Introduction
⌅Prescribed underburning (PB) is a silvicultural treatment widely used worldwide and has multiple objectives (Pyne et al., 1996Pyne SJ, Andrews PL, Laven RD, 1996. Introduction to wildland fire. No. Ed. 2. John Wiley and Sons.
), including reduction of the forest fuel load below the canopy in Pinus stands in order to prevent forest fires (e.g. Espinosa et al., 2020Espinosa
J, Rodríguez de Rivera O, Madrigal J, Guijarro M, Hernando C, 2020.
Predicting potential cambium damage and fire resistance in Pinus nigra Arn. ssp. salzmannii. For Ecol Manage 474: 118372. https://doi.org/10.1016/j.foreco.2020.118372
).
Although the implementation of PB for forest management in Spain was
first suggested in the 1980s, it was not until the last decade that
Autonomous Communities and Spanish Central Administration made efforts
to train forest firefighters in planning and executing PB (Fernandes et al., 2022Fernandes
P, Rossa C, Madrigal J, Rigolot E, Ascoli D, Hernando C, Guiomar NG,
Guijarro M, 2022. Prescribed burning in the European Mediterranean
Basin. In: Global application of prescribed fire, pag. 230-248. CSICO
Publishing, Australia.
). The technique is used in Pinus pinaster Ait. stands in Portugal, whereas in Spain it is used as management tool
in maritime pine stands in some autonomous regions. The National
Programme for experimental prescribed underburning (González-Sancho et al., 2020González-Sancho
D, Gómez-Molino R, Álvarez-Palomares R, López-Santalla A, 2020.
Programa nacional de quemas prescritas experimentales bajo arbolado.
Montes 142: 34-40
; García-Feced et al., 2022García-Feced
C, González-Sancho D, Gómez-Molino R, Álvarez-Palomares R,
Iglesias-Rodrigo A, López-Santalla A, 2022. Programa nacional de quemas
prescritas experimentales bajo arbolado. 8CFE - 347. Sociedad Española
de Ciencias Forestales. https://8cfe.congresoforestal.es/cat/node/4594
),
funded by the Ministry for Ecological Transition and Demographic
Challenge (MITECO), was launched in 2012 with the aim of fostering
application of the treatment across Spain. This programme has also
focused on PB in P. pinaster stands (Rodríguez-García et al. 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
). Nevertheless, studies on the effect of PB on trees are scarce in Spain (Valor et al., 2015Valor
T, González-Olabarria JR, Piqué M. 2015. Assessing the impact of
prescribed burning on the growth of European pines. For Ecol Manage 343:
101-109. https://doi.org/10.1016/j.foreco.2015.02.002
; Espinosa et al., 2018Espinosa
J, Madrigal J, De La Cruz AC, Guijarro M, Jiménez E, Hernando C. 2018.
Short-term effects of prescribed burning on litterfall biomass in mixed
stands of Pinus nigra and Pinus pinaster and pure stands of Pinus nigra in the Cuenca Mountains (Central-Eastern Spain). Sci Total Environ 618: 941-951. https://doi.org/10.1016/j.scitotenv.2017.08.291
, 2020Espinosa
J, Rodríguez de Rivera O, Madrigal J, Guijarro M, Hernando C, 2020.
Predicting potential cambium damage and fire resistance in Pinus nigra Arn. ssp. salzmannii. For Ecol Manage 474: 118372. https://doi.org/10.1016/j.foreco.2020.118372
, 2021Espinosa
J, Martin-Benito D. Rodríguez de Rivera Ó, Hernando C, Guijarro M,
Madrigal J, 2021. Tree growth response to low-intensity prescribed
burning in Pinus nigra stands: Effects of burn season and fire severity. Appl Sci 11(16): 7462. https://doi.org/10.3390/app11167462
; Madrigal et al., 2023Madrigal
J, Rodríguez de Rivera Ó, Carrillo C, Guijarro M, Hernando C, Vega JA,
Martín-Pinto P, Molina JR, Fernández C, Espinosa J, 2023. Empirical
Modelling of Stem Cambium Heating Caused by Prescribed Burning in
Mediterranean Pine Forest. Fire 6(11): 430. https://doi.org/10.3390/fire6110430
).
To our knowledge, only the previously mentioned study, carried out by
our research group, has assessed the effect of PB on resin canals in
tapped P. pinaster stands (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
).
Prescribed underburning tries to minimize the impact of fire on trees (Espinosa et al., 2020Espinosa
J, Rodríguez de Rivera O, Madrigal J, Guijarro M, Hernando C, 2020.
Predicting potential cambium damage and fire resistance in Pinus nigra Arn. ssp. salzmannii. For Ecol Manage 474: 118372. https://doi.org/10.1016/j.foreco.2020.118372
, 2021Espinosa
J, Martin-Benito D. Rodríguez de Rivera Ó, Hernando C, Guijarro M,
Madrigal J, 2021. Tree growth response to low-intensity prescribed
burning in Pinus nigra stands: Effects of burn season and fire severity. Appl Sci 11(16): 7462. https://doi.org/10.3390/app11167462
)
and it can be used to prune and thin young stands. Nevertheless, some
studies have shown that PB increases the exudates and resin-producing
capacity of trees and leads to alterations in the resin composition (Lombardero et al., 2006Lombardero MJ, Ayres MP, Ayres BD, 2006. Effects of fire and mechanical wounding on Pinus resinosa resin defenses, beetle attacks, and pathogens. For Ecol Manage 225: 349-358. https://doi.org/10.1016/j.foreco.2006.01.010
; Perrakis et al., 2011Perrakis
DD, Agee JK, Eglitis A, 2011. Effects of prescribed burning on
mortality and resin defenses in old growth ponderosa pine (Crater Lake,
Oregon): Four years of post-fire monitoring. Natural Areas J 31(1):
14-25. https://doi.org/10.3375/043.031.0103
), as well as altering the resin ducts (Perrakis et al., 2011Perrakis
DD, Agee JK, Eglitis A, 2011. Effects of prescribed burning on
mortality and resin defenses in old growth ponderosa pine (Crater Lake,
Oregon): Four years of post-fire monitoring. Natural Areas J 31(1):
14-25. https://doi.org/10.3375/043.031.0103
; Hood et al., 2015Hood
S, Sala A, Heyerdahl EK, Boutin M, 2015. Low severity fire increases
tree defense against bark beetle attacks. Ecology 96(7): 1846-1855. https://doi.org/10.1890/14-0487.1
).
An increase in resin production in the year of execution of the PB and
in the following years may therefore be expected due to the synthesis of
terpenes as a response mechanism to a wound or stress conditions for
the plant (Knebel et al., 2008Knebel
L, Robison DJ, Wentworth TR, Klepzig KD, 2008. Resin flow responses to
fertilization, wounding and fungal inoculation in loblolly pine (Pinus taeda) in North Carolina. Tree Physiol 28: 847-53. https://doi.org/10.1093/treephys/28.6.847
), potentially improving the resin yield (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
) and resilience to potential outbreaks (Vilà-Vilardell et al., 2024Vilà-Vilardell
L, Tepley AJ, Sala A, Casals P, Hood SH. 2024. Long-term sensitivity of
ponderosa pine axial resin ducts to harvesting and prescribed burning,
For Ecol Manage 572: 122301. https://doi.org/10.1016/j.foreco.2024.122301
).
Resin sector was a main activity in the Iberian Peninsula until the second half of the past century (Palma et al., 2016Palma,
A., Pereira, J. M., & Soares, P, 2016. Resin tapping activity as a
contribution to the management of maritime pine forest. Forest systems,
25(2), 18. http://dx.doi.org/10.5424/fs/2016252-08925
),
but almost disappeared in the late 1970′s. In the last 20 years, the
increasing demand of natural renewable resources, and the raising of
resin price were favouring a progressive resurgence of the resin sector (Rodriguez-García et al., 2016Rodríguez-García,
A., Martín, J.A., López, R., Sanz, A., Gil, L., 2016. Effect of four
tapping methods on anatomical traits and resin yield in maritime pine
(Pinus pinaster Ait.). Ind Crops Prod 86, 143-154. https://doi.org/10.1016/j.indcrop.2016.03.033
, 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
). In the context of revitalising resin activity due to the current market situation (Clopeau et al., 2022Clopeau
A, Lacerda R, Orazio C, 2022. Evolution du marché international de la
gemme depuis 1930 et situation en 2020. Revue Forestière Française
73(4): 499-511. https://doi.org/10.20870/revforfr.2021.5566
), the extensive monospecific stands of P. pinaster in the Northern Plateau of the Iberian Peninsula have a strong potential to revitalize the bioeconomy in rural areas (Rodríguez-García & Martínez-Carreira, 2022Rodríguez-García
A, Martínez-Carreira E, 2022. Estado de la técnica y del mercado en la
producción y consumo de resinas naturales. Montes 147: 30-34.
).
These products have multiple uses in different industrial sectors and
also provides relevant complementary ecosystem services such as fire
protection and rural employment (Soliño et al., 2018Soliño,
M., Yu, T., Alía, R., Auñón, F., Bravo-Oviedo, A., Chambel, M.R., de
Miguel, J., del Río, M., Justes, A., Martínez- Jauregui, M., Montero,
G., Mutke, S., Ruiz-Peinado, R., del Barrio, J.M.G., 2018. Resin-tapped
pine forests in Spain: Ecological diversity and economic valuation. Sci
Tot Environ 625, 1146-1155. https://doi.org/10.1016/j.scitotenv.2018.01.027
).
This includes areas in the province of Soria (Central Spain) where
tapping pines trees for resin production has traditionally been carried
out (Gil, 1991Gil L, 1991. Consideraciones históricas sobre Pinus pinaster Aiton en el paisaje vegetal de la Península Ibérica. Estudios geográficos. LII 202: 5-27.
)
and now emerges as an option to add value where timber profitability is
compromised, or low timber prices and a high risk of wildfires could be
present. However, managed stands using traditional resin tapping
methods are very vulnerable to wildfire. Among adaptations to the high
recurrence of fires, P. pinaster generates thick bark that protects living tissues from high temperatures (Fernandes & Rigolot, 2007Fernándes PM, Rigolot E, 2007. The fire ecology and management of maritime pine (Pinus pinaster Ait.). For Ecol Manage 241(1): 1-13. https://doi.org/10.1016/j.foreco.2007.01.010
).
The tapping operation makes trees very vulnerable to fire, reducing
their resistance to burning. For the same reasons, carrying out PB
before tapping in P. pinaster provenances with thick bark has been proposed as a suitable treatment for managing tapped stands (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
).
Analysis of the effect of PB before tapping enables evaluation of the potential of the procedure for use in P. pinaster stands. Use of PB would also improve accessibility, both for resin
collectors and firefighting teams and would also reduce fire hazard due
to reduction in fuel load. Rodríguez-García et al. (2018)Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
verified that burning generates a significant increase in the number of
resin canals but does not produce an increase in resin yield in the
same year of tapping or one year after. However, secondary defences are
not usually induced in trees until the third or fourth year after
disturbance (Knebel et al., 2008Knebel
L, Robison DJ, Wentworth TR, Klepzig KD, 2008. Resin flow responses to
fertilization, wounding and fungal inoculation in loblolly pine (Pinus taeda) in North Carolina. Tree Physiol 28: 847-53. https://doi.org/10.1093/treephys/28.6.847
).
With the aim of testing this hypothesis, a new experimental design was
applied to evaluate the resin yield four years after PB. The aim of this
study was therefore to answer the following question: Does the resin
yield increase in a Pinus pinaster stand when subjected to PB
before tapping? The underlying study hypothesis is that PB increases the
opening of the resin canals in the trees, which may be associated with
an increase in resin yield (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
).
Material and methods
⌅Study site and experimental design
⌅The study was carried out in the municipality of Quintana Redonda, province of Soria, central-eastern Spain (Fig. 1). In 2018, six experimental plots (50 m x 50 m) were established in monospecific Pinus pinaster Ait. stands of the Spanish provenance “Castilian northern Plateau” growing on siliceous sands deposited during the Quaternary (Alía et al., 1996Alía R, Martín S, De Miguel J, Galera R, Agúndez D, Gordo J, Salvador L, Catalán G, Gil A, 1996. Regiones de procedencia Pinus pinaster Aiton. Dirección General de Conservación de la Naturaleza. Madrid. 75 pp.
).
Experimental burning was carried out in three randomly assigned plots
(April 2018), and the other three plots were used as controls (Fig. 1).
The dendrometric characteristics of the stands are as follows
(average±standard error): density = 400±43 trees/ha; height = 17±1.2 m;
diameter at breast height = 44±9 cm; crown base height = 10±2.3 m; bark
thickness = 4.9±0.9 cm; and cover = 80±15 %). The understorey vegetation
is dominated by Cistus laurifolius L., Erica arborea L. (Average height = 1.1±0.3 m; Cover = 18±7 %) and scattered trees of Quercus faginea Lam.
Data collection
⌅Experimental
burning was conducted in April 2018 (temperature 19 ºC, relative
humidity 38%, in stand surface wind speed 3 km/h), with the strip
ignition technique, at a distance of 1-2 m, downhill and facing an
upslope wind. This technique is the most widely used in the study area
to produce low-medium intensity fire (González-Sancho, 2020González-Sancho
D, Gómez-Molino R, Álvarez-Palomares R, López-Santalla A, 2020.
Programa nacional de quemas prescritas experimentales bajo arbolado.
Montes 142: 34-40
) generating low stem char height
(0.95±0.73 m). The fuel load was evaluated before and after burning to
assess the efficacy of the treatment. Brown’s method (Brown, 1974Brown
JK, 1974. Handbook for inventorying downed woody material. USDA Forest
Service. Intermountain Forest and Range Experiment Station. General
Technical Report INT-16.
) was used to estimate woody
fuel loads in two transects (diagonal lines of each plot) for each fuel
size according to the USDA classification (Andrews et al., 2008Andrews
PL, Bevins CD, Seli RC, 2008. BehavePlus fire modeling system, version
4.0: User's guide. General Technical Report RMRS-GTR-106WWW. Revised.
Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky
Mountain Research Station. 132 pp.
): 1-h (needles and
woody debris ø<6mm), 10-h (ø =6-25 mm), 100-h (ø=25-75 mm). Needle
load was evaluated using 5 quadrats (30 x 30 cm2) per plot sited in centre of each plot (1 subplot) and in the middle of two diagonals (4 subplots).
Tapping operations were started in June 2018 in the burned and unburned plots. A sample of 15 trees per plot (45 trees in burned+tapped plots and 45 trees in tapped only plots) was randomly selected. To observe the influence of burning, the resin yield was collected, with the collaboration of a local resin worker, from tapped trees using a portable load cell (accuracy 1 g), during surveys conducted between June and September from 2018 to 2021 (4 years of monitoring).
Data analysis
⌅A generalised linear mixed model (GLMM) for repeated measures was used (after checking the assumptions for use of parametric tests) to analyse production considering the four years for which the weight of resin yield was available. The treatment was analysed as the inter-subject factor, with two levels (Burning +Tapping, Tapping only), with the measurement date as the intra-subject factor, with four levels (years 2018 to 2021). Considering the hierarchical nature of the data (repeated observations in a single tree, trees measured in the same plot), a nested linear mixed model including both fixed and random effects acting at plot and tree levels was fitted. After the model was fitted, the assumptions of normality and homoscedasticity of the residuals were evaluated. Finally, the goodness of fit statistics, referring to both the marginal (not considering random effects) and conditional (including random effects) predictions were determined. The analyses were conducted using SPSS 25.0 ©
Results and discussion
⌅Prescribed
underburning led to the consumption of 32.73±15.45% of litter biomass
and 77.82±13.09% of fine fuel (<6 mm). Low intensity burning (average
flame length 1±0.5m) and a conservative prescription (rate of spread
higher than 1.41±0.07 m/min, fuel fine moisture content 12%) generated
moderate consumption of heavier fuels (>6mm), of between 18 and 33% (Table 1). Mean consumption of the total fuel load from 1 to 100-h was 40.44±22.44% (Table 1). These values are similar to those reported for Pinus nigra and mixed P.nigra - P.pinaster stands (Espinosa et al., 2018Espinosa
J, Madrigal J, De La Cruz AC, Guijarro M, Jiménez E, Hernando C. 2018.
Short-term effects of prescribed burning on litterfall biomass in mixed
stands of Pinus nigra and Pinus pinaster and pure stands of Pinus nigra in the Cuenca Mountains (Central-Eastern Spain). Sci Total Environ 618: 941-951. https://doi.org/10.1016/j.scitotenv.2017.08.291
and 2020Espinosa
J, Rodríguez de Rivera O, Madrigal J, Guijarro M, Hernando C, 2020.
Predicting potential cambium damage and fire resistance in Pinus nigra Arn. ssp. salzmannii. For Ecol Manage 474: 118372. https://doi.org/10.1016/j.foreco.2020.118372
). Similar values were also reported by Rodriguez-García et al. (2018)Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
for experimental plots close to those in the present study, burned in
2015, and values obtained by the National Programme for experimental
prescribed underburning (González-Sancho et al., 2020González-Sancho
D, Gómez-Molino R, Álvarez-Palomares R, López-Santalla A, 2020.
Programa nacional de quemas prescritas experimentales bajo arbolado.
Montes 142: 34-40
, García-Feced et al., 2022García-Feced
C, González-Sancho D, Gómez-Molino R, Álvarez-Palomares R,
Iglesias-Rodrigo A, López-Santalla A, 2022. Programa nacional de quemas
prescritas experimentales bajo arbolado. 8CFE - 347. Sociedad Española
de Ciencias Forestales. https://8cfe.congresoforestal.es/cat/node/4594
). The results confirm the efficacy of PB in reducing fire hazard under canopy in Mediterranean ecosystems (Fernandes et al., 2022Fernandes
P, Rossa C, Madrigal J, Rigolot E, Ascoli D, Hernando C, Guiomar NG,
Guijarro M, 2022. Prescribed burning in the European Mediterranean
Basin. In: Global application of prescribed fire, pag. 230-248. CSICO
Publishing, Australia.
). Resin yields differed between
the four years of study (within-subject factor) (p<0.001), with mean
production levels of 1.46±0.24 kg in 2018, 1.90±0.35 kg in 2019,
1.77±0.30 kg in 2020 and 2.73±0.88 kg in 2021 (Fig. 2).
However, no significant differences in production were detected within
the same year (inter-subject factor) between the burned, tapped stands
relative to the tapped stands (p=0.93). The GLMM revealed a significant
effect of random variables (tree and plot) (p<0.01). A high level of
variability among resin yield in trees and sites is common in tapped
stands (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
).
| Size class | Before PB | After PB | % Fuel load consumed |
|---|---|---|---|
| Litter | 0.89 | 0.60 | 32.73 |
| SE | 0.14 | 0.05 | 15.45 |
| 1htr | 0.61 | 0.13 | 77.82 |
| SE | 0.05 | 0.06 | 13.09 |
| 10htr | 1.66 | 1.30 | 17.89 |
| SE | 0.69 | 0.15 | 27.33 |
| 100htr | 2.11 | 1.41 | 33.33 |
| SE | 0.71 | 0.15 | 22.27 |
| Total Fuel Load | 5.25 | 3.49 | 40.44 |
| SE | 0.59 | 0.53 | 22.44 |
We expected a cumulative effect of resin yield between 2018 and 2021 (Fig. 2) related to the generation of “traumatic” resin ducts (secondary defence in response to wounding) after treatment (Ruel et al., 1998Ruel
JJ, Ayres MP, Lorio JR, 1998. Loblolly pine responds to mechanical
wounding with increased resin flow. Can J For Res 28(4): 596-602. https://doi.org/10.1139/x98-030
, Lombardero et al., 2000Lombardero
MJ, Ayres MP, Lorio PL, Ruel JJ, 2000. Environmental effects on
constitutive and inducible resin defences of Pinus taeda. Ecol Letters 3
(4):329-339. https://doi.org/10.1046/j.1461-0248.2000.00163.x
).
Nevertheless, the absence of significant differences for inter-subject
factor indicates that the significant increase in the resin yield over
time (Fig. 2) may be more
closely related to the variability in weather and the increase in resin
canals for both treatments. Therefore, the stress produced by wounds
opened up during tapping operations may mask the potential effects of PB
(Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
).
The present study findings confirm those previously obtained by (Rodríguez-García et al., 2018Rodríguez-García
A, Madrigal J, Guijarro M, González D, Hernando C, 2018. Can prescribed
burning improve resin yield in a tapped Pinus pinaster stand? Ind Crops Prod 124: 91-98. https://doi.org/10.1016/j.indcrop.2018.07.049
),
in which no increase in resin yield was detected in the short term (two
years after burning). The experiment was specifically designed to
include a longer duration of resin yield monitoring. Robust results
would therefore be obtained with two independent experiments used in the
same area.
The findings indicate that prescribed under canopy burning in P. pinaster stands does not increase resin yield. However, the findings also
indicate that PB is an effective tool to reduce fire hazard compatible
with the first tapping in tapped stands managed for resin production, as
the reduction in fuel load will reduce the forest fire risk and
vulnerability of tree trunks to fire (Madrigal et al., 2019Madrigal J, Souto-García J, Calama R, Guijarro M, Picos J, Hernando C, 2019. Resistance of Pinus pinea L. bark to fire. Int J Wildland Fire 28(5): 342-353. https://doi.org/10.1071/WF18118
; Espinosa et al., 2020Espinosa
J, Rodríguez de Rivera O, Madrigal J, Guijarro M, Hernando C, 2020.
Predicting potential cambium damage and fire resistance in Pinus nigra Arn. ssp. salzmannii. For Ecol Manage 474: 118372. https://doi.org/10.1016/j.foreco.2020.118372
). The results suggest that PB would increase resin yield if a higher intensity fire (Vilà-Vilardell et al. 2024Vilà-Vilardell
L, Tepley AJ, Sala A, Casals P, Hood SH. 2024. Long-term sensitivity of
ponderosa pine axial resin ducts to harvesting and prescribed burning,
For Ecol Manage 572: 122301. https://doi.org/10.1016/j.foreco.2024.122301
) is prescribed. Thus, burn prescriptions compatible with tapped P. pinaster stands could improve the local bioeconomy.
Acknowledgements
⌅Prescribed burning was conducted by MITECO’s Forest Fire Reinforcement Brigade (BRIF) in Lubia (Soria). We thank the local worker who carried out the resin tapping and calculated the resin yields with the support of Forest managers from Soria province Forest Service (Government of Castilla y León Autonomous Region).
Competing interests
⌅The authors have declared that there are no competing interests.
Authors’ contributions
⌅Javier Madrigal: Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Writing – original draft, Writing – review & editing. Cristina Carrillo-García: Data curation, Formal analysis. Aida Rodríguez-García: Conceptualization, Methodology, Supervision, Writing – review & editing. David González-Sancho: Data curation. Juncal Espinosa: Data curation, Supervision. Mercedes Guijarro: Writing – review & editing. Carmen Hernando: Project administration. Celia García-Feced: Project administration, Supervision, Writing – review & editing