Posts Tagged ‘pinus’

Serotiny and WWI memorials

April 27th, 2021 No comments

On ANZAC Day (25 April; the national day of Australia, see wikipedia) I received the following query from an Australian colleague.

Apparently one of the few Australian soldiers that survived the Gallipoli battle (Turkey, 1915, WWI) picked up a pine cone (from a ‘Lone pine’), and took it back to Australia. The cone was kept on a shelf until 1933 when a horticulturalist extracted 5 seeds and germinated them. The seedlings were planted in botanic gardens; the 78-year-old trees now have special symbolic value to war veterans and the like (Fig. 1). The returned veterans are often referred to as ‘lone pine soldiers’ (and the battle, as the battle of the lone pine). My colleague asked me if the cone story had some credibility, for instance, would a pine seed germinate after 18 years?

Fig. 1. Plaque at the foot of pine tree in Kings Park, Perth, Western Australia. From [4]

The plaque in Kings Park (Fig. 1) suggest that the pine is a Pinus halepensis (Aleppo pine). However, the pines in Gallipoli peninsula (and in most Turkey) are of another species: Pinus brutia (Turkish Red Pine) [2]; the two species are very close related. So the cone that the soldier pick up should be a P. brutia, unless there was a plantation of P. halepensis there.

Pine seed, once there are out of the cone, do not last for long (mostly less than a year). However one of the characteristics of both P. halepensis and P. brutia is that they have some serotinous cones (the serotiny level is higher in P. halepensis than P. brutia, but both have a proportion of serotinous cones) [2,3]. Serotinous cones are those that remain closed after maturation, i.e., more than a year [1]. They accumulate for several years, forming a canopy seed bank; these cones open after the tree burns in a wildfire, and thus it is an adaptation to regenerate after fire [1]. At least in the case of P. halepensis, we have evidence that cones remaining close on the tree for many years; most cones open in less than 8 years, but some can last more than 15 years (Fig. 2). In addition we have evidence of cones remaining closed after harvest (at lest 12 years in my experience). This information is for P. halepensis, but could apply to P. brutia as well.

Fig. 2. Left: Frequency distribution of trees in relation to their maximum closed cone age for Pinus halepensis in eastern Spain. The gray pattern corresponds to the proportion of trees in population under high frequency of crown fires, the white to the proportion of trees where crown fires are rare. From [3]. Right: example of long-lived serotinous cones in P. halepensis in eastern Spain.

In conclusion, the Australian soldier may have picked up a serotinous cone, perhaps from a P. brutia. The seed were in the cone for 18 years and then extracted and planted. There are other accounts suggesting that several Australian soldiers took cones of both P. brutia, and P. halepensis (it’s difficult to understand why soldiers would collect pine cones after such a deadly battle, but this is another question …).

Currently most WWI memorials in Australia include a P. halepensis tree, a few a P. brutia. In the memorial cemetery near Gallipoli they planted (in the 1920s) a different pine, a Pinus pinea (stone pine, not native from Turkey, but from Italy and Spain). And in New Zealand (they shared with Australians the Gallipoli drama), the tree in ANZAC memorials includes Pinus radiata (from California) and Pinus canariensis (from Canary Islands, west Africa). That is, any of the ca. 120 pine species may do for a war memorial…

If Gallipoli has not been a fire-prone ecosystem, the pines would not be serotinous, the cones collected by the soldiers would not had kept the seeds, and we would not have pines in the Australian and New Zealand war memorials. So now, when you see a pine in a war memorial, just think about fire adaptations!


[1] Lamont BB, Pausas JG, He T, Witkowski, ETF, Hanley ME. 2020. Fire as a selective agent for both serotiny and nonserotiny over space and time. Crit. Rev. Plant Sci. 39:140-172. [doi | pdf | suppl.]  

[2] Pinus brutia

[3] Hernández-Serrano A., Verdú M., González-Martínez S.C., Pausas J.G. 2013. Fire structures pine serotiny at different scales. Amer. J. Bot. 100: 2349-2356. [doi | amjbot | pdf | supp.]  

[4] For more about the lone pine puzzle see: Underwood R. 2014 | wikipedia

More on serotiny|


Pinus yunnanesis

January 16th, 2021 2 comments

In the Yunnan Province of China, P. yunnanensis occurs in two growth forms: as a tree (var. yunnanensis) and as a shrub (var. pygmea) [1]. The shrubby form occurs mainly in upper slopes and ridges (Fig. 1), where soils are poor and dry, and fires are likely. This shrubby pine is very interesting and quite unique among pines: it has serotinous cones (Fig. 2), and resprouts after fire from basal buds (Fig. 3), generating multi-stemmed shrubby pine populations [1]. Serotiny is common among pines [2] while resprouting is not [3], so pines with both serotiny and resprouting are rare; and having a multi-stemmed growth form is even rarer.

Fig. 1. Pine shrubland (Pinus yunnanensis var. pygmea) in Yunnan, China. Photo C. Luo [1]
Fig. 2. Pinus yunnanensis var. pygmea showing serotinous cones, Yunnan, China. Photo: W.-H. Su [1]
Fig. 3. Pinus yunnanensis var. pygmea resprouting from basal buds after a fire, Yunnan, China. Photo: JG Pausas [1]


[1] Pausas JG, Su W-H, Luo C, & Shen Z. 2021. A shrubby resprouting pine with serotinous cones endemic to Southwest China. Ecology [doi | pdf]

[2] He T, Pausas JG, Belcher CM, Schwilk DW, Lamont BB. 2012. Fire-adapted traits of Pinus arose in the fiery Cretaceous. New Phytol. 194: 751-759. [doi | wiley | pdf | suppl.]

[3] Pausas, J.G. 2015. Evolutionary fire ecology: lessons learned from pines. Trends Pl. Sci. 20: 318-324. [doi | sciencedirect | cell | pdf]

Pine serotiny

November 14th, 2020 No comments

Some days ago I asked this question on Twitter.

What is the difference between the top and bottom pine cones in this photo? This is a question I often ask to my new students in the first field trip; in this case, Beniardà fire, 2020 [link]

These cones are from Pinus halepensis and were collected after a wildfire in Beniardà (Alicante, E Spain; burned in Aug 2020).

Many of you reply correctly; here is the full answer:

Top cones: before the fire, they were open on on the tree, i.e., without seeds. Fire burn them, and so they are all black

Bottom cones (see also the picture below): before the fire they were closed (serotinous cones), and fire opened them facilitating seed dispersal. Note that they are unburned inside. These cones contribute to the postfire regeneration of the pine.

Serotinous cones in Pinus halepensis: before (left) and after a fire (right)



  • Lamont BB, Pausas JG, He T, Witkowski, ETF, Hanley ME. 2020. Fire as a selective agent for both serotiny and nonserotiny over space and time. Critical Reviews Plant Sci 39:140-172. [doi | pdf | suppl.]
  • Pausas JG. 2015. Evolutionary fire ecology: lessons learned from pines. Trends Plant Sci 20: 318-324. [doi | sciencedirect | cell | pdf]
  • Castellanos MC, González-Martínez S. & Pausas JG. 2015. Field heritability of a plant adaptation to fire in heterogeneous landscapes. Mol Ecol 24: 5633-5642. [doi | pdf | suppl.]
  • Hernández-Serrano A, Verdú M, González-Martínez SC, Pausas JG. 2013. Fire structures pine serotiny at different scales. Am J Bot 100: 2349-2356. [doi | amjbot | pdf | supp.]
  • Hernández-Serrano A, Verdú M, Santos-Del-Blanco L, Climent J, González-Martínez SC & Pausas JG. 2014. Heritability and quantitative genetic divergence of serotiny, a fire-persistence plant trait. Ann Bot 114: 571-577. [doi | pdf | suppl.]


More on serotiny: Serotiny: a review | Pinus brutia | Heritability of serotiny | Heritability of serotiny (2) | Evolutionary fire ecology in plants | Serotiny |

The perch effect

March 30th, 2019 No comments

The perch effect refers to the process in which trees are used as perches by frugivorous birds, and because these birds defecate and/or regurgitate seeds while perching, they generate an increased recruitment of fleshy-fruited plants below the trees [1]. Thus, seed rain, and the resulting seedling recruitment and sapling spatial pattern of bird-dispersed (fleshy-fruited) plants is highly patchy and largely restricted to microhabitats beneath trees, in contrast to the pattern of other plants (e.g., wind-dispersed plants [1]). This effect is commonly observed in abandoned fruit orchards in the Mediterranean region, such as those oldfieds of carob trees [1], and thus is an example of how some of the species traditionally considered “late-successional species” occur at early stages of the oldfield succession.

In a recent visit to the Doñana Natural Park (southern Spain) I saw some of the most impressive cases of perch effect (photos below). Pines (Pinus pinea) were widely planted in the region during the 20th C and are currently the dominant tree of the area. However, little by little, junipers (Juniperus phoenicea) are naturally colonizing the area. They have fleshy fruits dispersed by birds, and thus they recruit below the pines where the bird perched. Some of the junipers has grown enough that the effect cannot be unnoticed at all. There are places where most pines have a juniper growing below. It is nice to feel the dynamic of this ecosystem, and the recolonization of the natural habitat.

The importance of bird perching for the dispersal of many plants is one of the reasons why dead trees after a fire should not be cut down, as too often is done in Spain (example1, example2). They help the colonization of bird-dispersed plants (as well as they are habitat for many animals, they reduce the water impact on the soil, retain fog, maintain certain humidity, etc.).


Juniperus phoenicea colonizing Pinus pinea (stone pine) plantations



[1] Pausas J.G., Bonet A., Maestre F.T., Climent A. 2006. The role of the perch effect on the nucleation process in Mediterranean semi-arid oldfields. Acta Oecologica 29: 346-352. [doi | pdf]

More on: Pines | Doñana postfire | Juniperus

Pinos, ¿nativos o exóticos?

November 19th, 2018 No comments

Recientemente se ha generado una cierta controversia sobre si hay pinos autóctonos o no en España y si se deben eliminar de algunos hábitats. Aquí un grupo de ecólogos de la AEET(*) intentamos ayudar a cerrar el debate.


Sobre los pinos ibéricos

Hace tiempo que existe un debate abierto sobre el carácter autóctono (nativo) o no de los pinos, y, recientemente, el debate se ha reavivado en relación a las revisiones de listas de especies exóticas. A escala regional la respuesta es clara: sí que hay pinos autóctonos en nuestro territorio, tanto en la península Ibérica como en las islas Baleares e islas Canarias. Por ejemplo, si consultamos una obra de referencia tal como la Flora Ibérica, veremos que se mencionan seis especies de pinos autóctonos. Y si analizamos registros de polen en estratos antiguos de turberas, o el registro fósil, o los estudios de biogeografía, vemos que todo indica que han existido pinos en nuestros paisajes desde hace millones de años, aunque no siempre podamos distinguir las especies concretas. De hecho, ninguna de las especies de pino ibéricas aparece en el Catálogo Español de Especies Exóticas Invasoras del Gobierno (a fecha de 15-10-2018).

Cada una de estas diferentes especies de pino tiene sus requerimientos y preferencias ecológicas; unas especies viven a baja altitud y soportan bien el calor y la sequía, otras viven en las montañas y están adaptadas al frío; unas viven sobre cualquier tipo de suelo, otras evitan los suelos calizos o los suelos muy ácidos; unas se regeneran muy bien incluso después de incendios intensos, otras prácticamente desaparecen si arden con elevada intensidad. Es decir, no todas las especies de pinos pueden vivir en cualquier parte; las diferentes especies se distribuyen a lo largo y ancho de la Península siguiendo unos patrones concretos relacionados con el clima, el suelo y los incendios, además de con el uso del territorio realizado desde antaño. En algunas zonas, los pinos forman masas densas, homogéneas y monoespecífias; en otras, la densidad es baja o muy baja y se mezclan con otras especies de árboles (bosques y dehesas mixtas) o con especies arbustivas (matorrales con pinos). Y hay zonas en las que prácticamente no crecen pinos de forma natural, ya sea por condiciones ambientales o por regímenes de perturbación no apropiados, o por competencia con otras especies más adaptadas a esas situaciones. Los humanos, a lo largo de la historia, han ido modificando la distribución natural mediante cortas, talas, plantaciones y restauraciones forestales, con el objetivo de aprovechar los recursos que proporcionan los pinos (madera, resina, piñones, protección del suelo, etc.). A pesar de ello, aún podemos apreciar relaciones entre la presencia o densidad de pinos de las diferentes especies y las características ambientales de los sitios, indicadoras de diferencias ecológicas entre las especies.

Lista de especies nativas, y principales especies exóticas, de la familia de los pinos (pináceas) en la península Ibérica, islas Baleares e islas Canarias:

Pináceas nativas:

Pinus halepensis (pino carrasco)
Pinus nigra subsp. salmannii (pino salgareño o laricio)
Pinus pinaster (pino rodeno)
Pinus pinea (pino piñonero)
Pinus sylvestris (pino albar o silvestre)
Pinus uncinata (pino negro)
Pinus canariensis (pino de Canarias; exclusivo de las Islas Canarias)
Abies alba (abeto)
Abies pinsapo (pinsapo)

Principales pináceas exóticas:

Pinus radiata (la mas abundante; origen: norteamérica)
Pseudotsuga menziessi (origen: norteamérica)
Laris decidua (origen: centro Europa)


Sobre las plantaciones y la restauración de los ecosistemas

Los objetivos y métodos para la restauración del medio natural han ido variando a lo largo de la historia a medida que ha ido evolucionando las prioridades, el conocimiento y la conciencia medioambiental. Por ejemplo, antiguamente, se plantaban árboles (reforestación) para restaurar áreas degradadas sin pensar mucho en su origen, ni teniendo en cuenta si la especie era o no autóctona ni si la variedad era local o no, y sin considerar si las densidades y estructura reflejaban las condiciones naturales y el hábitat para otras especies. Cuando más adelante se plantaron pinos autóctonos, algunas veces se hizo en zonas típicas de la especie, y otras en zonas donde la especie estaba ausente o en baja densidad. En cualquier caso, estas restauraciones cumplían algunos de los objetivos de la época (por ejemplo, frenar la erosión) y aún son visibles en nuestros paisajes. Por su estructura, densidad y heterogenidad, actualmente las plantaciones de pinos a menudo se asemejan bastante a ecosistemas naturales, cumpliendo una función ecológica importante; en otras ocasiones, sin embargo, se parecen más a cultivos para producción de madera. Una de las principales diferencias entre estos “cultivos de madera” y los demás cultivos es que los primeros son más propensos a propagar fuegos intensos, especialmente si están deficientemente gestionados. Esta repercusión en los incendios forestales puede tener consecuencias sociales y ambientales adicionales y requieren de una especial atención.

Actualmente, los objetivos de la restauración incluyen la conservación de la biodiversidad. Existe un gran acuerdo entre los ecólogos y gestores del medio ambiente en que ni los pinos, ni los bosques en general, constituyen la única alternativa en paisajes mediterráneos; los matorrales son también autoctónos, naturales, diversos y antiguos, y contribuyen en gran medida a la elevada biodiversidad de los ecosistemas mediterráneos, además de favorecer la protección de sus suelos. Cada vez más se tiende a realizar restauraciones ecológicas introduciendo especies y variedades locales, y no solo de árboles, sino también de arbustos y especies herbáceas. La sociedad actual convive con plantaciones y restauraciones realizadas con criterios del pasado, donde las percepciones ambientales y el conocimiento ecológico eran muy diferentes. Esta convivencia genera cierto conflicto social y está en el origen de muchos debates sobre la naturaleza nativa o no de los pinares.

Fotos, de izquierda a derecha: P. nigra (Cazorla, por Juli G. Pausas), P. halepensis (Bages, centro de Catalunya, por Jordi Garcia-Pausas), P. uncinata (Pirineo de Andorra, por Jordi Garcia-Pausas), P. pinea (Doñana, Pedro Jordano).

Sobre los pinares litorales en dunas

Un claro ejemplo del conflicto mencionado lo constituyen los pinares sobre dunas (por ejemplo, en Doñana o en Guardamar). En muchos casos, estas dunas se poblaron masivamente de pinos (en Doñana hay plantaciones documentadas desde el s. XVI, aunque masivas sólo en el s. XX). La finalidad de estas plantaciones era bienintencionada: fijar las dunas, crear puestos de trabajo, y generar un ambiente forestal agradable. En aquella época, se valoraba más cualquier estructura arbolada densa, aunque fuese pobre en especies, que un matorral, por muy diverso en especies que fuera. Además, plantar pinos era mucho más fácil y agradecido (mayor supervivencia) que plantar otras especies arbóreas. Con los años, esos pinares han pasado a formar parte de nuestro paisaje cultural. La vegetación original de estas dunas litorales era probablemente un mosaico donde alternaban arbustos y árboles pequeños típicos de la máquia esclerófila mediterránea, plantas de los brezales y sabinares ibéricos, y herbáceas propias de dunas; en ellas, la densidad de pinos era baja y variable según las condiciones topográficas, del nivel freático y salino, y las especies acompañantes. El sobrepastoreo y la explotación de leña fue degradando esos ecosistemas y generando erosión y movimientos no deseables de las dunas. En ese marco ambiental se realizaron las plantaciones de pino.

Cabe destacar que tras el incendio que afectó a los pinares de la zona de Doñana (julio 2017), se ha constatado una regeneración muy satisfactoria de muchas de las especies del mosaico de matorral y brezal que dominaron antes de las plantaciones, mientras que el pino prácticamente no se regenera. Si se facilita y potencia la regeneración de estos matorrales, que son muy diversos en especies, los incendios (inevitables) que ocurran en el futuro serán menos intensos (por la menor biomasa) y se regenerarán más rápidamente; por lo tanto, estas comunidades serían más sostenibles. Por tanto, desde el punto de vista ecológico, y en el contexto del calentamiento global, la reducción de la densidad de pinos en dunas litorales está en muchos casos justificada, mientras se realice de manera cuidadosa y favoreciendo la vegetación alternativa que puede albergar importantes valores de conservación. En cualquier caso, ante cualquier intención de reducción drástica del pinar, se debería evaluar con detalle las consecuencias, ya que plantaciones antiguas también pueden tener actualmente especies que dependan de ellas.

En conclusión

Vivimos en un territorio heterogéneo con una historia compleja, donde las dinámicas naturales se han visto frecuentemente alteradas por unos usos del territorio cambiantes en intensidad y objetivos. La presencia de pinos autóctonos en nuestro país es indiscutible, pero este hecho no justifica su plantación en cualquier sitio ni de cualquier manera. El conocimiento adquirido en los últimos años sobre la biodiversidad y la ecología de nuestros bosques, junto con la amenaza del cambio climático, nos lleva a repensar la gestión de las plantaciones de pino, y en general, la gestión de los recursos naturales. Mediante una planificación integrada del territorio deberíamos poder decidir con criterios objetivos dónde son preferibles pinares lo más naturales posibles (por ejemplo, en áreas protegidas), dónde queremos plantaciones de pinos para la protección del suelo y la regulación hídrica, y dónde queremos plantaciones de pinos productivas y sostenibles.

(*) Los miembros de la AEET que han contribuido a este texto son: Pedro Jordano (CSIC), Francisco Lloret (UAB-CREAF), Juli G. Pausas (CSIC), Anna Traveset (CSIC-UIB), Fernando Valladares (CSIC).

Este texto se ha publicado simultáneamente (19-11-2018) aquí y en el blog del CREAF (tanto en castellano como en catalán). Una versión resumida también se publico en (29-11-2018).


Pinus canariensis epicormic resprouting

November 23rd, 2017 No comments

The cover of the December issue of Trends in Plant Science (22:12) is a picture of Pinus canariensis resprouting epicormically (from stem buds) 3 months after a fire in Tenerife (Canary Islands, Nov 2012). It features our review paper on this type of resprouting [1]. Many plants resprout from basal buds after disturbance, however epicormic resprouting is globally far less common, and the Canary Island pine is a very good example; it resprouts in this way even after intense crown fires.


[1] Pausas J.G. & Keeley J.E. 2017. Epicormic resprouting in fire-prone ecosystems. Trends in Plant Science 22: 1008-1015. [doi | sciencedirect | pdf | post ]

More on: epicormic resprouting | pines | resprouting


Chile 2017 fires: fire-prone forest plantations

September 16th, 2017 No comments

During the 2016/17 fire season in central Chile, wildfires burned about 600,000 ha, a record for the region (most of the area burned between 18-Jan and 5-Feb, 2017). Two factors are considered the main responsible of such a large area burned: (1) an intense drought with strong head waves (January was the hottest month in record), and (2) the fact that the region is covered by large and dense tree plantations that create a continuous fuel bed. The tree planted are two alien species: Pinus radiata and Eucalyptus sp., from California and Australia, respectively. Most burned area (+60%) were plantations, and if we standardize the area burned in relation to the area with each landuse in the region (plantations, native forest, grasslands, agriculture) we see that the plantations were more affected by fire than expected by their area in each region; and this contrast with the other landuses (Figure 1, [1]). That is, tree plantations were an important driver for the large area burned (highly flammable).

Interesting is that the two species planted not only are highly flammable, they also have very good (although very different) postfire regeneration mechanisms, because both are originally from fire-prone ecosystems and have adapted to coupe with crown fires. Pinus radiata have serotinous cones (closed cones that open with fire) and showed an extraordinary “natural” seedling regeneration postfire (Figure 2 top), while those eucalytps planted show epicormic (stem) resprouting that allows a quick canopy recovery (even young trees, Figure 2 bottom). All suggest that these plantations were born to burn!

Figure 1: Analysis of the areas affected by fires according to types of use (forest plantations, native forest, Scrubland + pastures, and agricultural areas), in relation to what is available in each of the 4 regions that have burned the most (V, RM, VI, VII are: Valparaiso, Metropolitana, O’Higgins, and Maule). Positive data means that fire has positively selected this type of use (it has burned more than expected by the area it occupies); the negative data indicate that fire tends to avoid such landuse. There is a strong tendency for plantations to burn more than expected according to their abundance in the landscape (positive values), while native forests, scrub, or agricultural areas are burned similar or less than expected according to their abundance (negative values). The region VII (Maule) is the most extreme in positive selection of plantations and negative of other uses. Elaborated on the basis of official SIDCO-CONAF data (Chile) [1].


Figure. 2. Postfire regeneration of tree plantations. Top: Extraordinary postfire seedlings regeneration of Pinus radiata (adult trees are dead). Bottom: epicormic resprouting of eucalypts (mixed with dead pines). Photos from early September (ca. 7 months after fire), in the Nilahue Barahona fire (O’Higgins region, Chile).


[1] Incendios en Chile 2017,

More information on:  Chile and fires | Serotiny | Epicormic resprouting

UPDATE (Jan 2019): this post and this other have inspired the following article:

Leverkus AB, Murillo PG, Doña VJ, Pausas JG. 2019. Wildfires: opportunity for restoration? Science 363 (6423): 134-135. [doi | science | pdf]


Pinus canariensis

May 7th, 2017 No comments

The last post was about Pinus brutia [1] from the Eastern Mediterranean basin. Another pine of the mediterranean group (Pinaster group) is Pinus canariensis, endemic of Canary Islands, in the north west of Africa (in the Atlantic). P. canariensis have a thick bark and resprouts vigorously from stem buds (epicormic resprouting) after crown fires. In addition, it produce serotinous cones, a clear adaptation to recruit after fire [2,3]. Very few other trees have strong adaptations to both survival and regeneration postfire; P. canariensis is among the best fire-adapted trees in the world, likely to survive very different fire regimes.

Pictures of Pinus canariensis (by JG Pausas except mid-right from NASA).
· Top-left: 5 years after a crown-fire (La Palma, Canary Is.).
· Mid-left: plantation 2 years after fire (Vall d’Ebo, Alicante, eastern Spain; planted in the 50s).
· Bottom-left: Contrasted response of Pinus halepensis (left; fire-killed serotinous pine) and P. canariensis (right, resprouting) two years after fire (Alicante, eastern Spain).
· Top-, bottom-right: epicormic resprouts 3 months after fire (Tenerife, Canary Is.).
· Mid-right: a fire plume from a wildfire in La Palma (Canary Is.).

[1] Pinus brutia,, 19 Apr 2017

[2] Keeley J.E., Pausas J.G., Rundel P.W., Bond W.J., Bradstock R.A. 2011. Fire as an evolutionary pressure shaping plant traits. Trends Plant Sci. 16: 406-411. [doi | sciencedirect | trends | pdf | For managers]

[3] Pausas, J.G. 2015. Evolutionary fire ecology: lessons learned from pines. Trends Plant Sci. 20: 318-324. [doi | sciencedirect | cell | pdf]


Pinus brutia

April 19th, 2017 No comments

Pinus halepensis is a strongly serotinous pine [1,2] occurring mainly in the western part of the Mediterranean Basin (especially in Spain; see map below). The most phylogenetically closely related species to P. halepensis is Pinus brutia that occurs in the eastern Mediterranean Basin (mainly in Turkey). P. brutia is called ‘red pine’ in Turkish (Kızıl çam) because sometimes the upper part of the trunk is reddish (as in P. sylvestris); the leaves are pale green as in P. halepensis. In relation to their fire response strategy [3], the main differences between the two species are that P. brutia is taller, the bark is thicker and the serotiny level is lower. Our observations suggest that P. brutia have relatively few serotinous cones, and most of then are less than 4 years old; P. halepensis have a higher proportion of serotinous cones, with many of them over 5 year old (and some more than 20 year old) [1].

Distribution maps of P. halepensis and P. brutia (from Wikipedia)

Pinus brutia forest, serotinous cones (2 serotinous and one non-serotinous (open)), and an example of a bark of more than 5 cm thick (the gaude was too short!). Photos from SW Turkey (by JG Pausas). For an example of serotinous cones in P. halepensis, see here.


[1] Hernandez-Serrano A., Verdú M., González-Martínez S.C., Pausas J.G. 2013. Fire structures pine serotiny at different scales. Am. J. Bot. 100: 2349-2356. [doi | pdf | supp.]

[2] Castellanos, M.C., González-Martínez, S. & Pausas, J.G. 2015. Field heritability of a plant adaptation to fire in heterogeneous landscapes. Mol. Ecol. 24, 5633-5642. [doi | pdf | suppl. | blog]

[3] Pausas, J.G. 2015. Evolutionary fire ecology: lessons learned from pines. Trends Pl. Sci. 20: 318-324. [doi | pdf | blog]

Heritability of serotiny (2): a molecular approach

December 2nd, 2015 No comments

Not long ago we demonstrated that serotiny (i.e., the capacity to accumulate a seed bank in the canopy until the seeds are released by fire) is an heritable trait in pines [1]. This analysis was based on a classical provenance – progeny common garden experiment. However, trait variability under controlled environmental conditions may not fully reflect the variability observed in the field, and thus this estimate of heritability may not reflect how traits respond to natural selection. This is because there is higher environmental variability in the field and also because garden experiments typically include individuals that would not survive in the field (i.e., artificially increases progeny survival) [2]. With the aim of obtaining a more realistic estimate of heritability of serotiny, we have recently estimate it directly in the field for two pine species (P. halepensis, P. pinaster) [3]. Because in the field it is not possible to construct a pedigree, we used the relatedness among individuals estimated from molecular markers (SNPs) for the same individuals from which we had estimated serotiny previously [4]. The variance in serotiny was modelled incorporating the environmental variability (climate and fire regime) using a Bayesian ‘animal model’. As expected, field heritability was smaller (around 0.10 for both species) than previous estimates under common garden conditions (0.20). The difference is not surprising because wild P. halepensis and P. pinaster populations extend over heterogeneous landscapes with large environmental variations. Our results highlight the importance of measuring quantitative genetic parameters in natural populations, where environmental heterogeneity is a critical aspect. The heritability of serotiny, although not high, combined with high phenotypic variance within populations, confirms the potential of this fire-related trait for evolutionary change in the wild [2].

Pinus patula
Fig: Serotinous cones of P, halepensis and P. pinaster can be observed in previous posts (P, halepensis, P. pinaster). The photo here shows serotinous cones of Pinus patula from central Mexico (in a foggy rainy day).


[1] Hernández-Serrano, A., Verdú, M., Santos-Del-Blanco, L., Climent, J., González-Martínez, S.C. & Pausas, J.G. 2014. Heritability and quantitative genetic divergence of serotiny, a fire-persistence plant trait. Annals of Botany 114: 571-577.  [doi | pdf | suppl. | blog]

[2] Pausas, J.G. 2015. Evolutionary fire ecology: lessons learned from pines. Trends in Plant Science 20: 318-324. [doi | sciencedirect | cell | pdf]

[3] Castellanos, M.C., González-Martínez, S. & Pausas, J.G. 2015. Field heritability of a plant adaptation to fire in heterogeneous landscapes. Molecular Ecology 24: 5633–5642 [doi | pdf | suppl.]

[4] Hernández-Serrano A., Verdú M., González-Martínez S.C., Pausas J.G. 2013. Fire structures pine serotiny at different scales. American Journal of Botany 100: 2349-2356. [doi | amjbot | pdf | supp. | blog]


Fire – wind interactions

October 30th, 2015 1 comment

I’ve just had the opportunity to see some of the consequences of the hurricane Patricia that affected Jalisco, Mexico, last weekend. Here is the effects on a Pinus dauglasiana forest in the Sierra de Manantlán biosfere reserve. Some parts of this forest had burned several years ago (< 10 years) mainly as understory fire, and some trees were injured at the base but most survived (as in any typical undertory fires); there were also some crowning in small patches. Fire killed many understory fire-sensitive broadleaved shrubs, and were replaced by a high density of the pine seedlings (Fig. 1); there were also some plants resprouting (e.g., Quercus, Arbutus, etc.). Now, the strong winds of the hurricane is interacting with fire in two ways: (1) the wind have killed some of the fire-injured trees that had survived the fire (Fig. 1); and (2) the wind has greatly increased the fuel in the forest floor, even in the places where trees were not blown down (Fig. 2), which implies an increase in the chance for a surface fire of high intensity during the next dry season. That is, this seems an opportunity to study the interaction between these two disturbances, fire and hurricanes.

Pinus dauglasianaFig. 1. Pinus dauglasiana forest after a fire (see the seedling regeneration) followed by an hurricane.

Pinus dauglasiana 2Fig. 2. The forest floor of the Pinus dauglasiana forest (unburned) has greatly increased the fuel after the hurricane even in the places where trees were not blown down; the whole forest has a carpet of recently fallen branches and leaves.

Evolutionary fire ecology in pines

April 1st, 2015 No comments

Fire is an ancient and recurrent disturbance factor in our planet and has been present since the origin of terrestrial plants [1]. However, demonstrating whether fire has acted as an evolutionary force is not an easy task [2]. In this context, the emerging discipline of evolutionary fire ecology aims to understand the role of wildfires in shaping biodiversity. In a recent review paper I summarize what we have learned on evolutionary fire ecology by studying the iconic genus Pinus [3]. I suggest that the study of pines has greatly increased our understanding of the role of fire as an evolutionary pressure on plants.

Macro-evolutionary studies of the genus Pinus provide the oldest current evidence of fire as an evolutionary pressure on plants and date back to ca. 125 Million years ago (Ma). Micro-evolutionary studies show that fire traits are variable within and among populations, and especially among populations subject to different fire regimes. In addition, there is increasing evidence of an inherited genetic basis to variability in fire traits. Added together, pines provide compelling evidence that fire can exert an evolutionary pressure on plants and thus shape our biodiversity. In addition, evolutionary fire ecology is providing insights to improve the management of our pine forests under changing conditions. The lessons learned from pines may guide research on the evolutionary ecology in other taxa.

Figure: Example of trait divergence among populations living under different fire regime. Serotiny (as % of closed cones) in populations living under frequent crown fires (red boxes) and in populations where crown-fires are rare (green boxes) for two pine species, Pinus halepensis (Allepo pine, left) and P. pinaster (maritime pine, right).

[1] Pausas, J.G. and Keeley, J.E. 2009. A burning story: The role of fire in the history of life. Bioscience 59: 593-601. [doi | jstor | BioOne | pdf]

[2] Keeley, J.E., Pausas, J.G., Rundel, P.W., Bond, W.J. & Bradstock, R.A. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Science 16: 406-411. [doi | sciencedirect | trends | pdf]

[3] Pausas, J.G. (2015) Evolutionary fire ecology: lessons learned from pines. Trends in Plant Science 20(5): 318-324. [doi | sciencedirect | pdf]


Heritability of serotiny

September 29th, 2014 No comments

Evolution by mean of natural selection requires three conditions: there is variation in the trait, this variation is linked to differences in fitness, and the variation is heritable (Darwin!). In many traits we do not have reliable information for the three processes. For a serotinous species, there is evidence that the level of serotiny is variable, and specially it varies in relation to the fire regime of the population. This is because serotiny increases fitness in crown-fire ecosystems and it is not advantageous in ecosystems that do not suffer frequent fires or in ecosystems with understory fires. We recently studied how serotiny of two pine species (Pinus halepensis and Pinus pinaster) varies within population and between populations with different fire regimes and also provided a meta-analysis of the relation between serotiny and fire from other published studies [1]. We also performed a genetic association study for serotiny using SNPs and showed that 17 loci explained ca. 29% of the serotiny variation found in the field in Pinus pinaster [2], suggesting that serotiny variation have a genetic basis. In our most recent paper we provide the first estimate of heritability for a fire trait; specifically we computed the norrow-sense heritability (h2) of serotiny in Pinus halepensis using the common garden approach [3]. We also evaluated whether fire has left a selection signature on the level of serotiny among populations by comparing the genetic divergence of serotiny with the expected divergence of neutral molecular markers (QST – FST comparison). Serotiny showed a significant heritability (h2 = 0.20). The quantitative genetic differentiation among provenances for serotiny (QST= 0.44) was significantly higher than expected under a neutral process (FST = 0.12), suggesting adaptive differentiation. Overall we showed that serotiny is a heritable trait and that it has been shaped by natural selection driven by fire.

Figure: Serotinous cones of Pinus halepensis (Foto: J.G. Pausas)


[1] Hernández-Serrano A., Verdú M., González-Martínez S.C., Pausas J.G. 2013. Fire structures pine serotiny at different scales. American Journal of Botany 100 (12): 2349-2356. [doi | amjbot | pdf | supp. | blog]

[2] Budde, K. B., Heuertz, M., Hernández-Serrano, A., Pausas, J.G., Vendramin, G.G., Verdú, M. & González-Martínez, S.C. 2014. In situ genetic association for serotiny, a fire-related trait, in Mediterranean maritime pine (Pinus pinaster Aiton). New Phytologist 201: 230-241.  [doi | pdf | supp1 | supp2]

[3] Hernández-Serrano, A., Verdú, M., Santos-Del-Blanco, L., Climent, J., González-Martínez, S.C. & Pausas, J.G. 2014. Heritability and quantitative genetic divergence of serotiny, a fire-persistence plant trait. Annals of Botany 114: 571-577. [doi | pdf | suppl.]



November 16th, 2013 No comments

Serotiny is the delayed seed release for more than a year by retaining the seeds in a woody structure [1]. This implies an accumulation of a canopy seed bank. Serotiny confer fitness benefits in environments with frequent crown-fires, as the heat opens the cones and seeds are dispersed in the post-fire bed which is rich in resource and the competition and predation are low. It is typical of many Proteaceae and some conifers, like some pine species [1, 2; figure below].

Two recent papers analyse the serotiny of two mediterranean pines Pinus halepensis and Pinus pinaster [3, 4]. P. halepensis show higher proportion of serotinous cones than P. pinaster, but the latter retain the cones for longer [3]. The two species show high variability of serotiny within and between populations, but they show a clear pattern of higher serotiny in populations subject to high frequency of crown-fires than those living in areas where crown-fires are rare or absent. This is true either considering serotiny as the proportion of serotinous cones or as the age of the cones stored. Compared with other pines worldwide, the strength of the fire-serotiny relationship in P. pinaster is intermediate, and in P. halepensis is among the highest known [3]. For P. halepensis (the species with higher % serotiny), populations in high fire recurrence regimes have higher fine-scale spatial aggregation of serotiny than those inhabiting low fire recurrence systems. This phenotypic spatial structure generated by fire could be a consequence of the spatial genetic structure of the population. The second study used genomic tools to search for a genetic association for serotiny [4]. The analysis of 384 SNPs of 199 individuals of P. pinaster (in 3 populations included in the previous study [3])  shows that 17 loci were associated with serotiny and explain all together ca. 29% of the serotiny variation found in the field. All these results adds further evidence to the emerging view that fire shapes intraspecific variability of traits and generates phenotypic divergence between populations [5, 6, 7].

Figure: Serotinous cones of Pinus pinaster (Foto: K.B. Budde)


[1] Keeley J.E., Bond W.J., Bradstock R.A., Pausas J.G. & Rundel P.W. 2012. Fire in Mediterranean Ecosystems: Ecology, Evolution and Management. Cambridge University Press.  [The book]

[2] He T, Pausas JG, Belcher CM, Schwilk DW, Lamont BB. 2012. Fire-adapted traits of Pinus arose in the fiery Cretaceous. New Phytologist 194: 751-759. [doi | wiley | pdf (suppl.)]

[3] Hernández-Serrano A., Verdú M., González-Martínez S.C., Pausas J.G. 2013. Fire structures pine serotiny at different scales. American Journal of Botany 100: 2349-2356 [doi | amjbot | pdf | supp.]

[4] Budde, K. B., Heuertz, M., Hernández-Serrano, A., Pausas, J.G., Vendramin, G.G., Verdú, M. & González-Martínez, S.C. 2014. In situ genetic association for serotiny, a fire-related trait, in Mediterranean maritime pine (Pinus pinaster Aiton). New Phytologist  201: 230-241 [doi | pdf]

[5] Keeley J.E., Pausas J.G., Rundel P.W., Bond W.J., Bradstock R.A. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Science 16(8): 406-411. [doi] [trends] [pdf]

[6] Pausas, J. G., Schwilk, D. W. 2012. Fire and plant evolution. New Phytologist, 193:301-303. [doi | wiley | pdf]

[7] Pausas J.G., Alessio G., Moreira B. & Corcobado G. 2012. Fires enhance flammability in Ulex parviflorusNew Phytologist 193: 18-23. [doi | wiley | pdf]


Fire and the evolution of pine life histories

August 15th, 2012 No comments

Many pines species are fire adapted. In 1998, JE Keeley & PH Zedler provided a seminal paper showing the various fire adaptations of pines, and the relation between the different adaptations and the different fire regimes [1]. Recent phylogenetic [2,3] and conceptual [4,5] advances in fire ecology have allowed to better understand the evolutionary role of fire in plants, and specifically in pines [2-6]. In a recent paper, JE Keeley provides a new review on the ecology and evolution of pine life histories [7]. Pinus originated ~150 Ma in the mid-Mesozoic Era and radiated across the northern continent of Laurasia during the Cretaceous period, when fire activity was high [3]. Pines have followed two evolutionary strategies interpreted as responses to competition by the newly emerging angiosperms: 1) The Strobus lineage mostly has radiated into stressful sites of low nutrient soils and extremes in cold or heat; ans 2) The Pinus (subgenus) lineage has radiated into fire-prone landscapes with diverse fire regimes. Based on the life history traits associated to fire, JE Keeley define four pine syndromes [7]: fire-avoiders (no fire-adapted; with thin bark), fire-toleraters (adapted to surface fires; with thick bark and self-pruning of dead branches; tall pines), fire-embracers (adapted to crown fires; with retention of dead branches and serotinous cones), and fire-refugia (with marked metapopulation dynamics) strategies.

Figure: Basal fire scar (a) and cross-section of pine with previous fires delineated (b) demonstrating fire survival after recurrent fires. Photos by JE Keeley from [7].

[1] Keeley J.E. & Zedler P.H. 1998. Evolution of life histories in Pinus. In: Ecology and biogeography of Pinus (ed. Richardson DM). Cambridge University Press Cambridge (UK), pp. 219-250.

[2] Schwilk D.W. & Ackerly D.D. 2001. Flammability and serotiny as strategies: correlated evolution in pines. Oikos, 94, 326-336. [doi]

[3] He T., Pausas J.G., Belcher C.M., Schwilk D.W. & Lamont B.B. 2012. Fire-adapted traits of Pinus arose in the fiery Cretaceous. New Phytol., 194, 751-759. [doi | wiley | pdf ]

[4] Pausas, J. G. and J. E. Keeley. 2009. A burning story: The role of fire in the history of life. Bioscience 59: 593-601. [doi | jstor | pdf]

[5] Keeley, J. E., J. G. Pausas, P. W. Rundel, W. J. Bond, and R. A. Bradstock. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Sci. 16:406-411.  [doi | pdf]

[6] Pausas J.G. & Schwilk D.W. 2012. Fire and plant evolution. New Phytol., 193, 301-303.  [doi | wiley | pdf]

[7] Keeley J.E. 2012. Ecology and evolution of pine life histories. Ann. For. Sci., 69, 445–453. [doi]


The age of fire adaptations

February 20th, 2012 No comments

How old are wildfires? Probably as old as terrestrial ecosystems [1]. The origin of fire is tied to the origin of land plants, which are responsible for two of the three elements essential to the existence of fire: oxygen and fuel. The third element, a heat source, has probably been available throughout the history of the planet (mainly through lightning). There is charcoal evidencs of fires already in the Silurian (440 Ma). However, the existence of fire does not necessarily mean that fire was playing an evolutionary role at that time. So when did fire start to play an evolutionary role generating fire adaptations [2, 3]? By mapping fire adaptation onto a dated phylogeny of Pinaceae, we recently demonstrated [4] that at least, and for this family, fire was an agent of natural selection since about 90-125 Ma! This is far back from what was known until now [4]. At this time, fire-protective thick barks were originated in Pinus species as response to surface fires. With increasing fire intensity, thicker barks and serotiny appeared by 70-90 Ma. These innovations appear at the same time as the Earth’s paleoatmosphere experienced elevated oxygen levels that led to high burn probabilities (mid-Cretaceous). That is, the fiery environments of the Cretaceous strongly influenced trait evolution in Pinus. Whether fire had an evolutionary role prior to this is a challance for future research.

Fotos: In many pines, the thick bark and the discontinuity between the canopy and the understory (self-pruning) allows survival after surface fires (left: Pinus nigra, eastern Spain). Serotinous cones allow a quick seed regeneation after crown fire (right: P. halepensis, eastern Spain). Photos: JG Pausas

[1] Pausas, J. G. and J. E. Keeley. 2009. A burning story: The role of fire in the history of life. Bioscience 59: 593-601. [doijstor | BioOne | pdf]

[2] Keeley, J. E., J. G. Pausas, P. W. Rundel, W. J. Bond, and R. A. Bradstock. 2011. Fire as an evolutionary pressure shaping plant traits. Trends in Plant Science 16:406-411. [doi | trends | pdf] | For managers]

[3] Pausas, J. G. and D. W. Schwilk. 2012. Fire and plant evolution. New Phytologist 193:301-303. [doiwileypdf]

[4] He T., Pausas J.G., Belcher C.M., Schwilk D.W., Lamont B.B. (2012). Fire-adapted traits of Pinus arose in the fiery Cretaceous. New Phytologist 194: 751-759 [doi | wileypdf]