How plants survive the harsh environment of Australia

June 1st, 2015 No comments

New book: Groom, P. K., and Lamont, B. B. (2015). Plant Life of Southwestern Australia. Adaptations for Survival. De Gruyter Open

Early explorers described Western Australia as ‘the most barren spot on the face of the earth’. In this book we learn that south-western Australia is one of the world’s biodiversity hotspots – not despite but because of its harsh environment. Nutrient-poor soils, frequent droughts, and recurrent fires, together with adverse fauna interactions (e.g., strong-billed cockatoos, voracious kangaroos, and the lack of efficient pollinating bees and hummingbirds) have made this region the perfect evolutionary scenario for developing a plethora of plant adaptations and assembling an hyperdiverse flora. The authors nicely describe this scenario and offer an impressive wealth of knowledge on the natural history of the region in an attractive book with abundant tables and quality full-colour pictures. One of the strengths of the book is that it brings together both biotic and abiotic factors to explain biodiversity, something uncommon in most specialised books.

Overall this is a must-read book for Australian naturalists but will also be a key reference for international ecologists interested in how plants thrive and evolve in dry, nutrient-poor, fire-prone environments. The lessons learned from this region help us understand evolutionary pathways in other dry regions worldwide.

Groom-Lamont

Postfire flowering: Narcissus

May 2nd, 2015 No comments

Spectacular postfire flowering of Narcissus triandrus subsp. pallidulus in a recently burnt Erica australis heathland (Bustares, Guadalajara, Spain, April 2015).

Narcissus postfire

Narcissus_pallidulus_sm

Objeción a los gastos militares (renta 2014)

May 1st, 2015 No comments

Como cada año, en estas fechas los españoles realizamos la declaración de la renta. Y esta es una buena oportunidad para quejarse de los excesivos gastos militares que nuestro gobierno realiza; hay muchas otras prioridades antes que financiar guerras (todas las guerras son perjudiciales para la humanidad). La idea básica de la objeción a los gastos militares es desviar a una ONG una parte de los impuestos que nos toca pagar al estado, la ONG que queramos (que probablemente hace mucho más por la paz que desperdiciar el dinero en armamento). En la declaración se descuenta la parte que has ingresado a la ONG para que al hacer el balance se tenga en cuenta. La cantidad de dinero a desviar es voluntaria; hay quien utiliza el porcentaje de nuestros impuestos que va a gasto militar (aproximadamente el 5.3%) y calcula ese porcentaje de la "Cuota resultante de la autoliquidación" en su declaración (casilla 589); otros desvían un cantidad fija, a veces simbólica (p.e., 84 euros en relación a los 84 países empobrecidos por la deuda; o 500 euros que es aproximadamente el gasto militar por habitante y año en España). Lo importante no es la cantidad desviada, si no el realizar un gesto cívico y comprometido por la paz. Aquí abajo doy más detalles de como hago yo la objeción así como algunas direcciones con abundante información. La objeción a los gastos militares es una opción "alegal" y no está considerada en la declaración. Es un acto cívico de protesta. Creo que lo máximo que puede ocurrir es que hacienda reclamen el dinero desviado. Yo he hecho la objeción cada año (desde mi primera declaración) y nunca he tenido ningún problema. Pasos a seguir:

  • No aceptar el borrador enviado por la Agencia Tributaria
  • Descargar el programa PADRE (renta2014): elije Windows, Linux o Mac, y se bajará el fichero Renta2014_*.exe; es necesario ejecutarlo para que se instale en el ordenador.
  • Incorporar los datos personales, ya sea bajándolos por internet (de la Agencia Tributaria) o manualmente. El programa PADRE permite incorporar los datos automáticamente a partir de DNI electrónico o a partir del número de referencia enviado por la Agencia Tributaria. Una vez incorporados, se pueden modificar si se detectan errores o faltan detalles. Si no haces ninguna modificación, debería dar igual al borrador enviado por la Agencia Tributaria.
  • Una vez finalizada la declaración, ir al apartado “N. Cálculo del impuesto y resultado de la declaración” (página 16(I)), subapartado “Retenciones y demás pagos a cuenta”. En una de las casillas que no utilices, poner la cantidad que desviáis; por ejemplo yo  en la casilla 599 (Cuotas del impuesto sobre la renta de no residentes) pongo 100 euros (por ejemplo).
  • Si vuestra declaración os salía a pagar (positiva), ahora os saldrá a pagar 100 euros menos; si os salía a cobrar (negativa), ahora os saldrá a cobrar 100 euros más.
  • Imprimir la declaración normalmente (o generáis el PDF).
  • Escribir a mano (o modificando el PDF) al lado de la casilla 599 “Por objeción”.
  • Ingresar los 100 euros (o lo que hayáis desviado) a la ONG que queráis. Algunas asociaciones que promueven y apoyan la objeción, hacen anualmente sugerencias de posibles ONGs a ingresar, pero se puede hacer en cualquiera.
  • Se entrega la declaración en un banco, dentro de un sobre que proporcionan los bancos. En el sobre se incluye: la declaración, el justificante de ingreso a la ONG, y una carta explicativa (por ejemplo descargar doc).
  • Para las estadísticas, es conveniente que avises que has realizado la objeción fiscal, por ejemplo, rellenado el formulario 2015, enviando un mensaje a tortuga@nodo50.org, o contactando con tu asociación antimilitarista local (por ejemplo, en Valencia: moc-valencia ).

Ver vídeo con las instrucciones detalladas

Más información: Nodo50/objecionFiscal | ¿como se hace? | EcologistasEnAccion.org,  gasto militar 2015 | InsumissiaAntimilitaristas 2012 | grupo tortuga: instrucciones | vídeo ilustrativo | BarcelonaTVMOC-València: objecció | MOC-València: facebook |

Algunos datos ilustrativos del 2015: El presupuesto de España a gasto militar es de 23.374 millones de euros (= 64 millones diarios o 503 euros por persona), que corresponde a 2,2% del PIB y al 5,3% de los PGE, y generará una deuda de 8.722 millones de euros. Además el gasto suele ser superior a los presupuestos (en un 18% como media). El 44% de los funcionarios del estado son militares. Más detalles: ver documento completo o un resume.


Entradas relacionadas: Crisis: gasto social y gasto-militar | No a la guerra otra vez | Gestionar la crisis es gestionar prioridades: gasto social vs militar | si vis pacem para pacem

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.

pinus-serotiny
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).

References
[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]

 

Brazil

March 16th, 2015 No comments

I will give the following talks in Brazil:

March 20, 2015: "Flammability as en ecological and evolutionary driver", 15:00 h Bilogia, Universidade Estatual de Campinas (UNICAMP), SP.

March 27, 2015: "Fire and biodiversity: a global perspective", 9:00, Instituto Ciencias Biológicas, Universidade de Brasília

UPDATE:

IMG_20150328_191147311_sm
Vinicius Dantas (University of Campinas), Marcelo Simon (EMBRAPA, Brasilia) and myself having a caipirinha in Pirenópolis.

Ecology and evolution in fire-prone ecosystems

February 28th, 2015 2 comments

During the last years I've been working in many topics related to fire ecology and plant evolution in ecosystems subject to recurrent fires (mainly mediterranean and savanna ecosystems). Because I believe knowledge should be spread around easily, I make my results available to the public in my web page (see publications list) and in this blog. However, having the cumulative list of paper published each year is not very convenient for people searching for a specific topic. For this reason, I'm rearranging most of my articles by topics as follows:

1. Fire history
2. Fire regime: climate & fuel
3. Fire traits (resprouting, postfire germination, serotiny, bark thickness, flammability, data & methods)
4. Fire & plant strategies (in Mediterranean ecosystems, in pines, in savannas, community assembly)
5. Fire & evolution
6. Some fire-adapted species (Pinus halepensis, Quercus suber, Ulex parviflorus)
7. Fire & vegetation modelling
8. Plant-animal interactions
9. Restoration & conservation

See: fire-ecology-evolution.html

Some papers may be repeated if they clearly fit in more than one topic; some papers, mainly old ones, do not fit well in any of these topics and have not been included (at least at the moment), they still can be found in the section of publications sorted by year. I'm still working on this rearrangement, so some modifications are possible; and any comment is welcome.
I hope this is useful for somebody!

Publications: by year | by topic | books

 

Cultural trees: Cupressus sempervirens

January 4th, 2015 3 comments

 

Cupressus_sempervirens-Roma-01.2015_sm
Cupressus sempervirens (Mediterranean cypress; ciprés) and Colosseum, Rome,
1 January 2015 (photo: J.G. Pausas)

The ecology of bark thickness

December 1st, 2014 No comments

Bark is a vital and very visible part of woody plants, yet the functional and evolutionary ecology of the bark is still poorly understood. In a recent article I have studied one of the bark properties: bark thickness [1]. Bark thickness is very variable among woody plants and fire is a key factor selecting for a thick bark. This is because barks are very good heat insulators and under low intensity fires, small differences in bark thickness provides a great increase in the stem protection and survival. Consequently, at the global scale, an important proportion of the variability in bark thickness should be explained by the variability in fire regimes. In this paper I provide evidences supporting the role of fire regime in shaping bark thickness (in conjunction with other plant traits) on a global scale [1].

Forest environments with very frequent (and low intensity) understory fires select for trees with thick bark at the base of the bole. In some savannas, trees do not have specially thick barks as they tend to growth quickly to escape the height affected by grass fires. Savannas living in poor soils may not be able to growth quickly and thus trees can only survive if they have a very thick bark in the whole plant (including in the thin branches). In Mediterranean ecosystems, fires are less frequent than in savannas, and there is time for the accumulation of fine woody biomass. Consequently, fires burns intensely (crown fires) and thus small differences in bark thickness do not increase stem survival; in such conditions, most species have relatively thin barks. In wet tropical forests, tree barks are very thin because fire are very rare and thus a thick bark is not advantageous. In very arid ecosystems, fuels are too sparse for fire spread, and thus the observed variability in bark thickness is related to other factors like a response to water stress. In conclusion, fire regimes can explain a large proportion of the variability of bark thickness at the global scale, and thus this trait varies across ecosystems in a predictable manner.

thick-bark2

Figure: Examples of trees with thick bark: A. Myrcia bella (Myrtaceae, Brazil); B. Quercus suber (Fagaceae, Mediterranean Basin), in the cover of the book 'Cork oak Woodlands on the Edge' [2]; C: Eremanthus seidelii (Asteraceae, Brazil); and D: Enterolobium gummiferum (Fabaceae), small top branch. Photos from [1] and [2].

References

[1] Pausas, J.G. 2015. Bark thickness and fire regime. Functional Ecology   [doi | pdf | suppl.]

[2] Aronson J., Pereira J.S., Pausas J.G. (eds). 2009. Cork Oak Woodlands on the Edge: conservation, adaptive management, and restoration. Island Press, Washington DC. 315 pp. [The book]

NASA and Fire ecology

November 28th, 2014 No comments

NASA has featured our paper on the global fire-productivity relationship [1] in NASA Sensing Our Planet 2014

strange-bedfellows

 

Refereces
[1] Pausas J.G. & Ribeiro E. 2013. The global fire-productivity relationship. Global Ecol. & Biogeogr. 22: 728-736  [doi | pdf | blog post]

[2] Vizcarra N. 2014. Strange bedfellows. NASA Sensing Our Planet 2014 [link | PDF]

Alternative fire-driven vegetation states

November 1st, 2014 No comments

One of the clearest pieces of evidence for the role of fire in shaping vegetation is the occurrence of alternative vegetation types maintained by different fire regimes in a given climate. The different flammability of alternative communities generates different fire feedback processes that maintain contrasted vegetation types with clear boundaries in a given environment; and fire exclusion blurs this structure. This has been well documented in tropical landscapes (e.g., [1]) that are often mosaics of two alternative stable states – savannas and forests – with distinct structures and functions and sharp boundaries. Currently, there is an increasing evidence that alternative fire-driven vegetation states do occur in other environments, including temperate forests ([2, 3] and figure below). That is, the existence of alternative fire-driven vegetation states may be more frequent than previously thought, although human activities may favour one of the states and mask the original bistability.

modelv2

Figure: Factors determining the transition between two alternative vegetation states (fire sensitive forest and fire resilient shrubland) in a temperate landscape in Patagonia. Human factors (global warming, increased ignitions, and livestock grazing) favour transition to shrublands. From [2].

References
[1] Dantas V., Batalha MA & Pausas JG. 2013. Fire drives functional thresholds on the savanna-forest transition. Ecology 94:2454-2463.  [doi | pdf | appendix]

[2] Pausas, J.G. 2015. Alternative fire-driven vegetation states. Journal of Vegetation Science 26: 4-6 [doi | pdf | suppl.]

[3] Paritsis J., Veblen T.T. & Holz A. 2014. Positive fire feedbacks contribute to shifts from Nothofagus pumilio forests to fire-prone shrublands in Patagonia. J. Veget. Sci., 26.

 

Trait databases: BROT to EOL

October 26th, 2014 No comments

Some years ago we complied and published a database on plant traits related to fire for the Mediterranean basin, the BROT database [1, 2]. Now the Encyclopedia of Life (EOL, eol.org), which is an initiative to gather scientific knowledge about all animal and plant life on Earth, has incorporated the BROT database [link]! We are very happy that EOL consider BROT as a reliable source of information; this implies that our compilation effort is now much more widely accessible, with a friendly interface, and integrated with other sources of information. For instance, if you search a Mediterranean plant species in the EOL search engine (e.g., Cistus albidus), you get, a part from pictures, a description, and other details, a window with the trait information extracted from BROT (see the overview result here; you can also go to the full trait data). It is aslo possible to search by trait in all EOL databases (eol.org/traitbank). Note however that we were not responsible for translating the BROT database to the EOL format, so any error or misinterpretation during this process is not our fault! In fact we have never been asked or notified that EOL was going to incorporate BROT, I found it just by chance …

eol

References:

[1]  Paula S, Arianoutsou M, Kazanis D, Tavsanoglu Ç, Lloret F, Buhk C, Ojeda F, Luna B, Moreno JM, Rodrigo A, Espelta JM, Palacio S, Fernández-Santos B, Fernandes PM, and Pausas JG. 2009. Fire-related traits for plant species of the Mediterranean Basin. Ecology 90: 1420. [doi] [ESA journals] [Ecological Archives E090-094] [pdf]

[2] Paula S. & Pausas J.G. 2013. BROT: a plant trait database for Mediterranean Basin species. Version 2013.06. URL: http://www.uv.es/jgpausas/brot.htm

 

CONICET, Argentina

October 20th, 2014 No comments

Visiting Pedro Jaureguiberry and Sandra Díaz at CONICET, Córdoba, Argentina.

Talk:
??????????

 

Interview in "La Voz" (18 Oct 2014, in Spanish): La Voz (online version) | La Voz (printed version)

 

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.

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

References:

[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.]

 

The Fire Ecology journal now on JCR

August 22nd, 2014 No comments

The journal Fire Ecology (FE) has now been included in the Journal Citation Reports database (2013 JCR Edition, ISI) and thus, it has an Impact Factor. The 2013 impact factor is 1.156 which suggests that it is still a very minor ecology journal (ranking: 28/64 in Forestry and 104/140 in Ecology) but given that it is of open access, it has some potential for increasing success. For comparison, the International Journal of Wildland Fire, which is a more multidisciplinary journal for fire science has an IF= 2.506 (ranking = 5/64 in Forestry); other classical ecology journals have a much higher impact factor (e.g., Journal of Ecology: 5.69, Ecology: 5.00, Oikos: 3.56, Oecologia: 3.25). The FE journal is still very USA-oriented, and a strong internationalization would be needed. The last issue of the journal is also available at ISSUU, so it can be read it from Android systems. I must admit I have never published or submitted any paper to this journal (see details). Good luck to the FE in this new period!

FireEcol-journal

Journal archive in the web site of the Fire Ecology journal [link]

Evolutionary ecology of resprouting and seeding

July 15th, 2014 No comments

There are two broad mechanisms by which plant populations persist under recurrent fires: resprouting from surviving tissues, and seedling recruitment [1]. Species that live in fire-prone ecosystems can have one of these mechanisms or both [1]. In a recent review paper [2], we propose a model suggesting that changes in evolutionary pressures that modify adult (P) and juvenile (C) survival in postfire conditions (Fig. 1 below) determine the long-term success of each of the two regeneration mechanisms, and thus the postfire regeneration strategy: obligate resprouters, facultative species and obligate seeders (Fig. 2). Specifically we propose the following three hypotheses: 1) resprouting appeared early in plant evolution as a response to disturbance, and fire was an important driver in many lineages; 2) postfire seeding evolved under conditions where fires were predictable within the life span of the dominant plants and created conditions unfavorable for resprouting; and 3) the intensification of conditions favoring juvenile survival (C) and adult mortality (P) drove the loss of resprouting ability with the consequence of obligate-seeding species becoming entirely dependent on fire to complete their life cycle, with one generation per fire interval (monopyric life cyle). This approach provides a framework for understanding temporal and spatial variation in resprouting and seeding under crown-fire regimes. It accounts for patterns of coexistence and environmental changes that contribute to the evolution of seeding from resprouting ancestors. In this review, we also provide definitions and details of the main concepts used in evolutionary fire ecology: postfire regeneration traits, postfire strategies, life cycle in relation to fire, fire regimes (Box 1), costs of resprouting (Box 2), postfire seeding mechanisms (Box 3), and the possible evolutionary transitions (Box 4).

 

Fig2_sm
Fig. 1 : Main factors affecting adult and offspring seedling survival (P and C, respectively), and thus the P/C ratio, in fire-prone ecosystems (from Pausas & Keeley 2014 [2]).

 

Fig3_sm

Fig. 2: The changes in the probability of resprouting along an adult-to-offspring survival (P/C) gradient are not linear but show two turning points related to the acquisition of key innovations: the capacity to store a fire-resistant seed bank (postfire seeding), and the loss of resprouting capacity. Changes in P/C ratio may be produced by different drivers (Fig. 1) which drove the rise of innovations during evolution, e.g., during the increasing aridity from the Tertiary to the Quaternary (from Pausas & Keeley 2014 [2]).

 

Refecences

[1] Pausas, J.G., Bradstock, R.A., Keith, D.A., Keeley, J.E. 2004. Plant functional traits in relation to fire in crown-fire ecosystems. Ecology 85: 1085-1100. [doi | pdf | esa | jstor]

[2] Pausas J.G. & Keeley J.E. 2014. Evolutionary ecology of resprouting and seeding in fire-prone ecosystems. New Phytologist 204: 55-65 [doi | wiley | pdf]

 

Climate-independent fire regime changes

May 16th, 2014 No comments

It is well-known that fire regimes are strongly linked to climate, however, there are examples in which most variability in fire regime changes are better attributed to drivers other than climate. For instance, vegetation (fuel structure and continuity) also plays a role in shaping fire regimes [1-5]. In a recent paper [6], we reviewed evidences from different environmental and temporal settings of abupt fire regimes changes that are not directly attributed to climatic changes, but to changes driven by (i) fauna, (ii) invasive plant species, and (iii) socio-economic and policy changes. All these drivers might generate nonlinear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity and thus drastically change fire activity (figure below). The importance of climate-independent factors in abrupt fire regime changes can be viewed positively: while climate is very difficult to modify at short term, fuels can potentially be managed to shape fire regimes and to mitigate the effects of global warming [7]. However the success of these actions may be diverse, depending on the historical fire regimes and the adaptive traits of the species in the community [8].

Fig1_land3seed12

Figure: Schematic representation of how a gradual change in a driver (e.g., a constant colonization or invasion of a flammable plant) can produce an abrupt change in landscape structure (e.g., continuity of the flammable vegetation). The bottom panel represents the changes through time in mean and maximum patch size in an idealized landscape that is invaded by plants (green cells) with a constant probability (p= 0.01 in each time step). The upper panel shows three snapshots of these dynamics (time steps = 25, 75 and 125, also represented by vertical lines in the bottom panel). From Pausas & Keeley [6].

References

[1] Pausas, J.G. 2004. Changes in fire and climate in the eastern Iberian Peninsula (Mediterranean basin). Climatic Change 63: 337-350. [pdf | doi]

[2] Pausas J.G. & Bradstock R.A. 2007. Fire persistence traits of plants along a productivity and disturbance gradient in Mediterranean shrublands of SE Australia. Global Ecology & Biogeography 16: 330-340.  [pdf | doi]

[3] Pausas J.G. & Paula S. 2012. Fuel shapes the fire-climate relationship: evidence from Mediterranean ecosystems. Global Ecol. & Biogeogr. 21: 1074-1082.  [doi | pdf | supp]

[4] Pausas J.G. & Fernández-Muñoz S. 2012. Fire regime changes in the Western Mediterranean Basin: from fuel-limited to drought-driven fire regime. Climatic Change 110: 215-226.  [doi | springer | pdf]

[5] Pausas J.G. & Ribeiro E. 2013. The global fire-productivity relationship. Global Ecol. & Biogeogr. 22: 728-736. [doi | pdf | appendix]

[6] Pausas J.G. & Keeley J.E., 2014. Abrupt climate-independent fire regime changes. Ecosystems 17: 1109.1120 [doi | pdf] - New!

[7] Towards prescribed fires, jgpausas.blogs.uv.es, 7 Oct 2013.

[8] 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]

 

Vive la différence!

April 20th, 2014 No comments

This post is a bit off the main topics of this blog, but I found an interesting study that I would like to share [1]. Using virtual reality tools, the authors of this study performed an experiment placing white people with a body of black people for about 12 minutes. They compared the results of a test for racial bias performed few days before the experiment with the results of the same test performed after the experiment, and found a clear reduction in the scores! I guess virtual reality could be a tool to increase empathy, and therefore respect to the difference. So perhaps racism is curable!

colours-variability_sm

Figure:  Team of happy people working together (www.dreamstime.com; top left), variability of the Cuban Polymita (top right) and variability of the Harlequin ladybird (Harmonia axyridis; bottom; source).

References
[1] Peck TC, Seinfeld S, Aglioti SM, Slater M. 2013. Putting yourself in the skin of a black avatar reduces implicit racial bias, Consciousness and Cognition, 22, 779-787. [doi].  More virtual experiments at: http://presence-thoughts.blogspot.com.es

 

Postfire blooming of Asphodelous

April 5th, 2014 No comments

The 4th of February, 2014, a forest fire burnt ca. 200 ha in Segorbe, near Valencia, eastern Spain. Two months later (1st April 2014), few plants had started to resprout, others had started to germinate, but there were three species that had resprouted very quickly and were already flowering: Asphodelous cerasiferus (= A. ramosus; Spanish: gamón), Iris lutescens, and Asparagus horridus; the first showed an spectacular blooming (pictures below).

Asphodelus-bloom
Spectacular postfire bloom of Asphodelous cerasiferus in Segorbe, near Valencia, Spain (photos by MC Castellanos & JG Pausas, two months after fire).

Fire drives trait divergence: smoke-induced germination

April 3rd, 2014 No comments

There is an increasing evidence that recurrent fires are driving within species phenotypic variability, and that different fire regimes can generate trait divergence among populations [1]. For instance, populations of the annual species Helenium aromaticum (Asteraceae) growing under different fire histories in Chile have different seed traits in such a way that the anthropogenic increase in fire frequency selected for an increasing in seed pubescence [2]. In the Mediterranean Basin there is also evidence of phenotypic divergence among populations under different fire regimes: Ulex parviflorus (Fabaceae) plants living under high fire frequency are more flammable than those growing in sites that have not suffered fires [3-5]; Pinus halepensis and P. pinaster living under high crown-fire frequency have higher serotiny that those living in areas that rarely burn in crown fires [6]

A recent paper add further examples of this fire-driven trait divergence: Vandvik et al. show that smoke-induced germination is observed in populations of Calluna vulgaris (Ericaceae) from traditionally burnt coastal heathlands of Norway but it is lacking in populations from other habitats with infrequent fires [7]. The results are also consistent with the suggestion that smoke-induced germination is a fire adaptation [8-9].

Calluna-smoke-germination

Figure: Probability of germination of Calluna vulgaris in relation to time (days) since sowing for smoke-treated (pink) and control (grey) seeds, in coastal and inland heathlands of Norway. From Vandvik et al. 2014 [7].

References:

[1] Pausas, J. G. and D. W. Schwilk. 2012. Fire and plant evolution. New Phytologist 193 (2). [doi | pdf | blog]

[2] Gómez-González S, Torres-Díaz C, Bustos-Schindler C, Gianoli E, 2011. Anthropogenic fire drives the evolution of seed traits. PNAS 108: 18743-18747. [doi blog]

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

[4] Pausas J.G. & Moreira B. 2012. Flammability as a biological concept. New Phytologist 194: 610-613. [doi | wiley | pdf]

[5] Moreira B., Castellanos M.C., Pausas J.G. 2014. Genetic component of flammability variation in a Mediterranean shrub. Molecular Ecology 23: 1213-1223. [doi | pdf | suppl. | data:dryad | blog]

[6] 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]

[7] Vandvik, V., J. P. Töpper, Z. Cook, M. I. Daws, E. Heegaard, I. E. Måren, and L. G. Velle. 2014. Management-driven evolution in a domesticated ecosystem. Biology Letters 10 (2): 20131082. [doi]

[8] Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience 59: 593-601 [doi | jstor | BioOne | pdf | scribd | ppt slides | post]

[9] 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]

 

New fire books

March 23rd, 2014 No comments

Two new fire books has been recently published! And both have a global and interdisciplinary perspective. The first is edited by Claire Belcher (2013; [1]), and each of the 16 chapters is a scientific article written by different specialists (a total of 25 different authors, many of them from UK institutions); it includes few colour plates. As the publisher says, “the book shows how knowledge of fire phenomena and the nature of combustion of natural fuels can be used to understand modern wildfires, interpret fire events in the geological record and to understand the role of fire in a variety of Earth system processes ”. This book has perhaps little on fire ecology, and it is more focussed on fire history at the geological scale, combustion details and atmospheric impacts; all these topics are important for understanding fires at the global scale. The second book (Scott et al. 2014; [2]) is a full-colour textbook on fire written by five authors (two of them had also participated in the other book). This is probably the first general textbook on fire science ever published, and as such it covers all topics related to fire although with relatively little depth. Thus it provides a summary of the current knowledge on fire at a global scale. In the words of the publisher, it “is designed to provide a synthesis of contemporary thinking; bringing together the most powerful concepts and disciplinary voices to examine, in an international setting, why planetary fire exists, how it works, and why it looks the way it does today”.

firebookscover

[1] Belcher, C.M. (ed) 2013. Fire Phenomena and the Earth System: An Interdisciplinary Guide to Fire Science. Wiley.

[2] Scott, A.C., Bowman, D.M.J.S., Bond, W.J., Pyne, S.J. & Alexander, M.E. 2014. Fire on Earth: An Introduction. Wiley.

New fire book in 2012: link

 

Proyecto VIRRA

February 28th, 2014 No comments

El proyecto “El papel del fuego en la Variabilidad Intraespecífica (fenotípica y genética) de plantas del matoRRAl mediterráneo (VIRRA)” finalizó hace unos meses. Aquí se puede ver un resumen y los principales productos de este proyecto: enlace.

Ulex parviforus_juli_sm

La aliaga (Ulex parviflorus) es una de las principales especies estudiadas en VIRRA [1, 2].

[1] Ulex born to burn, jgpausas.blogs.uv.es, 9/Nov/2011

[2] Ulex born to burn (II): genetic basis of plant flammability,  jgpausas.blogs.uv.es, 25/Jan/2014

Ulex born to burn (II): genetic basis of plant flammability

January 25th, 2014 No comments

In an previous study we found that Ulex parviflorus (Fabaceae) populations that inhabit in recurrently burn areas (HiFi populations) were more flammable than populations of this species growing in old-fields where the recruitment was independent of fire (NoFi populations) [1,2, 3]. That is, HiFi plants ignited quicker, burn slower, released more heat and had higher bulk density than NoFi plants. Thus, it appeared that repeated fires selected for individuals with higher flammability, and thus driving trait divergence among populations living in different fire regimes. These results were based on the study of plant flammability (phenotypic variability) without knowing whether plant flammability was genetically controlled. In a recent study using the same individuals [4], we show that phenotypic variability in flammability was correlated to genetic variability (estimated using AFLP loci) [figure below]. This result provide the first field evidence supporting that traits enhancing plant flammability have a genetic component and thus can be responding to natural selection driven by fire [5]. These results highlight the importance of flammability as an adaptive trait in fire-prone ecosystems.

Ulex-flam-AFLP

Figure: Relationship between flammability and genotypic variability at individual level in Ulex parviflorus (red symbols: individuals in HiFi populations; green symbols: individuals in NoFi populations). Variations in flammability are described using the first axis of a Principal Component Analysis (PCA1) performed from different flammability traits, and genetic variability is described using the first axis of a Principal Coordinate Analysis (PCo1) from the set of AFPL loci that were significantly related to flammability. See details in [4].

References
[1] Ulex born to burn, jgpausas.blogs.uv.es, 9/Nov/2011

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

[3] Pausas J.G. & Moreira B. 2012. Flammability as a biological concept. New Phytologist 194: 610-613.  [doi | wiley | pdf]

[4] Moreira B., Castellanos M.C., Pausas J.G. 2014. Genetic component of flammability variation in a Mediterranean shrub. Molecular Ecology 23: 1213-1223 [doi | pdf | data:dryad]

[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: 406-411. [doi | trends | pdf]

 

Serotiny

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)

References:

[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]

 

Physiological differences between resprouters and seeders

November 9th, 2013 No comments

The ability to resprout and to recruit after fire are two extremely important traits for the persistence in fire-prone ecosystems [1,2], and they define three life histories: obligate resprouters, obligate seeders (non-resprouters), and facultative seeders. After a fire, obligate seeders die and recruit profusely from the seeds stored in the seed bank [3-5]. In contrast, resprouters survive after fire and their above-ground tissues regenerate from protected (often below-ground) buds by using stored carbohydrates [6]. Facultative seeders not only recruit profusely after fire, but are also able to resprout. In fact, seeders and resprouters have different regeneration niches: seedling regeneration of obligate resprouters is not linked to fire, and they recruit during the inter-fire period under sheltered conditions (i.e., under vegetation cover), while seedling regeneration of seeders occurs in open postfire environments. Given the marked difference in water availability between microsites under vegetation and microsites open to the sun under Mediterranean conditions, seedlings of resprouters and seeders are subjected to different water-stress conditions, and thus they are expected to have different physiological attributes. Despite these differences, resprouters and seeders co-exist, are often well-mixed on local and landscape scales [7,8], and represent the two main types of post-fire regeneration strategies in Mediterranean ecosystems [2].

A recent study demonstrates marked differences in physiological attributes between seedlings of seeders and resprouters [9]: Seeders show a range of physiological traits that better deal with water-limited and highly variable conditions (e.g., higher resistance to xylem cavitation, earlier stomatal closure with drought, higher leaf dehydration tolerance), but they are also capable of taking full advantage of periods with high water availability (greater efficiency in conducting water through the xylem to to sustain high gas exchange rates when water is available). Conversely, resprouter species are adapted to more stable water availability conditions, favoured by their deeper root system, but they also display traits that help them resist water shortages during long summers.

Previous studies already showed marked differences between seeders and resprouters in a range of attributes: resprouters tend to exhibit a deeper root-system, while seedling root structure of seeders are more efficient in exploring the upper soil layer [10]. Leaves of seeders show higher water use efficiency (WUE) and higher leaf mass per area (LMA; i.e., higher sclerophylly, lower SLA) [11]. Seeds of seeder species are more tolerant to heat shocks and have greater heat-stimulated germination [3]. All these differences support the idea that they are distinct syndromes with different functioning characteristics at the whole plant level and suggest that they undertook different evolutionary pathways [12].

Figure: Coexistence of resprouters (R+) and seeders (R-) in postfire conditions near Valencia, Spain. (Foto: A. Vilagrosa).

 

References:

[1] Pausas, J.G., Bradstock, R.A., Keith, D.A., Keeley, J.E. & GCTE Fire Network. 2004. Plant functional traits in relation to fire in crown-fire ecosystems. Ecology 85: 1085-1100. [jstor |[pdf | Ecological Archives E085-029]

[2] 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]

[3] Paula S. & Pausas J.G. 2008. Burning seeds: Germinative response to heat treatments in relation to resprouting ability. Journal of Ecology 96 (3): 543 - 552. [doi | pdf]

[4] Moreira B., Tormo J., Estrelles E., Pausas J.G. 2010. Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora. Annals of Botany 105: 627-635. [doi | pdf | blog]

[5] Moreira B. & Pausas J.G. 2012. Tanned or burned: The role of fire in shaping physical seed dormancy. PLoS ONE 7(12): e51523. [doi | plos | pdf | blog]

[6] Moreira B., Tormo J, Pausas J.G. 2012. To resprout or not to resprout: factors driving intraspecific variability in resprouting. Oikos 121: 1577-1584. [doi | pdf]

[7] Verdú M, & Pausas JG 2007. Fire drives phylogenetic clustering in Mediterranean Basin woody plant communities Journal of Ecology 95 (6), 1316-323 [doi | pdf]

[8] Ojeda, F., Pausas, J.G., Verdú, M. 2010. Soil shapes community structure through fire. Oecologia 163:729-735. [doi | pdf | blog]

[9] Vilagrosa A., Hernández E.I., Luis V.C., Cochard H., Pausas, J.G. 2014. Physiological differences explain the co-existence of different regeneration strategies in Mediterranean ecosystems. New Phytologist 201 : xx-xx [doi | pdf | suppl.] - NEW

[10] Paula S. & Pausas J.G. 2011. Root traits explain different foraging strategies between resprouting life histories. Oecologia 165:321-331. [doi | pdf | blog]

[11] Paula S. & Pausas J.G. 2006. Leaf traits and resprouting ability in the Mediterranean basin. Functional Ecology 20: 941-947. [doi | pdf | blog]

[12] Verdú M. & Pausas J.G. 2013. Syndrome-driven diversification in a Mediterranean ecosystem. Evolution 67: 1756-1766. [doi | pdf | blog]

 

Towards prescribed fires

October 7th, 2013 No comments

In the latest issue of Science (Oct 4th, 2013), there is a forum paper with some suggestion for the management of fires and forests in the face of changing climates [1]. Basically, the authors suggest that policy focused on fire suppression only delays the inevitable, promising more dangerous and destructive forests fires. They emphasize the importance of strategically managing wildfires and the use of prescribed fires in combination with mechanical fuel treatments to create fire resilient landscapes. In addition, the journal Frontiers in Ecology and Environment has recently published an special issue on prescribed burns in different ecosystems worldwide [2]. Fires are very important processes on many ecosystems [3,4], and what is important is to shape fire regimes to be sustainable (socially and ecologically). A zero-tolerance fire policy (which still dominates in many countries) cannot work in the long-term, especially in seasonal climates, as the high fuel accumulation coupled with a warming climate may drive the system to large and intense fires that threaten both people and biodiversity; and this may occurs despite major economic investments in fire prevention and suppression.


Foto: Prescribed understory burn of a mixed conifer forest in the Sierra Nevada, California. From [3].

References:
[1] Stephens, S.L., Agee, J.K., Fulé, P.Z., North, M.P., Romme, W.H., Swetnam, T.W., Turner, M.G., 2013. Managing forests and fire in changing climates. Science 342, 41-42.

[2] Perspectives on prescribed burning. Front. Ecol. Environ. 11, www.esajournals.org/toc/fron/11/s1

[3] Pausas J.G. & Keeley J.E. 2009. A burning story: The role of fire in the history of life. BioScience 59: 593-601 [doi | pdf]

[4] 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]

 

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