaining the nutritional quality and moist-‐holding capacity of forest soil which can never be attained in the presence of fire. Significant loss of Nitrogen during fire could adversely affect long-‐term productivity in many ecosystem particularly if Nitrogen replenishment mechanism are not provided during post-‐fire management. Significant loss of Nitrogen during fire could adversely affect long-‐term site productivity in many ecosystem particularly if Nitrogen replenishment mechanism are not provided during post-‐fire management. Spatial distribution of soil properties within a soil profile determines, to a large extent the magnitude of change occurring in a particular soil property during a fire. For example, those soil properties location or near soil surface are more likely to be changed by fire because they are directly exposed to surface heating. As a result organic materials are related to soil properties. Fire effect on soil is greatly adverse.


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4A Effects of a wildfire on soil properties – a case study in North Sardinia Canu, A.1 ([email protected]),

Secci, R.2, Motroni, A.3, Ventura, A.1, Uras, G.2

1. National Research Council -‐ Institute of Biometeorology, CNR -‐ IBIMET, Sassari , Italy 2. University of Cagliari, DICAAR, Italy 3. ARPAS Sassari, Italy

First experimental results of a wider-‐scale research activity aimed at developing collection and analysis methods of field data to evaluate the effects of fires on soil geochemistry are presented. After forest fires, soils show important transformations in their physical and chemical properties, besides modification of organic and mineral components, in relation to the intensity of fire. The experimental area is located in a hilly area of north-‐western Sardinia, where a human caused fire occurred in August 2013 and burned an area of 28 ha; fire severity has been moderate, according to USDA burn severity classification system. The area is mainly covered by typical Mediterranean chaparral vegetation. The climate is typically Mediterranean with water deficit conditions occurring from May through September and precipitation events mainly concentrated in autumn and winter. The mean annual rainfall is 730 mm and annual mean air temperature is 16.8 °C. After the fire, several pedological samples were collected in different period and analysed to find the variation of the geochemical elements. Only 10 elements (from a total of 63 analysed) showed a distinct reduction starting six months after fire occurring. In fact, the total content of Mn, Zn and B showed a very large increase in unburned soils, while that value was decreased by almost 50% in samples from soils after six months after fire occurring. In the coming months the sampling will be continued to clear out the evolution of the geochemical trend, and these values will be compared with those of other experimental sites to assess the variation the influence of these elements on cork plant regrowth.


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5A The impact of fire on soil water repellency after wildfires in recently abandoned citrus orchards in the Cànyoles river watershed Cerdà, A.1 ([email protected]), González-‐Pelayo, Ó.1, Jordán A.2,Pereira, P.3, Prosdocimi, M.4, Úbeda, X.5, Mataix-‐Solera, J.6,

1. Soil Erosion and Degradation Research Group, Department of Geography, University of Valencia, Valencia, Spain

2. MED_Soil Research Group. Dep. of Crystallography, Mineralogy and Agricultural Chemistry, University of Seville, Spain

3. Department of Environmental Policy, Mykolas Romeris University, Ateities g. 20, LT-‐08303 Vilnius, Lithuania

4. Department of Land, Environment, Agriculture and Forestry, University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy

5. GRAM (Mediterranean Environmental Research Group), Dept of Physical Geography and Regional Geographic Analysis, University of Barcelona, Montalegre, 6. 08001 Barcelona, Spain

6. Environmental Soil Science Group. Department of Agrochemistry and Environment. Miguel Hernández University, Avda. de la Universidad s/n, Elche, Alicante, Spain

Forest fires are found usually on rangelands where they are difficult to control. In the Mediterranean, the widespread development of forest fires is due to the land abandonment of the agriculture land in the mountainous terrain along the 20th century. This process of abandonment is also taking place in intensive irrigated citrus orchards due to the low income of the farmers and the pressure near the urban areas, where most of the properties now are not in the hands of the farmers, and as a consequence they are abandoned. After the orchard abandonment the recovery of the vegetation take place successfully due to the high soil fertility. Three years after the abandonment the wildfires can took place. This research focuses on the effect of land abandonment and fire on soil water repellency. Ten research sites were selected along the Cànyoles river watershed, and they shown three plots: a cultivated field, an abandoned one and an affected by a recent fire. In summer 2013 and 2014, and after the fires (one week) a hundred Water Drop Penetration Time measurements were carried out in each plot (10 sites x 30 plots) at then subplots randomly selected. The results show an increase in the water repellency after the orchard abandonment, but fire caused a contrasted response as some sites shown an increase, an others a decrease. The research projects GL2008-‐02879/BTE, LEDDRA 243857 and RECARE-‐FP7 CGL2013-‐ 47862-‐C2-‐1-‐R (nº 603498, http://recare-‐project.eu/) supported this research.


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6A Composition of soil lipids as semi-‐quantitative fire severity proxy Almendros, G.1 ([email protected]), González-‐Pérez, J.A.2, González-‐Vila, F.J.2

1. MNCN -‐ CSIC. Serrano 115B, E-‐28006 Madrid, Spain 2. IRNAS -‐ CSIC E-‐ 1052, E-‐41012 Sevilla, Spain

Fire effects on soil properties may be studied in laboratory simulation experiments, which help in differentiating fire intrinsic effects on soil organic matter (SOM) from those produced by inputs of organic matter from charred necromass after a fire. Chemical composition of soil lipid fraction comprises valuable information about environmental impact on soils i.e. effect of fire, reafforestation or cultivation. The present study simulates fire effects on topsoil from Central Spain: soil G is a Calcic Luvisol under barley from CSIC Experimental Farm 'La Higueruela', Toledo; soil R3 is a Mollic Cambisol under evergreen oak forest (Quercus pyrenaica), and soil R4 is an Ortieutric Cambisol on pine (Pinus pinaster) forest. Parent rock was limestone in site G and granite in R3 and R4. Soil samples were isothermally heated at 350 ºC for periods ranging from 0 to 660 seconds. Soil lipids were Soxhlet extracted with dichloromethane-‐methanol (3:1 v/v), methylated and injected in a GC/MS system fitted with an HP5 MS column. The concentrations of the major oxygen-‐containing lipid compounds i.e., alkanols, fatty acids and alkanoic diacids, were found poorly heat responsive. On the contrary, fire induced chain breakdowns in hydrocarbons. In fact unheated soil n-‐alkane series show maximum chain length ca. C31 with odd-‐C numbered chains dominance as typically produced by vascular plants. After heating, the carbon preference index (CPI) and average carbon length (ACL) systematically changed, leading to patterns with increased low molecular weight (<C25) homologues and a decrease in the odd-‐C numbered preference. In the alkane series from the heated soils the C maximum was ca. the C15–C22 range, with CPI>1. The fire-‐induced rearrangement of alkane series that was consistent in the three soils studied and more intense in the G1 cultivated soil under barley, and least intense in the R3, as could correspond to a more refractory SOM in clay-‐humus complexes in the latter.


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7A Effect of repeated prescribed burning on soil microbial community of a Pinus halepensis Mill. plantation in the National Park of Cilento and Vallo di Diano (Southern Italy)

Giuditta, E.1 ([email protected]), Marzaioli, R.1, Ascoli, D.2, Esposito, A.1, Mazzoleni S.3, Rutigliano, F.A.1

1. Department of Environmental, Biological and Pharmaceutical Sciences and Technologies

Second University of Naples, Caserta, Italy 2. Department of Land, Environment, Agriculture and Forestry, University of Padua,

Legnaro, Italy 3. Department of Agriculture, University of Napoli Federico II, Napoli, Italy Wildfires are a major environmental problem in the Mediterranean area. Prescribed burning is increasingly used throughout Europe as a practice to reduce fire risk, through dead fine fuels reduction. However, to evaluate the sustainability of this practice, potential negative effects on ecosystem components should be quantified and avoided. In this study the effect of repeated prescribed burning on soil microbial community was assayed in a Pinus halepensis Mill. plantation of the National Park of Cilento and Vallo di Diano, treated with two consecutive prescribed burning in 2009 and 2014. In both 2009 and 2014 burns fireline intensity and flame length never exceeded 200 kW m-‐1 and 0.5 m, respectively, and litter consumption was around 30 %. Microbial biomass and activity were determined 3 hours, 1, 3 and 6 months after 2014 burn in the fermentation layer and in the 5 cm of soil beneath in plots burned twice (2009 and 2014), in plots burned only in 2009 and in unburned plots (control). Prescribed burning did not affect soil microbial biomass in the short and medium term since no significant difference was detected between burn treatments and the control. Microbial activity showed a light decrease in the fermentation layer in plots burned twice, compared to control and 2009-‐burned plots, only 3 hours after 2014 burn, whereas no difference appeared later.


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8A Fire effects on soil after an experimental burnt Bento-‐Gonçalves, A.1 ([email protected]), Vieira, A.1, Castro, A.M.2, Ferreira-‐Leite, F.1

1. University of Minho, Dept. of Geography, Guimarães, Portugal 2. Instituto Politecnico do Porto, Portugal

The impacts of forest fires are multiple (economic, human, social, environmental and on landscape -‐ in the trees, the shrubs and herbaceous vegetation, on soil, on soil organisms, in birds and mammals, in the air, water, etc) and complex (direct, indirect, cumulative, immediate, subsequent, etc). Depend on factors as varied as the magnitude, intensity, duration and frequency of fires, the size and composition of the stands, fuel volume, concentration, distribution and characteristics, soil nature and characteristics, among many other factors. One of the most significant impacts of these catastrophic events in Portugal, occurs at the level of the soil (physical and chemical properties, hydrological and erosive effects, hydrophobicity, etc.).

Consequently, we intend to present and discuss in this work the results of experimental burns held in May 2014 in Santo Tirso (NW Portugal), in a eucalyptus stand and in shrub lands. This experimental burning was intended to reduce the fuel material, using different fire driving techniques and is the result of a cooperation between the University of Minho and the Municipality of Santo Tirso.

In this sense, we sought to evaluate the effects of fire on the ground by different conditions of progression of the fire, evaluating the temperature at different depths of the soil and its physical and chemical characteristics.

Session A Theme: Ash properties and effects on soils

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Theme: Ash properties and effects on soils

9A Impact of ash wettability on splash erosion and runoff rates in the postfire Jordán, A.1 ([email protected]), Gordillo-‐Rivero, Á.J. 1, García-‐Moreno, J. 1, de Celis, R. 1, Jiménez-‐Compán, E. 1, Pereira, P. 2, Granged, A.J.P. 1, Zavala, L.M. 1

1. University of Seville, 41004 Seville, Spain 2. Mykolas Romeris University, Vilnius 08303, Lithuania

During combustion, fuel (biomass, necromass and soil organic matter) is transformed in materials with new physical and chemical properties. After fire, the soil surface is covered by a layer of ash and organic residues, more or less charred depending on fire severity. Ash has important ecological, hydrological and geomorphological effects, even after being rearranged or mobilized by runoff or wind.

The characteristics of ash will depend on the burnt species, the amount of affected biomass, fuel flammability and structure, temperature and the residence time of thermal peaks. Some studies have emphasized the role of ash on soil protection during the after fire period, in which the vegetable coverage could be drastically decreased.

Soil protection by the ash coverage is critical during the time when the vegetal coverage is low. However, the ash coverage can be transient or last for some time, until it disappears or decreases due to erosion (water and wind), animals or crossing vehicles. The effect may be variable, since an intense combustion favors the appearance of white ash is predominantly of a mineral nature, and hydrophilic. Conversely, incomplete combustion promotes the appeareance of dark ashes often hydrophobic and capable of increasing the rate of run-‐off, and therefore the risk of erosion.

The aim of this work is to study the impact of the ash produced after a fire in water erosion risk by determining [i] sediment dispersion by splash erosion and [ii] impact on runoff rate trough rainfall simulations in soils affected by fire and covered by hydrophobic or hydrophilic ash after a prescribed fire.

Session A Theme: Ash properties and effects on soils

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10A The contrasted response of white and black ash covers to wetting. A laboratory rainfall simulation approach

Cerdà, A. 1 ([email protected]), Massimo, P . 2, Paulo, P. 3




After a forest fire, the ash cover determines the soil hydrology and the erosional response due to the contrasted wetting behaviour of the white and black ash. In order to determine the effect of the type of ash and the depth of the ash, laboratory rainfall simulation experiments at 45 mmh-‐1 rainfall intensity during on1 hours were carried out on 0.5 m2 plots (0.5 m width x 2 m height x 0.2 m depth) were carried out under different ash depths: 1, 3, 5, 10, 20, 30 and 50 mm depth. Water drop penetration time (WDPT) measurements were carried out before and after each run. The results show that water repellency was much higher on the black ash (15’ 40’’) than on the white ash (1’ 13’’) and that the runoff rates were higher on the white ash due to the development of a crust layer after some minutes of rainfall. The research projects GL2008-‐02879/BTE, LEDDRA 243857 and RECARE-‐FP7 CGL2013-‐ 47862-‐C2-‐1-‐R (nº 603498, http://recare-‐project.eu/) supported this research.

Session A Theme: New methodologies to study fire effects on soil properties

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Theme: New methodologies to study fire effects on soil properties

11A Soil depth affected by fire: a laboratory approach to measure temperature variations Antonio, G-‐G. 1 ([email protected]),

David, B-‐V. 1, Martí-‐Dalmau, C.1, Arjona-‐Gracia, B.1

1. Agricultural and Environmental Sciences Department, Huesca Polytechnic School, University of Zaragoza, Spain

It is known that wildfires have a significant impact on soil properties according to their intensity. Strong variations in temperature with soil depth have been found. Some studies are flawed because too much soil thickness is sampled, among other sources of variability.

The aim of this study is to analyse the temperature reached by the topsoil at centimeter scale under controlled laboratory conditions. Three topsoil unaltered monoliths of a mollic epipedon (25 x 25 square x 15 cm depth) were sampled in a pinewood of Montes de Zuera (Ebro Tertiary Basin, NE Spain). Each monolith was then burned in the laboratory under controlled conditions.

Burning consisted of applying thermal shock with a blowtorch placed 0.4 m over each unaltered soil blocks. Temperature was recorded in the soil monoliths during burning with three thermocouples placed at three levels: O-‐Ah transition, 1 and 2 cm Ah soil depth. The flame was kept until 250 °C was reached at 1 cm Ah depth. Data were recorded each minute during 220 minutes.

When at 1 cm temperature reached 250°C, the flame was switched off; at this moment, the maximum temperature (501.1±10.3°C) was reached in the O-‐Ah transition, 19.0±2.7 after the blowtorch was ignited. Nevertheless, temperature kept rising at 1 cm depth up to 310.6±19.9°C, approximately 18 min since the blowtorch was turned off, apparently due to the smoldering combustion of soil organic matter (SOM).

O-‐Ah transition and 1 cm depth temperature overlapped during 50 minutes when cooling down from 305.8°C to 206.8°C. About 30 minutes after the flame was switched off O-‐Ah temperature became lower than those at 1 cm depth.

It is remarkable that the maximum temperature at 2 cm depth (74.7±2.6°C) was reached 60 minutes after the flame was switched off, highlighting the slow heat transfer at such depth.

In conclusion, heating as well as cooling is quicker in soil upper layers, as opposed to what happens with depth. A strong thermal gradient is observed to centimeter scale, with temperatures about 500°C at soil surface falling down to 70°C just at 2 cm depth.

Hence, knowing temperature variations with soil depth should allow to determine how soil properties are affected by fire.


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12A Effect of different pretreatments on soil samples for estimation of maximum temperature reached by NIR spectroscopy Jordán, A.1 ([email protected]),

Granged, A.J.P.1, Zavala, L.M. 1, Arcenegui, V. 2, Elisabeth Jiménez-‐Compán, E.1, de Celis, R.1

1. University of Seville, 41004 Seville, Spain 2. University Miguel Hernández, Spain

Fire leads to changes in soil physical, chemical and biological properties which largely depend on the maximum temperature reached (MTR). This parameter cannot be easily determined due to logistical reasons. The construction of a model to estimate MTR by near infrared spectroscopy (NIR) from samples burned at different temperatures in the laboratory is proposed in this research. However, moisture content in soil samples causes some problems in NIR models, so that a treatment of samples, prior to the NIR analysis is necessary. To investigate this, soil samples were heated in the laboratory at different temperatures (in a range between 100 and 600 °C) during 15 minutes. The MTR was recorded at each case using termocouples. Previously to NIR analysis, three different pretreatments were applied to three subsets of heated samples: air-‐drying, lyophilization and wetting/lyophilization. Three different models were constructed from samples with different pretreatments to estimate MTR. The models were successfully validated using cross validation obtaining all higher r2 of 98.3, and with lower RMSECV of 25 °C. Although air-‐drying allowed more accurate results than simple lyophilization, the most accurate estimations of MTR were obtained after wetting-‐lyophilization. After this pretreatment, heated samples show a lower moisture content, reducing interference with NIR analysis.


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13A Metal silt fences to measure sediment transport along the slopes Cerdà, A. 1 ([email protected]),

Antonio, J. 2, Massimo, P. 3, Paulo, P. 4


2. MED Soil Research Group. Dep. of Crystallography, Mineralogy and Agricultural Chemistry, University of Seville, Spain



Soil erosion after wildfires are very intense and have dynamics in time and space. To monitor the post-‐fire soil erosion rates it is necessary to measure the soil erosion immediately after the pass of the wildfire. This makes necessary to have ready plots to be established in the study are in few days time. Traditional plots take weeks to install. We developed an easy to install and cheap silt-‐fence of 2 meter width that can be installed in one hour.

The research projects GL2008-‐02879/BTE, LEDDRA 243857 and RECARE-‐FP7 CGL2013-‐ 47862-‐C2-‐1-‐R (nº 603498, http://recare-‐project.eu/) supported this research.


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14A Post-‐fire scenario in central Portugal through the Landscape Function Analyses methodology (LFA) Cancelled


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15A O-‐Revealer: Novel technology for humanitarian demining in peatlands by controlled smouldering combustion Rein, Guillermo 1 ([email protected]), Huang, Xinyan1, Restuccia, Francesco1, McArdle, Thomas1

1. Department of Mechanical Engineering, Imperial College London, United Kingdom

A novel technology is proposed to detect various types of landmines buried in peat using the controlled smouldering combustion. The dummies for Italian SB-‐33 anti-‐personnel plastic landmine and Serbian PROM-‐1 anti-‐tank metal landmine are built, and buried in peat with the moisture content (MC) ranging from very dry (5%) to normal (130%) conditions. In all cases, the smouldering fire burns across the peat, left the dummy exposed to the open for easy identification and removal. As the peat MC increases, the fire spread slows down, and the temperatures inside and outside of the dummy decreases. The results show with normal peat with MC > 50%, the risk of thermal runaway of secondary explosive in both mines is very low, although the shell of plastic mine can be partially damaged by the smouldering fire. In addition, the smouldering fire is found to reveal other obstacles like stones in the soil, resulting in little interference to mine detection. This study proves the concept of this novel demining technology in small-‐scale laboratory conditions. Next, O-‐Revealer can be tested in small plots of land by combining with other demining methods, and further applied into many minefields around the world such as Falkland Islands.

Session B Theme: Global Aspects and fire management

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Theme: Global aspects and fire management

16B The frequency and intensity of very large forest fires -‐ the study-‐case of Barcelos municipality (NW Portugal) Ferreira-‐Leite, F. 1 ([email protected]),

Bento-‐Gonçalves, A.1, Vieira, A. 1

1. CEGOT, University de Minho, Guimarães, Portugal

The frequency and intensity of very large forest fires (LFF) over the last ten years raises concern about the increased occurrence of ‘megafires’ worldwide.

Throughout the years we have seen a new reality in Portugal regarding LFF, since they have become increasingly important. Although LFF's in Portugal represent a small fraction of the total of occurrences, in keeping with the trends of the Mediterranean Basin, they are responsible for a large percentage of burned area. In the last ten years, the largest forest fires in the Portuguese territory (mega-‐fires) have been recorded, and although they do not cover a larger percentage of LFFs there is more burned area, which means that, on average, each LFF burned more area when compared to the previous decades.

Consequently, and despite large forest fires having been “trivialised” in Portugal, until the 1980s they had never reached 10000 ha of burned area in a single occurrence. The first of these fires have occurred in 1986 and the second in 1987. However, among the large forest fires on record, the ones covering the largest area occurred after 2001.

The explanation of the occurrence of the LFF, depends on a number of varied factors. The truth is that the social and economic transformations that have taken place in Portuguese society since the second half of the 20th century have profoundly altered the habits and traditions of the population. The relation between the towns and the forests, which used to be a very close, stable and interconnected one, slowly disappeared and paved the way to the occurrence of extensive forest fires.

In this poster we aim to present the LFF's that have occurred in the municipality of Barcelos (NW of Portugal), where in the past 25 years have occurred 4 LFF in the same place, with high intensity, at regular intervals, and due to socio-‐cultural causes.

Session B Theme: Fire effects on hydrology

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Theme: Fire effects on hydrology

17B Evaluation of the impacts of log check dams applied to drainage channels, after forest fires, in the northwest of Portugal. Vieira, A.1 ([email protected]), Bento-‐Gonçalves, A.1, Radecki-‐Pawlik, A.2, Radecki-‐Pawlik, B.3

1. University de Minho, Dept. of Geography, Guimarães, Portugal 2. Agriculture University of Krakow, Dept. of Hydraulics Eng. and Geotechnics, Poland 3. Statik-‐EkoBud, Structural Designing Office, Krakow, Poland

Following the two fires that broke out on 8 and 10 August 2010, in the Peneda-‐Geres National Park (NW Portugal), a continuous burnt area of 1466 ha, subject to different fire intensities and severity, was registered. It is a large area, occupied by scrublands and stands of Pinus pinaster. The lithology is mainly granite, and the soils (cambisols) are generally thin and stony. In the context of this study, our aim was to implement a set of measures in channels where there is a concentration of runoff in order to reduce the gully erosion processes and the removal and transport of soil by implementing structures, materials, and techniques which favor the retention of sediments and the possible consolidation of ridges and pre-‐existing gullies. The measure selected for this purpose was applied specifically in the channels corresponding to the drainage lines (ephemeral or low order), and aimed at changing the flow of water and sediments in order to decrease the amount of soil swept into the watercourses downstream and the subsequent destruction of infrastructure or human cultures. The implemented technique was log check dams. In order to model the response of the log check dams, we proceed with hydraulic calculations, as described in Dąbkowsk et al. (1982). Calculations were done for three water discharges, respectively: Q = 0.5 m3/sec, Q = 1,0 m3/sec and Q = 2,0 m3/sec. For the calculations we employed VC master model by Veit Christoph GmbH (1996). Sediment transport calculations were done using the surface-‐based bedload equation of Wilcock and Crowe (2003). The calculations allow us to understand the impact of log check dams on the downstream part of the channel, under different discharge values, and its effectiveness in terms of sediment retention. We found the design and critical discharge for log check dams in terms of hydraulics as well as we showed under which water discharge conditions the upstream check dam retention pools are clogged with sediment.


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18B Soil water repellency changes after wildfires at the Serra de Grossa, La Costera, Eastern Spain Cerdà, A.1 ([email protected]), Jordán, A.2, Úbeda, X.3, Mataix-‐Solera, J.4


2. MED_Soil Research Group. Dep. of Crystallography, Mineralogy and Agricultural Chemistry, University of Seville, Spain

3. GRAM (Mediterranean Environmental Research Group), Dept of Physical Geography and Regional Geographic Analysis, University of Barcelona, Montalegre, 6. 08001 Barcelona, Spain

4. Environmental Soil Science Group. Department of Agrochemistry and Environment. Miguel Hernández University, Avda. de la Universidad s/n, Elche, Alicante, Spain

Soil water repellency is a key property to understand the soil and water relationships. Fire affects the soil water repellency due to the volatilization of the hydrophobic compounds and vegetation recovery after the fire also determines the hydrophobic degree of the soils. In order to determine how the fire and the post-‐fire changes change the soil properties we selected 10 research sites at the study area of La Costera on the Serra Grossa and the Massis del Caroig, Eastern Spain, which suffered different fires during the last century. Limestone are the parent material in all study sites and the mean annual rainfall range from 480 to 550 mm per year in average. Vegetation is scrubland, although on the areas free of fires for more than 16 years Aleppo pines are present. All the selected plots were located on the middle tram of the slopes, where the erosion rates are more intense. Each site was selected upon the last fire registered: 0, 1, 5, 9, 16, 24, 33, 44, 51, and 63 years. The measurements were carried out in August 2014 by means of the Water Drop Penetration Time method. Ten plots (100 drops per plot) were applied at each site at surface (0 cm depth) and at 1, 2, 5 and 10 cm depth. The results show that after the wildfires the water repellency was negligible on the soil surface, but present at the deeper horizons. The water repellency increased from the recently affected by a fire to the one that is free of fire for 63 years.



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19B Effects of repeated fires on soil nutrients and on its mobilization Santos, L.1 ([email protected]), Hosseini, M.1,2, González-‐Pelayo, O.1, de Oliveira Alves Coelho, C.1, Keizer, J.J.1

1. Centre for Environmental and Marine Studies (CESAM),University of Aveiro, Portugal 2. University of Wageningen, Wageningen, the Netherlands

The main objectives of the present work were to study the effects of repeated fires on nitrogen and phosphorus availability on soil, in the first year after fire, and on total nitrogen and total phosphorus export by runoff, during the second year. The study area is located in Várzea, in the municipality of Viseu, north-‐central Portugal. In this area, three sites were selected, and each zone had a different fire history regarding the period between 1975 and 2012. One site was burnt 4 times (Degraded), another one was burnt only in 2012 (Semidegraded) and the last site is the control one.

In terms of nitrogen availability on soil, there were no significant differences between the burnt sites, in the first year. Regarding phosphorus availability, the Semidegraded site had much smaller concentration than the Degraded site, in the end of the first year. There was a decrease of nutrients availability between the two samplings of the first year. The control site had less nutrients on soil than the burnt sites.

The export of total nitrogen and total phosphorus was higher in the Degraded site (1443 mg/m2 TN and 218 mg/m2 TP), followed by the semi-‐degraded site (341 mg/m2 TN and 77 mg/m2 TP) and the control site (26 mg/m2 TN and 4 mg/m2 TP). The export of nutrients was especially higher when strong rainfall events occurred. The presence of vegetation was an important factor to reduce the amount of nutrients and runoff, when there wasn´t a significant component of litter on soil surface. Only in Degraded site there was a slight decrease of nutrients export along with the vegetation recovery.

Fire frequency has revealed to be an important factor when it comes to nutrients export, and this can have a huge impact on ecosystem productivity and contribute to land degradation in the long term.

Session B Theme: Fire effects in organic soils and carbon dynamics

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Theme: Fire effects in organic soils and carbon dynamics

20B Free and aggregate-‐occluded soil organic matter in two forest soils as affected by wildfires of different severity Mastrolonardo, G.1 ([email protected]), Rumpel, C.2, Forte, C.3, Doerr, S. H.4, Certini G.1

1. University of Florence, Italy 2. CNRS; Institute of Ecology and Enviroment, Paris, France 3. Istituto di Chimica dei Composti OrganoMetallici (ICCOM), Italy 4. Geography Department, Swansea University, UK

In this study, we investigated the direct impact of fire on soil organic matter (SOM) in density fractions isolated from the top 2.5 cm of mineral soil in two forests that recently experienced wildfires of different severity. One of these forests, located in Tuscany, Central Italy, underwent a moderate severity fire, the other, located in Victoria, South-‐East Australia, underwent an extremely severe fire. The main purpose of the study was the assessment of fire-‐induced changes on amount and composition of SOM, distinguishing between free and aggregate-‐occluded SOM.

The extremely severe fire in Australia resulted in a dramatic loss of SOM; however, solid-‐state 13C nuclear magnetic resonance spectroscopy showed that the residual SOM did not change substantially its composition. The moderate fire occurred in Italy, conversely, even caused slight SOM enrichment, perhaps due to the incorporation of charred residues of the aboveground biomass. Both fires apparently broke up soil aggregates, hence promoting the release of some occluded organic matter. Such an outcome implied significant organic matter redistribution between the soil density fractions, which exhibit different properties and turnover time of SOM. The fire-‐induced changes of SOM observed most probably have implications for the C cycle, so highlighting the eventual critical role of wildfires severity in climate change.


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21B Latitudinal effects on the intrinsic flammability of peat Belcher, C.M.1 ([email protected]), Gallego-‐Sala, A.1, New, S. L.1, Charman, D.J.1, Hudspith, V.A.1, Page, S.E.2, Swindles, G.T.3

1. University of Exeter, UK 2. University of Leicester, UK 3. University of Leeds, UK

Peatland ecosystems are vulnerable to wildfires even though, in a natural state, these are environments where the water table remains at or near the surface for most of the year. Fires in these ecosystems can cause severe irreversible damage to peatland soils, where losses may involve millennia-‐old carbon when the fires affect deep peat layers. Building an understanding of the intrinsic flammability of different peats across different bioclimatic zones may provide clues as to which areas may experience increased fire severity. Here we present the results of intrinsic flammability measurements of peat soils of different origins and from different depths through peat profiles. The peat samples were gathered from a range of latitudes from subarctic peatlands in Scandinavia, through blanket bog ecozones such as the British Isles and into the tropical peatland systems of Indonesia. The peats were oven dried and then combusted in a microcalorimeter to assess the intrinsic flammability of the material forming each of the peats. The peats were found to show considerable variation with their heat release capacity ranging from 0.56 to 2.54 JK-‐1cm-‐3 and peak heat release rate varying between 0.97 and 6.76 Wcm-‐3. This implies that under conditions conducive to ignition fires that spread in certain peats could experience greater fire severity and carbon losses than in other peatland ecosystems.


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22B Fire severity effects on peat carbon dynamics Grau-‐Andres, R.1 (r.grau-‐[email protected] ), Davies, G.M.2, Waldron, S.1, Gray, A.3, Scott, M.1

1. University of Glasgow, UK 2. The Ohio State University, USA 3. Centre for Ecology and Hydrology, UK

Introduction

Intense summer droughts are projected to become more frequent in northern regions due to climate change. Northern peatlands store up to 621 Gt of carbon in deep organic soils. With fuel flammability likely to increase as a result of drought, increased fire severity may alter surface-‐atmosphere C exchanges and contribute to a positive feedback to climate change.

Methodology

Experimental fires were completed on sites where drought had been simulated in 2 x 2 m microplots using rain-‐out shelters. Two sites were used: a raised bog with deep (>2 m) saturated organic soils (peat) and thick Sphagnum/pleurocarpous moss layers (7 ± 2.4 cm), and a heather moorland with shallower peaty podzols (O layer < 10 cm) and a thin moss and litter (M/L) layer (3.9 ± 1.5 cm). Both sites were dominated by Calluna vulgaris. We monitored post-‐fire dissolved organic carbon concentration, [DOC], and CO2 and CH4 fluxes.

Results

A substantial increase in fire-‐induced temperature pulses into the peat was measured in drought-‐treated microplots (see abstract “Fuel and climate controls on peatland fire severity”). Preliminary results suggest an increase in [DOC] (10 – 20 mg C /l) after fire, with drought microplots having a slightly higher mean concentration and higher SD. Differences between treatments decreased with time since fire. No CH4 fluxes were observed in the dry heath. In the wet peatland, burning substantially increased net CH4 fluxes (e.g. -‐0.8 ± 7.8 unburnt v. 34 ± 90 nmol CH4 m-‐2 s-‐1 burnt). Burning also increased net CO2 flux (respiration minus photosynthesis) in both dry and wet peatland from negative (C fixation > efflux) to positive values (e.g. peatland -‐0.6 ± 0.6 unburnt v. 0.19 ± 0.6 µmol CH4 m-‐2 s-‐1 burnt). Net CO2 fluxes were similar between burnt microplots and across sites.

Conclusion

We highlight the importance of ground fuels in controlling fire severity in a changing climate: the MC of the M/L layer was found to substantially alter fire-‐induced peat temperature pulses and the consumption of the M/L layer. These could be important mechanisms affecting peat carbon dynamics. DOC and gas flux monitoring is ongoing but preliminary data analysis indicates that burning increased [DOC] and net CO2 and CH4 fluxes. Differences between treatments were small and need to be investigated further.


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23B Soil C-‐sequestration mechanisms driven by wildfires Almendros, G.1 ([email protected]), González-‐Pérez, J.A.2, González-‐Vila, F.J.2

1. MNCN -‐ CSIC. Serrano 115B, E-‐28006 Madrid, Spain 2. IRNAS -‐ CSIC. Avd. Reina Mercedes, 10, E-‐41012-‐Sevilla, Spain

The influence of fire on soil C-‐sequestration mechanisms is reviewed on the light of recent findings from soil organic matter (SOM) laboratory–controlled heating. Concerning fire-‐induced accumulation of organic C forms, it is useful to differentiate between: i) stabilization of the originally biodegradable SOM for extended periods (i.e., selective preservation leading to the so called ‘inherited organic matter’), and ii) accumulation of humic-‐like macromolecules, including pyrogenic soil C-‐ and N-‐forms in soil. In fact, fire effects may result in SOM structural alteration of functional groups, which may lead to soil hydrophobicity e.g. after severe decarboxylations. Fire may also increase the stability of the links between SOM and minerals through the formation of irreversible H-‐bridges which remain after rewetting the soil. As described elsewhere, intense fires may also determine the formation of new cyclic, condensed organic structures through the polymerization of reactive compounds of low molecular weight.

In general, fire causes structural alteration of biomacromolecules (cellulose, lignin, etc.), which became less biodegradable and not easily recognizable by soil enzymes. In fact, very stable complex SOM forms generated after fire include pseudomelanoidins from the thermal dehydration of carbohydrates , or Maillard products (melanoidins) from N compounds and carbohydrates. It has also been shown the formation of stable macromolecular polyalkyl C-‐forms from the condensation of lipid compounds. Finally, severe heating leads to the accumulation of a continuum of charred lignocellulosic biomass generically referred to as 'black carbon'. From the experimental viewpoint, it is difficult to observe any microbial assimilation of charcoal, either because it did not occur, or because the methods frequently used are not sufficiently sensitive. A schema showing hypothetical mechanisms involved in soil C sequestration driven by heating is provided and discussed.


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24B Fire effects on soil organic carbon content and stability in calcareous and gypseous soils Mora, J.L.1 ([email protected]), Badía-‐Villas, D.1, Martí, C.1, Girona, A.1, Aznar, J.M.1, González-‐Pérez, J.A.2, Knicker, H.2

1. Departamento de Ciencias Agrarias y del Medio Natural, Universidad de Zaragoza, Spain 2. Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, Spain

Fires largely affect soil organic carbon (SOC), resulting both in loss of organic matter and the genesis of pyromorphic forms that are generally considered to be highly resistant to degradation. Calcium is known to contribute to SOC stabilisation, so SOC is more protected and fire effects might be less pronounced for soils developed from Ca-‐bearing materials (e.g., limestone, gypsum) than in other soils.

In this work, we investigated the effect of fire on SOC stability in soils developed from calcareous and gypseous bedrocks. Twelve monoliths (15 x 25 x 5 cm) were collected from the top of soils with calcareous mollic (Rendzic Phaeozem, PHrz) or gypseous ochric (Haplic Gypsisol, GYha) horizons in a semiarid pinewood forest in Northeast Spain. In a laboratory designed experiment six blocks were heated from the surface until 250 °C was reached at 1 cm depth, and other six monoliths were preserved as control samples. The O layer and first and second cm from Ah horizon were scrapped from the surface of the monoliths and analysed separately. Total SOC content was obtained by dry combustion. To assess the content and mean residence time (MRTs) of labile and stable SOC pools, the samples were incubated during 100 days at 25 ºC in a Respicond IV apparatus. Respiration data were acquired continuously and fitted to a double-‐exponential decay model. The results are analysed in relation to the thermal treatment, soil type and depth using ANOVA for repeated measures.

Thermal treatment had contrasting effects on the GYha and PHrz. At the GYha, burning decreased the contents and MRTs of both labile and stable SOC, but the effects were larger on the stable SOC, pointing to a conversion of stable SOC into forms more prone to degradation. For the PHrz, burning decreased the labile SOC contents while increased its MRT, but did not affect the amount of stable SOC, which indeed tended to increase, suggesting the formation of stable SOC due to fire at expenses of the more labile forms.

Session B Theme: From fire intensity to fire severity

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Theme: From fire intensity to fire severity

25B Use of soil properties for assessing fire severity in fire prone ecosystems Marcos, E.1 ([email protected]), Fernández-‐García, V. 1, Fernández-‐Manso, A. 1, Quintano, C.2, Calvo, L.1

1. University of Leon, Spain 2. University of Vallodolid, Spain

Large forest fires are becoming more frequent in Mediterranean areas due to climatic factors and changes in socioeconomic conditions. Fire affects physical, chemical and biological properties of soils depending on their severity. The post-‐fire recovery of the ecosystems also depends, among others factor, on the fire severity. So, to design proper post-‐fire management strategies it is necessary to develop assessment tools for managers. For this reason, it is essential to know if soil visual indicators reflect post-‐fire changes of soil properties in a proper way. The main aim of this paper is to establish the relationship between soil visual indicators and soil properties. The relationship between land surface temperature (LST) and soil parameters will be studied. The study site is located in the Sierra del Teleno, in NW Spain. In August 2012 there was a large wildfire on Pinus pinaster forest. To evaluate fire severity and changes in soil properties we measured a total of 57 plots. In each plot fire severity was determined using CBI (Key and Benson, 2006). Four soil samples (0-‐5 cm) were collected to identify the changes in soil properties (pH, organic carbon, water repellence, mean weight diameter (MWD) and size distribution were analysed) in each plot. CBI measurements and soil sampling were carried out from 9 to 12 weeks after the wildfire. Not precipitation was registered from fire until the end of that period. Also, some plots were selected in non-‐burning area and considered as 0 severity class. We use immediately post-‐fire LST values from Quintano et al. (2015). We identify three fire severity levels. A significant relationship was detected between fire severity and some soil properties (MWD). The main changes in soil characteristics were a decreased in organic carbon and MWD plus an increased in pH and water repellence associated with an increase in fire severity. We also found a significant relationship between fire severity and LST values.


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26B A post-‐burn assessment of four tussock tundra wildfires in Alaska Hudspith, V.1 ([email protected]), Belcher, C.M. 1, Kelly, R. 2, B. Dash, C.2, Barnes, J.3, Collinson, M.E.4, Hu, F.S.2

1. University of Exeter, UK 2. University of Illinois at Urbana-‐Champaign, USA 3. National Park Service, USA 4. Royal Holloway University of London, UK

Climate-‐driven changes in vegetation structure and fire regime are occurring in one of the world’s largest soil organic carbon pools, the Arctic tundra. Within the tundra biome, tussock tundra ecoregions burn most frequently, and recent burns in such areas may provide analogues for the effects of future fire-‐related changes in vegetation and soil properties in Alaska. In the unprecedented 2010 fire season in the Noatak National Preserve, Alaska 37 tundra fires burned a combined area of over 40,000 ha. This record fire season presented an opportunity to ground-‐truth the impact fire has on this tussock tundra ecoregion. Sixteen soil monoliths were sampled from four burned areas, which encompassed a range of burn severities (scorched, low, low-‐moderate, moderate, and moderate-‐high). Surface charcoals were later extracted from these monoliths, and studied using reflectance microscopy. Charcoal reflectance has been suggested to relate to charring temperature and has been used as a temperature proxy, to estimate the temperature that plant material is heated to during the pyrolysis stage of combustion in flaming fires (which we have termed pyrolysis intensity). Fires in tussock tundra ecosystems are typically low intensity, rapidly spreading surface (flaming) fires and this should therefore be expressed in the charcoal reflectance data. We found very little variation in the reflectance estimates among burn severity classes, from 0.52%Ro to 1.55%Ro, with the majority (90%) of individual charcoal reflectance values <2%Ro. These low reflectance values suggest that the fires were of low pyrolysis intensity despite the wide range of observed burn severity classes.


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27B Influence of a step-‐change increase of peat moisture content on the horizontal propagation of smouldering fires Prat-‐Guitart, N.1 (nuria.prat-‐[email protected]), Rein,G.2, Hadden, R.M.3, Belcher, C.M.4, Yearsley, J.M.1

1. University College Dublin, Ireland 2. Imperial College London, UK 3. University of Edinburgh, UK 4. University of Exeter, UK

Post-‐fire studies in peatlands reported shallow peat layers being consumed in irregular distributions. The unburned areas were found to be patches of wet moss. Our laboratory scale study analyses the effect of a horizontal step-‐change in peat moisture content on the spread of smouldering. We designed a laboratory-‐scale experiment consisting in an insulated box (20×18×5 cm) filled with milled peat. The sample was ignited at one side of the box starting a self-‐sustained smouldering fire propagating horizontally, first, through a region of dry peat and second through a region of wetter peat. An infrared camera, a webcam and thermocouples monitored the position of the smouldering fire. The experiment was repeated with peats at different moisture contents to analyse the smouldering behaviour on a range of moisture step-‐change conditions reproducing realistic scenarios. We found that the area burned depends on peat moisture content before the step-‐change as well as the increase in moisture of the step-‐change itself. Our study provides a better understanding of the influence of peat moisture content in the propagation of smouldering fire in peatlands. We contribute to a better interpretation of the post-‐fire peatland landscape as well as support the reconstruction of smouldering fire events.


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28B Soil heating and impact of prescribed burning in Dutch heathland Stoof, Cathelijne1 ([email protected])

1. Wageningen University, Netherlands

Prescribed burning is highly uncommon in the Netherlands, where wildfire awareness is increasing but its risk management does not yet include fuel management strategies. A major exception is on two military bases, that need to burn their fields in winter and spring to prevent wildfires during summer shooting practice. Research on these very frequent burns has so far been limited to effects on biodiversity, yet site managers and policy makers have questions regarding the soil temperatures reached during these burns because of potential impact on soil properties and soil dwelling fauna. In March 2015, I therefore measured soil and litter temperatures under heath and grass vegetation during a prescribed burn on military terrain in the Netherlands. Soil and litter moisture were sampled pre-‐ and post-‐fire, ash was collected, and fireline intensity was estimated from flame length. While standing vegetation was dry (0.13 g water/g biomass for grass and 0.6 g/g for heather), soil and litter were moist (0.21 cm3/cm3 and 1.6 g/g, respectively). Soil heating was therefore very limited, with maximum soil temperature at the soil-‐litter interface remaining being as low as 6.5 to 11.5°C, and litter temperatures reaching a maximum of 77.5°C at the top of the litter layer. As a result, any changes in physical properties like soil organic matter content and bulk density were not significant. These results are a first step towards a database of soil heating in relation to fuel load and fire intensity in this temperate country, which is not only valuable to increase understanding of the relationships between fire intensity and severity, but also instrumental in the policy debate regarding the sustainability of prescribed burns.

Session B Theme: Soil recovery after fires

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Theme: Soil recovery after fires

29B Application of remote sensing techniques and GIS analysis to the study of post-‐fire vegetation recovery and soil erosion implications after 22-‐years (Rio Verde, South of Spain) Martínez-‐Murillo, J.F.1 ([email protected]), Remond, R2.

1. Department of Geography, University of Malaga, Spain 2. University of La Habana, Cuba

The aim is to analyse the post-‐fire vegetation recovery after 22-‐years and assess its implication from the soil recovery point of view and the erosional implications. The burned area (wildfire date: August 8th, 1991; Area: 8156 ha.; severity: highly variable) is located in the Rio Verde watershed (Sierra de las Nieves, South of Spain) and characterised by: mountainous topography (250-‐1700 m; slope gradient >25%; exposure mainly southfacing); geology (peridotite, gneiss and limestone); sub-‐humid Mediterranean climate (750-‐900 mm y-‐1) and Mediterranean rangeland (Pinus pinaster sp. woodlands, 10%; pinus opened forest/shrubland, 40%; shrubland, 35%; and bare soil/grassland, 15%).

The database used corresponded to: Landsat 5 and Landsat 8 images (July 13th, 1991 and July 1st, 2013, for the previous wildfire situation and 22-‐years after, respectively); 1990-‐CORINE Land Cover to map 1991 land uses prior the wildfire; and Andalucía Regional Government wildfire historic records to select the burned area and its geographical limit. Remote sensing techniques and GIS analysis were applied for 1991 and 2013: land cover map by means of object-‐oriented classifications; NDVI and PVI1 vegetation indexes; images transformations and kernel density to determine the lowest recovered areas (bare soil).

According to the results, the applied methodology let map the lowest recovered areas affected by the wildfire in 1991. After 22-‐years and favourable climatic conditions, the vegetation recovery is far from the previous situation to the wildfire. This recovery is spatially very variable and some local geographic factors seem to control it. Indeed, the lowest recovered areas where totally or partially bare soil and sheet washed process are dominant are more prone to be located in very steep slopes on peridotite and limestone, common in southfacing exposure. However, concentrated erosion in rills and gullies developed after the wildfire can be more frequently observed in gneiss rock slopes.


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30B Short-‐term monitoring of clearance techniques and their consequences in post-‐fire erosion (South of Spain) Martínez-‐Murillo, J.F.1 ([email protected]), Pereira, P. 2

1. Department of Geography, University of Málaga. Spain 2. Environmental Research Center, Mykolas Romeris University, Lithuania

The study aim is to monitor the effects of clearance techniques after a wildfire and their implications from the point of view of water erosion processes. Namely, the objectives are to: i) characterise the technical procedures of removing burned material; ii) observe water erosion processes; and iii) evaluate the short-‐term consequences from the post-‐fire recovery point of view. The study area corresponds to a wildfire occurred in 2014 June. The wildfire affected 240 ha. highly variable regarding fire severity. The geographic features are: mountainous topography, marble rocks, Mediterranean climate, and land use of Pine wood (Pinus Pinaster sp.) and opened Pine wood with shrubland in north and southfacing exposure, respectively. The methodology consisted in field surveys carried out from the wildfire until six-‐months later. The fire severity was visually assessed few days after the fire. The technical procedures for removing the burned material, which started one week after the wildfire, were monitored. Also, once rainfalls occurred after the summer, water erosion features (sheet wash, rills, sediment deposits, etc.) were monitored by means of serials of photography made from the same location. The technical procedures consisted in the removal of dead and/or burned trees after the wildfire. Only few trees, partially burned, remained in the hillslopes. Some of the wooden material was used to build check-‐dams in the streams in order to reduce water erosion and flooding hazard due to one village is located very closed downstream. However, the results indicated that the technical procedures could have enhanced water erosion processes. Not only sheet wash erosion, which widely occurred across the burned area, but also the rill formation could be easily formed following the paths made by the wood removal. The formation of alluvial fans could also be monitored at the bottom of some hillslopes, especially, when rural roads cut them. Finally, it can be pointed out that the technical procedures applied after the fire could act as a negative factor from the post-‐fire recovery point of view due to their enhancement of water erosion processes.


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31B Soil erosion rates after forest fires on terraced and non-‐terraced slopes in Eastern Spain. A field rainfall simulation experimental approach Cerdà, A.1 ([email protected]), Prosdocimi, M.2, Tarolli, P.2

1. Soil Erosion and Degradation Research Group, Department of Geography, University of Valencia, Valencia, Spain.

2. Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro (PD), Italy

The Mediterranean landscapes are characterised by the recurrency of fires and the terraced slopes. How they interact is unknown. This research measure the soil erosion at pedon scale by means of simulated rainfall experiments on terraced and non-‐terraced slopes after the fire of 2012 in Cortes de Pallas. Thirty plots were selected on terraced slopes (angle slope < 5 %) and on sloping terrain (> 15 % of angle slope). Rainfall simulation experiments were carried out by means of 0.25 m2 plots in August 2012 (one month after the forest fire), winter 2013, and Summer 2013. The results show that under intense rainfall events of 55 mm h-‐1 in one hour, the erosional response was very intense on the sloping terrain, and negligible on the flat terrain of the abandoned terraces.


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